<?php
/**
 * 数据库扩展
 *
 * @since 2009-6-29
 * @copyright http://www.96654.com.cn
 */
class app_db
{
	/**
	 * 当前执行的SQL
	 * @var string
	 */
	protected static $sql ;
	protected static $link_read = null;
	protected static $link_write = null;
	protected static $current_link = null; // 当前连接标识
	protected static $query;
	protected static $query_count = 0;

	/**
	 * 连接数据库
	 *
	 * @return void
	 */
	protected static function init_mysql ($is_read = true, $is_master = false)
	{
		if (empty(self::$$link))
		{
			try
			{
				$link = 'link_read';
				$host = $GLOBALS['database']['db_host'];
				self::$$link = @mysql_pconnect($host, $GLOBALS['database']['db_user'], $GLOBALS['database']['db_pass']);
				if (empty(self::$$link))
				{
					throw new Exception(mysql_error(), 10);
				}
				else
				{
					if (mysql_get_server_info() > '4.1')
					{
						$charset = str_replace('-', '', strtolower($GLOBALS['database']['db_charset']));
						mysql_query("SET character_set_connection=" . $charset . ", character_set_results=" . $charset . ", character_set_client=binary");
					}
					if (mysql_get_server_info() > '5.0')
					{
						mysql_query("SET sql_mode=''");
					}
					if (@mysql_select_db($GLOBALS['database']['db_name']) === false)
					{                                                           
						//throw new Exception(mysql_error(), 11);
					}
				}
			}
			catch (Exception $e)
			{
				if (!defined('DEBUG_LEVEL') || !DEBUG_LEVEL)
				{
					if ($e->getCode() == 10)
					{
						echo '数据库连接失败，可能是数据库服务器地址、账号或密码错误';
					}
					elseif($e->getCode() == 11)
					{
						echo '数据库' . $GLOBALS['database']['db_name'] . '不存在';
					}
					else
					{
						echo 'Can\'t connect to MySQL server';
					}
				}
				else
				{
					echo $e->getMessage(), '<br/>', '<pre>', $e->getTraceAsString(), '</pre>';
				}

				
				exit;
			}
		}
		return self::$$link;
	}


	/**
	 * (读 + 写)
	 *
	 * @param  string $sql
	 * @return bool
	 */
	public static function query ($sql, $is_master = false)
	{
		$sql = trim($sql);
		$GLOBALS ['database'] ['table_prefix'] == '96654_' || $sql = str_replace('96654_', $GLOBALS ['database'] ['table_prefix'], $sql);

		if (substr(strtolower($sql), 0, 1) === 's')
		{
			self::$current_link = self::init_mysql(true, $is_master);
		}
		else
		{
			self::$current_link = self::init_mysql(false, $is_master);
		}
		try
		{
			self::$query = @mysql_query($sql, self::$current_link);
			if (self::$query === false)
			{
				throw new Exception(mysql_error());
			}
			else
			{
				self::$query_count ++;
				return self::$query;
			}
		}
		catch (Exception $e)
		{
			if (!defined('DEBUG_LEVEL') || !DEBUG_LEVEL) ;
			else
			{
				echo $e->getMessage(), '<br/>';
				echo '<pre>', $e->getTraceAsString(), '</pre>';
				echo '<strong>Query: </strong> ' . $sql;
			}
			
			return false;
		}
	}


	/**
	 * 取得最后一次插入记录的ID值
	 *
	 * @return int
	 */
	public static function insert_id ()
	{
		return mysql_insert_id(self::$current_link);
	}


	/**
	 * 返回受影响数目
	 *
	 * @return init
	 */
	public static function affected_rows ()
	{
		return mysql_affected_rows(self::$current_link);
	}


	/**
	 * 返回本次查询所得的总记录数...
	 *
	 * @return int
	 */
	public static function num_rows ()
	{
		return mysql_num_rows(self::$query);
	}


	/**
	 * (读)返回单条记录数据
	 *
	 * @deprecated   MYSQL_ASSOC==1 MYSQL_NUM==2 MYSQL_BOTH==3
	 * @param  int   $result_type
	 * @return array
	 */
	public static function fetch_one ()
	{
		return mysql_fetch_array(self::$query, MYSQL_ASSOC);
	}


	/**
	 * (读)返回多条记录数据
	 *
	 * @deprecated    MYSQL_ASSOC==1 MYSQL_NUM==2 MYSQL_BOTH==3
	 * @param   int   $result_type
	 * @return  array
	 */
	public static function fetch_all ()
	{
		$row = $rows = array();
		while ($row = @mysql_fetch_array(self::$query, MYSQL_ASSOC))
		{
			$rows[] = $row;
		}
		if (empty($rows))
		{
			return false;
		}
		else
		{
			return $rows;
		}
	}


	/**
	 * 查询数据库记录，以数组方式返回数据
	 *
	 * @param string $table
	 * @param string $fields
	 * @param string $condition
	 * @return array
	 */
	public static function select($table, $fields, $condition)
	{
		try
		{
			if (empty($table) || empty($fields) || empty($condition))
			{
				throw new Exception('查询数据的表名，字段，条件不能为空', 444);
			}

		    	self::$sql = "SELECT {$fields} FROM `{$table}` WHERE {$condition}";
			$result = self::query(self::$sql, false);

			return self::fetch_all();
		}
		catch (Exception $e)
		{
			if (!defined('DEBUG_LEVEL') || !DEBUG_LEVEL) ;
			else {
				echo $e->getMessage(), '<br/>';
				echo '<pre>', $e->getTraceAsString(), '</pre>';
				echo '<strong>Query: </strong>[select] ', (!empty(self::$sql)) && self::$sql;
			}
			
			exit;
		}
	}


	/**
	 * 更新数据库记录 UPDATE，返回更新的记录数量
	 *
	 * @param string $table
	 * @param string $data
	 * @param string $condition
	 * @return int
	 */
	public static function update($table, $data, $condition)
	{
		try
		{
			if (empty($table) || empty($data) || empty($condition))
				throw new Exception('更新数据的表名，数据，条件不能为空', 444);

			if(!is_array($data))
				throw new Exception('更新数据必须是数组', 444);

			$set = '';
			foreach ($data as $k => $v)
				$set .= empty($set) ? ("`{$k}` = '{$v}'") : (", `{$k}` = '{$v}'");

			if (empty($set)) throw new Exception('更新数据格式化失败', 444);

			self::$sql = "UPDATE `{$table}` SET {$set} WHERE {$condition}";
			$result = self::query(self::$sql, true);

			// 返回影响行数
			return self::affected_rows();
		}
		catch (Exception $e)
		{
			if (!defined('DEBUG_LEVEL') || !DEBUG_LEVEL) ;
			else {
				echo $e->getMessage(), '<br/>';
				echo '<pre>', $e->getTraceAsString(), '</pre>';
				echo '<strong>Query: </strong>[update]' . (!empty(self::$sql)) && self::$sql;
			}
			
			exit;
		}
	}


	/**
	 * 插入数据
	 *
	 * @param string $table
	 * @param array $fields
	 * @param array $data
	 * @return boolean
	 */
	public function insert($table, $fields, $data)
	{
		try
		{
			if (empty($table) || empty($fields) || empty($data)) {
				throw new Exception('插入数据的表名，字段、数据不能为空', 444);
			}

			if (!is_array($fields) || !is_array($data))
			{
				throw new Exception('插入数据的字段和数据必须是数组', 444);
			}

			// 格式化字段
			$_fields = '`' . implode('`, `', $fields) . '`';

			// 格式化需要插入的数据
			$_data = self::format_insert_data($data);

			if (empty($_fields) || empty($_data))
			{
				throw new Exception('插入数据的字段和数据必须是数组', 444);
			}

			self::$sql = "INSERT INTO `{$table}` ({$_fields}) VALUES {$_data}";
			$result = self::query(self::$sql, true);

			return self::affected_rows();
		}
		catch (Exception $e)
		{
			if (!defined('DEBUG_LEVEL') || !DEBUG_LEVEL) ;
			else
			{
				echo $e->getMessage(), '<br/>';
				echo '<pre>', $e->getTraceAsString(), '</pre>';
				echo '<strong>Query: </strong>[insert] ' . (!empty(self::$sql)) && self::$sql;
			}
			
			exit;
		}
	}


	/**
	 * 格式化 insert 数据，将数组（二维数组）转换成向数据库插入记录时接受的字符串
	 *
	 * @param array $data
	 * @return string
	 */
	protected static function format_insert_data($data)
	{
		if (!is_array($data) || empty($data))
		{
			throw new Exception('数据的类型不是数组', 445);
		}

		$output = '';
		foreach ($data as $value)
		{
			// 如果是二维数组
			if (is_array($value))
			{
				$tmp = '(\'' . implode("', '", $value) . '\')';
				$output .= !empty($output) ? ", {$tmp}" : $tmp;
				unset($tmp);
			}
			else
			{
				$output = '(\'' . implode("', '", $data) . '\')';
			}
		} //foreach

		return $output;
	}


	/**
	 * 删除记录
	 *
	 * @param string $table
	 * @param string $condition
	 * @return num
	 */
	public function delete($table, $condition)
	{
		try
		{
			if (empty($table) || empty($condition))
			{
				throw new Exception('表名和条件不能为空', 444);
			}

			self::$sql = "DELETE FROM `{$table}` WHERE {$condition}";
			$result = self::query(self::$sql, true);

			return self::affected_rows();
		}
		catch (Exception $e)
		{
			if (!defined('DEBUG_LEVEL') || !DEBUG_LEVEL) ;
			else
			{
				echo $e->getMessage(), '<br/>';
				echo '<pre>', $e->getTraceAsString(), '</pre>';
				echo '<strong>Query: </strong>[delete] ' . (!empty(self::$sql)) && self::$sql;
			}
			
			exit;
		}
	}


	/**
	 * 查询记录数
	 *
	 * @param string $table
	 * @param string $condition
	 * @return int
	 */
	public static function get_rows_num($table, $condition)
	{
		try
		{
			if (empty($table) || empty($condition))
				throw new Exception('查询记录数的表名，字段，条件不能为空', 444);

			self::$sql = "SELECT count(*) AS total FROM {$table} WHERE {$condition}";
			$result = self::query(self::$sql);

			$tmp = self::fetch_one();
			return (empty($tmp)) ? false : $tmp['total'];
		}
		catch (Exception $e)
		{
			if (!defined('DEBUG_LEVEL') || !DEBUG_LEVEL) ;
			else
			{
				echo $e->getMessage(), '<br/>';
				echo '<pre>', $e->getTraceAsString(), '</pre>';
				echo '<strong>Query: </strong>[rows_num] ' . (!empty(self::$sql)) && self::$sql;
			}
			
			exit;
		}
	}

	/**
	 * 返回版本信息
	 * @return <type>
	 */
	public static function server_info()
	{
		return mysql_get_server_info();
	}

	/**
	 * 选择数据库
	 * @return <type>
	 */
	public static function select_db($dbname)
	{
		return mysql_select_db($dbname);
	}

	/**
	 * 获取当前执行的 SQL
	 *
	 * @return string
	 */
	public static function get_sql()
	{
		return self::$sql;
	}

}
