1 files changed, 168 insertions, 0 deletions
diff --git a/lib/private/Migration/MetadataManager.php b/lib/private/Migration/MetadataManager.php
new file mode 100644
index 00000000000..f4cb95342b4
--- /dev/null
+++ b/lib/private/Migration/MetadataManager.php
@@ -0,0 +1,168 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\Migration;
+
+use OC\DB\Connection;
+use OC\DB\MigrationService;
+use OC\Migration\Exceptions\AttributeException;
+use OCP\App\IAppManager;
+use OCP\Migration\Attributes\GenericMigrationAttribute;
+use OCP\Migration\Attributes\MigrationAttribute;
+use Psr\Log\LoggerInterface;
+use ReflectionClass;
+
+/**
+ * Helps managing DB Migrations' Metadata
+ *
+ * @since 30.0.0
+ */
+class MetadataManager {
+	public function __construct(
+		private readonly IAppManager $appManager,
+		private readonly Connection $connection,
+		private readonly LoggerInterface $logger,
+	) {
+	}
+
+	/**
+	 * We get all migrations from an app (or 'core'), and
+	 * for each migration files we extract its attributes
+	 *
+	 * @param string $appId
+	 *
+	 * @return array<string, MigrationAttribute[]>
+	 * @since 30.0.0
+	 */
+	public function extractMigrationAttributes(string $appId): array {
+		$ms = new MigrationService($appId, $this->connection);
+
+		$metadata = [];
+		foreach ($ms->getAvailableVersions() as $version) {
+			$metadata[$version] = [];
+			$class = new ReflectionClass($ms->createInstance($version));
+			$attributes = $class->getAttributes();
+			foreach ($attributes as $attribute) {
+				$item = $attribute->newInstance();
+				if ($item instanceof MigrationAttribute) {
+					$metadata[$version][] = $item;
+				}
+			}
+		}
+
+		return $metadata;
+	}
+
+	/**
+	 * convert direct data from release metadata into a list of Migrations' Attribute
+	 *
+	 * @param array<array-key, array<array-key, array>> $metadata
+	 * @param bool $filterKnownMigrations ignore metadata already done in local instance
+	 *
+	 * @return array{apps: array<array-key, array<string, MigrationAttribute[]>>, core: array<string, MigrationAttribute[]>}
+	 * @since 30.0.0
+	 */
+	public function getMigrationsAttributesFromReleaseMetadata(
+		array $metadata,
+		bool $filterKnownMigrations = false,
+	): array {
+		$appsAttributes = [];
+		foreach (array_keys($metadata['apps']) as $appId) {
+			if ($filterKnownMigrations && !$this->appManager->isEnabledForAnyone($appId)) {
+				continue; // if not interested and app is not installed
+			}
+
+			$done = ($filterKnownMigrations) ? $this->getKnownMigrations($appId) : [];
+			$appsAttributes[$appId] = $this->parseMigrations($metadata['apps'][$appId] ?? [], $done);
+		}
+
+		$done = ($filterKnownMigrations) ? $this->getKnownMigrations('core') : [];
+		return [
+			'core' => $this->parseMigrations($metadata['core'] ?? [], $done),
+			'apps' => $appsAttributes
+		];
+	}
+
+	/**
+	 * returns list of installed apps that does not support migrations metadata (yet)
+	 *
+	 * @param array<array-key, array<array-key, array>> $metadata
+	 *
+	 * @return string[]
+	 * @since 30.0.0
+	 */
+	public function getUnsupportedApps(array $metadata): array {
+		return array_values(array_diff($this->appManager->getEnabledApps(), array_keys($metadata['apps'])));
+	}
+
+	/**
+	 * convert raw data to a list of MigrationAttribute
+	 *
+	 * @param array $migrations
+	 * @param array $ignoreMigrations
+	 *
+	 * @return array<string, MigrationAttribute[]>
+	 */
+	private function parseMigrations(array $migrations, array $ignoreMigrations = []): array {
+		$parsed = [];
+		foreach (array_keys($migrations) as $entry) {
+			if (in_array($entry, $ignoreMigrations)) {
+				continue;
+			}
+
+			$parsed[$entry] = [];
+			foreach ($migrations[$entry] as $item) {
+				try {
+					$parsed[$entry][] = $this->createAttribute($item);
+				} catch (AttributeException $e) {
+					$this->logger->warning('exception while trying to create attribute', ['exception' => $e, 'item' => json_encode($item)]);
+					$parsed[$entry][] = new GenericMigrationAttribute($item);
+				}
+			}
+		}
+
+		return $parsed;
+	}
+
+	/**
+	 * returns migrations already done
+	 *
+	 * @param string $appId
+	 *
+	 * @return array
+	 * @throws \Exception
+	 */
+	private function getKnownMigrations(string $appId): array {
+		$ms = new MigrationService($appId, $this->connection);
+		return $ms->getMigratedVersions();
+	}
+
+	/**
+	 * generate (deserialize) a MigrationAttribute from a serialized version
+	 *
+	 * @param array $item
+	 *
+	 * @return MigrationAttribute
+	 * @throws AttributeException
+	 */
+	private function createAttribute(array $item): MigrationAttribute {
+		$class = $item['class'] ?? '';
+		$namespace = 'OCP\Migration\Attributes\\';
+		if (!str_starts_with($class, $namespace)
+			|| !ctype_alpha(substr($class, strlen($namespace)))) {
+			throw new AttributeException('class name does not looks valid');
+		}
+
+		try {
+			$attribute = new $class($item['table'] ?? '');
+			return $attribute->import($item);
+		} catch (\Error) {
+			throw new AttributeException('cannot import Attribute');
+		}
+	}
+}