<?php
  /**
   * Copyright (c) 2012 Bart Visscher <bartv@thisnet.nl>
   * This file is licensed under the Affero General Public License version 3 or
   * later.
   * See the COPYING-README file.
   */
  
  namespace OC\DB;

  use Doctrine\DBAL\Platforms\MySqlPlatform;
  use Doctrine\DBAL\Platforms\OraclePlatform;
  use Doctrine\DBAL\Platforms\PostgreSqlPlatform;
  use Doctrine\DBAL\Platforms\SqlitePlatform;

  class MDB2SchemaManager {
  	/**
  	 * @var \OC\DB\Connection $conn
  	 */
  	protected $conn;
  
  	/**
  	 * @param \OC\DB\Connection $conn
  	 */
  	public function __construct($conn) {
  		$this->conn = $conn;

  	}
  
  	/**

  	 * saves database scheme to xml file

  	 * @param string $file name of file
  	 * @param int|string $mode
  	 * @return bool
  	 *
  	 * TODO: write more documentation
  	 */

  	public function getDbStructure($file, $mode = MDB2_SCHEMA_DUMP_STRUCTURE) {

  		$sm = $this->conn->getSchemaManager();
  
  		return \OC_DB_MDB2SchemaWriter::saveSchemaToFile($file, $sm);
  	}
  
  	/**

  	 * Creates tables from XML file

  	 * @param string $file file to read structure from
  	 * @return bool
  	 *
  	 * TODO: write more documentation
  	 */

  	public function createDbFromStructure($file) {

  		$schemaReader = new MDB2SchemaReader(\OC_Config::getObject(), $this->conn->getDatabasePlatform());
  		$toSchema = $schemaReader->loadSchemaFromFile($file);
  		return $this->executeSchemaChange($toSchema);
  	}
  
  	/**

  	 * @return \OC\DB\Migrator

  	 */

  	public function getMigrator() {
  		$platform = $this->conn->getDatabasePlatform();
  		if ($platform instanceof SqlitePlatform) {
  			$config = \OC::$server->getConfig();
  			return new SQLiteMigrator($this->conn, $config);
  		} else if ($platform instanceof OraclePlatform) {
  			return new OracleMigrator($this->conn);
  		} else if ($platform instanceof MySqlPlatform) {
  			return new MySQLMigrator($this->conn);
  		} else if ($platform instanceof PostgreSqlPlatform) {
  			return new Migrator($this->conn);
  		} else {
  			return new NoCheckMigrator($this->conn);

  		}

  	}

  	/**
  	 * Reads database schema from file
  	 *
  	 * @param string $file file to read from
  	 */
  	private function readSchemaFromFile($file) {

  		$platform = $this->conn->getDatabasePlatform();

  		$schemaReader = new MDB2SchemaReader(\OC_Config::getObject(), $platform);
  		return $schemaReader->loadSchemaFromFile($file);
  	}
  
  	/**
  	 * update the database scheme
  	 * @param string $file file to read structure from
  	 * @param bool $generateSql only return the sql needed for the upgrade
  	 * @return string|boolean
  	 */
  	public function updateDbFromStructure($file, $generateSql = false) {
  		$toSchema = $this->readSchemaFromFile($file);
  		$migrator = $this->getMigrator();

  		if ($generateSql) {

  			return $migrator->generateChangeScript($toSchema);
  		} else {
  			$migrator->migrate($toSchema);
  			return true;

  		}

  	}

  	/**
  	 * update the database scheme
  	 * @param string $file file to read structure from
  	 * @return string|boolean
  	 */
  	public function simulateUpdateDbFromStructure($file) {
  		$toSchema = $this->readSchemaFromFile($file);
  		$this->getMigrator()->checkMigrate($toSchema);
  		return true;

  	}
  
  	/**

  	 * @param \Doctrine\DBAL\Schema\Schema $schema
  	 * @return string

  	 */

  	public function generateChangeScript($schema) {
  		$migrator = $this->getMigrator();
  		return $migrator->generateChangeScript($schema);

  	}
  
  	/**
  	 * remove all tables defined in a database structure xml file

  	 *

  	 * @param string $file the xml file describing the tables
  	 */
  	public function removeDBStructure($file) {
  		$schemaReader = new MDB2SchemaReader(\OC_Config::getObject(), $this->conn->getDatabasePlatform());
  		$fromSchema = $schemaReader->loadSchemaFromFile($file);
  		$toSchema = clone $fromSchema;
  		/** @var $table \Doctrine\DBAL\Schema\Table */

  		foreach ($toSchema->getTables() as $table) {

  			$toSchema->dropTable($table->getName());
  		}
  		$comparator = new \Doctrine\DBAL\Schema\Comparator();
  		$schemaDiff = $comparator->compare($fromSchema, $toSchema);
  		$this->executeSchemaChange($schemaDiff);
  	}
  
  	/**

  	 * @param \Doctrine\DBAL\Schema\Schema $schema
  	 * @return bool
  	 */
  	private function executeSchemaChange($schema) {
  		$this->conn->beginTransaction();

  		foreach ($schema->toSql($this->conn->getDatabasePlatform()) as $sql) {

  			$this->conn->query($sql);
  		}
  		$this->conn->commit();

  		if ($this->conn->getDatabasePlatform() instanceof SqlitePlatform) {
  			\OC_DB::reconnect();

  		}

  		return true;

  	}
  }