1 files changed, 173 insertions, 0 deletions
diff --git a/lib/private/DB/Migrator.php b/lib/private/DB/Migrator.php
new file mode 100644
index 00000000000..40f8ad9676a
--- /dev/null
+++ b/lib/private/DB/Migrator.php
@@ -0,0 +1,173 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\DB;
+
+use Doctrine\DBAL\Connection;
+use Doctrine\DBAL\Exception;
+use Doctrine\DBAL\Platforms\MySQLPlatform;
+use Doctrine\DBAL\Schema\AbstractAsset;
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\DBAL\Schema\SchemaDiff;
+use Doctrine\DBAL\Types\StringType;
+use Doctrine\DBAL\Types\Type;
+use OCP\EventDispatcher\IEventDispatcher;
+use OCP\IConfig;
+use function preg_match;
+
+class Migrator {
+	/** @var Connection */
+	protected $connection;
+
+	/** @var IConfig */
+	protected $config;
+
+	private ?IEventDispatcher $dispatcher;
+
+	/** @var bool */
+	private $noEmit = false;
+
+	public function __construct(Connection $connection,
+		IConfig $config,
+		?IEventDispatcher $dispatcher = null) {
+		$this->connection = $connection;
+		$this->config = $config;
+		$this->dispatcher = $dispatcher;
+	}
+
+	/**
+	 * @throws Exception
+	 */
+	public function migrate(Schema $targetSchema) {
+		$this->noEmit = true;
+		$this->applySchema($targetSchema);
+	}
+
+	/**
+	 * @return string
+	 */
+	public function generateChangeScript(Schema $targetSchema) {
+		$schemaDiff = $this->getDiff($targetSchema, $this->connection);
+
+		$script = '';
+		$sqls = $this->connection->getDatabasePlatform()->getAlterSchemaSQL($schemaDiff);
+		foreach ($sqls as $sql) {
+			$script .= $this->convertStatementToScript($sql);
+		}
+
+		return $script;
+	}
+
+	/**
+	 * @throws Exception
+	 */
+	public function createSchema() {
+		$this->connection->getConfiguration()->setSchemaAssetsFilter(function ($asset) {
+			/** @var string|AbstractAsset $asset */
+			$filterExpression = $this->getFilterExpression();
+			if ($asset instanceof AbstractAsset) {
+				return preg_match($filterExpression, $asset->getName()) === 1;
+			}
+			return preg_match($filterExpression, $asset) === 1;
+		});
+		return $this->connection->createSchemaManager()->introspectSchema();
+	}
+
+	/**
+	 * @return SchemaDiff
+	 */
+	protected function getDiff(Schema $targetSchema, Connection $connection) {
+		// Adjust STRING columns with a length higher than 4000 to TEXT (clob)
+		// for consistency between the supported databases and
+		// old vs. new installations.
+		foreach ($targetSchema->getTables() as $table) {
+			foreach ($table->getColumns() as $column) {
+				if ($column->getType() instanceof StringType) {
+					if ($column->getLength() > 4000) {
+						$column->setType(Type::getType('text'));
+						$column->setLength(null);
+					}
+				}
+			}
+		}
+
+		$this->connection->getConfiguration()->setSchemaAssetsFilter(function ($asset) {
+			/** @var string|AbstractAsset $asset */
+			$filterExpression = $this->getFilterExpression();
+			if ($asset instanceof AbstractAsset) {
+				return preg_match($filterExpression, $asset->getName()) === 1;
+			}
+			return preg_match($filterExpression, $asset) === 1;
+		});
+		$sourceSchema = $connection->createSchemaManager()->introspectSchema();
+
+		// remove tables we don't know about
+		foreach ($sourceSchema->getTables() as $table) {
+			if (!$targetSchema->hasTable($table->getName())) {
+				$sourceSchema->dropTable($table->getName());
+			}
+		}
+		// remove sequences we don't know about
+		foreach ($sourceSchema->getSequences() as $table) {
+			if (!$targetSchema->hasSequence($table->getName())) {
+				$sourceSchema->dropSequence($table->getName());
+			}
+		}
+
+		$comparator = $connection->createSchemaManager()->createComparator();
+		return $comparator->compareSchemas($sourceSchema, $targetSchema);
+	}
+
+	/**
+	 * @throws Exception
+	 */
+	protected function applySchema(Schema $targetSchema, ?Connection $connection = null) {
+		if (is_null($connection)) {
+			$connection = $this->connection;
+		}
+
+		$schemaDiff = $this->getDiff($targetSchema, $connection);
+
+		if (!$connection->getDatabasePlatform() instanceof MySQLPlatform) {
+			$connection->beginTransaction();
+		}
+		$sqls = $connection->getDatabasePlatform()->getAlterSchemaSQL($schemaDiff);
+		$step = 0;
+		foreach ($sqls as $sql) {
+			$this->emit($sql, $step++, count($sqls));
+			$connection->executeStatement($sql);
+		}
+		if (!$connection->getDatabasePlatform() instanceof MySQLPlatform) {
+			$connection->commit();
+		}
+	}
+
+	/**
+	 * @param $statement
+	 * @return string
+	 */
+	protected function convertStatementToScript($statement) {
+		$script = $statement . ';';
+		$script .= PHP_EOL;
+		$script .= PHP_EOL;
+		return $script;
+	}
+
+	protected function getFilterExpression() {
+		return '/^' . preg_quote($this->config->getSystemValueString('dbtableprefix', 'oc_'), '/') . '/';
+	}
+
+	protected function emit(string $sql, int $step, int $max): void {
+		if ($this->noEmit) {
+			return;
+		}
+		if (is_null($this->dispatcher)) {
+			return;
+		}
+		$this->dispatcher->dispatchTyped(new MigratorExecuteSqlEvent($sql, $step, $max));
+	}
+}