Refactored and cleaned code

.phpmd.dist.xml

@@ -7,20 +7,35 @@
          xsi:noNamespaceSchemaLocation="
                      http://pmd.sf.net/ruleset_xml_schema.xsd">
     <description>
-        Open Culture Consulting follows PHP Mess Detector standards.
+        Open Culture Consulting follows PHP Mess Detector standards with few exceptions.
     </description>
 
     <rule ref="rulesets/cleancode.xml">
+        <!--
+            We sometimes want to use else expressions for better readability.
+        -->
         <exclude name="ElseExpression" />
-        <!-- We need to statically access third-party helpers from Symfony. -->
         <exclude name="StaticAccess" />
+        <exclude name="BooleanArgumentFlag" />
     </rule>
     <rule ref="rulesets/codesize.xml" />
     <rule ref="rulesets/controversial.xml" />
     <rule ref="rulesets/design.xml" />
-    <rule ref="rulesets/naming.xml" />
+    <rule ref="rulesets/naming.xml">
+        <exclude name="ShortVariable" />
+    </rule>
+    <rule ref="rulesets/naming.xml/ShortVariable">
+        <properties>
+            <!--
+                We want to allow shorter variable names as long as they are self-explanatory.
+            -->
+            <property name="minimum" value="2" />
+        </properties>
+    </rule>
     <rule ref="rulesets/unusedcode.xml">
-        <!-- We have to declare unused parameters to satisfy interface requirements. -->
+        <!--
+            We have to declare unused parameters to satisfy interface requirements.
+        -->
         <exclude name="UnusedFormalParameter" />
     </rule>
 </ruleset>

CODE_OF_CONDUCT.md

@@ -60,7 +60,7 @@ representative at an online or offline event.
 
 Instances of abusive, harassing, or otherwise unacceptable behavior may be
 reported to the community leaders responsible for enforcement at
-office@opencultureconsulting.com.
+<office@opencultureconsulting.com>.
 All complaints will be reviewed and investigated promptly and fairly.
 
 All community leaders are obligated to respect the privacy and security of the

CONTRIBUTING.md

@@ -1,3 +1,9 @@
-Please read the excellent [GitHub Open Source Guide](https://opensource.guide/how-to-contribute/) on *How to Contribute on Open Source*.
+Please read the excellent [GitHub Open Source Guide][guide] on *How to
+Contribute on Open Source*.
 
-If you have any further questions just [open a new issue](https://github.com/opencultureconsulting/oai-pmh2/issues/new) and I'll be happy to assist!
+[guide]: <https://opensource.guide/how-to-contribute/>
+
+If you have any further questions just [open a new issue][issuetracker] and
+I'll be happy to assist!
+
+[issuetracker]: <https://github.com/opencultureconsulting/oai-pmh2/issues/new>

bin/cli

@@ -49,7 +49,7 @@ $commands = [
 try {
     ConsoleRunner::run(
         new SingleManagerProvider(
-            Database::getInstance()->getEntityManager()
+            EntityManager::getInstance()
         ),
         $commands
     );

composer.json

@@ -31,10 +31,10 @@
         "ext-dom": "*",
         "ext-libxml": "*",
         "ext-sqlite3": "*",
-        "doctrine/dbal": "^3.8",
+        "doctrine/dbal": "^4.1",
         "doctrine/orm": "^3.2",
-        "opencultureconsulting/basics": "^1.1",
+        "opencultureconsulting/basics": "^2.1",
-        "opencultureconsulting/psr15": "^1.0",
+        "opencultureconsulting/psr15": "^1.2",
         "symfony/cache": "^6.4",
         "symfony/console": "^6.4",
         "symfony/filesystem": "^6.4",
@@ -44,11 +44,13 @@
     "require-dev": {
         "phpdocumentor/shim": "^3.5",
         "phpmd/phpmd": "^2.15",
-        "phpstan/phpstan": "^1.11",
+        "phpstan/phpstan": "^1.12",
+        "phpstan/phpstan-doctrine": "^1.5",
         "phpstan/phpstan-strict-rules": "^1.6",
-        "friendsofphp/php-cs-fixer": "^3.59",
+        "phpstan/phpstan-symfony": "^1.4",
+        "friendsofphp/php-cs-fixer": "^3.64",
         "squizlabs/php_codesniffer": "^3.10",
-        "vimeo/psalm": "^5.25"
+        "vimeo/psalm": "^5.26"
     },
     "autoload": {
         "psr-4": {
@@ -74,7 +76,7 @@
         ],
         "doctrine:clear-cache": [
             "@php bin/cli orm:clear-cache:metadata --flush",
-            "@php bin/cli orm:clear-cache:query --flush",
+            "@php bin/cli orm:clear-cache:query",
             "@php bin/cli orm:clear-cache:result --flush"
         ],
         "doctrine:initialize-database": [
@@ -95,7 +97,7 @@
         ],
         "phpmd:check": [
             "@php -r \"if (!file_exists('./.phpmd.xml')) { copy('./.phpmd.dist.xml', './.phpmd.xml'); }\"",
-            "@php vendor/bin/phpmd ./bin,./public,./src ansi .phpmd.xml --cache"
+            "@php vendor/bin/phpmd bin/,public/,src/ ansi .phpmd.xml --cache"
         ],
         "phpstan:check": [
             "@php vendor/bin/phpstan"

phpcs.xml.dist

@@ -1,11 +1,11 @@
 <?xml version="1.0"?>
 <ruleset name="OCC Standard Ruleset">
     <description>Open Culture Consulting strictly follows PSR standards.</description>
+    <file>./bin</file>
+    <file>./public</file>
     <file>./src</file>
     <arg name="extensions" value="php"/>
     <rule ref="PSR12">
         <exclude name="Generic.Files.LineLength"/>
-        <exclude name="PSR2.Classes.PropertyDeclaration.Underscore"/>
-        <exclude name="PSR2.Methods.MethodDeclaration.Underscore"/>
     </rule>
 </ruleset>

phpstan.dist.neon

@@ -5,11 +5,14 @@
 
 includes:
     - vendor/phpstan/phpstan-strict-rules/rules.neon
+    - vendor/phpstan/phpstan-doctrine/extension.neon
+    - vendor/phpstan/phpstan-symfony/extension.neon
 
 parameters:
     level: 9
-    strictRules:
+    treatPhpDocTypesAsCertain: false
-        noVariableVariables: false
+    ignoreErrors:
+        - identifier: ternary.shortNotAllowed
     paths:
         - bin
         - public

psalm.xml.dist

@@ -8,23 +8,40 @@
     findUnusedBaselineEntry="true"
     findUnusedCode="true"
     findUnusedVariablesAndParams="true"
+    reportMixedIssues="false"
 >
     <issueHandlers>
         <!--
-            Psalm doesn't recognize $columns['idColumn'] and $columns['contentColumn'] always being set in execute().
+            Psalm doesn't recognize some variables always being set because of prior validation.
         -->
-        <PossiblyNullArrayOffset>
+        <PossiblyNullReference>
             <errorLevel type="suppress">
-                <file name="src/Console/CsvImportCommand.php"/>
+                <file name="src/Console/UpdateFormatsCommand.php"/>
             </errorLevel>
-        </PossiblyNullArrayOffset>
+        </PossiblyNullReference>
+        <!--
+            DBAL entities require getter/setter methods even if they are never called directly.
+        -->
         <PossiblyUnusedMethod errorLevel="suppress"/>
         <PossiblyUnusedReturnValue errorLevel="suppress"/>
+        <!--
+            Some properties are not set in the constructor and hence checked for initialization.
+        -->
         <PropertyNotSetInConstructor errorLevel="suppress"/>
-        <RedundantCastGivenDocblockType errorLevel="suppress"/>
-        <RedundantConditionGivenDocblockType errorLevel="suppress"/>
-        <RedundantFunctionCallGivenDocblockType errorLevel="suppress"/>
         <RedundantPropertyInitializationCheck errorLevel="suppress"/>
+        <!--
+            We deliberately want to evaluate empty strings as FALSE in those files.
+        -->
+        <RiskyTruthyFalsyComparison>
+            <errorLevel type="suppress">
+                <file name="src/Console/AddRecordCommand.php"/>
+                <file name="src/Console/AddSetCommand.php"/>
+            </errorLevel>
+        </RiskyTruthyFalsyComparison>
+        <!--
+            Those classes are dynamically used depending on the given OAI verb.
+            @see src/Middleware/Dispatcher.php:95
+        -->
         <UnusedClass>
             <errorLevel type="suppress">
                 <referencedClass name="OCC\OaiPmh2\Middleware\GetRecord"/>

src/App.php

@@ -31,19 +31,19 @@ use OCC\PSR15\QueueRequestHandler;
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
  */
-class App
+final class App
 {
     /**
      * The PSR-15 Server Request Handler.
      */
-    protected QueueRequestHandler $requestHandler;
+    private QueueRequestHandler $requestHandler;
 
     /**
      * Instantiate application.
      */
     public function __construct()
     {
-        $this->requestHandler = new QueueRequestHandler([new Dispatcher()]);
+        $this->requestHandler = new QueueRequestHandler(middlewares: [new Dispatcher()]);
     }
 
     /**
@@ -54,6 +54,9 @@ class App
     public function run(): void
     {
         $this->requestHandler->handle();
+        if ($this->requestHandler->response->hasHeader('Warning')) {
+            // An exception occured. Maybe we don't want to output the response, but log an error instead?
+        }
         $this->requestHandler->respond();
     }
 }

src/Configuration.php

@@ -23,11 +23,10 @@ declare(strict_types=1);
 namespace OCC\OaiPmh2;
 
 use OCC\Basics\Traits\Singleton;
+use OCC\OaiPmh2\Validator\ConfigurationValidator;
 use Symfony\Component\Filesystem\Exception\FileNotFoundException;
 use Symfony\Component\Filesystem\Path;
-use Symfony\Component\Validator\Constraints as Assert;
 use Symfony\Component\Validator\Exception\ValidationFailedException;
-use Symfony\Component\Validator\Validation;
 use Symfony\Component\Yaml\Yaml;
 
 /**
@@ -36,18 +35,18 @@ use Symfony\Component\Yaml\Yaml;
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
  *
- * @property-read string $repositoryName
+ * @property-read string $repositoryName Common name of this repository
- * @property-read string $adminEmail
+ * @property-read string $adminEmail Repository contact's e-mail address
- * @property-read string $database
+ * @property-read string $database Database's data source name (DSN)
- * @property-read array $metadataPrefix
+ * @property-read array $metadataPrefix Array of served metadata prefixes
- * @property-read string $deletedRecords
+ * @property-read string $deletedRecords Repository's deleted records policy
- * @property-read int $maxRecords
+ * @property-read int $maxRecords Maximum number of records served per request
- * @property-read int $tokenValid
+ * @property-read int $tokenValid Number of seconds resumption tokens are valid
  *
  * @template TKey of string
  * @template TValue of array|int|string
  */
-class Configuration
+final class Configuration
 {
     use Singleton;
 
@@ -65,98 +64,6 @@ class Configuration
      */
     protected readonly array $settings;
 
-    /**
-     * Get constraints for configuration array.
-     *
-     * @return Assert\Collection The collection of constraints
-     */
-    protected function getValidationConstraints(): Assert\Collection
-    {
-        return new Assert\Collection([
-            'repositoryName' => [
-                new Assert\Type('string'),
-                new Assert\NotBlank()
-            ],
-            'adminEmail' => [
-                new Assert\Type('string'),
-                new Assert\Email(['mode' => 'html5']),
-                new Assert\NotBlank()
-            ],
-            'database' => [
-                new Assert\Type('string'),
-                new Assert\NotBlank()
-            ],
-            'metadataPrefix' => [
-                new Assert\Type('array'),
-                new Assert\All([
-                    new Assert\Collection([
-                        'schema' => [
-                            new Assert\Type('string'),
-                            new Assert\Url(),
-                            new Assert\NotBlank()
-                        ],
-                        'namespace' => [
-                            new Assert\Type('string'),
-                            new Assert\Url(),
-                            new Assert\NotBlank()
-                        ]
-                    ])
-                ])
-            ],
-            'deletedRecords' => [
-                new Assert\Type('string'),
-                new Assert\Choice(['no', 'persistent', 'transient']),
-                new Assert\NotBlank()
-            ],
-            'maxRecords' => [
-                new Assert\Type('int'),
-                new Assert\Range([
-                    'min' => 1,
-                    'max' => 100
-                ])
-            ],
-            'tokenValid' => [
-                new Assert\Type('int'),
-                new Assert\Range([
-                    'min' => 300,
-                    'max' => 86400
-                ])
-            ]
-        ]);
-    }
-
-    /**
-     * Read and validate configuration file.
-     *
-     * @return array<TKey, TValue> The configuration array
-     *
-     * @throws FileNotFoundException if configuration file does not exist
-     * @throws ValidationFailedException if configuration file is not valid
-     */
-    protected function loadConfigFile(): array
-    {
-        $configPath = Path::canonicalize(self::CONFIG_FILE);
-        if (!is_readable($configPath)) {
-            throw new FileNotFoundException(
-                sprintf(
-                    'Configuration file "%s" not found or not readable.',
-                    $configPath
-                ),
-                500,
-                null,
-                $configPath
-            );
-        }
-        /** @var array<TKey, TValue> */
-        $config = Yaml::parseFile($configPath);
-        $validator = Validation::createValidator();
-        $violations = $validator->validate($config, $this->getValidationConstraints());
-        if ($violations->count() > 0) {
-            throw new ValidationFailedException(null, $violations);
-        }
-        return $config;
-    }
-
     /**
      * Load and validate configuration settings from YAML file.
      *
@@ -165,11 +72,24 @@ class Configuration
      */
     private function __construct()
     {
-        try {
+        $configPath = Path::canonicalize(path: self::CONFIG_FILE);
-            $this->settings = $this->loadConfigFile();
+        if (!is_readable(filename: $configPath)) {
-        } catch (FileNotFoundException | ValidationFailedException $exception) {
+            throw new FileNotFoundException(
-            throw $exception;
+                message: 'Configuration file not found or not readable.',
+                code: 500,
+                path: $configPath
+            );
         }
+        /** @var array<TKey, TValue> */
+        $config = Yaml::parseFile(filename: $configPath);
+        $violations = ConfigurationValidator::validate(config: $config);
+        if ($violations->count() > 0) {
+            throw new ValidationFailedException(
+                value: null,
+                violations: $violations
+            );
+        }
+        $this->settings = $config;
     }
 
     /**
@@ -177,7 +97,7 @@ class Configuration
      *
      * @param TKey $name The setting to retrieve
      *
-     * @return TValue|null The setting or NULL
+     * @return ?TValue The setting or NULL
      */
     public function __get(string $name): mixed
     {

src/Console.php

@@ -34,9 +34,53 @@ use Symfony\Component\Console\Output\OutputInterface;
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
+ *
+ * @psalm-type CliArguments = array{
+ *     identifier: string,
+ *     format: string,
+ *     file: string,
+ *     sets?: list<string>,
+ *     setSpec: string,
+ *     setName: string,
+ *     idColumn: string,
+ *     contentColumn: string,
+ *     dateColumn: string,
+ *     setColumn: string,
+ *     noValidation: bool,
+ *     force: bool
+ * }
  */
 abstract class Console extends Command
 {
+    /**
+     * This holds the command's arguments and options.
+     *
+     * @var CliArguments
+     */
+    protected array $arguments;
+
+    /**
+     * This holds the entity manager singleton.
+     */
+    protected EntityManager $em;
+
+    /**
+     * This holds the PHP memory limit in bytes.
+     */
+    protected int $memoryLimit;
+
+    /**
+     * Flushes changes to the database if memory limit reaches 50%.
+     *
+     * @return void
+     */
+    protected function checkMemoryUsage(): void
+    {
+        if ((memory_get_usage() / $this->getPhpMemoryLimit()) > 0.5) {
+            $this->em->flush();
+        }
+    }
+
     /**
      * Clears the result cache.
      *
@@ -47,11 +91,13 @@ abstract class Console extends Command
         /** @var Application */
         $app = $this->getApplication();
         $app->doRun(
-            new ArrayInput([
+            input: new ArrayInput(
+                parameters: [
                     'command' => 'orm:clear-cache:result',
                     '--flush' => true
-            ]),
+                ]
-            new NullOutput()
+            ),
+            output: new NullOutput()
         );
     }
 
@@ -62,7 +108,8 @@ abstract class Console extends Command
      */
     protected function getPhpMemoryLimit(): int
     {
-        $ini = trim(ini_get('memory_limit'));
+        if (!isset($this->memoryLimit)) {
+            $ini = trim(string: ini_get(option: 'memory_limit'));
             $limit = (int) $ini;
             if ($limit < 0) {
                 return -1;
@@ -78,7 +125,9 @@ abstract class Console extends Command
                 case 'k':
                     $limit *= 1024;
             }
-        return $limit;
+            $this->memoryLimit = $limit;
+        }
+        return $this->memoryLimit;
     }
 
     /**
@@ -91,32 +140,68 @@ abstract class Console extends Command
      */
     protected function validateInput(InputInterface $input, OutputInterface $output): bool
     {
-        /** @var array<string, string> */
+        /** @var CliArguments */
-        $arguments = $input->getArguments();
+        $mergedArguments = array_merge($input->getArguments(), $input->getOptions());
+        $this->arguments = $mergedArguments;
 
-        $formats = Database::getInstance()->getMetadataFormats()->getQueryResult();
+        if (array_key_exists('format', $this->arguments)) {
-        if (!array_key_exists($arguments['format'], $formats)) {
+            $formats = $this->em->getMetadataFormats();
-            $output->writeln([
+            if (!$formats->containsKey(key: $this->arguments['format'])) {
+                $output->writeln(
+                    messages: [
                         '',
                         sprintf(
-                    ' [ERROR] Metadata format "%s" is not supported. ',
+                            format: ' [ERROR] Metadata format "%s" is not supported. ',
-                    $arguments['format']
+                            values: $this->arguments['format']
                         ),
                         ''
-            ]);
+                    ]
+                );
                 return false;
             }
-        if (!is_readable($arguments['file'])) {
+        }
-            $output->writeln([
+        if (array_key_exists('file', $this->arguments) && !is_readable(filename: $this->arguments['file'])) {
+            $output->writeln(
+                messages: [
                     '',
                     sprintf(
-                    ' [ERROR] File "%s" not found or not readable. ',
+                        format: ' [ERROR] File "%s" not found or not readable. ',
-                    $arguments['file']
+                        values: $this->arguments['file']
                     ),
                     ''
-            ]);
+                ]
+            );
             return false;
         }
+        if (array_key_exists('sets', $this->arguments)) {
+            $sets = $this->em->getSets();
+            $invalidSets = array_diff($this->arguments['sets'], $sets->getKeys());
+            if (count($invalidSets) !== 0) {
+                $output->writeln(
+                    messages: [
+                        '',
+                        sprintf(
+                            format: ' [ERROR] Sets "%s" are not supported. ',
+                            values: implode('", "', $invalidSets)
+                        ),
+                        ''
+                    ]
+                );
+                return false;
+            }
+        }
         return true;
     }
+
+    /**
+     * Create new console command instance.
+     *
+     * @param ?string $name The name of the command
+     *                      passing null means it must be set in configure()
+     */
+    public function __construct(?string $name = null)
+    {
+        $this->em = EntityManager::getInstance();
+        parent::__construct($name);
+    }
 }

src/Console/AddRecordCommand.php

@@ -23,7 +23,6 @@ declare(strict_types=1);
 namespace OCC\OaiPmh2\Console;
 
 use OCC\OaiPmh2\Console;
-use OCC\OaiPmh2\Database;
 use OCC\OaiPmh2\Entity\Format;
 use OCC\OaiPmh2\Entity\Record;
 use OCC\OaiPmh2\Entity\Set;
@@ -70,7 +69,7 @@ class AddRecordCommand extends Console
         $this->addArgument(
             'sets',
             InputArgument::IS_ARRAY | InputArgument::OPTIONAL,
-            'The list of sets to associate the record with.'
+            'Optional: The list of sets to associate the record with.'
         );
         parent::configure();
     }
@@ -85,36 +84,31 @@ class AddRecordCommand extends Console
      */
     protected function execute(InputInterface $input, OutputInterface $output): int
     {
-        if (!$this->validateInput($input, $output)) {
+        if (!$this->validateInput(input: $input, output: $output)) {
             return Command::INVALID;
         }
-        /** @var string */
+
-        $identifier = $input->getArgument('identifier');
         /** @var Format */
-        $format = Database::getInstance()
+        $format = $this->em->getMetadataFormat(prefix: $this->arguments['format']);
-            ->getEntityManager()
+        $content = file_get_contents(filename: $this->arguments['file']) ?: '';
-            ->getReference(Format::class, $input->getArgument('format'));
-        /** @var string */
-        $file = $input->getArgument('file');
-        /** @var string[] */
-        $sets = $input->getArgument('sets');
-        /** @var string */
-        $content = file_get_contents($file);
 
-        $record = new Record($identifier, $format);
+        $record = new Record(
+            identifier: $this->arguments['identifier'],
+            format: $format
+        );
         if (trim($content) !== '') {
-            $record->setContent($content);
+            $record->setContent(data: $content);
         }
-        foreach ($sets as $set) {
+        if (array_key_exists('sets', $this->arguments)) {
+            foreach ($this->arguments['sets'] as $set) {
                 /** @var Set */
-            $setSpec = Database::getInstance()
+                $setSpec = $this->em->getSet(spec: $set);
-                ->getEntityManager()
+                $record->addSet(set: $setSpec);
-                ->getReference(Set::class, $set);
+            }
-            $record->addSet($setSpec);
         }
 
-        Database::getInstance()->addOrUpdateRecord($record);
+        $this->em->addOrUpdate(entity: $record);
-        Database::getInstance()->pruneOrphanSets();
+        $this->em->pruneOrphanedSets();
 
         $this->clearResultCache();
 
@@ -122,7 +116,7 @@ class AddRecordCommand extends Console
             '',
             sprintf(
                 ' [OK] Record "%s" with metadata prefix "%s" added or updated successfully! ',
-                $identifier,
+                $this->arguments['identifier'],
                 $format->getPrefix()
             ),
             ''

src/Console/AddSetCommand.php

@@ -23,7 +23,6 @@ declare(strict_types=1);
 namespace OCC\OaiPmh2\Console;
 
 use OCC\OaiPmh2\Console;
-use OCC\OaiPmh2\Database;
 use OCC\OaiPmh2\Entity\Set;
 use Symfony\Component\Console\Attribute\AsCommand;
 use Symfony\Component\Console\Command\Command;
@@ -53,10 +52,10 @@ class AddSetCommand extends Console
         $this->addArgument(
             'setSpec',
             InputArgument::REQUIRED,
-            'The set (spec) to update.',
+            'The set (spec) to add or update.',
             null,
             function (): array {
-                return array_keys(Database::getInstance()->getAllSets()->getQueryResult());
+                return $this->em->getSets()->getKeys();
             }
         );
         $this->addArgument(
@@ -67,7 +66,7 @@ class AddSetCommand extends Console
         $this->addArgument(
             'file',
             InputArgument::OPTIONAL,
-            'The optional file containing the set description XML.'
+            'Optional: The file containing the set description XML.'
         );
         parent::configure();
     }
@@ -82,32 +81,20 @@ class AddSetCommand extends Console
      */
     protected function execute(InputInterface $input, OutputInterface $output): int
     {
-        /** @var array<string, string> */
+        if (!$this->validateInput(input: $input, output: $output)) {
-        $arguments = $input->getArguments();
-        $description = null;
-
-        if (isset($arguments['file'])) {
-            if (!is_readable($arguments['file'])) {
-                $output->writeln([
-                    '',
-                    sprintf(
-                        ' [ERROR] File "%s" not found or not readable. ',
-                        $arguments['file']
-                    ),
-                    ''
-                ]);
             return Command::INVALID;
-            } else {
-                $description = (string) file_get_contents($arguments['file']);
         }
+
+        if (array_key_exists('file', $this->arguments)) {
+            $description = file_get_contents(filename: $this->arguments['file']) ?: null;
         }
 
         $set = new Set(
-            $arguments['setSpec'],
+            spec: $this->arguments['setSpec'],
-            $arguments['setName'],
+            name: $this->arguments['setName'],
-            $description
+            description: $description ?? null
         );
-        Database::getInstance()->addOrUpdateSet($set);
+        $this->em->addOrUpdate(entity: $set);
 
         return Command::SUCCESS;
     }

src/Console/CsvImportCommand.php

@@ -23,9 +23,7 @@ declare(strict_types=1);
 namespace OCC\OaiPmh2\Console;
 
 use DateTime;
-use OCC\OaiPmh2\Configuration;
 use OCC\OaiPmh2\Console;
-use OCC\OaiPmh2\Database;
 use OCC\OaiPmh2\Entity\Format;
 use OCC\OaiPmh2\Entity\Record;
 use OCC\OaiPmh2\Entity\Set;
@@ -42,6 +40,13 @@ use Symfony\Component\Console\Output\OutputInterface;
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
+ *
+ * @psalm-type ColumnMapping = array{
+ *     idColumn: int,
+ *     contentColumn: int,
+ *     dateColumn: ?int,
+ *     setColumn: ?int
+ * }
  */
 #[AsCommand(
     name: 'oai:records:import:csv',
@@ -62,7 +67,7 @@ class CsvImportCommand extends Console
             'The format (metadata prefix) of the records.',
             null,
             function (): array {
-                return array_keys(Database::getInstance()->getMetadataFormats()->getQueryResult());
+                return $this->em->getMetadataFormats()->getKeys();
             }
         );
         $this->addArgument(
@@ -88,21 +93,21 @@ class CsvImportCommand extends Console
             'dateColumn',
             'd',
             InputOption::VALUE_OPTIONAL,
-            'Name of the CSV column which holds the records\' datetime of last change.',
+            'Optional: Name of the CSV column which holds the records\' datetime of last change.',
             'lastChanged'
         );
         $this->addOption(
             'setColumn',
             's',
             InputOption::VALUE_OPTIONAL,
-            'Name of the CSV column which holds the comma-separated list of the records\' sets.',
+            'Optional: Name of the CSV column which holds the comma-separated list of the records\' sets.',
             'sets'
         );
         $this->addOption(
             'noValidation',
             null,
             InputOption::VALUE_NONE,
-            'Skip content validation (improves performance for large record sets).'
+            'Optional: Skip content validation (improves ingest performance for large record sets).'
         );
         parent::configure();
     }
@@ -117,69 +122,60 @@ class CsvImportCommand extends Console
      */
     protected function execute(InputInterface $input, OutputInterface $output): int
     {
-        if (!$this->validateInput($input, $output)) {
+        if (!$this->validateInput(input: $input, output: $output)) {
             return Command::INVALID;
         }
-        $phpMemoryLimit = $this->getPhpMemoryLimit();
 
-        /** @var array<string, string> */
-        $arguments = $input->getArguments();
-        /** @var bool */
-        $noValidation = $input->getOption('noValidation');
         /** @var resource */
-        $file = fopen($arguments['file'], 'r');
+        $file = fopen(filename: $this->arguments['file'], mode: 'r');
 
-        $columns = $this->getColumnNames($input, $output, $file);
+        $columnMapping = $this->getColumnNames(input: $input, output: $output, file: $file);
-        if (count($columns) === 0) {
+
-            return Command::INVALID;
+        if (!isset($columnMapping)) {
+            return Command::FAILURE;
         }
 
         $count = 0;
         $progressIndicator = new ProgressIndicator($output, null, 100, ['⠏', '⠛', '⠹', '⢸', '⣰', '⣤', '⣆', '⡇']);
         $progressIndicator->start('Importing...');
 
-        while ($row = fgetcsv($file)) {
+        while ($row = fgetcsv(stream: $file)) {
             /** @var Format */
-            $format = Database::getInstance()
+            $format = $this->em->getMetadataFormat(prefix: $this->arguments['format']);
-                ->getEntityManager()
+            $record = new Record(
-                ->getReference(Format::class, $arguments['format']);
+                identifier: $row[$columnMapping['idColumn']],
-            $record = new Record($row[$columns['idColumn']], $format);
+                format: $format
-            if (strlen(trim($row[$columns['contentColumn']])) > 0) {
+            );
-                $record->setContent($row[$columns['contentColumn']], !$noValidation);
+            if (strlen(trim($row[$columnMapping['contentColumn']])) > 0) {
+                $record->setContent(
+                    data: $row[$columnMapping['contentColumn']],
+                    validate: !$this->arguments['noValidation']
+                );
             }
-            if (isset($columns['dateColumn'])) {
+            if (isset($columnMapping['dateColumn'])) {
-                $record->setLastChanged(new DateTime($row[$columns['dateColumn']]));
+                $record->setLastChanged(dateTime: new DateTime($row[$columnMapping['dateColumn']]));
             }
-            if (isset($columns['setColumn'])) {
+            if (isset($columnMapping['setColumn'])) {
-                $sets = $row[$columns['setColumn']];
+                $sets = $row[$columnMapping['setColumn']];
                 foreach (explode(',', $sets) as $set) {
                     /** @var Set */
-                    $setSpec = Database::getInstance()
+                    $setSpec = $this->em->getSet(spec: trim($set));
-                        ->getEntityManager()
+                    $record->addSet(set: $setSpec);
-                        ->getReference(Set::class, trim($set));
-                    $record->addSet($setSpec);
                 }
             }
-            Database::getInstance()->addOrUpdateRecord($record, true);
+            $this->em->addOrUpdate(entity: $record, bulkMode: true);
 
             ++$count;
             $progressIndicator->advance();
             $progressIndicator->setMessage('Importing... ' . (string) $count . ' records processed.');
-
+            $this->checkMemoryUsage();
-            // Flush to database if memory usage reaches 50% or every 10.000 records.
-            if ((memory_get_usage() / $phpMemoryLimit) > 0.5 || ($count % 10000) === 0) {
-                $progressIndicator->setMessage(
-                    'Importing... ' . (string) $count . ' records processed. Flushing to database...'
-                );
-                Database::getInstance()->flush(true);
         }
-        }
+        $this->em->flush();
-        Database::getInstance()->flush(true);
+        $this->em->pruneOrphanedSets();
-        Database::getInstance()->pruneOrphanSets();
 
         $progressIndicator->finish('All done!');
 
-        fclose($file);
+        fclose(stream: $file);
 
         $this->clearResultCache();
 
@@ -188,7 +184,7 @@ class CsvImportCommand extends Console
             sprintf(
                 ' [OK] %d records with metadata prefix "%s" were imported successfully! ',
                 $count,
-                $arguments['format']
+                $this->arguments['format']
             ),
             ''
         ]);
@@ -196,49 +192,57 @@ class CsvImportCommand extends Console
     }
 
     /**
-     * Get the column names of CSV.
+     * Get the column numbers of CSV.
      *
-     * @param InputInterface $input The inputs
+     * @param InputInterface $input The input
-     * @param OutputInterface $output The output interface
+     * @param OutputInterface $output The output
      * @param resource $file The handle for the CSV file
      *
-     * @return array<string, int|string|null> The mapped column names
+     * @return ?ColumnMapping The mapped columns or NULL in case of an error
      */
-    protected function getColumnNames(InputInterface $input, OutputInterface $output, $file): array
+    protected function getColumnNames(InputInterface $input, OutputInterface $output, $file): ?array
     {
-        /** @var array<string, string> */
+        /** @var array{idColumn: string, contentColumn: string, dateColumn: string, setColumn: string} */
-        $options = $input->getOptions();
+        $columns = [
-
+            'idColumn' => $input->getOption('idColumn'),
-        $columns = [];
+            'contentColumn' => $input->getOption('contentColumn'),
+            'dateColumn' => $input->getOption('dateColumn'),
+            'setColumn' => $input->getOption('setColumn')
+        ];
 
         $headers = fgetcsv($file);
-        if (!is_array($headers)) {
+        if (!is_array($headers) || !isset($headers[0])) {
             $output->writeln([
                 '',
                 sprintf(
-                    ' [ERROR] File "%s" does not contain valid CSV. ',
+                    format: ' [ERROR] File "%s" does not contain valid CSV. ',
-                    stream_get_meta_data($file)['uri'] ?? 'unknown'
+                    /** @phpstan-ignore-next-line - URI is always set for fopen() resources. */
+                    values: stream_get_meta_data(stream: $file)['uri'] ?: 'unknown'
                 ),
                 ''
             ]);
-            return [];
+            return null;
-        } else {
+        }
+        /** @var array<string, int> */
         $headers = array_flip($headers);
-        }
+
-        foreach ($options as $option => $value) {
+        $callback = function (string $column) use ($headers): ?int {
-            $columns[$option] = $headers[$value] ?? null;
+            return array_key_exists($column, $headers) ? $headers[$column] : null;
-        }
+        };
+
+        $columns = array_map($callback, $columns);
 
         if (!isset($columns['idColumn']) || !isset($columns['contentColumn'])) {
             $output->writeln([
                 '',
                 sprintf(
-                    ' [ERROR] File "%s" does not contain valid CSV. ',
+                    format: ' [ERROR] File "%s" does not contain mandatory columns. ',
-                    stream_get_meta_data($file)['uri'] ?? 'unknown'
+                    /** @phpstan-ignore-next-line - URI is always set for fopen() resources. */
+                    values: stream_get_meta_data($file)['uri'] ?: 'unknown'
                 ),
                 ''
             ]);
-            return [];
+            return null;
         }
         return $columns;
     }

src/Console/DeleteRecordCommand.php

@@ -23,9 +23,6 @@ declare(strict_types=1);
 namespace OCC\OaiPmh2\Console;
 
 use OCC\OaiPmh2\Console;
-use OCC\OaiPmh2\Database;
-use OCC\OaiPmh2\Entity\Format;
-use OCC\OaiPmh2\Entity\Record;
 use Symfony\Component\Console\Attribute\AsCommand;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputArgument;
@@ -40,7 +37,7 @@ use Symfony\Component\Console\Output\OutputInterface;
  */
 #[AsCommand(
     name: 'oai:records:delete',
-    description: 'Delete a record from database'
+    description: 'Delete a record while obeying deleted record policy'
 )]
 class DeleteRecordCommand extends Console
 {
@@ -74,28 +71,24 @@ class DeleteRecordCommand extends Console
      */
     protected function execute(InputInterface $input, OutputInterface $output): int
     {
-        /** @var array<string, string> */
+        if (!$this->validateInput(input: $input, output: $output)) {
-        $arguments = $input->getArguments();
+            return Command::INVALID;
-        $entityManager = Database::getInstance()->getEntityManager();
+        }
 
-        $format = $entityManager->getReference(Format::class, $arguments['format']);
+        $record = $this->em->getRecord(
-        $record = $entityManager->find(
+            identifier: $this->arguments['identifier'],
-            Record::class,
+            format: $this->arguments['format']
-            [
-                'identifier' => $arguments['identifier'],
-                'format' => $format
-            ]
         );
 
         if (isset($record)) {
-            Database::getInstance()->deleteRecord($record);
+            $this->em->delete(entity: $record);
             $this->clearResultCache();
             $output->writeln([
                 '',
                 sprintf(
-                    ' [OK] Record "%s" with metadata prefix "%s" successfully deleted. ',
+                    ' [OK] Record "%s" with metadata prefix "%s" successfully (marked as) deleted. ',
-                    $arguments['identifier'],
+                    $this->arguments['identifier'],
-                    $arguments['format']
+                    $this->arguments['format']
                 ),
                 ''
             ]);
@@ -105,8 +98,8 @@ class DeleteRecordCommand extends Console
                 '',
                 sprintf(
                     ' [ERROR] Record "%s" with metadata prefix "%s" not found. ',
-                    $arguments['identifier'],
+                    $this->arguments['identifier'],
-                    $arguments['format']
+                    $this->arguments['format']
                 ),
                 ''
             ]);

src/Console/PruneDeletedRecordsCommand.php

@@ -24,7 +24,6 @@ namespace OCC\OaiPmh2\Console;
 
 use OCC\OaiPmh2\Configuration;
 use OCC\OaiPmh2\Console;
-use OCC\OaiPmh2\Database;
 use Symfony\Component\Console\Attribute\AsCommand;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputInterface;
@@ -54,7 +53,7 @@ class PruneDeletedRecordsCommand extends Console
             'force',
             'f',
             InputOption::VALUE_NONE,
-            'Deletes records even under "transient" policy.'
+            'Optional: Deletes records even under "transient" policy.'
         );
         parent::configure();
     }
@@ -75,13 +74,13 @@ class PruneDeletedRecordsCommand extends Console
             $policy === 'no'
             or ($policy === 'transient' && $forced)
         ) {
-            $deleted = Database::getInstance()->pruneDeletedRecords();
+            $deleted = $this->em->pruneDeletedRecords();
             $this->clearResultCache();
             $output->writeln([
                 '',
                 sprintf(
-                    ' [OK] %d records are deleted and were successfully removed! ',
+                    format: ' [OK] %d deleted records were successfully removed! ',
-                    $deleted
+                    values: $deleted
                 ),
                 ''
             ]);

src/Console/PruneResumptionTokensCommand.php

@@ -23,7 +23,6 @@ declare(strict_types=1);
 namespace OCC\OaiPmh2\Console;
 
 use OCC\OaiPmh2\Console;
-use OCC\OaiPmh2\Database;
 use Symfony\Component\Console\Attribute\AsCommand;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputInterface;
@@ -51,12 +50,12 @@ class PruneResumptionTokensCommand extends Console
      */
     protected function execute(InputInterface $input, OutputInterface $output): int
     {
-        $expired = Database::getInstance()->pruneResumptionTokens();
+        $expired = $this->em->pruneExpiredTokens();
         $output->writeln([
             '',
             sprintf(
-                ' [OK] %d resumption tokens are expired and were successfully deleted! ',
+                format: ' [OK] %d expired resumption tokens were successfully deleted! ',
-                $expired
+                values: $expired
             ),
             ''
         ]);

src/Console/UpdateFormatsCommand.php

@@ -24,7 +24,6 @@ namespace OCC\OaiPmh2\Console;
 
 use OCC\OaiPmh2\Configuration;
 use OCC\OaiPmh2\Console;
-use OCC\OaiPmh2\Database;
 use OCC\OaiPmh2\Entity\Format;
 use Symfony\Component\Console\Attribute\AsCommand;
 use Symfony\Component\Console\Command\Command;
@@ -57,56 +56,55 @@ class UpdateFormatsCommand extends Console
         /** @var array<string, array<string, string>> */
         $formats = Configuration::getInstance()->metadataPrefix;
         $this->clearResultCache();
-        $inDatabase = Database::getInstance()
+        $inDatabase = $this->em->getMetadataFormats();
-            ->getMetadataFormats()
-            ->getQueryResult();
-        $added = 0;
-        $deleted = 0;
         $failure = false;
         foreach ($formats as $prefix => $format) {
-            if (array_key_exists($prefix, $inDatabase)) {
             if (
-                    $format['namespace'] === $inDatabase[$prefix]->getNamespace()
+                $inDatabase->containsKey(key: $prefix)
+                /** @phpstan-ignore-next-line - $inDatabase[$prefix] is always of type Format. */
+                and $format['namespace'] === $inDatabase[$prefix]->getNamespace()
+                /** @phpstan-ignore-next-line - $inDatabase[$prefix] is always of type Format. */
                 and $format['schema'] === $inDatabase[$prefix]->getSchema()
             ) {
                 continue;
             }
-            }
             try {
-                $format = new Format($prefix, $format['namespace'], $format['schema']);
+                $format = new Format(
-                Database::getInstance()->addOrUpdateMetadataFormat($format);
+                    prefix: $prefix,
-                ++$added;
+                    namespace: $format['namespace'],
+                    schema: $format['schema']
+                );
+                $this->em->addOrUpdate(entity: $format);
                 $output->writeln([
                     sprintf(
-                        ' [OK] Metadata format "%s" added or updated successfully! ',
+                        format: ' [OK] Metadata format "%s" added or updated successfully! ',
-                        $prefix
+                        values: $prefix
                     )
                 ]);
             } catch (ValidationFailedException $exception) {
                 $failure = true;
                 $output->writeln([
                     sprintf(
-                        ' [ERROR] Could not add or update metadata format "%s". ',
+                        format: ' [ERROR] Could not add or update metadata format "%s". ',
-                        $prefix
+                        values: $prefix
                     ),
                     $exception->getMessage()
                 ]);
             }
         }
-        foreach (array_keys($inDatabase) as $prefix) {
+        foreach (array_diff($inDatabase->getKeys(), array_keys($formats)) as $prefix) {
-            if (!array_key_exists($prefix, $formats)) {
+            /** @var Format */
-                Database::getInstance()->deleteMetadataFormat($inDatabase[$prefix]);
+            $format = $inDatabase[$prefix];
-                ++$deleted;
+            $this->em->delete(entity: $format);
             $output->writeln([
                 sprintf(
-                        ' [OK] Metadata format "%s" and all associated records deleted successfully! ',
+                    format: ' [OK] Metadata format "%s" and all associated records deleted successfully! ',
-                        $prefix
+                    values: $prefix
                 )
             ]);
         }
-        }
         $this->clearResultCache();
-        $currentFormats = array_keys(Database::getInstance()->getMetadataFormats()->getQueryResult());
+        $currentFormats = $this->em->getMetadataFormats()->getKeys();
         if (count($currentFormats) > 0) {
             $output->writeln(
                 [
@@ -118,7 +116,7 @@ class UpdateFormatsCommand extends Console
                     ' command "php bin/cli oai:formats:update" again! ',
                     ''
                 ],
-                1 | 16
+                OutputInterface::OUTPUT_NORMAL | OutputInterface::VERBOSITY_QUIET
             );
         } else {
             $output->writeln(
@@ -129,13 +127,9 @@ class UpdateFormatsCommand extends Console
                     ' command "php bin/cli oai:formats:update" again! ',
                     ''
                 ],
-                1 | 16
+                OutputInterface::OUTPUT_NORMAL | OutputInterface::VERBOSITY_QUIET
             );
         }
-        if (!$failure) {
+        return $failure ? Command::FAILURE : Command::SUCCESS;
-            return Command::SUCCESS;
-        } else {
-            return Command::FAILURE;
-        }
     }
 }

src/Database.php

@@ -1,573 +0,0 @@
-<?php
-
-/**
- * OAI-PMH 2.0 Data Provider
- * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-declare(strict_types=1);
-
-namespace OCC\OaiPmh2;
-
-use DateTime;
-use Doctrine\Common\Collections\Criteria;
-use Doctrine\DBAL\DriverManager;
-use Doctrine\DBAL\Schema\AbstractAsset;
-use Doctrine\DBAL\Tools\DsnParser;
-use Doctrine\ORM\AbstractQuery;
-use Doctrine\ORM\Configuration as DoctrineConfiguration;
-use Doctrine\ORM\EntityManager;
-use Doctrine\ORM\Mapping\Driver\AttributeDriver;
-use Doctrine\ORM\Proxy\ProxyFactory;
-use Doctrine\ORM\Query\Expr\Join;
-use Doctrine\ORM\Tools\Pagination\Paginator;
-use OCC\Basics\Traits\Singleton;
-use OCC\OaiPmh2\Entity\Format;
-use OCC\OaiPmh2\Entity\Record;
-use OCC\OaiPmh2\Entity\Set;
-use OCC\OaiPmh2\Entity\Token;
-use OCC\OaiPmh2\Result;
-use Symfony\Component\Cache\Adapter\PhpFilesAdapter;
-use Symfony\Component\Filesystem\Path;
-
-/**
- * Handles all database shenanigans.
- *
- * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
- * @package OAIPMH2
- *
- * @template Formats of array<string, Format>
- * @template Records of array<string, Record>
- * @template Sets of array<string, Set>
- */
-class Database
-{
-    use Singleton;
-
-    protected const DB_TABLES = [
-        'formats',
-        'records',
-        'records_sets',
-        'sets',
-        'tokens'
-    ];
-
-    /**
-     * This holds the Doctrine entity manager.
-     */
-    protected EntityManager $entityManager;
-
-    /**
-     * Add or update metadata format.
-     *
-     * @param Format $newFormat The metadata format
-     *
-     * @return void
-     */
-    public function addOrUpdateMetadataFormat(Format $newFormat): void
-    {
-        $oldFormat = $this->entityManager->find(Format::class, $newFormat->getPrefix());
-        if (isset($oldFormat)) {
-            $oldFormat->setNamespace($newFormat->getNamespace());
-            $oldFormat->setSchema($newFormat->getSchema());
-        } else {
-            $this->entityManager->persist($newFormat);
-        }
-        $this->entityManager->flush();
-    }
-
-    /**
-     * Add or update record.
-     *
-     * @param Record $newRecord The record
-     * @param bool $bulkMode Should we operate in bulk mode (no flush)?
-     *
-     * @return void
-     */
-    public function addOrUpdateRecord(Record $newRecord, bool $bulkMode = false): void
-    {
-        $oldRecord = $this->entityManager->find(
-            Record::class,
-            [
-                'identifier' => $newRecord->getIdentifier(),
-                'format' => $newRecord->getFormat()
-            ]
-        );
-        if (isset($oldRecord)) {
-            if ($newRecord->hasContent() || Configuration::getInstance()->deletedRecords !== 'no') {
-                $oldRecord->setContent($newRecord->getContent(), false);
-                $oldRecord->setLastChanged($newRecord->getLastChanged());
-                // Add new sets.
-                foreach (array_diff($newRecord->getSets(), $oldRecord->getSets()) as $newSet) {
-                    $oldRecord->addSet($newSet);
-                }
-                // Remove old sets.
-                foreach (array_diff($oldRecord->getSets(), $newRecord->getSets()) as $oldSet) {
-                    $oldRecord->removeSet($oldSet);
-                }
-            } else {
-                $this->entityManager->remove($oldRecord);
-            }
-        } else {
-            if ($newRecord->hasContent() || Configuration::getInstance()->deletedRecords !== 'no') {
-                $this->entityManager->persist($newRecord);
-            }
-        }
-        if (!$bulkMode) {
-            $this->entityManager->flush();
-        }
-    }
-
-    /**
-     * Add or update set.
-     *
-     * @param Set $newSet The set
-     *
-     * @return void
-     */
-    public function addOrUpdateSet(Set $newSet): void
-    {
-        $oldSet = $this->entityManager->find(Set::class, $newSet->getSpec());
-        if (isset($oldSet)) {
-            $oldSet->setName($newSet->getName());
-            $oldSet->setDescription($newSet->getDescription());
-        } else {
-            $this->entityManager->persist($newSet);
-        }
-        $this->entityManager->flush();
-    }
-
-    /**
-     * Delete metadata format and all associated records.
-     *
-     * @param Format $format The metadata format
-     *
-     * @return void
-     */
-    public function deleteMetadataFormat(Format $format): void
-    {
-        $dql = $this->entityManager->createQueryBuilder();
-        $dql->delete(Record::class, 'record')
-            ->where($dql->expr()->eq('record.format', ':format'))
-            ->setParameter('format', $format->getPrefix());
-        $query = $dql->getQuery();
-        $query->execute();
-
-        // Explicitly remove associations with sets for deleted records.
-        $sql = $this->entityManager->getConnection();
-        $sql->executeStatement("DELETE FROM records_sets WHERE record_format='{$format->getPrefix()}'");
-
-        $this->entityManager->remove($format);
-        $this->entityManager->flush();
-
-        $this->pruneOrphanSets();
-    }
-
-    /**
-     * Delete a record.
-     *
-     * @param Record $record The record
-     *
-     * @return void
-     */
-    public function deleteRecord(Record $record): void
-    {
-        if (Configuration::getInstance()->deletedRecords === 'no') {
-            $this->entityManager->remove($record);
-        } else {
-            $record->setContent(null);
-            $record->setLastChanged(new DateTime());
-        }
-        $this->entityManager->flush();
-        $this->pruneOrphanSets();
-    }
-
-    /**
-     * Flush all changes to the database.
-     *
-     * @param bool $clear Should the entity manager get cleared as well?
-     * @return void
-     */
-    public function flush(bool $clear = false): void
-    {
-        $this->entityManager->flush();
-        if ($clear) {
-            $this->entityManager->clear();
-        }
-    }
-
-    /**
-     * Get all sets without pagination.
-     *
-     * @return Result<Sets> The sets
-     */
-    public function getAllSets(): Result
-    {
-        $dql = $this->entityManager->createQueryBuilder();
-        $dql->select('sets')
-            ->from(Set::class, 'sets', 'sets.spec');
-        $query = $dql->getQuery();
-        $query->enableResultCache();
-        /** @var Sets $resultQuery */
-        $resultQuery = $query->getResult();
-        return new Result($resultQuery);
-    }
-
-    /**
-     * Get the earliest datestamp of any record.
-     *
-     * @return string The earliest datestamp
-     */
-    public function getEarliestDatestamp(): string
-    {
-        $timestamp = '0000-00-00T00:00:00Z';
-        $dql = $this->entityManager->createQueryBuilder();
-        $dql->select($dql->expr()->min('record.lastChanged'))
-            ->from(Record::class, 'record');
-        $query = $dql->getQuery();
-        $query->enableResultCache();
-        /** @var ?string $result */
-        $result = $query->getOneOrNullResult(AbstractQuery::HYDRATE_SCALAR_COLUMN);
-        return $result ?? $timestamp;
-    }
-
-    /**
-     * Get the Doctrine entity manager.
-     *
-     * @return EntityManager The entity manager instance
-     */
-    public function getEntityManager(): EntityManager
-    {
-        return $this->entityManager;
-    }
-
-    /**
-     * Get all metadata prefixes.
-     *
-     * @param ?string $identifier Optional record identifier
-     *
-     * @return Result<Formats> The metadata prefixes
-     */
-    public function getMetadataFormats(?string $identifier = null): Result
-    {
-        $dql = $this->entityManager->createQueryBuilder();
-        $dql->select('format')
-            ->from(Format::class, 'format', 'format.prefix');
-        if (isset($identifier)) {
-            $dql->innerJoin(Record::class, 'record')
-                ->where(
-                    $dql->expr()->andX(
-                        $dql->expr()->eq('record.identifier', ':identifier'),
-                        $dql->expr()->isNotNull('record.content')
-                    )
-                )
-                ->setParameter('identifier', $identifier);
-        }
-        $query = $dql->getQuery();
-        $query->enableResultCache();
-        /** @var Formats $queryResult */
-        $queryResult = $query->getResult();
-        return new Result($queryResult);
-    }
-
-    /**
-     * Get a single record.
-     *
-     * @param string $identifier The record identifier
-     * @param Format $format The metadata format
-     *
-     * @return ?Record The record or NULL on failure
-     */
-    public function getRecord(string $identifier, Format $format): ?Record
-    {
-        return $this->entityManager->find(
-            Record::class,
-            [
-                'identifier' => $identifier,
-                'format' => $format
-            ]
-        );
-    }
-
-    /**
-     * Get list of records.
-     *
-     * @param string $verb The currently requested verb ('ListIdentifiers' or 'ListRecords')
-     * @param Format $metadataPrefix The metadata format
-     * @param int $counter Counter for split result sets
-     * @param ?DateTime $from The "from" datestamp
-     * @param ?DateTime $until The "until" datestamp
-     * @param ?Set $set The set spec
-     *
-     * @return Result<Records> The records and possibly a resumtion token
-     */
-    public function getRecords(
-        string $verb,
-        Format $metadataPrefix,
-        int $counter = 0,
-        ?DateTime $from = null,
-        ?DateTime $until = null,
-        ?Set $set = null
-    ): Result {
-        $maxRecords = Configuration::getInstance()->maxRecords;
-        $cursor = $counter * $maxRecords;
-
-        $dql = $this->entityManager->createQueryBuilder();
-        $dql->select('record')
-            ->from(Record::class, 'record', 'record.identifier')
-            ->where($dql->expr()->eq('record.format', ':metadataPrefix'))
-            ->setParameter('metadataPrefix', $metadataPrefix)
-            ->setFirstResult($cursor)
-            ->setMaxResults($maxRecords);
-        if (isset($from)) {
-            $dql->andWhere($dql->expr()->gte('record.lastChanged', ':from'));
-            $dql->setParameter('from', $from);
-            $from = $from->format('Y-m-d\TH:i:s\Z');
-        }
-        if (isset($until)) {
-            $dql->andWhere($dql->expr()->lte('record.lastChanged', ':until'));
-            $dql->setParameter('until', $until);
-            $until = $until->format('Y-m-d\TH:i:s\Z');
-        }
-        if (isset($set)) {
-            $dql->innerJoin(
-                Set::class,
-                'sets',
-                Join::WITH,
-                $dql->expr()->orX(
-                    $dql->expr()->eq('sets.spec', ':setSpec'),
-                    $dql->expr()->like('sets.spec', ':setLike')
-                )
-            );
-            $dql->setParameter('setSpec', $set->getSpec());
-            $dql->setParameter('setLike', $set->getSpec() . ':%');
-            $set = $set->getSpec();
-        }
-        $query = $dql->getQuery();
-        /** @var Records $queryResult */
-        $queryResult = $query->getResult();
-        $result = new Result($queryResult);
-        $paginator = new Paginator($query, true);
-        if (count($paginator) > ($cursor + count($result))) {
-            $token = new Token($verb, [
-                'counter' => $counter + 1,
-                'completeListSize' => count($paginator),
-                'metadataPrefix' => $metadataPrefix->getPrefix(),
-                'from' => $from,
-                'until' => $until,
-                'set' => $set
-            ]);
-            $this->entityManager->persist($token);
-            $this->entityManager->flush();
-            $result->setResumptionToken($token);
-        }
-        return $result;
-    }
-
-    /**
-     * Get resumption token.
-     *
-     * @param string $token The token
-     * @param string $verb The current verb to validate token
-     *
-     * @return ?Token The resumption token or NULL if invalid
-     */
-    public function getResumptionToken(string $token, string $verb): ?Token
-    {
-        $dql = $this->entityManager->createQueryBuilder();
-        $dql->select('token')
-            ->from(Token::class, 'token')
-            ->where($dql->expr()->gte('token.validUntil', ':now'))
-            ->andWhere($dql->expr()->eq('token.token', ':token'))
-            ->andWhere($dql->expr()->eq('token.verb', ':verb'))
-            ->setParameter('now', new DateTime())
-            ->setParameter('token', $token)
-            ->setParameter('verb', $verb)
-            ->setMaxResults(1);
-        $query = $dql->getQuery();
-        /** @var ?Token */
-        return $query->getOneOrNullResult();
-    }
-
-    /**
-     * Get all sets.
-     *
-     * @param int $counter Counter for split result sets
-     *
-     * @return Result<Sets> The sets and possibly a resumption token
-     */
-    public function getSets(int $counter = 0): Result
-    {
-        $maxRecords = Configuration::getInstance()->maxRecords;
-        $cursor = $counter * $maxRecords;
-
-        $dql = $this->entityManager->createQueryBuilder();
-        $dql->select('sets')
-            ->from(Set::class, 'sets', 'sets.spec')
-            ->setFirstResult($cursor)
-            ->setMaxResults($maxRecords);
-        $query = $dql->getQuery();
-        $query->enableResultCache();
-        /** @var Sets $queryResult */
-        $queryResult = $query->getResult();
-        $result = new Result($queryResult);
-        $paginator = new Paginator($query, false);
-        if (count($paginator) > ($cursor + count($result))) {
-            $token = new Token('ListSets', [
-                'counter' => $counter + 1,
-                'completeListSize' => count($paginator)
-            ]);
-            $this->entityManager->persist($token);
-            $this->entityManager->flush();
-            $result->setResumptionToken($token);
-        }
-        return $result;
-    }
-
-    /**
-     * Check if a record identifier exists.
-     *
-     * @param string $identifier The record identifier
-     *
-     * @return bool Whether the identifier exists
-     */
-    public function idDoesExist(string $identifier): bool
-    {
-        $dql = $this->entityManager->createQueryBuilder();
-        $dql->select($dql->expr()->count('record.identifier'))
-            ->from(Record::class, 'record')
-            ->where($dql->expr()->eq('record.identifier', ':identifier'))
-            ->setParameter('identifier', $identifier);
-        $query = $dql->getQuery();
-        return (bool) $query->getOneOrNullResult(AbstractQuery::HYDRATE_SCALAR_COLUMN);
-    }
-
-    /**
-     * Prune deleted records.
-     *
-     * @return int The number of removed records
-     */
-    public function pruneDeletedRecords(): int
-    {
-        $repository = $this->entityManager->getRepository(Record::class);
-        $criteria = Criteria::create()->where(Criteria::expr()->isNull('content'));
-        $records = $repository->matching($criteria);
-        foreach ($records as $record) {
-            $this->entityManager->remove($record);
-        }
-        $this->entityManager->flush();
-        $this->pruneOrphanSets();
-        return count($records);
-    }
-
-    /**
-     * Prune orphan sets.
-     *
-     * @return int The number of removed sets
-     */
-    public function pruneOrphanSets(): int
-    {
-        $repository = $this->entityManager->getRepository(Set::class);
-        $sets = $repository->findAll();
-        $count = 0;
-        foreach ($sets as $set) {
-            if ($set->isEmpty()) {
-                $this->entityManager->remove($set);
-                ++$count;
-            }
-        }
-        $this->entityManager->flush();
-        return $count;
-    }
-
-    /**
-     * Prune expired resumption tokens.
-     *
-     * @return int The number of deleted tokens
-     */
-    public function pruneResumptionTokens(): int
-    {
-        $repository = $this->entityManager->getRepository(Token::class);
-        $criteria = Criteria::create()->where(Criteria::expr()->lt('validUntil', new DateTime()));
-        $tokens = $repository->matching($criteria);
-        foreach ($tokens as $token) {
-            $this->entityManager->remove($token);
-        }
-        $this->entityManager->flush();
-        return count($tokens);
-    }
-
-    /**
-     * This is a singleton class, thus the constructor is private.
-     *
-     * Usage: Get an instance of this class by calling Database::getInstance()
-     */
-    private function __construct()
-    {
-        $configuration = new DoctrineConfiguration();
-        $configuration->setAutoGenerateProxyClasses(
-            ProxyFactory::AUTOGENERATE_NEVER
-        );
-        $configuration->setMetadataCache(
-            new PhpFilesAdapter(
-                'Metadata',
-                0,
-                __DIR__ . '/../var/cache'
-            )
-        );
-        $configuration->setMetadataDriverImpl(
-            new AttributeDriver([__DIR__ . '/Entity'])
-        );
-        $configuration->setProxyDir(__DIR__ . '/../var/generated');
-        $configuration->setProxyNamespace('OCC\OaiPmh2\Entity\Proxy');
-        $configuration->setQueryCache(
-            new PhpFilesAdapter(
-                'Query',
-                0,
-                __DIR__ . '/../var/cache'
-            )
-        );
-        $configuration->setResultCache(
-            new PhpFilesAdapter(
-                'Result',
-                0,
-                __DIR__ . '/../var/cache'
-            )
-        );
-        $configuration->setSchemaAssetsFilter(
-            static function (string|AbstractAsset $assetName): bool {
-                if ($assetName instanceof AbstractAsset) {
-                    $assetName = $assetName->getName();
-                }
-                return in_array($assetName, self::DB_TABLES, true);
-            }
-        );
-
-        $baseDir = Path::canonicalize(__DIR__ . '/../');
-        $dsn = str_replace('%BASEDIR%', $baseDir, Configuration::getInstance()->database);
-        $parser = new DsnParser([
-            'mariadb' => 'pdo_mysql',
-            'mssql' => 'pdo_sqlsrv',
-            'mysql' => 'pdo_mysql',
-            'oracle' => 'pdo_oci',
-            'postgresql' => 'pdo_pgsql',
-            'sqlite' => 'pdo_sqlite'
-        ]);
-        $connection = DriverManager::getConnection($parser->parse($dsn), $configuration);
-
-        $this->entityManager = new EntityManager($connection, $configuration);
-    }
-}

src/Entity.php

@@ -22,9 +22,10 @@ declare(strict_types=1);
 
 namespace OCC\OaiPmh2;
 
-use Symfony\Component\Validator\Constraints as Assert;
+use OCC\OaiPmh2\Validator\RegExValidator;
+use OCC\OaiPmh2\Validator\UrlValidator;
+use OCC\OaiPmh2\Validator\XmlValidator;
 use Symfony\Component\Validator\Exception\ValidationFailedException;
-use Symfony\Component\Validator\Validation;
 
 /**
  * Base class for all Doctrine/ORM entities.
@@ -45,17 +46,13 @@ abstract class Entity
      */
     protected function validateUrl(string $url): string
     {
-        $url = trim($url);
+        $url = trim(string: $url);
-        $validator = Validation::createValidator();
+        $violations = UrlValidator::validate(url: $url);
-        $violations = $validator->validate(
-            $url,
-            [
-                new Assert\Url(),
-                new Assert\NotBlank()
-            ]
-        );
         if ($violations->count() > 0) {
-            throw new ValidationFailedException(null, $violations);
+            throw new ValidationFailedException(
+                value: null,
+                violations: $violations
+            );
         }
         return $url;
     }
@@ -72,18 +69,12 @@ abstract class Entity
      */
     protected function validateRegEx(string $string, string $regEx): string
     {
-        $validator = Validation::createValidator();
+        $violations = RegExValidator::validate(string: $string, regEx: $regEx);
-        $violations = $validator->validate(
-            $string,
-            [
-                new Assert\Regex([
-                    'pattern' => $regEx,
-                    'message' => 'This value does not match the regular expression "{{ pattern }}".'
-                ])
-            ]
-        );
         if ($violations->count() > 0) {
-            throw new ValidationFailedException(null, $violations);
+            throw new ValidationFailedException(
+                value: null,
+                violations: $violations
+            );
         }
         return $string;
     }
@@ -99,19 +90,12 @@ abstract class Entity
      */
     protected function validateXml(string $xml): string
     {
-        $validator = Validation::createValidator();
+        $violations = XmlValidator::validate(xml: $xml);
-        $violations = $validator->validate(
+        if ($violations->count() > 0) {
-            $xml,
+            throw new ValidationFailedException(
-            [
+                value: null,
-                new Assert\Type('string'),
+                violations: $violations
-                new Assert\NotBlank()
-            ]
             );
-        if (
-            $violations->count() > 0
-            or simplexml_load_string($xml) === false
-        ) {
-            throw new ValidationFailedException(null, $violations);
         }
         return $xml;
     }

src/Entity/Format.php

@@ -22,8 +22,11 @@ declare(strict_types=1);
 
 namespace OCC\OaiPmh2\Entity;
 
+use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
 use OCC\OaiPmh2\Entity;
+use OCC\OaiPmh2\Repository\FormatRepository;
 use Symfony\Component\Validator\Exception\ValidationFailedException;
 
 /**
@@ -32,9 +35,9 @@ use Symfony\Component\Validator\Exception\ValidationFailedException;
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: FormatRepository::class)]
 #[ORM\Table(name: 'formats')]
-class Format extends Entity
+final class Format extends Entity
 {
     /**
      * The unique metadata prefix.
@@ -56,7 +59,21 @@ class Format extends Entity
     private string $xmlSchema;
 
     /**
-     * Get the format's namespace URI.
+     * The format's associated records.
+     *
+     * @var Collection<string, Record>
+     */
+    #[ORM\OneToMany(
+        targetEntity: Record::class,
+        mappedBy: 'format',
+        fetch: 'EXTRA_LAZY',
+        orphanRemoval: true,
+        indexBy: 'identifier'
+    )]
+    private Collection $records;
+
+    /**
+     * Get the namespace URI for this format.
      *
      * @return string The namespace URI
      */
@@ -76,7 +93,17 @@ class Format extends Entity
     }
 
     /**
-     * Get the format's schema URL.
+     * Get the associated records for this format.
+     *
+     * @return Collection<string, Record> The collection of records
+     */
+    public function getRecords(): Collection
+    {
+        return $this->records;
+    }
+
+    /**
+     * Get the schema URL for this format.
      *
      * @return string The schema URL
      */
@@ -86,7 +113,7 @@ class Format extends Entity
     }
 
     /**
-     * Set the format's namespace URI.
+     * Set the namespace URI for this format.
      *
      * @param string $namespace The namespace URI
      *
@@ -97,14 +124,14 @@ class Format extends Entity
     public function setNamespace(string $namespace): void
     {
         try {
-            $this->namespace = $this->validateUrl($namespace);
+            $this->namespace = $this->validateUrl(url: $namespace);
         } catch (ValidationFailedException $exception) {
             throw $exception;
         }
     }
 
     /**
-     * Set the format's schema URL.
+     * Set the schema URL for this format.
      *
      * @param string $schema The schema URL
      *
@@ -115,7 +142,7 @@ class Format extends Entity
     public function setSchema(string $schema): void
     {
         try {
-            $this->xmlSchema = $this->validateUrl($schema);
+            $this->xmlSchema = $this->validateUrl(url: $schema);
         } catch (ValidationFailedException $exception) {
             throw $exception;
         }
@@ -133,9 +160,13 @@ class Format extends Entity
     public function __construct(string $prefix, string $namespace, string $schema)
     {
         try {
-            $this->prefix = $this->validateRegEx($prefix, '/^[A-Za-z0-9\-_\.!~\*\'\(\)]+$/');
+            $this->prefix = $this->validateRegEx(
-            $this->setNamespace($namespace);
+                string: $prefix,
-            $this->setSchema($schema);
+                regEx: '/^[A-Za-z0-9\-_\.!~\*\'\(\)]+$/'
+            );
+            $this->setNamespace(namespace: $namespace);
+            $this->setSchema(schema: $schema);
+            $this->records = new ArrayCollection();
         } catch (ValidationFailedException $exception) {
             throw $exception;
         }

src/Entity/Record.php

@@ -27,6 +27,7 @@ use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
 use OCC\OaiPmh2\Entity;
+use OCC\OaiPmh2\Repository\RecordRepository;
 use Symfony\Component\Validator\Exception\ValidationFailedException;
 
 /**
@@ -35,13 +36,13 @@ use Symfony\Component\Validator\Exception\ValidationFailedException;
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: RecordRepository::class)]
 #[ORM\Table(name: 'records')]
 #[ORM\Index(name: 'identifier_idx', columns: ['identifier'])]
 #[ORM\Index(name: 'format_idx', columns: ['format'])]
 #[ORM\Index(name: 'last_changed_idx', columns: ['last_changed'])]
 #[ORM\Index(name: 'format_last_changed_idx', columns: ['format', 'last_changed'])]
-class Record extends Entity
+final class Record extends Entity
 {
     /**
      * The record identifier.
@@ -54,8 +55,16 @@ class Record extends Entity
      * The associated format.
      */
     #[ORM\Id]
-    #[ORM\ManyToOne(targetEntity: Format::class, fetch: 'EXTRA_LAZY')]
+    #[ORM\ManyToOne(
-    #[ORM\JoinColumn(name: 'format', referencedColumnName: 'prefix')]
+        targetEntity: Format::class,
+        fetch: 'EXTRA_LAZY',
+        inversedBy: 'records'
+    )]
+    #[ORM\JoinColumn(
+        name: 'format',
+        referencedColumnName: 'prefix',
+        onDelete: 'CASCADE'
+    )]
     private Format $format;
 
     /**
@@ -75,7 +84,13 @@ class Record extends Entity
      *
      * @var Collection<string, Set>
      */
-    #[ORM\ManyToMany(targetEntity: Set::class, inversedBy: 'records', indexBy: 'spec', fetch: 'EXTRA_LAZY', cascade: ['persist'])]
+    #[ORM\ManyToMany(
+        targetEntity: Set::class,
+        inversedBy: 'records',
+        cascade: ['persist'],
+        fetch: 'EXTRA_LAZY',
+        indexBy: 'spec'
+    )]
     #[ORM\JoinTable(name: 'records_sets')]
     #[ORM\JoinColumn(name: 'record_identifier', referencedColumnName: 'identifier')]
     #[ORM\JoinColumn(name: 'record_format', referencedColumnName: 'format')]
@@ -91,9 +106,9 @@ class Record extends Entity
      */
     public function addSet(Set $set): void
     {
-        if (!$this->sets->contains($set)) {
+        if (!$this->sets->contains(element: $set)) {
-            $this->sets->add($set);
+            $this->sets->add(element: $set);
-            $set->addRecord($this);
+            $set->addRecord(record: $this);
         }
     }
 
@@ -146,23 +161,26 @@ class Record extends Entity
      */
     public function getSet(string $setSpec): ?Set
     {
-        return $this->sets->get($setSpec);
+        return $this->sets->get(key: $setSpec);
     }
 
     /**
      * Get a collection of associated sets.
      *
-     * @return array<string, Set> The associated sets
+     * @return Collection<string, Set> The associated sets
      */
-    public function getSets(): array
+    public function getSets(): Collection
     {
-        return $this->sets->toArray();
+        return $this->sets;
     }
 
     /**
      * Whether this record has any content.
      *
      * @return bool TRUE if content exists, FALSE otherwise
+     *
+     * @psalm-assert-if-true string $this->content
+     * @psalm-assert-if-true string $this->getContent()
      */
     public function hasContent(): bool
     {
@@ -178,9 +196,9 @@ class Record extends Entity
      */
     public function removeSet(Set $set): void
     {
-        if ($this->sets->contains($set)) {
+        if ($this->sets->contains(element: $set)) {
-            $this->sets->removeElement($set);
+            $this->sets->removeElement(element: $set);
-            $set->removeRecord($this);
+            $set->removeRecord(record: $this);
         }
     }
 
@@ -200,7 +218,7 @@ class Record extends Entity
             $data = trim($data);
             if ($validate) {
                 try {
-                    $data = $this->validateXml($data);
+                    $data = $this->validateXml(xml: $data);
                 } catch (ValidationFailedException $exception) {
                     throw $exception;
                 }
@@ -250,13 +268,13 @@ class Record extends Entity
     {
         try {
             $this->identifier = $this->validateRegEx(
-                $identifier,
+                string: $identifier,
                 // xs:anyURI
-                '/^(([a-zA-Z][0-9a-zA-Z+\\-\\.]*:)?\/{0,2}[0-9a-zA-Z;\/?:@&=+$\\.\\-_!~*\'()%]+)?(#[0-9a-zA-Z;\/?:@&=+$\\.\\-_!~*\'()%]+)?$/'
+                regEx: '/^(([a-zA-Z][0-9a-zA-Z+\\-\\.]*:)?\/{0,2}[0-9a-zA-Z;\/?:@&=+$\\.\\-_!~*\'()%]+)?(#[0-9a-zA-Z;\/?:@&=+$\\.\\-_!~*\'()%]+)?$/'
             );
-            $this->setFormat($format);
+            $this->setFormat(format: $format);
-            $this->setContent($data);
+            $this->setContent(data: $data);
-            $this->setLastChanged($lastChanged);
+            $this->setLastChanged(dateTime: $lastChanged);
             $this->sets = new ArrayCollection();
         } catch (ValidationFailedException $exception) {
             throw $exception;

src/Entity/Set.php

@@ -26,6 +26,7 @@ use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
 use OCC\OaiPmh2\Entity;
+use OCC\OaiPmh2\Repository\SetRepository;
 use Symfony\Component\Validator\Exception\ValidationFailedException;
 
 /**
@@ -34,9 +35,9 @@ use Symfony\Component\Validator\Exception\ValidationFailedException;
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: SetRepository::class)]
 #[ORM\Table(name: 'sets')]
-class Set extends Entity
+final class Set extends Entity
 {
     /**
      * The unique set spec.
@@ -60,9 +61,14 @@ class Set extends Entity
     /**
      * Collection of associated records.
      *
-     * @var Collection<int, Record>
+     * @var Collection<string, Record>
      */
-    #[ORM\ManyToMany(targetEntity: Record::class, mappedBy: 'sets', fetch: 'EXTRA_LAZY')]
+    #[ORM\ManyToMany(
+        targetEntity: Record::class,
+        mappedBy: 'sets',
+        fetch: 'EXTRA_LAZY',
+        indexBy: 'identifier'
+    )]
     private Collection $records;
 
     /**
@@ -74,9 +80,9 @@ class Set extends Entity
      */
     public function addRecord(Record $record): void
     {
-        if (!$this->records->contains($record)) {
+        if (!$this->records->contains(element: $record)) {
-            $this->records->add($record);
+            $this->records->add(element: $record);
-            $record->addSet($this);
+            $record->addSet(set: $this);
         }
     }
 
@@ -113,17 +119,20 @@ class Set extends Entity
     /**
      * Get a collection of associated records.
      *
-     * @return array<int, Record> The associated records
+     * @return Collection<string, Record> The associated records
      */
-    public function getRecords(): array
+    public function getRecords(): Collection
     {
-        return $this->records->toArray();
+        return $this->records;
     }
 
     /**
      * Whether this set has a description.
      *
      * @return bool TRUE if description exists, FALSE otherwise
+     *
+     * @psalm-assert-if-true string $this->description
+     * @psalm-assert-if-true string $this->getDescription()
      */
     public function hasDescription(): bool
     {
@@ -149,16 +158,16 @@ class Set extends Entity
      */
     public function removeRecord(Record $record): void
     {
-        if ($this->records->contains($record)) {
+        if ($this->records->contains(element: $record)) {
-            $this->records->removeElement($record);
+            $this->records->removeElement(element: $record);
-            $record->removeSet($this);
+            $record->removeSet(set: $this);
         }
     }
 
     /**
      * Set the description for this set.
      *
-     * @param ?string $description The description
+     * @param ?string $description The description XML or NULL to unset
      *
      * @return void
      *
@@ -169,7 +178,7 @@ class Set extends Entity
         if (isset($description)) {
             $description = trim($description);
             try {
-                $description = $this->validateXml($description);
+                $description = $this->validateXml(xml: $description);
             } catch (ValidationFailedException $exception) {
                 throw $exception;
             }
@@ -198,15 +207,15 @@ class Set extends Entity
      *
      * @throws ValidationFailedException
      */
-    public function __construct(string $spec, ?string $name = null, string $description = null)
+    public function __construct(string $spec, ?string $name = null, ?string $description = null)
     {
         try {
             $this->spec = $this->validateRegEx(
-                $spec,
+                string: $spec,
-                '/^([A-Za-z0-9\-_\.!~\*\'\(\)])+(:[A-Za-z0-9\-_\.!~\*\'\(\)]+)*$/'
+                regEx: '/^([A-Za-z0-9\-_\.!~\*\'\(\)])+(:[A-Za-z0-9\-_\.!~\*\'\(\)]+)*$/'
             );
-            $this->setName($name);
+            $this->setName(name: $name);
-            $this->setDescription($description);
+            $this->setDescription(description: $description);
             $this->records = new ArrayCollection();
         } catch (ValidationFailedException $exception) {
             throw $exception;

src/Entity/Token.php

@@ -27,17 +27,20 @@ use DateTime;
 use Doctrine\ORM\Mapping as ORM;
 use OCC\OaiPmh2\Configuration;
 use OCC\OaiPmh2\Entity;
+use OCC\OaiPmh2\Repository\TokenRepository;
 
 /**
  * Doctrine/ORM Entity for resumption tokens.
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
+ *
+ * @psalm-import-type OaiRequestMetadata from \OCC\OaiPmh2\Middleware
  */
-#[ORM\Entity]
+#[ORM\Entity(repositoryClass: TokenRepository::class)]
 #[ORM\Table(name: 'tokens')]
 #[ORM\Index(name: 'valid_until_idx', columns: ['valid_until'])]
-class Token extends Entity
+final class Token extends Entity
 {
     /**
      * The resumption token.
@@ -77,11 +80,11 @@ class Token extends Entity
     /**
      * Get the query parameters.
      *
-     * @return array<string, int|string|null> The query parameters
+     * @return OaiRequestMetadata The query parameters
      */
     public function getParameters(): array
     {
-        /** @var array<string, int|string|null> */
+        /** @var OaiRequestMetadata */
         return unserialize($this->parameters);
     }
 
@@ -109,15 +112,15 @@ class Token extends Entity
      * Get new entity of resumption token.
      *
      * @param string $verb The verb for which the token is issued
-     * @param array<string, int|string|null> $parameters The query parameters
+     * @param OaiRequestMetadata $parameters The query parameters
      */
     public function __construct(string $verb, array $parameters)
     {
         $this->token = substr(md5(microtime()), 0, 8);
         $this->verb = $verb;
         $this->parameters = serialize($parameters);
-        $validity = new DateTime();
+        $validUntil = new DateTime();
-        $validity->add(new DateInterval('PT' . Configuration::getInstance()->tokenValid . 'S'));
+        $validUntil->add(interval: new DateInterval(duration: 'PT' . Configuration::getInstance()->tokenValid . 'S'));
-        $this->validUntil = $validity;
+        $this->validUntil = $validUntil;
     }
 }

src/EntityManager.php

@@ -0,0 +1,471 @@
+<?php
+
+/**
+ * OAI-PMH 2.0 Data Provider
+ * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OCC\OaiPmh2;
+
+use DateTime;
+use Doctrine\DBAL\DriverManager;
+use Doctrine\DBAL\Schema\AbstractAsset;
+use Doctrine\DBAL\Tools\DsnParser;
+use Doctrine\ORM\AbstractQuery;
+use Doctrine\ORM\Configuration as DoctrineConfiguration;
+use Doctrine\ORM\Decorator\EntityManagerDecorator;
+use Doctrine\ORM\EntityManager as DoctrineEntityManager;
+use Doctrine\ORM\Mapping\Driver\AttributeDriver;
+use Doctrine\ORM\Proxy\ProxyFactory;
+use Doctrine\ORM\Query\Expr\Join;
+use Doctrine\ORM\Tools\Pagination\Paginator;
+use OCC\Basics\Traits\Singleton;
+use OCC\OaiPmh2\Entity\Format;
+use OCC\OaiPmh2\Entity\Record;
+use OCC\OaiPmh2\Entity\Set;
+use OCC\OaiPmh2\Entity\Token;
+use Symfony\Component\Cache\Adapter\PhpFilesAdapter;
+use Symfony\Component\Filesystem\Path;
+
+/**
+ * The Entity Manager controls all database shenanigans.
+ *
+ * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ * @package OAIPMH2
+ *
+ * @mixin DoctrineEntityManager
+ *
+ * @psalm-import-type Params from DriverManager
+ * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
+ */
+final class EntityManager extends EntityManagerDecorator
+{
+    use Singleton;
+
+    /**
+     * The database tables this class is allowed to handle.
+     *
+     * @var string[]
+     */
+    private const TABLES = [
+        'formats',
+        'records',
+        'records_sets',
+        'sets',
+        'tokens'
+    ];
+
+    /**
+     * Add or update entity.
+     *
+     * @param Format|Record|Set|Token $entity The entity
+     * @param bool $bulkMode Should we operate in bulk mode (no flush)?
+     *
+     * @return void
+     */
+    public function addOrUpdate(Format|Record|Set|Token $entity, bool $bulkMode = false): void
+    {
+        $this->getRepository(className: get_class($entity))->addOrUpdate(entity: $entity);
+        if (!$bulkMode) {
+            $this->flush();
+        }
+    }
+
+    /**
+     * Delete entity.
+     *
+     * @param Format|Record|Set|Token $entity The entity
+     *
+     * @return void
+     */
+    public function delete(Format|Record|Set|Token $entity): void
+    {
+        $this->getRepository(className: get_class($entity))->delete(entity: $entity);
+    }
+
+    /**
+     * Get the earliest datestamp of any record.
+     *
+     * @return string The earliest datestamp
+     */
+    public function getEarliestDatestamp(): string
+    {
+        $timestamp = '0000-00-00T00:00:00Z';
+        $dql = $this->createQueryBuilder();
+        $dql->select(select: $dql->expr()->min('record.lastChanged'));
+        $dql->from(from: Record::class, alias: 'record');
+        $query = $dql->getQuery()->enableResultCache();
+        /** @var ?string $result */
+        $result = $query->getOneOrNullResult(hydrationMode: AbstractQuery::HYDRATE_SCALAR_COLUMN);
+        return $result ?? $timestamp;
+    }
+
+    /**
+     * Get reference to a single metadata format.
+     *
+     * @param string $prefix The metadata prefix
+     *
+     * @return ?Format The reference to the metadata format or NULL if invalid
+     */
+    public function getMetadataFormat(string $prefix): ?Format
+    {
+        return $this->getReference(entityName: Format::class, id: $prefix);
+    }
+
+    /**
+     * Get all available metadata formats (optionally for a given record identifier).
+     *
+     * @param ?string $recordIdentifier Optional record identifier
+     *
+     * @return ResultSet<Format> The metadata formats indexed by prefix
+     */
+    public function getMetadataFormats(?string $recordIdentifier = null): ResultSet
+    {
+        $entities = [];
+        if ($recordIdentifier === null) {
+            $formats = $this->getRepository(className: Format::class)->findAll();
+        } else {
+            $dql = $this->createQueryBuilder();
+            $dql->select(select: 'record.format')
+                ->from(from: Record::class, alias: 'record')
+                ->where(predicates: $dql->expr()->eq('record.identifier', ':recordIdentifier'))
+                ->setParameter(key: 'recordIdentifier', value: $recordIdentifier);
+            $query = $dql->getQuery()->enableResultCache();
+            /** @var Format[] */
+            $formats = $query->getResult(hydrationMode: AbstractQuery::HYDRATE_OBJECT);
+        }
+        foreach ($formats as $format) {
+            $entities[$format->getPrefix()] = $format;
+        }
+        return new ResultSet(elements: $entities);
+    }
+
+    /**
+     * Get a single record.
+     *
+     * @param string $identifier The record identifier
+     * @param string $format The metadata prefix
+     *
+     * @return ?Record The record or NULL if invalid
+     */
+    public function getRecord(string $identifier, string $format): ?Record
+    {
+        return $this->getRepository(className: Record::class)->findOneBy(
+            criteria: [
+                'identifier' => $identifier,
+                'format' => $this->getMetadataFormat(prefix: $format)
+            ]
+        );
+    }
+
+    /**
+     * Get list of records.
+     *
+     * @param string $verb The currently requested verb
+     *                     'ListIdentifiers' or 'ListRecords'
+     * @param string $metadataPrefix The metadata prefix
+     * @param int $counter Counter for split result sets
+     * @param ?string $from The "from" datestamp
+     * @param ?string $until The "until" datestamp
+     * @param ?string $set The set spec
+     *
+     * @return ResultSet<Record> The records indexed by id and maybe a resumption token
+     */
+    public function getRecords(
+        string $verb,
+        string $metadataPrefix,
+        int $counter = 0,
+        ?string $from = null,
+        ?string $until = null,
+        ?string $set = null
+    ): ResultSet {
+        $maxRecords = Configuration::getInstance()->maxRecords;
+        $cursor = $counter * $maxRecords;
+
+        $dql = $this->createQueryBuilder();
+        $dql->select(select: 'record')
+            ->from(from: Record::class, alias: 'record', indexBy: 'record.identifier')
+            ->where(predicates: $dql->expr()->eq('record.format', ':metadataPrefix'))
+            ->setParameter(
+                key: 'metadataPrefix',
+                value: $this->getMetadataFormat(prefix: $metadataPrefix)
+            )
+            ->setFirstResult(firstResult: $cursor)
+            ->setMaxResults(maxResults: $maxRecords);
+        if (isset($from)) {
+            $dql->andWhere(where: $dql->expr()->gte('record.lastChanged', ':from'));
+            $dql->setParameter(key: 'from', value: new DateTime($from));
+        }
+        if (isset($until)) {
+            $dql->andWhere(where: $dql->expr()->lte('record.lastChanged', ':until'));
+            $dql->setParameter(key: 'until', value: new DateTime($until));
+        }
+        if (isset($set)) {
+            $dql->innerJoin(
+                join: Set::class,
+                alias: 'sets',
+                conditionType: Join::WITH,
+                condition: $dql->expr()->orX(
+                    $dql->expr()->eq('sets.spec', ':setSpec'),
+                    $dql->expr()->like('sets.spec', ':setLike')
+                )
+            );
+            $dql->setParameter(key: 'setSpec', value: $set);
+            $dql->setParameter(key: 'setLike', value: $set . ':%');
+        }
+        $query = $dql->getQuery();
+        /** @var array<string, Record> */
+        $queryResult = $query->getResult();
+        $result = new ResultSet(elements: $queryResult);
+        $paginator = new Paginator(query: $query, fetchJoinCollection: true);
+        if (count($paginator) > ($cursor + count($result))) {
+            $token = new Token(
+                verb: $verb,
+                parameters: [
+                    'verb' => $verb,
+                    'identifier' => null,
+                    'metadataPrefix' => $metadataPrefix,
+                    'from' => $from,
+                    'until' => $until,
+                    'set' => $set,
+                    'resumptionToken' => null,
+                    'counter' => $counter + 1,
+                    'completeListSize' => count($paginator)
+                ]
+            );
+            $this->persist(object: $token);
+            $this->flush();
+            $result->setResumptionToken(token: $token);
+        }
+        return $result;
+    }
+
+    /**
+     * Get resumption token.
+     *
+     * @param string $token The token
+     * @param string $verb The current verb to validate token
+     *
+     * @return ?Token The resumption token or NULL if invalid
+     */
+    public function getResumptionToken(string $token, string $verb): ?Token
+    {
+        $resumptionToken = $this->getRepository(className: Token::class)->findOneBy(
+            criteria: [
+                'token' => $token,
+                'verb' => $verb
+            ]
+        );
+        if (isset($resumptionToken) && $resumptionToken->getValidUntil() < new DateTime()) {
+            $this->delete(entity: $resumptionToken);
+            return null;
+        }
+        return $resumptionToken;
+    }
+
+    /**
+     * Get reference to a single set.
+     *
+     * @param string $spec The set spec
+     *
+     * @return ?Set The reference to the set or NULL if invalid
+     */
+    public function getSet(string $spec): ?Set
+    {
+        return $this->getReference(entityName: Set::class, id: $spec);
+    }
+
+    /**
+     * Get all available sets.
+     *
+     * @param int $counter Counter for split result sets
+     *
+     * @return ResultSet<Set> The sets indexed by spec
+     */
+    public function getSets(int $counter = 0): ResultSet
+    {
+        $maxRecords = Configuration::getInstance()->maxRecords;
+        $cursor = $counter * $maxRecords;
+
+        $dql = $this->createQueryBuilder();
+        $dql->select(select: 'set')
+            ->from(from: Set::class, alias: 'set', indexBy: 'set.spec')
+            ->setFirstResult(firstResult: $cursor)
+            ->setMaxResults(maxResults: $maxRecords);
+        $query = $dql->getQuery()->enableResultCache();
+        /** @var array<string, Set> */
+        $queryResult = $query->getResult(hydrationMode: AbstractQuery::HYDRATE_OBJECT);
+        $result = new ResultSet(elements: $queryResult);
+        $paginator = new Paginator(query: $query);
+        if (count($paginator) > ($cursor + count($result))) {
+            $token = new Token(
+                verb: 'ListSets',
+                parameters: [
+                    'verb' => 'ListSets',
+                    'identifier' => null,
+                    'metadataPrefix' => null,
+                    'from' => null,
+                    'until' => null,
+                    'set' => null,
+                    'resumptionToken' => null,
+                    'counter' => $counter + 1,
+                    'completeListSize' => count($paginator)
+                ]
+            );
+            $this->persist(object: $token);
+            $this->flush();
+            $result->setResumptionToken(token: $token);
+        }
+        return $result;
+    }
+
+    /**
+     * Check if a record with the given identifier exists.
+     *
+     * @param string $identifier The record identifier
+     *
+     * @return bool Whether a record with the identifier exists
+     */
+    public function isValidRecordIdentifier(string $identifier): bool
+    {
+        $records = $this->getRepository(className: Record::class)->findBy(criteria: ['identifier' => $identifier]);
+        return (bool) count($records) > 0;
+    }
+
+    /**
+     * Prune deleted records.
+     *
+     * @return int The number of removed records
+     */
+    public function pruneDeletedRecords(): int
+    {
+        $dql = $this->createQueryBuilder();
+        $dql->delete(delete: Record::class, alias: 'record')
+            ->where(predicates: $dql->expr()->isNull('record.content'));
+        /** @var int */
+        $deleted = $dql->getQuery()->execute();
+        if ($deleted > 0) {
+            $this->pruneOrphanedSets();
+        }
+        return $deleted;
+    }
+
+    /**
+     * Prune expired resumption tokens.
+     *
+     * @return int The number of deleted tokens
+     */
+    public function pruneExpiredTokens(): int
+    {
+        $dql = $this->createQueryBuilder();
+        $dql->delete(delete: Token::class, alias: 'token')
+            ->where(predicates: $dql->expr()->lt('token.validUntil', new DateTime()));
+        /** @var int */
+        return $dql->getQuery()->execute();
+    }
+
+    /**
+     * Prune orphan sets.
+     *
+     * @return int The number of removed sets
+     */
+    public function pruneOrphanedSets(): int
+    {
+        $sets = $this->getRepository(className: Set::class)->findAll();
+        $count = 0;
+        foreach ($sets as $set) {
+            if ($set->isEmpty()) {
+                $count += 1;
+                $this->remove(object: $set);
+            }
+        }
+        if ($count > 0) {
+            $this->flush();
+        }
+        return $count;
+    }
+
+    /**
+     * Instantiate new Doctrine entity manager and connect to database.
+     */
+    private function __construct()
+    {
+        $config = new DoctrineConfiguration();
+        $config->setAutoGenerateProxyClasses(
+            autoGenerate: ProxyFactory::AUTOGENERATE_NEVER
+        );
+        $config->setMetadataCache(
+            cache: new PhpFilesAdapter(
+                namespace: 'Metadata',
+                directory: __DIR__ . '/../var/cache'
+            )
+        );
+        $config->setMetadataDriverImpl(
+            driverImpl: new AttributeDriver(
+                paths: [__DIR__ . '/Entity']
+            )
+        );
+        $config->setProxyDir(dir: __DIR__ . '/../var/generated');
+        $config->setProxyNamespace(ns: 'OCC\OaiPmh2\Entity\Proxy');
+        $config->setQueryCache(
+            cache: new PhpFilesAdapter(
+                namespace: 'Query',
+                directory: __DIR__ . '/../var/cache'
+            )
+        );
+        $config->setResultCache(
+            cache: new PhpFilesAdapter(
+                namespace: 'Result',
+                directory: __DIR__ . '/../var/cache'
+            )
+        );
+        $config->setSchemaAssetsFilter(
+            schemaAssetsFilter: static function (string|AbstractAsset $assetName): bool {
+                if ($assetName instanceof AbstractAsset) {
+                    $assetName = $assetName->getName();
+                }
+                return in_array(needle: $assetName, haystack: self::TABLES, strict: true);
+            }
+        );
+
+        $baseDir = Path::canonicalize(path: __DIR__ . '/../');
+        $dsn = str_replace(
+            search: '%BASEDIR%',
+            replace: $baseDir,
+            subject: Configuration::getInstance()->database
+        );
+        $parser = new DsnParser(
+            schemeMapping: [
+                'mariadb' => 'pdo_mysql',
+                'mssql' => 'pdo_sqlsrv',
+                'mysql' => 'pdo_mysql',
+                'oracle' => 'pdo_oci',
+                'postgresql' => 'pdo_pgsql',
+                'sqlite' => 'pdo_sqlite'
+            ]
+        );
+        $conn = DriverManager::getConnection(
+            // Generic return type of DsnParser::parse() is not correctly recognized.
+            // phpcs:ignore
+            params: $parser->parse(dsn: $dsn),
+            config: $config
+        );
+
+        parent::__construct(new DoctrineEntityManager(conn: $conn, config: $config));
+    }
+}

src/Middleware.php

@@ -22,7 +22,9 @@ declare(strict_types=1);
 
 namespace OCC\OaiPmh2;
 
+use DOMElement;
 use GuzzleHttp\Psr7\Utils;
+use OCC\OaiPmh2\Entity\Token;
 use OCC\OaiPmh2\Middleware\ErrorHandler;
 use OCC\PSR15\AbstractMiddleware;
 use Psr\Http\Message\ResponseInterface;
@@ -33,13 +35,99 @@ use Psr\Http\Message\ServerRequestInterface;
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
+ *
+ * @psalm-type OaiRequestMetadata = array{
+ *     verb: string,
+ *     identifier: ?string,
+ *     metadataPrefix: ?string,
+ *     from: ?string,
+ *     until: ?string,
+ *     set: ?string,
+ *     resumptionToken: ?string,
+ *     counter: int,
+ *     completeListSize: int
+ * }
  */
 abstract class Middleware extends AbstractMiddleware
 {
+    /**
+     * This holds the request metadata.
+     *
+     * @var OaiRequestMetadata
+     */
+    protected array $arguments = [
+        'verb' => '',
+        'identifier' => null,
+        'metadataPrefix' => null,
+        'from' => null,
+        'until' => null,
+        'set' => null,
+        'resumptionToken' => null,
+        'counter' => 0,
+        'completeListSize' => 0
+    ];
+
+    /**
+     * This holds the entity manager singleton.
+     */
+    protected EntityManager $em;
+
     /**
      * This holds the prepared response document.
      */
-    protected Document $preparedResponse;
+    protected Response $preparedResponse;
+
+    /**
+     * Add resumption token information to response document.
+     *
+     * @param DOMElement $node The DOM node to add the resumption token to
+     * @param ?Token $token The new resumption token or NULL if none
+     *
+     * @return void
+     */
+    protected function addResumptionToken(DOMElement $node, ?Token $token): void
+    {
+        if (isset($token) || isset($this->arguments['resumptionToken'])) {
+            $resumptionToken = $this->preparedResponse->createElement(localName: 'resumptionToken');
+            if (isset($token)) {
+                $resumptionToken->nodeValue = $token->getToken();
+                $resumptionToken->setAttribute(
+                    qualifiedName: 'expirationDate',
+                    value: $token->getValidUntil()->format(format: 'Y-m-d\TH:i:s\Z')
+                );
+                $this->arguments['completeListSize'] = $token->getParameters()['completeListSize'];
+            }
+            $resumptionToken->setAttribute(
+                qualifiedName: 'completeListSize',
+                value: (string) $this->arguments['completeListSize']
+            );
+            $resumptionToken->setAttribute(
+                qualifiedName: 'cursor',
+                value: (string) ($this->arguments['counter'] * Configuration::getInstance()->maxRecords)
+            );
+            $node->appendChild(node: $resumptionToken);
+        }
+    }
+
+    /**
+     * Check for resumption token and populate request arguments.
+     *
+     * @return void
+     */
+    protected function checkResumptionToken(): void
+    {
+        if (isset($this->arguments['resumptionToken'])) {
+            $token = $this->em->getResumptionToken(
+                token: $this->arguments['resumptionToken'],
+                verb: $this->arguments['verb']
+            );
+            if (isset($token)) {
+                $this->arguments = array_merge($this->arguments, $token->getParameters());
+            } else {
+                ErrorHandler::getInstance()->withError(errorCode: 'badResumptionToken');
+            }
+        }
+    }
 
     /**
      * Prepare response document.
@@ -59,7 +147,10 @@ abstract class Middleware extends AbstractMiddleware
      */
     protected function processRequest(ServerRequestInterface $request): ServerRequestInterface
     {
-        $this->prepareResponse($request);
+        /** @var OaiRequestMetadata */
+        $arguments = $request->getAttributes();
+        $this->arguments = array_merge($this->arguments, $arguments);
+        $this->prepareResponse(request: $request);
         return $request;
     }
 
@@ -73,18 +164,22 @@ abstract class Middleware extends AbstractMiddleware
     protected function processResponse(ResponseInterface $response): ResponseInterface
     {
         if (!ErrorHandler::getInstance()->hasErrors() && isset($this->preparedResponse)) {
-            $response = $response->withBody(Utils::streamFor((string) $this->preparedResponse));
+            $response = $response->withBody(
+                body: Utils::streamFor(
+                    resource: (string) $this->preparedResponse
+                )
+            );
         }
         return $response;
     }
 
     /**
      * The constructor must have the same signature for all derived classes, thus make it final.
+     *
+     * @see https://psalm.dev/229
      */
     final public function __construct()
     {
-        // Make constructor final to avoid issues in dispatcher.
+        $this->em = EntityManager::getInstance();
-        // @see https://psalm.dev/229
     }
-
 }

src/Middleware/Dispatcher.php

@@ -22,6 +22,7 @@ declare(strict_types=1);
 
 namespace OCC\OaiPmh2\Middleware;
 
+use OCC\OaiPmh2\EntityManager;
 use OCC\OaiPmh2\Middleware;
 use OCC\PSR15\AbstractMiddleware;
 use Psr\Http\Message\ResponseInterface;
@@ -37,6 +38,8 @@ class Dispatcher extends AbstractMiddleware
 {
     /**
      * List of defined OAI-PMH parameters.
+     *
+     * @var string[]
      */
     protected const OAI_PARAMS = [
         'verb',
@@ -62,14 +65,14 @@ class Dispatcher extends AbstractMiddleware
             /** @var array<string, string> */
             $arguments = $request->getQueryParams();
         } elseif ($request->getMethod() === 'POST') {
-            if ($request->getHeaderLine('Content-Type') === 'application/x-www-form-urlencoded') {
+            if ($request->getHeaderLine(name: 'Content-Type') === 'application/x-www-form-urlencoded') {
                 /** @var array<string, string> */
                 $arguments = (array) $request->getParsedBody();
             }
         }
-        if ($this->validateArguments($arguments)) {
+        if ($this->validateArguments(arguments: $arguments)) {
             foreach ($arguments as $param => $value) {
-                $request = $request->withAttribute($param, $value);
+                $request = $request->withAttribute(name: $param, value: $value);
             }
         }
         return $request;
@@ -84,17 +87,17 @@ class Dispatcher extends AbstractMiddleware
      */
     protected function processRequest(ServerRequestInterface $request): ServerRequestInterface
     {
-        $request = $this->getRequestWithAttributes($request);
+        $request = $this->getRequestWithAttributes(request: $request);
         $errorHandler = ErrorHandler::getInstance();
         if (!$errorHandler->hasErrors()) {
             /** @var string */
-            $verb = $request->getAttribute('verb');
+            $verb = $request->getAttribute(name: 'verb');
             $middleware = __NAMESPACE__ . '\\' . $verb;
-            if (is_a($middleware, Middleware::class, true)) {
+            if (is_a(object_or_class: $middleware, class: Middleware::class, allow_string: true)) {
-                $this->requestHandler->queue->enqueue(new $middleware());
+                $this->requestHandler->queue->enqueue(value: new $middleware());
             }
         }
-        $this->requestHandler->queue->enqueue($errorHandler);
+        $this->requestHandler->queue->enqueue(value: $errorHandler);
         return $request;
     }
 
@@ -110,7 +113,7 @@ class Dispatcher extends AbstractMiddleware
         // TODO: Add support for content compression
         // https://openarchives.org/OAI/openarchivesprotocol.html#ResponseCompression
         // https://github.com/middlewares/encoder
-        return $response->withHeader('Content-Type', 'text/xml');
+        return $response->withHeader(name: 'Content-Type', value: 'text/xml');
     }
 
     /**
@@ -124,30 +127,104 @@ class Dispatcher extends AbstractMiddleware
      */
     protected function validateArguments(array $arguments): bool
     {
-        $errorHandler = ErrorHandler::getInstance();
         if (
             count(array_diff(array_keys($arguments), self::OAI_PARAMS)) !== 0
             or !isset($arguments['verb'])
         ) {
-            $errorHandler->withError('badArgument');
+            ErrorHandler::getInstance()->withError(errorCode: 'badArgument');
         } else {
-            switch ($arguments['verb']) {
+            match ($arguments['verb']) {
-                case 'GetRecord':
+                'GetRecord' => $this->validateGetRecord(arguments: $arguments),
+                'Identify' => $this->validateIdentify(arguments: $arguments),
+                'ListIdentifiers', 'ListRecords' => $this->validateListRecords(arguments: $arguments),
+                'ListMetadataFormats' => $this->validateListFormats(arguments: $arguments),
+                'ListSets' => $this->validateListSets(arguments: $arguments),
+                default => ErrorHandler::getInstance()->withError(errorCode: 'badVerb')
+            };
+            if (!ErrorHandler::getInstance()->hasErrors()) {
+                $this->validateMetadataPrefix(prefix: $arguments['metadataPrefix'] ?? null);
+                $this->validateDateTime(datetime: $arguments['from'] ?? null);
+                $this->validateDateTime(datetime: $arguments['until'] ?? null);
+                $this->validateSet($arguments['set'] ?? null);
+            }
+        }
+        return !ErrorHandler::getInstance()->hasErrors();
+    }
+
+    /**
+     * Validate "from" and "until" argument.
+     *
+     * @param ?string $datetime The datetime string to validate or NULL if none
+     *
+     * @return void
+     */
+    protected function validateDateTime(?string $datetime): void
+    {
+        if (isset($datetime)) {
+            $date = date_parse(datetime: $datetime);
+            if ($date['warning_count'] > 0 || $date['error_count'] > 0) {
+                ErrorHandler::getInstance()->withError(errorCode: 'badArgument');
+            }
+        }
+    }
+
+    /**
+     * Validate request arguments for verb GetRecord.
+     *
+     * @param string[] $arguments The request parameters
+     *
+     * @return void
+     */
+    protected function validateGetRecord(array $arguments): void
+    {
         if (
             count($arguments) !== 3
             or !isset($arguments['identifier'])
             or !isset($arguments['metadataPrefix'])
         ) {
-                        $errorHandler->withError('badArgument');
+            ErrorHandler::getInstance()->withError(errorCode: 'badArgument');
         }
-                    break;
+    }
-                case 'Identify':
+
+    /**
+     * Validate request arguments for verb Identify.
+     *
+     * @param string[] $arguments The request parameters
+     *
+     * @return void
+     */
+    protected function validateIdentify(array $arguments): void
+    {
         if (count($arguments) !== 1) {
-                        $errorHandler->withError('badArgument');
+            ErrorHandler::getInstance()->withError(errorCode: 'badArgument');
         }
-                    break;
+    }
-                case 'ListIdentifiers':
+
-                case 'ListRecords':
+    /**
+     * Validate request arguments for verb ListMetadataFormats.
+     *
+     * @param string[] $arguments The request parameters
+     *
+     * @return void
+     */
+    protected function validateListFormats(array $arguments): void
+    {
+        if (count($arguments) !== 1) {
+            if (!isset($arguments['identifier']) || count($arguments) !== 2) {
+                ErrorHandler::getInstance()->withError(errorCode: 'badArgument');
+            }
+        }
+    }
+
+    /**
+     * Validate request arguments for verbs ListIdentifiers and ListRecords.
+     *
+     * @param string[] $arguments The request parameters
+     *
+     * @return void
+     */
+    protected function validateListRecords(array $arguments): void
+    {
         if (
             isset($arguments['metadataPrefix'])
             xor isset($arguments['resumptionToken'])
@@ -156,30 +233,60 @@ class Dispatcher extends AbstractMiddleware
                 (isset($arguments['resumptionToken']) && count($arguments) !== 2)
                 or isset($arguments['identifier'])
             ) {
-                            $errorHandler->withError('badArgument');
+                ErrorHandler::getInstance()->withError(errorCode: 'badArgument');
             }
         } else {
-                        $errorHandler->withError('badArgument');
+            ErrorHandler::getInstance()->withError(errorCode: 'badArgument');
-                    }
-                    break;
-                case 'ListMetadataFormats':
-                    if (count($arguments) !== 1) {
-                        if (!isset($arguments['identifier']) || count($arguments) !== 2) {
-                            $errorHandler->withError('badArgument');
         }
     }
-                    break;
+
-                case 'ListSets':
+    /**
+     * Validate request arguments for verb ListSets.
+     *
+     * @param string[] $arguments The request parameters
+     *
+     * @return void
+     */
+    protected function validateListSets(array $arguments): void
+    {
         if (count($arguments) !== 1) {
             if (!isset($arguments['resumptionToken']) || count($arguments) !== 2) {
-                            $errorHandler->withError('badArgument');
+                ErrorHandler::getInstance()->withError(errorCode: 'badArgument');
             }
         }
-                    break;
+    }
-                default:
+
-                $errorHandler->withError('badVerb');
+    /**
+     * Validate "metadataPrefix" argument.
+     *
+     * @param ?string $prefix The metadata prefix
+     *
+     * @return void
+     */
+    protected function validateMetadataPrefix(?string $prefix): void
+    {
+        if (isset($prefix)) {
+            $formats = EntityManager::getInstance()->getMetadataFormats();
+            if (!$formats->containsKey(key: $prefix)) {
+                ErrorHandler::getInstance()->withError(errorCode: 'cannotDisseminateFormat');
+            }
+        }
+    }
+
+    /**
+     * Validate "set" argument.
+     *
+     * @param ?string $spec The set spec
+     *
+     * @return void
+     */
+    protected function validateSet(?string $spec): void
+    {
+        if (isset($spec)) {
+            $sets = EntityManager::getInstance()->getSets();
+            if (!$sets->containsKey(key: $spec)) {
+                ErrorHandler::getInstance()->withError(errorCode: 'badArgument');
             }
         }
-        return !$errorHandler->hasErrors();
     }
 }

src/Middleware/ErrorHandler.php

@@ -25,7 +25,7 @@ namespace OCC\OaiPmh2\Middleware;
 use DomainException;
 use GuzzleHttp\Psr7\Utils;
 use OCC\Basics\Traits\Singleton;
-use OCC\OaiPmh2\Document;
+use OCC\OaiPmh2\Response;
 use OCC\PSR15\AbstractMiddleware;
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\StreamInterface;
@@ -48,7 +48,7 @@ class ErrorHandler extends AbstractMiddleware
     protected const OAI_ERRORS = [
         'badArgument' => 'The request includes illegal arguments, is missing required arguments, includes a repeated argument, or values for arguments have an illegal syntax.',
         'badResumptionToken' => 'The value of the resumptionToken argument is invalid or expired.',
-        'badVerb' => 'Value of the verb argument is not a legal OAI-PMH verb, the verb argument is missing, or the verb argument is repeated.',
+        'badVerb' => 'The value of the verb argument is not a legal OAI-PMH verb, the verb argument is missing, or the verb argument is repeated.',
         'cannotDisseminateFormat' => 'The metadata format identified by the value given for the metadataPrefix argument is not supported by the item or by the repository.',
         'idDoesNotExist' => 'The value of the identifier argument is unknown or illegal in this repository.',
         'noRecordsMatch' => 'The combination of the values of the from, until, set and metadataPrefix arguments results in an empty list.',
@@ -70,12 +70,19 @@ class ErrorHandler extends AbstractMiddleware
      */
     protected function getResponseBody(): StreamInterface
     {
-        $document = new Document($this->requestHandler->request);
+        $response = new Response(serverRequest: $this->requestHandler->request);
         foreach (array_unique($this->errors) as $errorCode) {
-            $error = $document->createElement('error', self::OAI_ERRORS[$errorCode], true);
+            $error = $response->createElement(
-            $error->setAttribute('code', $errorCode);
+                localName: 'error',
+                value: self::OAI_ERRORS[$errorCode],
+                appendToRoot: true
+            );
+            $error->setAttribute(
+                qualifiedName: 'code',
+                value: $errorCode
+            );
         }
-        return Utils::streamFor((string) $document);
+        return Utils::streamFor(resource: (string) $response);
     }
 
     /**
@@ -98,7 +105,7 @@ class ErrorHandler extends AbstractMiddleware
     protected function processResponse(ResponseInterface $response): ResponseInterface
     {
         if ($this->hasErrors()) {
-            $response = $response->withBody($this->getResponseBody());
+            $response = $response->withBody(body: $this->getResponseBody());
         }
         return $response;
     }
@@ -118,11 +125,11 @@ class ErrorHandler extends AbstractMiddleware
             $this->errors[] = $errorCode;
         } else {
             throw new DomainException(
-                sprintf(
+                message: sprintf(
-                    'Valid OAI-PMH error code expected, "%s" given.',
+                    format: 'Valid OAI-PMH error code expected, "%s" given.',
-                    $errorCode
+                    values: $errorCode
                 ),
-                500
+                code: 500
             );
         }
         return $this;

src/Middleware/GetRecord.php

@@ -22,14 +22,13 @@ declare(strict_types=1);
 
 namespace OCC\OaiPmh2\Middleware;
 
-use OCC\OaiPmh2\Database;
-use OCC\OaiPmh2\Document;
-use OCC\OaiPmh2\Entity\Format;
 use OCC\OaiPmh2\Middleware;
+use OCC\OaiPmh2\Response;
 use Psr\Http\Message\ServerRequestInterface;
 
 /**
  * Process the "GetRecord" request.
+ *
  * @see https://www.openarchives.org/OAI/openarchivesprotocol.html#GetRecord
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
@@ -46,54 +45,67 @@ class GetRecord extends Middleware
      */
     protected function prepareResponse(ServerRequestInterface $request): void
     {
-        /** @var array<string, string> */
+        $oaiRecord = $this->em->getRecord(
-        $params = $request->getAttributes();
+            identifier: (string) $this->arguments['identifier'],
-        /** @var Format */
+            format: (string) $this->arguments['metadataPrefix']
-        $format = Database::getInstance()->getEntityManager()->getReference(Format::class, $params['metadataPrefix']);
+        );
-        $oaiRecord = Database::getInstance()->getRecord($params['identifier'], $format);
 
         if (!isset($oaiRecord)) {
-            if (Database::getInstance()->idDoesExist($params['identifier'])) {
+            if ($this->em->isValidRecordIdentifier(identifier: (string) $this->arguments['identifier'])) {
-                ErrorHandler::getInstance()->withError('cannotDisseminateFormat');
+                ErrorHandler::getInstance()->withError(errorCode: 'cannotDisseminateFormat');
             } else {
-                ErrorHandler::getInstance()->withError('idDoesNotExist');
+                ErrorHandler::getInstance()->withError(errorCode: 'idDoesNotExist');
             }
             return;
-        } else {
-            $oaiRecordContent = $oaiRecord->getContent();
         }
 
-        $document = new Document($request);
+        $response = new Response(serverRequest: $request);
-        $getRecord = $document->createElement('GetRecord', '', true);
+        $getRecord = $response->createElement(
+            localName: 'GetRecord',
+            value: '',
+            appendToRoot: true
+        );
 
-        $record = $document->createElement('record');
+        $record = $response->createElement(localName: 'record');
-        $getRecord->appendChild($record);
+        $getRecord->appendChild(node: $record);
 
-        $header = $document->createElement('header');
+        $header = $response->createElement(localName: 'header');
-        if (!isset($oaiRecordContent)) {
+        if (!$oaiRecord->hasContent()) {
-            $header->setAttribute('status', 'deleted');
+            $header->setAttribute(
+                qualifiedName: 'status',
+                value: 'deleted'
+            );
         }
-        $record->appendChild($header);
+        $record->appendChild(node: $header);
 
-        $identifier = $document->createElement('identifier', $oaiRecord->getIdentifier());
+        $identifier = $response->createElement(
-        $header->appendChild($identifier);
+            localName: 'identifier',
+            value: $oaiRecord->getIdentifier()
+        );
+        $header->appendChild(node: $identifier);
 
-        $datestamp = $document->createElement('datestamp', $oaiRecord->getLastChanged()->format('Y-m-d\TH:i:s\Z'));
+        $datestamp = $response->createElement(
-        $header->appendChild($datestamp);
+            localName: 'datestamp',
+            value: $oaiRecord->getLastChanged()->format(format: 'Y-m-d\TH:i:s\Z')
+        );
+        $header->appendChild(node: $datestamp);
 
         foreach ($oaiRecord->getSets() as $set) {
-            $setSpec = $document->createElement('setSpec', $set->getName());
+            $setSpec = $response->createElement(
-            $header->appendChild($setSpec);
+                localName: 'setSpec',
+                value: $set->getName()
+            );
+            $header->appendChild(node: $setSpec);
         }
 
-        if (isset($oaiRecordContent)) {
+        if ($oaiRecord->hasContent()) {
-            $metadata = $document->createElement('metadata');
+            $metadata = $response->createElement(localName: 'metadata');
-            $record->appendChild($metadata);
+            $record->appendChild(node: $metadata);
 
-            $data = $document->importData($oaiRecordContent);
+            $data = $response->importData(data: $oaiRecord->getContent());
-            $metadata->appendChild($data);
+            $metadata->appendChild(node: $data);
         }
 
-        $this->preparedResponse = $document;
+        $this->preparedResponse = $response;
     }
 }

src/Middleware/Identify.php

@@ -24,13 +24,13 @@ namespace OCC\OaiPmh2\Middleware;
 
 use GuzzleHttp\Psr7\Uri;
 use OCC\OaiPmh2\Configuration;
-use OCC\OaiPmh2\Database;
-use OCC\OaiPmh2\Document;
 use OCC\OaiPmh2\Middleware;
+use OCC\OaiPmh2\Response;
 use Psr\Http\Message\ServerRequestInterface;
 
 /**
  * Process the "Identify" request.
+ *
  * @see https://www.openarchives.org/OAI/openarchivesprotocol.html#Identify
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
@@ -47,47 +47,75 @@ class Identify extends Middleware
      */
     protected function prepareResponse(ServerRequestInterface $request): void
     {
-        $document = new Document($request);
+        $response = new Response(serverRequest: $request);
-        $identify = $document->createElement('Identify', '', true);
+        $identify = $response->createElement(
+            localName: 'Identify',
+            value: '',
+            appendToRoot: true
+        );
 
-        $name = Configuration::getInstance()->repositoryName;
+        $repositoryName = $response->createElement(
-        $repositoryName = $document->createElement('repositoryName', $name);
+            localName: 'repositoryName',
-        $identify->appendChild($repositoryName);
+            value: Configuration::getInstance()->repositoryName
+        );
+        $identify->appendChild(node: $repositoryName);
 
         $uri = Uri::composeComponents(
-            $request->getUri()->getScheme(),
+            scheme: $request->getUri()->getScheme(),
-            $request->getUri()->getAuthority(),
+            authority: $request->getUri()->getAuthority(),
-            $request->getUri()->getPath(),
+            path: $request->getUri()->getPath(),
-            null,
+            query: null,
-            null
+            fragment: null
         );
-        $baseURL = $document->createElement('baseURL', $uri);
+        $baseURL = $response->createElement(
-        $identify->appendChild($baseURL);
+            localName: 'baseURL',
+            value: $uri
+        );
+        $identify->appendChild(node: $baseURL);
 
-        $protocolVersion = $document->createElement('protocolVersion', '2.0');
+        $protocolVersion = $response->createElement(
-        $identify->appendChild($protocolVersion);
+            localName: 'protocolVersion',
+            value: '2.0'
+        );
+        $identify->appendChild(node: $protocolVersion);
 
-        $email = Configuration::getInstance()->adminEmail;
+        $adminEmail = $response->createElement(
-        $adminEmail = $document->createElement('adminEmail', $email);
+            localName: 'adminEmail',
-        $identify->appendChild($adminEmail);
+            value: Configuration::getInstance()->adminEmail
+        );
+        $identify->appendChild(node: $adminEmail);
 
-        $datestamp = Database::getInstance()->getEarliestDatestamp();
+        $earliestDatestamp = $response->createElement(
-        $earliestDatestamp = $document->createElement('earliestDatestamp', $datestamp);
+            localName: 'earliestDatestamp',
-        $identify->appendChild($earliestDatestamp);
+            value: $this->em->getEarliestDatestamp()
+        );
+        $identify->appendChild(node: $earliestDatestamp);
 
-        $deletedRecord = $document->createElement('deletedRecord', 'transient');
+        $deletedRecord = $response->createElement(
-        $identify->appendChild($deletedRecord);
+            localName: 'deletedRecord',
+            value: Configuration::getInstance()->deletedRecords
+        );
+        $identify->appendChild(node: $deletedRecord);
 
-        $granularity = $document->createElement('granularity', 'YYYY-MM-DDThh:mm:ssZ');
+        $granularity = $response->createElement(
-        $identify->appendChild($granularity);
+            localName: 'granularity',
+            value: 'YYYY-MM-DDThh:mm:ssZ'
+        );
+        $identify->appendChild(node: $granularity);
 
         // TODO: Implement explicit content compression support.
-        // $compressionDeflate = $document->createElement('compression', 'deflate');
+        // $compressionDeflate = $response->createElement(
-        // $identify->appendChild($compressionDeflate);
+        //     localName: 'compression',
+        //     value: 'deflate'
+        // );
+        // $identify->appendChild(node: $compressionDeflate);
 
-        // $compressionGzip = $document->createElement('compression', 'gzip');
+        // $compressionGzip = $response->createElement(
-        // $identify->appendChild($compressionGzip);
+        //     localName: 'compression',
+        //     value: 'gzip'
+        // );
+        // $identify->appendChild(node: $compressionGzip);
 
-        $this->preparedResponse = $document;
+        $this->preparedResponse = $response;
     }
 }

src/Middleware/ListIdentifiers.php

@@ -22,16 +22,13 @@ declare(strict_types=1);
 
 namespace OCC\OaiPmh2\Middleware;
 
-use DateTime;
-use OCC\OaiPmh2\Configuration;
-use OCC\OaiPmh2\Database;
-use OCC\OaiPmh2\Document;
-use OCC\OaiPmh2\Entity\Record;
 use OCC\OaiPmh2\Middleware;
+use OCC\OaiPmh2\Response;
 use Psr\Http\Message\ServerRequestInterface;
 
 /**
  * Process the "ListIdentifiers" request.
+ *
  * @see https://www.openarchives.org/OAI/openarchivesprotocol.html#ListIdentifiers
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
@@ -40,7 +37,7 @@ use Psr\Http\Message\ServerRequestInterface;
 class ListIdentifiers extends Middleware
 {
     /**
-     * Prepare the response body for verb "ListIdentifiers" and "ListRecords".
+     * Prepare the response body for verbs "ListIdentifiers" and "ListRecords".
      *
      * @param ServerRequestInterface $request The incoming request
      *
@@ -48,127 +45,78 @@ class ListIdentifiers extends Middleware
      */
     protected function prepareResponse(ServerRequestInterface $request): void
     {
-        $counter = 0;
+        $this->checkResumptionToken();
-        $completeListSize = 0;
-        $maxRecords = Configuration::getInstance()->maxRecords;
 
-        /** @var array<string, string> */
+        $records = $this->em->getRecords(
-        $params = $request->getAttributes();
+            verb: $this->arguments['verb'],
-        $verb = $params['verb'];
+            metadataPrefix: (string) $this->arguments['metadataPrefix'],
-        $metadataPrefix = $params['metadataPrefix'] ?? '';
+            counter: $this->arguments['counter'],
-        $from = $params['from'] ?? null;
+            from: $this->arguments['from'],
-        $until = $params['until'] ?? null;
+            until: $this->arguments['until'],
-        $set = $params['set'] ?? null;
+            set: $this->arguments['set']
-        $resumptionToken = $params['resumptionToken'] ?? null;
-
-        if (isset($resumptionToken)) {
-            $oldToken = Database::getInstance()->getResumptionToken($resumptionToken, $verb);
-            if (!isset($oldToken)) {
-                ErrorHandler::getInstance()->withError('badResumptionToken');
-                return;
-            } else {
-                foreach ($oldToken->getParameters() as $key => $value) {
-                    $$key = $value;
-                }
-            }
-        }
-        $prefixes = Database::getInstance()->getMetadataFormats()->getQueryResult();
-        if (!array_key_exists($metadataPrefix, $prefixes)) {
-            ErrorHandler::getInstance()->withError('cannotDisseminateFormat');
-            return;
-        }
-        if (isset($from)) {
-            $from = new DateTime($from);
-        }
-        if (isset($until)) {
-            $until = new DateTime($until);
-        }
-        if (isset($set)) {
-            $sets = Database::getInstance()->getSets()->getQueryResult();
-            if (!array_key_exists($set, $sets)) {
-                ErrorHandler::getInstance()->withError('noSetHierarchy');
-                return;
-            }
-            $set = $sets[$set];
-        }
-
-        $records = Database::getInstance()->getRecords(
-            $verb,
-            $prefixes[$metadataPrefix],
-            $counter,
-            $from,
-            $until,
-            $set
         );
-        $newToken = $records->getResumptionToken();
         if (count($records) === 0) {
-            ErrorHandler::getInstance()->withError('noRecordsMatch');
+            ErrorHandler::getInstance()->withError(errorCode: 'noRecordsMatch');
             return;
-        } elseif (isset($newToken)) {
-            $completeListSize = $newToken->getParameters()['completeListSize'];
         }
 
-        $document = new Document($request);
+        $response = new Response(serverRequest: $request);
-        $list = $document->createElement($verb, '', true);
+        $list = $response->createElement(
-
+            localName: $this->arguments['verb'],
-        /** @var Record $oaiRecord */
+            value: '',
-        foreach ($records as $oaiRecord) {
+            appendToRoot: true
-            if ($verb === 'ListIdentifiers') {
+        );
         $baseNode = $list;
-            } else {
+
-                $record = $document->createElement('record');
+        foreach ($records as $oaiRecord) {
-                $list->appendChild($record);
+            if ($this->arguments['verb'] === 'ListRecords') {
+                $record = $response->createElement(localName: 'record');
+                $list->appendChild(node: $record);
                 $baseNode = $record;
             }
 
-            $header = $document->createElement('header');
+            $header = $response->createElement(localName: 'header');
-            if (!$oaiRecord->hasContent()) {
+            $baseNode->appendChild(node: $header);
-                $header->setAttribute('status', 'deleted');
-            }
-            $baseNode->appendChild($header);
 
-            $identifier = $document->createElement('identifier', $oaiRecord->getIdentifier());
+            $identifier = $response->createElement(
-            $header->appendChild($identifier);
+                localName: 'identifier',
+                value: $oaiRecord->getIdentifier()
+            );
+            $header->appendChild(node: $identifier);
 
-            $datestamp = $document->createElement('datestamp', $oaiRecord->getLastChanged()->format('Y-m-d\TH:i:s\Z'));
+            $datestamp = $response->createElement(
-            $header->appendChild($datestamp);
+                localName: 'datestamp',
+                value: $oaiRecord->getLastChanged()->format(format: 'Y-m-d\TH:i:s\Z')
+            );
+            $header->appendChild(node: $datestamp);
 
             foreach ($oaiRecord->getSets() as $oaiSet) {
-                $setSpec = $document->createElement('setSpec', $oaiSet->getName());
+                $setSpec = $response->createElement(
-                $header->appendChild($setSpec);
+                    localName: 'setSpec',
-            }
+                    value: $oaiSet->getName()
-
-            if ($verb === 'ListRecords' && $oaiRecord->hasContent()) {
-                $metadata = $document->createElement('metadata');
-                $baseNode->appendChild($metadata);
-
-                /** @var string */
-                $content = $oaiRecord->getContent();
-                $data = $document->importData($content);
-                $metadata->appendChild($data);
-            }
-        }
-
-        if (isset($oldToken) || isset($newToken)) {
-            $resumptionToken = $document->createElement('resumptionToken');
-            $list->appendChild($resumptionToken);
-            if (isset($newToken)) {
-                $resumptionToken->nodeValue = $newToken->getToken();
-                $resumptionToken->setAttribute(
-                    'expirationDate',
-                    $newToken->getValidUntil()->format('Y-m-d\TH:i:s\Z')
-                );
-            }
-            $resumptionToken->setAttribute(
-                'completeListSize',
-                (string) $completeListSize
-            );
-            $resumptionToken->setAttribute(
-                'cursor',
-                (string) ($counter * $maxRecords)
                 );
+                $header->appendChild(node: $setSpec);
             }
 
-        $this->preparedResponse = $document;
+            if (!$oaiRecord->hasContent()) {
+                $header->setAttribute(
+                    qualifiedName: 'status',
+                    value: 'deleted'
+                );
+            } elseif ($this->arguments['verb'] === 'ListRecords') {
+                $metadata = $response->createElement(localName: 'metadata');
+                $baseNode->appendChild(node: $metadata);
+
+                $data = $response->importData(data: $oaiRecord->getContent());
+                $metadata->appendChild(node: $data);
+            }
+        }
+
+        $this->preparedResponse = $response;
+
+        $this->addResumptionToken(
+            node: $list,
+            token: $records->getResumptionToken() ?? null
+        );
     }
 }

src/Middleware/ListMetadataFormats.php

@@ -22,14 +22,13 @@ declare(strict_types=1);
 
 namespace OCC\OaiPmh2\Middleware;
 
-use OCC\OaiPmh2\Database;
-use OCC\OaiPmh2\Document;
-use OCC\OaiPmh2\Entity\Format;
 use OCC\OaiPmh2\Middleware;
+use OCC\OaiPmh2\Response;
 use Psr\Http\Message\ServerRequestInterface;
 
 /**
  * Process the "ListMetadataFormats" request.
+ *
  * @see https://www.openarchives.org/OAI/openarchivesprotocol.html#ListMetadataFormats
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
@@ -46,37 +45,50 @@ class ListMetadataFormats extends Middleware
      */
     protected function prepareResponse(ServerRequestInterface $request): void
     {
-        /** @var ?string */
+        $formats = $this->em->getMetadataFormats(recordIdentifier: $this->arguments['identifier']);
-        $identifier = $request->getAttribute('identifier');
-        $formats = Database::getInstance()->getMetadataFormats($identifier);
 
         if (count($formats) === 0) {
-            if (!isset($identifier) || Database::getInstance()->idDoesExist($identifier)) {
+            if (
-                ErrorHandler::getInstance()->withError('noMetadataFormats');
+                !isset($this->arguments['identifier'])
+                || $this->em->isValidRecordIdentifier(identifier: $this->arguments['identifier'])
+            ) {
+                ErrorHandler::getInstance()->withError(errorCode: 'noMetadataFormats');
             } else {
-                ErrorHandler::getInstance()->withError('idDoesNotExist');
+                ErrorHandler::getInstance()->withError(errorCode: 'idDoesNotExist');
             }
             return;
         }
 
-        $document = new Document($request);
+        $response = new Response(serverRequest: $request);
-        $listMetadataFormats = $document->createElement('ListMetadataFormats', '', true);
+        $listMetadataFormats = $response->createElement(
+            localName: 'ListMetadataFormats',
+            value: '',
+            appendToRoot: true
+        );
 
-        /** @var Format $oaiFormat */
         foreach ($formats as $oaiFormat) {
-            $metadataFormat = $document->createElement('metadataFormat');
+            $metadataFormat = $response->createElement(localName: 'metadataFormat');
-            $listMetadataFormats->appendChild($metadataFormat);
+            $listMetadataFormats->appendChild(node: $metadataFormat);
 
-            $metadataPrefix = $document->createElement('metadataPrefix', $oaiFormat->getPrefix());
+            $metadataPrefix = $response->createElement(
-            $metadataFormat->appendChild($metadataPrefix);
+                localName: 'metadataPrefix',
+                value: $oaiFormat->getPrefix()
+            );
+            $metadataFormat->appendChild(node: $metadataPrefix);
 
-            $schema = $document->createElement('schema', $oaiFormat->getSchema());
+            $schema = $response->createElement(
-            $metadataFormat->appendChild($schema);
+                localName: 'schema',
+                value: $oaiFormat->getSchema()
+            );
+            $metadataFormat->appendChild(node: $schema);
 
-            $metadataNamespace = $document->createElement('metadataNamespace', $oaiFormat->getNamespace());
+            $metadataNamespace = $response->createElement(
-            $metadataFormat->appendChild($metadataNamespace);
+                localName: 'metadataNamespace',
+                value: $oaiFormat->getNamespace()
+            );
+            $metadataFormat->appendChild(node: $metadataNamespace);
         }
 
-        $this->preparedResponse = $document;
+        $this->preparedResponse = $response;
     }
 }

src/Middleware/ListRecords.php

@@ -24,6 +24,7 @@ namespace OCC\OaiPmh2\Middleware;
 
 /**
  * Process the "ListRecords" request.
+ *
  * @see https://www.openarchives.org/OAI/openarchivesprotocol.html#ListRecords
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
@@ -34,6 +35,6 @@ class ListRecords extends ListIdentifiers
     /**
      * "ListIdentifiers" and "ListRecords" are practically identical except the
      * former returns the header information only while the latter also returns
-     * the records' data.
+     * the records' data. Hence this is just a class alias.
      */
 }

src/Middleware/ListSets.php

@@ -22,21 +22,17 @@ declare(strict_types=1);
 
 namespace OCC\OaiPmh2\Middleware;
 
-use OCC\OaiPmh2\Configuration;
-use OCC\OaiPmh2\Database;
-use OCC\OaiPmh2\Document;
-use OCC\OaiPmh2\Entity\Set;
 use OCC\OaiPmh2\Middleware;
+use OCC\OaiPmh2\Response;
 use Psr\Http\Message\ServerRequestInterface;
 
 /**
  * Process the "ListSets" request.
+ *
  * @see https://openarchives.org/OAI/openarchivesprotocol.html#ListSets
  *
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
- *
- * @template Sets of array<string, Set>
  */
 class ListSets extends Middleware
 {
@@ -49,78 +45,52 @@ class ListSets extends Middleware
      */
     protected function prepareResponse(ServerRequestInterface $request): void
     {
-        $counter = 0;
+        $this->checkResumptionToken();
-        $completeListSize = 0;
-        $maxRecords = Configuration::getInstance()->maxRecords;
 
-        /** @var ?string */
+        $sets = $this->em->getSets(counter: $this->arguments['counter']);
-        $token = $request->getAttribute('resumptionToken');
-        if (isset($token)) {
-            $oldToken = Database::getInstance()->getResumptionToken($token, 'ListSets');
-            if (!isset($oldToken)) {
-                ErrorHandler::getInstance()->withError('badResumptionToken');
-                return;
-            } else {
-                foreach ($oldToken->getParameters() as $key => $value) {
-                    $$key = $value;
-                }
-            }
-        }
 
-        $sets = Database::getInstance()->getSets($counter);
-        $newToken = $sets->getResumptionToken();
         if (count($sets) === 0) {
-            ErrorHandler::getInstance()->withError('noSetHierarchy');
+            ErrorHandler::getInstance()->withError(errorCode: 'noSetHierarchy');
             return;
-        } elseif (isset($newToken)) {
-            $completeListSize = $newToken->getParameters()['completeListSize'];
         }
 
-        $document = new Document($request);
+        $response = new Response(serverRequest: $request);
-        $list = $document->createElement('ListSets', '', true);
+        $list = $response->createElement(
+            localName: 'ListSets',
+            value: '',
+            appendToRoot: true
+        );
 
-        /** @var Set $oaiSet */
         foreach ($sets as $oaiSet) {
-            $set = $document->createElement('set');
+            $set = $response->createElement(localName: 'set');
-            $list->appendChild($set);
+            $list->appendChild(node: $set);
 
-            $setSpec = $document->createElement('setSpec', $oaiSet->getSpec());
+            $setSpec = $response->createElement(
-            $set->appendChild($setSpec);
+                localName: 'setSpec',
+                value: $oaiSet->getSpec()
+            );
+            $set->appendChild(node: $setSpec);
 
-            $setName = $document->createElement('setName', $oaiSet->getName());
+            $setName = $response->createElement(
-            $set->appendChild($setName);
+                localName: 'setName',
+                value: $oaiSet->getName()
+            );
+            $set->appendChild(node: $setName);
 
             if ($oaiSet->hasDescription()) {
-                $setDescription = $document->createElement('setDescription');
+                $setDescription = $response->createElement(localName: 'setDescription');
-                $set->appendChild($setDescription);
+                $set->appendChild(node: $setDescription);
 
-                /** @var string */
+                $data = $response->importData(data: $oaiSet->getDescription());
-                $description = $oaiSet->getDescription();
+                $setDescription->appendChild(node: $data);
-                $data = $document->importData($description);
-                $setDescription->appendChild($data);
             }
         }
 
-        if (isset($oldToken) || isset($newToken)) {
+        $this->preparedResponse = $response;
-            $resumptionToken = $document->createElement('resumptionToken');
-            $list->appendChild($resumptionToken);
-            if (isset($newToken)) {
-                $resumptionToken->nodeValue = $newToken->getToken();
-                $resumptionToken->setAttribute(
-                    'expirationDate',
-                    $newToken->getValidUntil()->format('Y-m-d\TH:i:s\Z')
-                );
-            }
-            $resumptionToken->setAttribute(
-                'completeListSize',
-                (string) $completeListSize
-            );
-            $resumptionToken->setAttribute(
-                'cursor',
-                (string) ($counter * $maxRecords)
-            );
-        }
 
-        $this->preparedResponse = $document;
+        $this->addResumptionToken(
+            node: $list,
+            token: $sets->getResumptionToken() ?? null
+        );
     }
 }

src/Repository/FormatRepository.php

@@ -0,0 +1,72 @@
+<?php
+
+/**
+ * OAI-PMH 2.0 Data Provider
+ * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OCC\OaiPmh2\Repository;
+
+use Doctrine\ORM\EntityRepository;
+use OCC\OaiPmh2\Entity\Format;
+use OCC\OaiPmh2\EntityManager;
+
+/**
+ * Doctrine/ORM Repository for formats.
+ *
+ * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ * @package OAIPMH2
+ *
+ * @extends EntityRepository<Format>
+ */
+final class FormatRepository extends EntityRepository
+{
+    /**
+     * Add or update metadata format.
+     *
+     * @param Format $entity The metadata format
+     *
+     * @return void
+     */
+    public function addOrUpdate(Format $entity): void
+    {
+        $oldFormat = $this->find(id: $entity->getPrefix());
+        if (isset($oldFormat)) {
+            $oldFormat->setNamespace(namespace: $entity->getNamespace());
+            $oldFormat->setSchema(schema: $entity->getSchema());
+        } else {
+            $this->getEntityManager()->persist(object: $entity);
+        }
+    }
+
+    /**
+     * Delete metadata format and all associated records.
+     *
+     * @param Format $entity The metadata format
+     *
+     * @return void
+     */
+    public function delete(Format $entity): void
+    {
+        /** @var EntityManager */
+        $entityManager = $this->getEntityManager();
+        $entityManager->remove(object: $entity);
+        $entityManager->flush();
+        $entityManager->pruneOrphanedSets();
+    }
+}

src/Repository/RecordRepository.php

@@ -0,0 +1,103 @@
+<?php
+
+/**
+ * OAI-PMH 2.0 Data Provider
+ * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OCC\OaiPmh2\Repository;
+
+use DateTime;
+use Doctrine\ORM\EntityRepository;
+use OCC\OaiPmh2\Configuration;
+use OCC\OaiPmh2\Entity\Record;
+use OCC\OaiPmh2\EntityManager;
+
+/**
+ * Doctrine/ORM Repository for records.
+ *
+ * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ * @package OAIPMH2
+ *
+ * @extends EntityRepository<Record>
+ */
+final class RecordRepository extends EntityRepository
+{
+    /**
+     * Add or update record.
+     *
+     * @param Record $entity The record
+     *
+     * @return void
+     */
+    public function addOrUpdate(Record $entity): void
+    {
+        /** @var EntityManager */
+        $entityManager = $this->getEntityManager();
+        $oldRecord = $this->find(
+            id: [
+                'identifier' => $entity->getIdentifier(),
+                'format' => $entity->getFormat()
+            ]
+        );
+        if (isset($oldRecord)) {
+            if ($entity->hasContent() || Configuration::getInstance()->deletedRecords !== 'no') {
+                $oldRecord->setContent(data: $entity->getContent(), validate: false);
+                $oldRecord->setLastChanged(dateTime: $entity->getLastChanged());
+                $newSets = $entity->getSets()->toArray();
+                $oldSets = $oldRecord->getSets()->toArray();
+                // Add new sets.
+                foreach (array_diff(array: $newSets, arrays: $oldSets) as $newSet) {
+                    $oldRecord->addSet(set: $newSet);
+                }
+                // Remove old sets.
+                foreach (array_diff(array: $oldSets, arrays: $newSets) as $oldSet) {
+                    $oldRecord->removeSet(set: $oldSet);
+                }
+            } else {
+                $entityManager->remove(object: $oldRecord);
+            }
+        } else {
+            if ($entity->hasContent() || Configuration::getInstance()->deletedRecords !== 'no') {
+                $entityManager->persist(object: $entity);
+            }
+        }
+    }
+
+    /**
+     * Delete a record.
+     *
+     * @param Record $entity The record
+     *
+     * @return void
+     */
+    public function delete(Record $entity): void
+    {
+        /** @var EntityManager */
+        $entityManager = $this->getEntityManager();
+        if (Configuration::getInstance()->deletedRecords === 'no') {
+            $entityManager->remove(object: $entity);
+            $entityManager->flush();
+            $entityManager->pruneOrphanedSets();
+        } else {
+            $entity->setContent();
+            $entity->setLastChanged(dateTime: new DateTime());
+            $entityManager->flush();
+        }
+    }
+}

src/Repository/SetRepository.php

@@ -0,0 +1,71 @@
+<?php
+
+/**
+ * OAI-PMH 2.0 Data Provider
+ * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OCC\OaiPmh2\Repository;
+
+use Doctrine\ORM\EntityRepository;
+use OCC\OaiPmh2\Configuration;
+use OCC\OaiPmh2\Entity\Set;
+use OCC\OaiPmh2\ResultSet;
+
+/**
+ * Doctrine/ORM Repository for sets.
+ *
+ * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ * @package OAIPMH2
+ *
+ * @extends EntityRepository<Set>
+ */
+final class SetRepository extends EntityRepository
+{
+    /**
+     * Add or update set.
+     *
+     * @param Set $entity The set
+     *
+     * @return void
+     */
+    public function addOrUpdate(Set $entity): void
+    {
+        $oldSet = $this->find(id: $entity->getSpec());
+        if (isset($oldSet)) {
+            $oldSet->setName(name: $entity->getName());
+            $oldSet->setDescription(description: $entity->getDescription());
+        } else {
+            $this->getEntityManager()->persist(object: $entity);
+        }
+    }
+
+    /**
+     * Delete set.
+     *
+     * @param Set $entity The set
+     *
+     * @return void
+     */
+    public function delete(Set $entity): void
+    {
+        $entityManager = $this->getEntityManager();
+        $entityManager->remove(object: $entity);
+        $entityManager->flush();
+    }
+}

src/Repository/TokenRepository.php

@@ -0,0 +1,64 @@
+<?php
+
+/**
+ * OAI-PMH 2.0 Data Provider
+ * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OCC\OaiPmh2\Repository;
+
+use DateTime;
+use Doctrine\ORM\EntityRepository;
+use OCC\OaiPmh2\Entity\Token;
+
+/**
+ * Doctrine/ORM Repository for resumption tokens.
+ *
+ * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ * @package OAIPMH2
+ *
+ * @extends EntityRepository<Token>
+ */
+final class TokenRepository extends EntityRepository
+{
+    /**
+     * Add resumption token.
+     *
+     * @param Token $entity The resumption token
+     *
+     * @return void
+     */
+    public function addOrUpdate(Token $entity): void
+    {
+        $this->getEntityManager()->persist(object: $entity);
+    }
+
+    /**
+     * Delete resumption token.
+     *
+     * @param Token $entity The resumption token
+     *
+     * @return void
+     */
+    public function delete(Token $entity): void
+    {
+        $entityManager = $this->getEntityManager();
+        $entityManager->remove(object: $entity);
+        $entityManager->flush();
+    }
+}

src/Response.php

@@ -35,22 +35,17 @@ use Psr\Http\Message\ServerRequestInterface;
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
  */
-class Document
+final class Response
 {
     /**
      * This holds the DOMDocument of the OAI-PMH XML response.
      */
-    protected DOMDocument $dom;
+    private DOMDocument $dom;
 
     /**
      * This holds the root node of the OAI-PMH XML response.
      */
-    protected DOMElement $rootNode;
+    private DOMElement $rootNode;
-
-    /**
-     * This holds the current server request.
-     */
-    protected ServerRequestInterface $serverRequest;
 
     /**
      * Add XSL processing instructions to XML response document.
@@ -61,24 +56,24 @@ class Document
     {
         $uri = $this->serverRequest->getUri();
         $basePath = $uri->getPath();
-        if (str_ends_with($basePath, 'index.php')) {
+        if (str_ends_with(haystack: $basePath, needle: 'index.php')) {
-            $basePath = pathinfo($basePath, PATHINFO_DIRNAME);
+            $basePath = pathinfo(path: $basePath, flags: PATHINFO_DIRNAME);
         }
         $stylesheet = Uri::composeComponents(
-            $uri->getScheme(),
+            scheme: $uri->getScheme(),
-            $uri->getAuthority(),
+            authority: $uri->getAuthority(),
-            rtrim($basePath, '/') . '/resources/stylesheet.xsl',
+            path: rtrim(string: $basePath, characters: '/') . '/resources/stylesheet.xsl',
-            null,
+            query: null,
-            null
+            fragment: null
         );
         $xslt = $this->dom->createProcessingInstruction(
-            'xml-stylesheet',
+            target: 'xml-stylesheet',
-            sprintf(
+            data: sprintf(
-                'type="text/xsl" href="%s"',
+                format: 'type="text/xsl" href="%s"',
-                $stylesheet
+                values: $stylesheet
             )
         );
-        $this->dom->appendChild($xslt);
+        $this->dom->appendChild(node: $xslt);
     }
 
     /**
@@ -90,20 +85,27 @@ class Document
     {
         $uri = $this->serverRequest->getUri();
         $baseUrl = Uri::composeComponents(
-            $uri->getScheme(),
+            scheme: $uri->getScheme(),
-            $uri->getAuthority(),
+            authority: $uri->getAuthority(),
-            $uri->getPath(),
+            path: $uri->getPath(),
-            null,
+            query: null,
-            null
+            fragment: null
+        );
+        $request = $this->createElement(
+            localName: 'request',
+            value: $baseUrl,
+            appendToRoot: true
         );
-        $request = $this->dom->createElement('request', $baseUrl);
-        $this->rootNode->appendChild($request);
         /** @var array<string, string> */
         $params = $this->serverRequest->getAttributes();
         foreach ($params as $param => $value) {
             $request->setAttribute(
-                $param,
+                qualifiedName: $param,
-                htmlspecialchars($value, ENT_XML1 | ENT_COMPAT, 'UTF-8')
+                value: htmlspecialchars(
+                    string: $value,
+                    flags: ENT_XML1 | ENT_COMPAT,
+                    encoding: 'UTF-8'
+                )
             );
         }
     }
@@ -115,8 +117,11 @@ class Document
      */
     protected function appendResponseDate(): void
     {
-        $responseDate = $this->dom->createElement('responseDate', gmdate('Y-m-d\TH:i:s\Z'));
+        $this->createElement(
-        $this->rootNode->appendChild($responseDate);
+            localName: 'responseDate',
+            value: gmdate(format: 'Y-m-d\TH:i:s\Z'),
+            appendToRoot: true
+        );
     }
 
     /**
@@ -126,20 +131,20 @@ class Document
      */
     protected function appendRootElement(): void
     {
-        $this->rootNode = $this->dom->createElement('OAI-PMH');
+        $this->rootNode = $this->dom->createElement(localName: 'OAI-PMH');
         $this->rootNode->setAttribute(
-            'xmlns',
+            qualifiedName: 'xmlns',
-            'http://www.openarchives.org/OAI/2.0/'
+            value: 'http://www.openarchives.org/OAI/2.0/'
         );
         $this->rootNode->setAttribute(
-            'xmlns:xsi',
+            qualifiedName: 'xmlns:xsi',
-            'http://www.w3.org/2001/XMLSchema-instance'
+            value: 'http://www.w3.org/2001/XMLSchema-instance'
         );
         $this->rootNode->setAttribute(
-            'xsi:schemaLocation',
+            qualifiedName: 'xsi:schemaLocation',
-            'http://www.openarchives.org/OAI/2.0/ https://www.openarchives.org/OAI/2.0/OAI-PMH.xsd'
+            value: 'http://www.openarchives.org/OAI/2.0/ https://www.openarchives.org/OAI/2.0/OAI-PMH.xsd'
         );
-        $this->dom->appendChild($this->rootNode);
+        $this->dom->appendChild(node: $this->rootNode);
     }
 
     /**
@@ -149,7 +154,7 @@ class Document
      */
     protected function createDocument(): void
     {
-        $this->dom = new DOMDocument('1.0', 'UTF-8');
+        $this->dom = new DOMDocument(version: '1.0', encoding: 'UTF-8');
         $this->dom->preserveWhiteSpace = false;
         $this->addProcessingInstructions();
     }
@@ -166,11 +171,15 @@ class Document
     public function createElement(string $localName, string $value = '', bool $appendToRoot = false): DOMElement
     {
         $node = $this->dom->createElement(
-            $localName,
+            localName: $localName,
-            htmlspecialchars($value, ENT_XML1, 'UTF-8')
+            value: htmlspecialchars(
+                string: $value,
+                flags: ENT_XML1,
+                encoding: 'UTF-8'
+            )
         );
         if ($appendToRoot) {
-            $this->rootNode->appendChild($node);
+            $this->rootNode->appendChild(node: $node);
         }
         return $node;
     }
@@ -182,21 +191,21 @@ class Document
      *
      * @return DOMNode The imported XML node
      *
-     * @throws DOMException
+     * @throws DOMException if the data cannot be imported
      */
     public function importData(string $data): DOMNode
     {
-        $document = new DOMDocument('1.0', 'UTF-8');
+        $document = new DOMDocument(version: '1.0', encoding: 'UTF-8');
         $document->preserveWhiteSpace = false;
-        if ($document->loadXML($data) === true) {
+        if ($document->loadXML(source: $data) === true) {
             /** @var DOMElement */
             $rootNode = $document->documentElement;
-            $node = $this->dom->importNode($rootNode, true);
+            $node = $this->dom->importNode(node: $rootNode, deep: true);
             return $node;
         } else {
             throw new DOMException(
-                'Could not import the XML data. Most likely it is not well-formed.',
+                message: 'Could not import the XML data. Most likely it is not well-formed.',
-                500
+                code: 500
             );
         }
     }
@@ -206,9 +215,8 @@ class Document
      *
      * @param ServerRequestInterface $serverRequest The PSR-7 HTTP Server Request
      */
-    public function __construct(ServerRequestInterface $serverRequest)
+    public function __construct(private ServerRequestInterface $serverRequest)
     {
-        $this->serverRequest = $serverRequest;
         $this->createDocument();
         $this->appendRootElement();
         $this->appendResponseDate();

src/ResultSet.php

@@ -22,13 +22,7 @@ declare(strict_types=1);
 
 namespace OCC\OaiPmh2;
 
-use Countable;
+use Doctrine\Common\Collections\ArrayCollection;
-use Iterator;
-use OCC\Basics\InterfaceTraits\Countable as CountableTrait;
-use OCC\Basics\InterfaceTraits\Iterator as IteratorTrait;
-use OCC\OaiPmh2\Entity\Format;
-use OCC\OaiPmh2\Entity\Record;
-use OCC\OaiPmh2\Entity\Set;
 use OCC\OaiPmh2\Entity\Token;
 
 /**
@@ -37,35 +31,15 @@ use OCC\OaiPmh2\Entity\Token;
  * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
  * @package OAIPMH2
  *
- * @template QueryResult of array<string, Format|Record|Set>
+ * @template TEntity of Entity
- * @implements Iterator<QueryResult>
+ * @extends ArrayCollection<string, TEntity>
  */
-class Result implements Countable, Iterator
+final class ResultSet extends ArrayCollection
 {
-    use CountableTrait;
-    use IteratorTrait;
-
-    /**
-     * This holds the Doctrine result set.
-     *
-     * @var QueryResult
-     */
-    private array $data;
-
     /**
      * This holds the optional resumption token.
      */
-    protected ?Token $resumptionToken = null;
+    private ?Token $resumptionToken;
-
-    /**
-     * Get the query result.
-     *
-     * @return QueryResult The result set
-     */
-    public function getQueryResult(): array
-    {
-        return $this->data;
-    }
 
     /**
      * Get the resumption token.
@@ -92,10 +66,12 @@ class Result implements Countable, Iterator
     /**
      * Create new result set.
      *
-     * @param QueryResult $queryResult The Doctrine result set
+     * @param array<string, TEntity> $elements Array of entities
+     * @param Token $token Optional resumption token
      */
-    public function __construct(array $queryResult)
+    public function __construct(array $elements = [], Token $token = null)
     {
-        $this->data = $queryResult;
+        parent::__construct(elements: $elements);
+        $this->resumptionToken = $token;
     }
 }

src/Validator/ConfigurationValidator.php

@@ -0,0 +1,114 @@
+<?php
+
+/**
+ * OAI-PMH 2.0 Data Provider
+ * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OCC\OaiPmh2\Validator;
+
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\Constraints as Assert;
+use Symfony\Component\Validator\ConstraintViolationListInterface;
+use Symfony\Component\Validator\Validation;
+
+/**
+ * Validator for configuration settings.
+ *
+ * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ * @package OAIPMH2
+ */
+class ConfigurationValidator
+{
+    /**
+     * Get constraints for configuration array.
+     *
+     * @return array<Constraint> The collection of constraints
+     */
+    protected static function getValidationConstraints(): array
+    {
+        return [
+            new Assert\Collection(
+                fields: [
+                    'repositoryName' => [
+                        new Assert\Type(type: 'string'),
+                        new Assert\NotBlank()
+                    ],
+                    'adminEmail' => [
+                        new Assert\Type(type: 'string'),
+                        new Assert\Email(options: ['mode' => 'html5']),
+                        new Assert\NotBlank()
+                    ],
+                    'database' => [
+                        new Assert\Type(type: 'string'),
+                        new Assert\NotBlank()
+                    ],
+                    'metadataPrefix' => [
+                        new Assert\Type(type: 'array'),
+                        new Assert\All(
+                            constraints: [
+                                new Assert\Collection(
+                                    fields: [
+                                        'schema' => [
+                                            new Assert\Type(type: 'string'),
+                                            new Assert\Url(),
+                                            new Assert\NotBlank()
+                                        ],
+                                        'namespace' => [
+                                            new Assert\Type(type: 'string'),
+                                            new Assert\Url(),
+                                            new Assert\NotBlank()
+                                        ]
+                                    ]
+                                )
+                            ]
+                        )
+                    ],
+                    'deletedRecords' => [
+                        new Assert\Type(type: 'string'),
+                        new Assert\Choice(options: ['no', 'persistent', 'transient']),
+                        new Assert\NotBlank()
+                    ],
+                    'maxRecords' => [
+                        new Assert\Type(type: 'int'),
+                        new Assert\Range(options: ['min' => 1, 'max' => 100])
+                    ],
+                    'tokenValid' => [
+                        new Assert\Type(type: 'int'),
+                        new Assert\Range(options: ['min' => 300, 'max' => 86400])
+                    ]
+                ]
+            )
+        ];
+    }
+
+    /**
+     * Validate the given configuration array.
+     *
+     * @param array<array-key, mixed> $config The configuration array to validate
+     *
+     * @return ConstraintViolationListInterface The list of violations
+     */
+    public static function validate(array $config): ConstraintViolationListInterface
+    {
+        return Validation::createValidator()->validate(
+            value: $config,
+            constraints: self::getValidationConstraints()
+        );
+    }
+}

src/Validator/RegExValidator.php

@@ -0,0 +1,72 @@
+<?php
+
+/**
+ * OAI-PMH 2.0 Data Provider
+ * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OCC\OaiPmh2\Validator;
+
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\Constraints as Assert;
+use Symfony\Component\Validator\ConstraintViolationListInterface;
+use Symfony\Component\Validator\Validation;
+
+/**
+ * Validator for Regular Expressions.
+ *
+ * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ * @package OAIPMH2
+ */
+class RegExValidator
+{
+    /**
+     * Get constraints for regular expression.
+     *
+     * @param string $regEx The regular expression for validation
+     *
+     * @return array<Constraint> The array of constraints
+     */
+    protected static function getValidationConstraints(string $regEx): array
+    {
+        return [
+            new Assert\Regex(
+                pattern: [
+                    'pattern' => $regEx,
+                    'message' => 'This value does not match the regular expression "{{ pattern }}".'
+                ]
+            )
+        ];
+    }
+
+    /**
+     * Check if a string matches a given regular expression.
+     *
+     * @param string $string The string
+     * @param string $regEx The regular expression
+     *
+     * @return ConstraintViolationListInterface The list of violations
+     */
+    public static function validate(string $string, string $regEx): ConstraintViolationListInterface
+    {
+        return Validation::createValidator()->validate(
+            value: $string,
+            constraints: self::getValidationConstraints(regEx: $regEx)
+        );
+    }
+}

src/Validator/UrlValidator.php

@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * OAI-PMH 2.0 Data Provider
+ * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OCC\OaiPmh2\Validator;
+
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\Constraints as Assert;
+use Symfony\Component\Validator\ConstraintViolationListInterface;
+use Symfony\Component\Validator\Validation;
+
+/**
+ * Validator for URLs.
+ *
+ * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ * @package OAIPMH2
+ */
+class UrlValidator
+{
+    /**
+     * Get constraints for URLs.
+     *
+     * @return array<Constraint> The array of constraints
+     */
+    protected static function getValidationConstraints(): array
+    {
+        return [
+            new Assert\Url(),
+            new Assert\NotBlank()
+        ];
+    }
+
+    /**
+     * Check if the given string is a valid URL.
+     *
+     * @param string $url The URL
+     *
+     * @return ConstraintViolationListInterface The list of violations
+     */
+    public static function validate(string $url): ConstraintViolationListInterface
+    {
+        return Validation::createValidator()->validate(
+            value: $url,
+            constraints: self::getValidationConstraints()
+        );
+    }
+}

src/Validator/XmlValidator.php

@@ -0,0 +1,79 @@
+<?php
+
+/**
+ * OAI-PMH 2.0 Data Provider
+ * Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace OCC\OaiPmh2\Validator;
+
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\Constraints as Assert;
+use Symfony\Component\Validator\ConstraintViolation;
+use Symfony\Component\Validator\ConstraintViolationListInterface;
+use Symfony\Component\Validator\Validation;
+
+/**
+ * Validator for XML.
+ *
+ * @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
+ * @package OAIPMH2
+ */
+class XmlValidator
+{
+    /**
+     * Get constraints for XML.
+     *
+     * @return array<Constraint> The array of constraints
+     */
+    protected static function getValidationConstraints(): array
+    {
+        return [
+            new Assert\Type(type: 'string'),
+            new Assert\NotBlank()
+        ];
+    }
+
+    /**
+     * Check if the given string is valid XML.
+     *
+     * @param string $xml The XML string
+     *
+     * @return ConstraintViolationListInterface The list of violations
+     */
+    public static function validate(string $xml): ConstraintViolationListInterface
+    {
+        $violations = Validation::createValidator()->validate(
+            value: $xml,
+            constraints: self::getValidationConstraints()
+        );
+        if (simplexml_load_string(data: $xml) === false) {
+            $violations->add(
+                violation: new ConstraintViolation(
+                    message: 'Value could not be parsed as XML.',
+                    messageTemplate: 'Value could not be parsed as XML.',
+                    parameters: [],
+                    root: $xml,
+                    propertyPath: null,
+                    invalidValue: $xml
+                )
+            );
+        }
+        return $violations;
+    }
+}