<?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;
  
  class MDB2SchemaManager {
  	/**
  	 * @var \OC\DB\Connection $conn
  	 */
  	protected $conn;
  
  	/**
  	 * @param \OC\DB\Connection $conn
  	 */
  	public function __construct($conn) {
  		$this->conn = $conn;
  		$this->conn->close();
  		$this->conn->connect();
  	}
  
  	/**
  	 * @brief 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);
  	}
  
  	/**
  	 * @brief 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);
  	}
  
  	/**
  	 * @brief update the database scheme
  	 * @param string $file file to read structure from
  	 * @return bool
  	 */
  	public function updateDbFromStructure($file, $generateSql = false) {
  		$sm = $this->conn->getSchemaManager();
  		$fromSchema = $sm->createSchema();
  
  		$schemaReader = new MDB2SchemaReader(\OC_Config::getObject(), $this->conn->getDatabasePlatform());
  		$toSchema = $schemaReader->loadSchemaFromFile($file);
  
  		// remove tables we don't know about
  		/** @var $table \Doctrine\DBAL\Schema\Table */
  		foreach($fromSchema->getTables() as $table) {
  			if (!$toSchema->hasTable($table->getName())) {
  				$fromSchema->dropTable($table->getName());
  			}
  		}
  		// remove sequences we don't know about
  		foreach($fromSchema->getSequences() as $table) {
  			if (!$toSchema->hasSequence($table->getName())) {
  				$fromSchema->dropSequence($table->getName());
  			}
  		}
  
  		$comparator = new \Doctrine\DBAL\Schema\Comparator();
  		$schemaDiff = $comparator->compare($fromSchema, $toSchema);
  
  		$platform = $this->conn->getDatabasePlatform();
  		foreach($schemaDiff->changedTables as $tableDiff) {
  			$tableDiff->name = $platform->quoteIdentifier($tableDiff->name);
  		}
  		
  		if ($generateSql) {
  			return $this->generateChangeScript($schemaDiff);
  		}
  
  		return $this->executeSchemaChange($schemaDiff);
  	}
  
  	/**
  	 * @brief drop a table
  	 * @param string $tableName the table to drop
  	 */
  	public function dropTable($tableName) {
  		$sm = $this->conn->getSchemaManager();
  		$fromSchema = $sm->createSchema();
  		$toSchema = clone $fromSchema;
  		$toSchema->dropTable($tableName);
  		$sql = $fromSchema->getMigrateToSql($toSchema, $this->conn->getDatabasePlatform());
  		$this->conn->executeQuery($sql);
  	}
  
  	/**
  	 * 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);
  	}
  
  	/**
  	 * @brief replaces the ownCloud tables with a new set
  	 * @param $file string path to the MDB2 xml db export file
  	 */
  	public function replaceDB( $file ) {
  		$apps = \OC_App::getAllApps();
  		$this->conn->beginTransaction();
  		// Delete the old tables
  		$this->removeDBStructure( \OC::$SERVERROOT . '/db_structure.xml' );
  
  		foreach($apps as $app) {
  			$path = \OC_App::getAppPath($app).'/appinfo/database.xml';
  			if(file_exists($path)) {
  				$this->removeDBStructure( $path );
  			}
  		}
  
  		// Create new tables
  		$this->conn->commit();
  	}
  
  	/**
  	 * @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();
  		return true;
  	}
  
  	/**
  	 * @param \Doctrine\DBAL\Schema\Schema $schema
  	 * @return string
  	 */
  	public function generateChangeScript($schema) {
  
  		$script = '';
  		$sqls = $schema->toSql($this->conn->getDatabasePlatform());
  		foreach($sqls as $sql) {
  			$script .= $sql . ';';
  			$script .= PHP_EOL;
  		}
  
  		return $script;
  	}
  }