<?php
/**
 * CMysqlSchema class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright Copyright &copy; 2008-2011 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CMysqlSchema is the class for retrieving metadata information from a MySQL database (version 4.1.x and 5.x).
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id: CMysqlSchema.php 3304 2011-06-23 14:53:50Z qiang.xue $
 * @package system.db.schema.mysql
 * @since 1.0
 */
class CMysqlSchema extends CDbSchema
{
	/**
	 * @var array the abstract column types mapped to physical column types.
	 * @since 1.1.6
	 */
    public $columnTypes = array(
        'pk' => 'int(11) NOT NULL AUTO_INCREMENT PRIMARY KEY',
        'string' => 'varchar(255)',
        'text' => 'text',
        'integer' => 'int(11)',
        'float' => 'float',
        'decimal' => 'decimal',
        'datetime' => 'datetime',
        'timestamp' => 'timestamp',
        'time' => 'time',
        'date' => 'date',
        'binary' => 'blob',
        'boolean' => 'tinyint(1)',
		'money' => 'decimal(19,4)',
    );

	/**
	 * Quotes a table name for use in a query.
	 * A simple table name does not schema prefix.
	 * @param string $name table name
	 * @return string the properly quoted table name
	 * @since 1.1.6
	 */
	public function quoteSimpleTableName($name)
	{
		return '`' . $name . '`';
	}

	/**
	 * Quotes a column name for use in a query.
	 * A simple column name does not contain prefix.
	 * @param string $name column name
	 * @return string the properly quoted column name
	 * @since 1.1.6
	 */
	public function quoteSimpleColumnName($name)
	{
		return '`' . $name . '`';
	}

	/**
	 * Compares two table names.
	 * The table names can be either quoted or unquoted. This method
	 * will consider both cases.
	 * @param string $name1 table name 1
	 * @param string $name2 table name 2
	 * @return boolean whether the two table names refer to the same table.
	 */
	public function compareTableNames($name1, $name2)
	{
		return parent::compareTableNames(strtolower($name1), strtolower($name2));
	}

	/**
	 * Resets the sequence value of a table's primary key.
	 * The sequence will be reset such that the primary key of the next new row inserted
	 * will have the specified value or 1.
	 * @param CDbTableSchema $table the table schema whose primary key sequence will be reset
	 * @param mixed $value the value for the primary key of the next new row inserted. If this is not set,
	 * the next new row's primary key will have a value 1.
	 * @since 1.1
	 */
	public function resetSequence($table, $value = null)
	{
		if ($table->sequenceName !== null)
		{
			if ($value === null)
				$value = $this->getDbConnection()->createCommand("SELECT MAX(` {$table->primaryKey}`) FROM  {$table->rawName}")->queryScalar() + 1;
			else
				$value = (int)$value;
			$this->getDbConnection()->createCommand("ALTER TABLE  {$table->rawName} AUTO_INCREMENT=$value")->execute();
		}
	}

	/**
	 * Enables or disables integrity check.
	 * @param boolean $check whether to turn on or off the integrity check.
	 * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
	 * @since 1.1
	 */
	public function checkIntegrity($check = true, $schema = '')
	{
		$this->getDbConnection()->createCommand('SET FOREIGN_KEY_CHECKS=' . ($check ? 1 : 0))->execute();
	}

	/**
	 * Loads the metadata for the specified table.
	 * @param string $name table name
	 * @return CMysqlTableSchema driver dependent table metadata. Null if the table does not exist.
	 */
	protected function loadTable($name)
	{
		$table = new CMysqlTableSchema;
		$this->resolveTableNames($table, $name);

		if ($this->findColumns($table))
		{
			$this->findConstraints($table);
			return $table;
		}
		else
			return null;
	}

	/**
	 * Generates various kinds of table names.
	 * @param CMysqlTableSchema $table the table instance
	 * @param string $name the unquoted table name
	 */
	protected function resolveTableNames($table, $name)
	{
		$parts = explode('.', str_replace('`', '', $name));
		if (isset($parts[1]))
		{
			$table->schemaName = $parts[0];
			$table->name = $parts[1];
			$table->rawName = $this->quoteTableName($table->schemaName) . '.' . $this->quoteTableName($table->name);
		}
		else
		{
			$table->name = $parts[0];
			$table->rawName = $this->quoteTableName($table->name);
		}
	}

	/**
	 * Collects the table column metadata.
	 * @param CMysqlTableSchema $table the table metadata
	 * @return boolean whether the table exists in the database
	 */
	protected function findColumns($table)
	{
		$sql = 'SHOW COLUMNS FROM ' . $table->rawName;
		try
		{
			$columns = $this->getDbConnection()->createCommand($sql)->queryAll();
		}
		catch(Exception $e)
		{
			return false;
		}
		foreach ($columns as $column)
		{
			$c = $this->createColumn($column);
			$table->columns[$c->name] = $c;
			if ($c->isPrimaryKey)
			{
				if ($table->primaryKey === null)
					$table->primaryKey = $c->name;
				elseif (is_string($table->primaryKey))
					$table->primaryKey = array($table->primaryKey, $c->name);
				else
					$table->primaryKey[] = $c->name;
				if ($c->autoIncrement)
					$table->sequenceName = '';
			}
		}
		return true;
	}

	/**
	 * Creates a table column.
	 * @param array $column column metadata
	 * @return CDbColumnSchema normalized column metadata
	 */
	protected function createColumn($column)
	{
		$c = new CMysqlColumnSchema;
		$c->name = $column['Field'];
		$c->rawName = $this->quoteColumnName($c->name);
		$c->allowNull = $column['Null'] === 'YES';
		$c->isPrimaryKey = strpos($column['Key'], 'PRI') !== false;
		$c->isForeignKey = false;
		$c->init($column['Type'], $column['Default']);
		$c->autoIncrement = strpos(strtolower($column['Extra']), 'auto_increment') !== false;

		return $c;
	}

	/**
	 * @return float server version.
	 */
	protected function getServerVersion()
	{
		$version = $this->getDbConnection()->getAttribute(PDO::ATTR_SERVER_VERSION);
		$digits = array();
		preg_match('/(\d+)\.(\d+)\.(\d+)/', $version, $digits);
		return floatval($digits[1] . '.' . $digits[2] . $digits[3]);
	}

	/**
	 * Collects the foreign key column details for the given table.
	 * @param CMysqlTableSchema $table the table metadata
	 */
	protected function findConstraints($table)
	{
		$row = $this->getDbConnection()->createCommand('SHOW CREATE TABLE ' . $table->rawName)->queryRow();
		$matches = array();
		$regexp = '/FOREIGN KEY\s+\(([^\)]+)\)\s+REFERENCES\s+([^\(^\s]+)\s*\(([^\)]+)\)/mi';
		foreach ($row as $sql)
		{
			if (preg_match_all($regexp, $sql, $matches, PREG_SET_ORDER))
				break;
		}
		foreach ($matches as $match)
		{
			$keys = array_map('trim', explode(',', str_replace('`', '', $match[1])));
			$fks = array_map('trim', explode(',', str_replace('`', '', $match[3])));
			foreach ($keys as $k => $name)
			{
				$table->foreignKeys[$name] = array(str_replace('`', '', $match[2]), $fks[$k]);
				if (isset($table->columns[$name]))
					$table->columns[$name]->isForeignKey = true;
			}
		}
	}

	/**
	 * Returns all table names in the database.
	 * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
	 * If not empty, the returned table names will be prefixed with the schema name.
	 * @return array all table names in the database.
	 * @since 1.0.2
	 */
	protected function findTableNames($schema = '')
	{
		if ($schema === '')
			return $this->getDbConnection()->createCommand('SHOW TABLES')->queryColumn();
		$names = $this->getDbConnection()->createCommand('SHOW TABLES FROM ' . $this->quoteTableName($schema))->queryColumn();
		foreach ($names as &$name)
			$name = $schema . '.' . $name;
		return $names;
	}

	/**
	 * Builds a SQL statement for renaming a column.
	 * @param string $table the table whose column is to be renamed. The name will be properly quoted by the method.
	 * @param string $name the old name of the column. The name will be properly quoted by the method.
	 * @param string $newName the new name of the column. The name will be properly quoted by the method.
	 * @return string the SQL statement for renaming a DB column.
	 * @since 1.1.6
	 */
	public function renameColumn($table, $name, $newName)
	{
		$db = $this->getDbConnection();
		$row = $db->createCommand('SHOW CREATE TABLE ' . $db->quoteTableName($table))->queryRow();
		if ($row === false)
			throw new CDbException(Yii::t('yii', 'Unable to find "{column}" in table "{table}".', array('{column}' => $name, '{table}' => $table)));
		if (isset($row['Create Table']))
			$sql = $row['Create Table'];
		else
		{
			$row = array_values($row);
			$sql = $row[1];
		}
		if (preg_match_all('/^\s*`(.*?)`\s+(.*?),?$/m', $sql, $matches))
		{
			foreach ($matches[1] as $i => $c)
			{
				if ($c === $name)
				{
					return "ALTER TABLE " . $db->quoteTableName($table)
						. " CHANGE " . $db->quoteColumnName($name)
						. ' ' . $db->quoteColumnName($newName) . ' ' . $matches[2][$i];
				}
			}
		}

		// try to give back a SQL anyway
		return "ALTER TABLE " . $db->quoteTableName($table)
			. " CHANGE " . $db->quoteColumnName($name) . ' ' . $newName;
	}

	/**
	 * Builds a SQL statement for dropping a foreign key constraint.
	 * @param string $name the name of the foreign key constraint to be dropped. The name will be properly quoted by the method.
	 * @param string $table the table whose foreign is to be dropped. The name will be properly quoted by the method.
	 * @return string the SQL statement for dropping a foreign key constraint.
	 * @since 1.1.6
	 */
	public function dropForeignKey($name, $table)
	{
		return 'ALTER TABLE ' . $this->quoteTableName($table)
			. ' DROP FOREIGN KEY ' . $this->quoteColumnName($name);
	}
}