<?php
# -- BEGIN LICENSE BLOCK ---------------------------------------
#
# This file is part of Clearbricks.
#
# Copyright (c) 2003-2011 Olivier Meunier & Association Dotclear
# Licensed under the GPL version 2.0 license.
# See LICENSE file or
# http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
#
# -- END LICENSE BLOCK -----------------------------------------

/**
* MySQL Database Driver
* 
* See the {@link dbLayer} documentation for common methods.
* 
* @package Clearbricks
* @subpackage DBLayer
*/
if (class_exists('dbLayer'))
{
	class mysqlConnection extends dbLayer implements i_dbLayer
	{
		/** @var boolean	Enables weak locks if true */
		public static $weak_locks = false;
		
		/** @ignore */
		protected $__driver = 'mysql';
		
		/** @ignore */
		public function db_connect($host,$user,$password,$database)
		{
			if (!function_exists('mysql_connect')) {
				throw new Exception('PHP MySQL functions are not available');
			}
			
			if (($link = @mysql_connect($host,$user,$password,true)) === false) {
				throw new Exception('Unable to connect to database');
			}
			
			$this->db_post_connect($link,$database);
			
			return $link;
		}
		
		/** @ignore */
		public function db_pconnect($host,$user,$password,$database)
		{
			if (!function_exists('mysql_pconnect')) {
				throw new Exception('PHP MySQL functions are not available');
			}
			
			if (($link = @mysql_pconnect($host,$user,$password)) === false) {
				throw new Exception('Unable to connect to database');
			}
			
			$this->db_post_connect($link,$database);
			
			return $link;
		}
		
		/** @ignore */
		private function db_post_connect($link,$database)
		{
			if (@mysql_select_db($database,$link) === false) {
				throw new Exception('Unable to use database '.$database);
			}
			
			if (version_compare($this->db_version($link),'4.1','>='))
			{
				$this->db_query($link,'SET NAMES utf8');
				$this->db_query($link,'SET CHARACTER SET utf8');
				$this->db_query($link,"SET COLLATION_CONNECTION = 'utf8_general_ci'");
				$this->db_query($link,"SET COLLATION_SERVER = 'utf8_general_ci'");
				$this->db_query($link,"SET CHARACTER_SET_SERVER = 'utf8'");
				$this->db_query($link,"SET CHARACTER_SET_DATABASE = 'utf8'");
			}
		}
		
		/** @ignore */
		public function db_close($handle)
		{
			if (is_resource($handle)) {
				mysql_close($handle);
			}
		}
		
		/** @ignore */
		public function db_version($handle)
		{
			if (is_resource($handle)) {
				return mysql_get_server_info();
			}
			return null;
		}
		
		/** @ignore */
		public function db_query($handle,$query)
		{
			if (is_resource($handle))
			{
				$res = @mysql_query($query,$handle);
				if ($res === false) {
					$e = new Exception($this->db_last_error($handle));
					$e->sql = $query;
					throw $e;
				}
				return $res;
			}
		}
		
		/** @ignore */
		public function db_exec($handle,$query)
		{
			return $this->db_query($handle,$query);
		}
		
		/** @ignore */
		public function db_num_fields($res)
		{
			if (is_resource($res)) {
				return mysql_num_fields($res);
			}
			return 0;
		}
		
		/** @ignore */
		public function db_num_rows($res)
		{
			if (is_resource($res)) {
				return mysql_num_rows($res);
			}
			return 0;
		}
		
		/** @ignore */
		public function db_field_name($res,$position)
		{
			if (is_resource($res)) {
				return mysql_field_name($res,$position);
			}
		}
		
		/** @ignore */
		public function db_field_type($res,$position)
		{
			if (is_resource($res)) {
				return mysql_field_type($res,$position);
			}
		}
		
		/** @ignore */
		public function db_fetch_assoc($res)
		{
			if (is_resource($res)) {
				return mysql_fetch_assoc($res);
			}
		}
		
		/** @ignore */
		public function db_result_seek($res,$row)
		{
			if (is_resource($res)) {
				return mysql_data_seek($res,$row);
			}
		}
		
		/** @ignore */
		public function db_changes($handle,$res)
		{
			if (is_resource($handle)) {
				return mysql_affected_rows($handle);
			}
		}
		
		/** @ignore */
		public function db_last_error($handle)
		{
			if (is_resource($handle))
			{
				$e = mysql_error($handle);
				if ($e) {
					return $e.' ('.mysql_errno($handle).')';
				}
			}		
			return false;
		}
		
		/** @ignore */
		public function db_escape_string($str,$handle=null)
		{
			if (is_resource($handle)) {
				return mysql_real_escape_string($str,$handle);
			} else {
				return mysql_escape_string($str);
			}
		}
		
		/** @ignore */
		public function db_write_lock($table)
		{
			try {
				$this->execute('LOCK TABLES '.$this->escapeSystem($table).' WRITE');
			} catch (Exception $e) {
				# As lock is a privilege in MySQL, we can avoid errors with weak_locks static var
				if (!self::$weak_locks) {
					throw $e;
				}
			}
		}
		
		/** @ignore */
		public function db_unlock()
		{
			try {
				$this->execute('UNLOCK TABLES');
			} catch (Exception $e) {
				if (!self::$weak_locks) {
					throw $e;
				}
			}
		}
		
		/** @ignore */
		public function vacuum($table)
		{
			$this->execute('OPTIMIZE TABLE '.$this->escapeSystem($table));
		}
		
		/** @ignore */
		public function dateFormat($field,$pattern)
		{
			$pattern = str_replace('%M','%i',$pattern);
			
			return 'DATE_FORMAT('.$field.','."'".$this->escape($pattern)."') ";
		}
		
		/** @ignore */
		public function concat()
		{
			$args = func_get_args();
			return 'CONCAT('.implode(',',$args).')';
		}
		
		/** @ignore */
		public function escapeSystem($str)
		{
			return '`'.$str.'`';
		}
	}
}
?>