<?php

if (!defined('SQL_DEBUG')) die(basename(__FILE__));

class sql_db
{
	var $cfg            = array();
	var $cfg_keys       = array('dbhost', 'dbname', 'dbuser', 'dbpasswd', 'charset', 'persist');
	var $link           = null;
	var $result         = null;
	var $db_server      = '';
	var $selected_db    = null;
	var $inited         = false;

	var $locked         = false;
	var $locks          = array();

	var $num_queries    = 0;
	var $sql_starttime  = 0;
	var $sql_inittime   = 0;
	var $sql_timetotal  = 0;
	var $cur_query_time = 0;
	var $slow_time      = 0;

	var $dbg            = array();
	var $dbg_id         = 0;
	var $dbg_enabled    = false;
	var $cur_query      = null;

	var $do_explain     = false;
	var $explain_hold   = '';
	var $explain_out    = '';

	var $shutdown       = array();

	var $DBS            = array();

	var $engine         = 'MySQL';

	/**
	* Constructor
	*/
	function sql_db ($cfg_values)
	{
		global $DBS;

		// Check MySQL installed
		if (!function_exists('mysql_connect') || !extension_loaded('mysql'))
		{
			$init_error = "Error: {$this->engine} extension not installed";
			if (DBG_LOG)
			{
				dbg_log($init_error, "{$this->engine}-DB-INIT-FAIL");
			}
			die($init_error);
		}

		$this->cfg         = array_combine($this->cfg_keys, $cfg_values);
		$this->dbg_enabled = (sql_dbg_enabled() || !empty($_COOKIE['explain']));
		$this->do_explain  = ($this->dbg_enabled && !empty($_COOKIE['explain']));
		$this->slow_time   = SQL_SLOW_QUERY_TIME;

		// ссылки на глобальные переменные (для включения логов сразу на всех серверах, подсчета общего количества запросов и т.д.)
		$this->DBS['log_file']      =& $DBS->log_file;
		$this->DBS['log_counter']   =& $DBS->log_counter;
		$this->DBS['num_queries']   =& $DBS->num_queries;
		$this->DBS['sql_inittime']  =& $DBS->sql_inittime;
		$this->DBS['sql_timetotal'] =& $DBS->sql_timetotal;
	}

	/**
	* Initialize connection
	*/
	function init ()
	{
		// Connect to server
		$this->link = $this->connect();

		// Select database
		$this->selected_db = $this->select_db();

		// Set charset
		if ($this->cfg['charset'] && !@mysql_set_charset($this->cfg['charset'], $this->link))
		{
			if (!$this->sql_query("SET NAMES '{$this->cfg['charset']}'"))
			{
				$charset_error = "Could not set charset '{$this->cfg['charset']}'";
				if (DBG_LOG)
				{
					dbg_log($charset_error, "{$this->cfg['charset']}-DB-charset-FAIL");
				}
				die($charset_error);
			}
		}

		$this->inited = true;
		$this->num_queries = 0;
		$this->sql_inittime = $this->sql_timetotal;
		$this->DBS['sql_inittime'] += $this->sql_inittime;
	}

	/**
	* Open connection
	*/
	function connect ()
	{
		$this->cur_query = ($this->dbg_enabled) ? ($this->cfg['persist'] ? 'p' : '') . "connect to: '{$this->cfg['dbhost']}'" : 'connect';
		$this->debug('start');

		$connect_type = ($this->cfg['persist']) ? 'mysql_pconnect' : 'mysql_connect';

		if (!$link = @$connect_type($this->cfg['dbhost'], $this->cfg['dbuser'], $this->cfg['dbpasswd']))
		{
			$server = (DBG_USER) ? "'" . $this->cfg['dbhost'] . "'" : '';
			header("HTTP/1.0 503 Service Unavailable");
			$con_error = "Could not connect to {$this->engine} server $server";
			if (DBG_LOG)
			{
				dbg_log($con_error, "{$this->cfg['dbhost']}-DB-connect-FAIL");
			}
			die($con_error);
		}

		register_shutdown_function(array(&$this, 'close'));

		$this->debug('stop');
		$this->cur_query = null;

		return $link;
	}

	/**
	* Select database
	*/
	function select_db ()
	{
		$this->cur_query = ($this->dbg_enabled) ? "select db: '{$this->cfg['dbname']}'" : 'select db';
		$this->debug('start');

		if (!@mysql_select_db($this->cfg['dbname'], $this->link))
		{
			$db_name = (DBG_USER) ? "'" . $this->cfg['dbname'] . "'" : '';
			$select_error = "Could not select database $db_name";
			if (DBG_LOG)
			{
				dbg_log($select_error, "{$this->cfg['dbname']}-DB-select-FAIL");
			}
			die($select_error);
		}

		$this->debug('stop');
		$this->cur_query = null;

		return $this->cfg['dbname'];
	}

	/**
	* Base query method
	*/
	function sql_query ($query)
	{
		if (!is_resource($this->link))
		{
			$this->init();
		}
		if (is_array($query))
		{
			$query = $this->build_sql($query);
		}
		$query = '/* '. $this->debug_find_source() .' */ '. $query;
		$this->cur_query = $query;
		$this->debug('start');

		if (!$this->result = mysql_query($query, $this->link))
		{
			$this->log_error();
		}

		$this->debug('stop');
		$this->cur_query = null;

		if ($this->inited)
		{
			$this->num_queries++;
			$this->DBS['num_queries']++;
		}

		return $this->result;
	}

	/**
	* Execute query WRAPPER (with error handling)
	*/
	function query ($query)
	{
		if (!$result = $this->sql_query($query))
		{
			$this->trigger_error();
		}

		return $result;
	}

	/**
	* Return number of rows
	*/
	function num_rows ($result = false)
	{
		$num_rows = false;

		if ($result OR $result = $this->result)
		{
			$num_rows = is_resource($result) ? mysql_num_rows($result) : false;
		}

		return $num_rows;
	}

	/**
	* Return number of affected rows
	*/
	function affected_rows ()
	{
		return is_resource($this->link) ? mysql_affected_rows($this->link) : -1;
	}

	/**
	* Fetch current field
	*/
	function sql_fetchfield($field, $rownum = -1, $query_id = 0)
	{
		if(!$query_id)
		{
			$query_id = $this->query_result;
		}
		if($query_id)
		{
			if($rownum > -1)
			{
				$result = @mysql_result($query_id, $rownum, $field);
			}
			else
			{
				if(empty($this->row[$query_id]) && empty($this->rowset[$query_id]))
				{
					if($this->sql_fetchrow())
					{
						$result = $this->row[$query_id][$field];
					}
				}
				else
				{
					if($this->rowset[$query_id])
					{
						$result = $this->rowset[$query_id][0][$field];
					}
					else if($this->row[$query_id])
					{
						$result = $this->row[$query_id][$field];
					}
				}
			}
			return $result;
		}
		else
		{
			return false;
		}
	}

	/**
	* Fetch current row
	*/
	function sql_fetchrow ($result, $field_name = '')
	{
		$row = mysql_fetch_assoc($result);

		if ($field_name)
		{
			return isset($row[$field_name]) ? $row[$field_name] : false;
		}
		else
		{
			return $row;
		}
	}

	/**
	* Alias of sql_fetchrow()
	*/
	function fetch_next ($result)
	{
		return $this->sql_fetchrow($result);
	}

	/**
	* Fetch row WRAPPER (with error handling)
	*/
	function fetch_row ($query, $field_name = '')
	{
		if (!$result = $this->sql_query($query))
		{
			$this->trigger_error();
		}

		return $this->sql_fetchrow($result, $field_name);
	}

	/**
	* Fetch all rows
	*/
	function sql_fetchrowset ($result, $field_name = '')
	{
		$rowset = array();

		while ($row = mysql_fetch_assoc($result))
		{
			$rowset[] = ($field_name) ? $row[$field_name] : $row;
		}

		return $rowset;
	}

	/**
	* Fetch all rows WRAPPER (with error handling)
	*/
	function fetch_rowset ($query, $field_name = '')
	{
		if (!$result = $this->sql_query($query))
		{
			$this->trigger_error();
		}

		return $this->sql_fetchrowset($result, $field_name);
	}

	/**
	* Fetch all rows WRAPPER (with error handling)
	*/
	function fetch_all ($query, $field_name = '')
	{
		if (!$result = $this->sql_query($query))
		{
			$this->trigger_error();
		}

		return $this->sql_fetchrowset($result, $field_name);
	}

	/**
	* Get last inserted id after insert statement
	*/
	function sql_nextid ()
	{
		return mysql_insert_id($this->link);
	}

	/**
	* Free sql result
	*/
	function sql_freeresult ($result = false)
	{
		if ($result OR $result = $this->result)
		{
			$return_value = is_resource($result) ? mysql_free_result($result) : false;
		}

		$this->result = null;
	}

	/**
	* Escape data used in sql query
	*/
	function escape ($v, $check_type = false, $dont_escape = false)
	{
		if ($dont_escape) return $v;
		if (!$check_type) return $this->escape_string($v);

		switch (true)
		{
			case is_string ($v): return "'". $this->escape_string($v) ."'";
			case is_int    ($v): return "$v";
			case is_bool   ($v): return ($v) ? '1' : '0';
			case is_float  ($v): return "'$v'";
			case is_null   ($v): return 'NULL';
		}
		// if $v has unsuitable type
		$this->trigger_error(__FUNCTION__ .' - wrong params');
	}

	/**
	* Escape string
	*/
	function escape_string ($str)
	{
		if (!is_resource($this->link))
		{
			$this->init();
		}

		return mysql_real_escape_string($str, $this->link);
	}

	/**
	* Build SQL statement from array (based on same method from phpBB3, idea from Ikonboard)
	*
	* Possible $query_type values: INSERT, INSERT_SELECT, MULTI_INSERT, UPDATE, SELECT
	*/
	function build_array ($query_type, $input_ary, $data_already_escaped = false, $check_data_type_in_escape = true)
	{
		$fields = $values = $ary = $query = array();
		$dont_escape = $data_already_escaped;
		$check_type = $check_data_type_in_escape;

		if (empty($input_ary) || !is_array($input_ary))
		{
			$this->trigger_error(__FUNCTION__ .' - wrong params: $input_ary');
		}

		if ($query_type == 'INSERT')
		{
			foreach ($input_ary as $field => $val)
			{
				$fields[] = $field;
				$values[] = $this->escape($val, $check_type, $dont_escape);
			}
			$fields = join(', ', $fields);
			$values = join(', ', $values);
			$query = "($fields)\nVALUES\n($values)";
		}
		else if ($query_type == 'INSERT_SELECT')
		{
			foreach ($input_ary as $field => $val)
			{
				$fields[] = $field;
				$values[] = $this->escape($val, $check_type, $dont_escape);
			}
			$fields = join(', ', $fields);
			$values = join(', ', $values);
			$query = "($fields)\nSELECT\n$values";
		}
		else if ($query_type == 'MULTI_INSERT')
		{
			foreach ($input_ary as $id => $sql_ary)
			{
				foreach ($sql_ary as $field => $val)
				{
					$values[] = $this->escape($val, $check_type, $dont_escape);
				}
				$ary[] = '('. join(', ', $values) .')';
				$values = array();
			}
			$fields = join(', ', array_keys($input_ary[0]));
			$values = join(",\n", $ary);
			$query = "($fields)\nVALUES\n$values";
		}
		else if ($query_type == 'SELECT' || $query_type == 'UPDATE')
		{
			foreach ($input_ary as $field => $val)
			{
				$ary[] = "$field = ". $this->escape($val, $check_type, $dont_escape);
			}
			$glue = ($query_type == 'SELECT') ? "\nAND " : ",\n";
			$query = join($glue, $ary);
		}

		if (!$query)
		{
			bb_die('<pre><b>'. __FUNCTION__ ."</b>: Wrong params for <b>$query_type</b> query type\n\n\$input_ary:\n\n". htmlCHR(print_r($input_ary, true)) .'</pre>');
		}

		return "\n". $query ."\n";
	}

	function get_empty_sql_array ()
	{
		return array(
			'SELECT'         => array(),
			'select_options' => array(),
			'FROM'           => array(),
			'INNER JOIN'     => array(),
			'LEFT JOIN'      => array(),
			'WHERE'          => array(),
			'GROUP BY'       => array(),
			'HAVING'         => array(),
			'ORDER BY'       => array(),
			'LIMIT'          => array(),
		);
	}

	function build_sql ($sql_ary)
	{
		$sql = '';
		array_deep($sql_ary, 'array_unique', false, true);

		foreach ($sql_ary as $clause => $ary)
		{
			switch ($clause)
			{
				case 'SELECT':
					$sql .= ($ary) ? ' SELECT '. join(' ', $sql_ary['select_options']) .' '. join(', ', $ary) : '';
					break;
				case 'FROM':
					$sql .= ($ary) ? ' FROM '. join(', ', $ary) : '';
					break;
				case 'INNER JOIN':
					$sql .= ($ary) ? ' INNER JOIN '. join(' INNER JOIN ', $ary) : '';
					break;
				case 'LEFT JOIN':
					$sql .= ($ary) ? ' LEFT JOIN '. join(' LEFT JOIN ', $ary) : '';
					break;
				case 'WHERE':
					$sql .= ($ary) ? ' WHERE '. join(' AND ', $ary) : '';
					break;
				case 'GROUP BY':
					$sql .= ($ary) ? ' GROUP BY '. join(', ', $ary) : '';
					break;
				case 'HAVING':
					$sql .= ($ary) ? ' HAVING '. join(' AND ', $ary) : '';
					break;
				case 'ORDER BY':
					$sql .= ($ary) ? ' ORDER BY '. join(', ', $ary) : '';
					break;
				case 'LIMIT':
					$sql .= ($ary) ? ' LIMIT '. join(', ', $ary) : '';
					break;
			}
		}

		return trim($sql);
	}

	/**
	* Return sql error array
	*/
	function sql_error ()
	{
		if (is_resource($this->link))
		{
			return array('code' => mysql_errno($this->link), 'message' => mysql_error($this->link));
		}
		else
		{
			return array('code' => '', 'message' => 'not connected');
		}
	}

	/**
	* Close sql connection
	*/
	function close ()
	{
		if (is_resource($this->link))
		{
			$this->unlock();

			if (!empty($this->locks))
			{
				foreach ($this->locks as $name => $void)
				{
					$this->release_lock($name);
				}
			}

			$this->exec_shutdown_queries();

			mysql_close($this->link);
		}

		$this->link = $this->selected_db = null;
	}

	/**
	* Add shutdown query
	*/
	function add_shutdown_query ($sql)
	{
		$this->shutdown['__sql'][] = $sql;
	}

	/**
	* Exec shutdown queries
	*/
	function exec_shutdown_queries ()
	{
		if (empty($this->shutdown)) return;

		if (!empty($this->shutdown['post_html']))
		{
			$post_html_sql = $this->build_array('MULTI_INSERT', $this->shutdown['post_html']);
			$this->query("REPLACE INTO ". BB_POSTS_HTML ." $post_html_sql");
		}

		if (!empty($this->shutdown['__sql']))
		{
			foreach ($this->shutdown['__sql'] as $sql)
			{
				$this->query($sql);
			}
		}
	}

	/**
	* Lock tables
	*/
	function lock ($tables, $lock_type = 'WRITE')
	{
		if ($this->cfg['persist'])
		{
#			return true;
		}

		$tables_sql = array();

		foreach ((array) $tables as $table_name)
		{
			$tables_sql[] = "$table_name $lock_type";
		}
		if ($tables_sql = join(', ', $tables_sql))
		{
			$this->locked = $this->sql_query("LOCK TABLES $tables_sql");
		}

		return $this->locked;
	}

	/**
	* Unlock tables
	*/
	function unlock ()
	{
		if ($this->locked && $this->sql_query("UNLOCK TABLES"))
		{
			$this->locked = false;
		}

		return !$this->locked;
	}

	/**
	* Obtain user level lock
	*/
	function get_lock ($name, $timeout = 0)
	{
		$lock_name = $this->get_lock_name($name);
		$timeout   = (int) $timeout;
		$row = $this->fetch_row("SELECT GET_LOCK('$lock_name', $timeout) AS lock_result");

		if ($row['lock_result'])
		{
			$this->locks[$name] = true;
		}

		return $row['lock_result'];
	}

	/**
	* Obtain user level lock status
	*/
	function release_lock ($name)
	{
		$lock_name = $this->get_lock_name($name);
		$row = $this->fetch_row("SELECT RELEASE_LOCK('$lock_name') AS lock_result");

		if ($row['lock_result'])
		{
			unset($this->locks[$name]);
		}

		return $row['lock_result'];
	}

	/**
	* Release user level lock
	*/
	function is_free_lock ($name)
	{
		$lock_name = $this->get_lock_name($name);
		$row = $this->fetch_row("SELECT IS_FREE_LOCK('$lock_name') AS lock_result");
		return $row['lock_result'];
	}

	/**
	* Make per db unique lock name
	*/
	function get_lock_name ($name)
	{
		if (!$this->selected_db)
		{
			$this->init();
		}

		return "{$this->selected_db}_{$name}";
	}

	/**
	* Get info about last query
	*/
	function query_info ()
	{
		$info = array();

		if ($num = $this->num_rows($this->result))
		{
			$info[] = "$num rows";
		}

		if (is_resource($this->link) AND $ext = mysql_info($this->link))
		{
			$info[] = "$ext";
		}
		else if (!$num && ($aff = $this->affected_rows($this->result) AND $aff != -1))
		{
			$info[] = "$aff rows";
		}

		return str_compact(join(', ', $info));
	}

	/**
	* Get server version
	*/
	function server_version ()
	{
		preg_match('#^(\d+\.\d+\.\d+).*#', mysql_get_server_info(), $m);
		return $m[1];
	}

	/**
	* Set slow query marker for xx seconds
	* This will disable counting other queries as "slow" during this time
	*/
	function expect_slow_query ($ignoring_time = 60, $new_priority = 10)
	{
		if ($old_priority = CACHE('bb_cache')->get('dont_log_slow_query'))
		{
			if ($old_priority > $new_priority)
			{
				return;
			}
		}

		@define('IN_FIRST_SLOW_QUERY', true);
		CACHE('bb_cache')->set('dont_log_slow_query', $new_priority, $ignoring_time);
	}

	/**
	* Store debug info
	*/
	function debug ($mode)
	{
		if (!SQL_DEBUG) return;

		$id  =& $this->dbg_id;
		$dbg =& $this->dbg[$id];

		if ($mode == 'start')
		{
			$this->sql_starttime = utime();
			if ($this->dbg_enabled)
			{
				$dbg['sql']  = preg_replace('#^(\s*)(/\*)(.*)(\*/)(\s*)#', '', $this->cur_query);
				$dbg['src']  = $this->debug_find_source();
				$dbg['file'] = $this->debug_find_source('file');
				$dbg['line'] = $this->debug_find_source('line');
				$dbg['time'] = '';
				$dbg['info'] = '';
				$dbg['mem_before'] = sys('mem');
			}
			if ($this->do_explain)
			{
				$this->explain('start');
			}
		}
		else if ($mode == 'stop')
		{
			$this->cur_query_time = utime() - $this->sql_starttime;
			$this->sql_timetotal += $this->cur_query_time;
			$this->DBS['sql_timetotal'] += $this->cur_query_time;

			if (SQL_LOG_SLOW_QUERIES && ($this->cur_query_time > $this->slow_time))
			{
				$this->log_slow_query();
			}
			if ($this->dbg_enabled)
			{
				$dbg['time'] = utime() - $this->sql_starttime;
				$dbg['info'] = $this->query_info();
				$dbg['mem_after'] = sys('mem');
				$id++;
			}
			if ($this->do_explain)
			{
				$this->explain('stop');
			}
			// проверка установки $this->inited - для пропуска инициализационных запросов
			if ($this->DBS['log_counter'] && $this->inited)
			{
				$this->log_query($this->DBS['log_file']);
				$this->DBS['log_counter']--;
			}
		}
		else
		{
			die("[MySQL] Invalid debug mode: $mode");
		}
	}

	/**
	* Trigger error
	*/
	function trigger_error ($msg = 'DB Error')
	{
		if (error_reporting())
		{
			if (DBG_LOG === true)
			{
				$err = $this->sql_error();
				$msg .= "\n". trim(sprintf('#%06d %s', $err['code'], $err['message']));
			}
			else
			{
				$msg .= " [". $this->debug_find_source() ."]";
			}

			trigger_error($msg, E_USER_ERROR);
		}
	}

	/**
	* Find caller source
	*/
	function debug_find_source ($mode = '')
	{
		if (!SQL_PREPEND_SRC_COMM) return 'src disabled';
		foreach (debug_backtrace() as $trace)
		{
			if (!empty($trace['file']) && $trace['file'] !== __FILE__)
			{
				switch ($mode)
				{
					case 'file': return $trace['file'];
					case 'line': return $trace['line'];
					default: return hide_bb_path($trace['file']) .'('. $trace['line'] .')';
				}
			}
		}
		return 'src not found';
	}

	/**
	* Prepare for logging
	*/
	function log_next_query ($queries_count = 1, $log_file = 'sql_queries')
	{
		$this->DBS['log_file'] = $log_file;
		$this->DBS['log_counter'] = $queries_count;
	}

	/**
	* Log query
	*/
	function log_query ($log_file = 'sql_queries')
	{
		$q_time = ($this->cur_query_time >= 10) ? round($this->cur_query_time, 0) : sprintf('%.4f', $this->cur_query_time);
		$msg = array();
		$msg[] = round($this->sql_starttime);
		$msg[] = date('m-d H:i:s', $this->sql_starttime);
		$msg[] = sprintf('%-6s', $q_time);
		if ($l = sys('la'))
		{
			$l = explode(' ', $l);
			for ($i=0; $i < 3; $i++)
			{
				$l[$i] = round($l[$i], 1);
			}
			$msg[] = "loadavg: $l[0] $l[1] $l[2]";
		}
		$msg[] = sprintf('%05d', getmypid());
		$msg[] = $this->db_server;
		$msg[] = short_query($this->cur_query);
		$msg = join(LOG_SEPR, $msg);
		$msg .= ($info = $this->query_info()) ? ' # '. $info : '';
		$msg .= ' # '. $this->debug_find_source() .' ';
		$msg .= defined('IN_CRON') ? 'cron' : basename($_SERVER['REQUEST_URI']);
		bb_log($msg . LOG_LF, $log_file);
	}

	/**
	* Log slow query
	*/
	function log_slow_query ($log_file = 'sql_slow_bb')
	{
		if (!defined('IN_FIRST_SLOW_QUERY') && CACHE('bb_cache')->get('dont_log_slow_query'))
		{
			return;
		}
		$this->log_query($log_file);
	}

	/**
	* Log error
	*/
	function log_error ()
	{
		if (!SQL_LOG_ERRORS) return;

		$msg = array();
		$err = $this->sql_error();
		$msg[] = str_compact(sprintf('#%06d %s', $err['code'], $err['message']));
		$msg[] = '';
		if (!empty($this->cur_query)) $msg[] = str_compact($this->cur_query);
		$msg[] = '';
		if (!empty($this->selected_db)) $msg[] = 'Source  : '. $this->debug_find_source() ." :: $this->db_server.$this->selected_db";
		$msg[] = 'IP      : '. @$_SERVER['REMOTE_ADDR'];
		$msg[] = 'Date    : '. date('Y-m-d H:i:s');
		$msg[] = 'Agent   : '. @$_SERVER['HTTP_USER_AGENT'];
		$msg[] = 'Req_URI : '. @$_SERVER['REQUEST_URI'];
		if (!empty($_SERVER['HTTP_REFERER'])) $msg[] = 'Referer : '. @$_SERVER['HTTP_REFERER'];
		$msg[] = 'Method  : '. @$_SERVER['REQUEST_METHOD'];
		$msg[] = 'PID     : '. sprintf('%05d', getmypid());
		$msg[] = 'Request : '. trim(print_r($_REQUEST, true)) . str_repeat('_', 78) . LOG_LF;
		$msg[] = '';
		bb_log($msg, SQL_BB_LOG_NAME);
	}

	/**
	* Explain queries (based on code from phpBB3)
	*/
	function explain ($mode, $html_table = '', $row = '')
	{
		$query = str_compact($this->cur_query);
		// remove comments
		$query = preg_replace('#(\s*)(/\*)(.*)(\*/)(\s*)#', '', $query);

		switch ($mode)
		{
			case 'start':
				$this->explain_hold = '';
				// TODO: добавить поддержку многотабличных запросов
				if (preg_match('#UPDATE ([a-z0-9_]+).*?WHERE(.*)/#', $query, $m))
				{
					$query = "SELECT * FROM $m[1] WHERE $m[2]";
				}
				else if (preg_match('#DELETE FROM ([a-z0-9_]+).*?WHERE(.*)#s', $query, $m))
				{
					$query = "SELECT * FROM $m[1] WHERE $m[2]";
				}

				if (preg_match('#^SELECT#', $query))
				{
					$html_table = false;

					if ($result = @mysql_query("EXPLAIN $query", $this->link))
					{
						while ($row = @mysql_fetch_assoc($result))
						{
							$html_table = $this->explain('add_explain_row', $html_table, $row);
						}
					}
					if ($html_table)
					{
						$this->explain_hold .= '</table>';
					}
				}
				break;

			case 'stop':
				if (!$this->explain_hold) break;

				$id   = $this->dbg_id-1;
				$htid = 'expl-'. intval($this->link) .'-'. $id;
				$dbg  = $this->dbg[$id];

				$query_time = SQL_CALC_QUERY_TIME ? ('&nbsp;[' . sprintf('%.4f', $dbg['time']) . 's]&nbsp;') : '&nbsp;';
				$this->explain_out .= '
					<table width="98%" cellpadding="0" cellspacing="0" class="bodyline row2 bCenter" style="border-bottom: 0px;">
						<tr>
							<th title="'.$dbg['src'].'" style="height: 22px; cursor: pointer;" align="left">&nbsp;'. $dbg['src'] . $query_time .'<i>'. $dbg['info'] .'</i></th>
							<th style="height: 22px; cursor: pointer;" align="right" title="Copy to clipboard" onclick="$(\'#'. $htid .'\').CopyToClipboard();">'. "[$this->engine] $this->db_server.$this->selected_db" .' :: Query #'. ($this->num_queries+1) .'&nbsp;</th>
						</tr>
						<tr><td colspan="2">'. $this->explain_hold .'</td></tr>
					</table>
					<div class="sqlLog"><div id="'. $htid .'" class="sqlLogRow sqlExplain" style="padding: 0px;">'. short_query($dbg['sql'], true) .'&nbsp;&nbsp;</div></div>
					<br />';
				break;

			case 'add_explain_row':
				if (!$html_table && $row)
				{
					$html_table = true;
					$this->explain_hold .= '<table width="100%" cellpadding="3" cellspacing="1" class="bodyline" style="border-width: 0;"><tr>';
					foreach (array_keys($row) as $val)
					{
						$this->explain_hold .= '<td class="row3 gensmall" align="center"><b>'. $val .'</b></td>';
					}
					$this->explain_hold .= '</tr>';
				}
				$this->explain_hold .= '<tr>';
				foreach (array_values($row) as $i => $val)
				{
					$class = !($i % 2) ? 'row1' : 'row2';
					$this->explain_hold .= '<td class="'. $class .' gen">'. str_replace(array("{$this->selected_db}.", ',', ';'), array('', ', ', ';<br />'), $val) .'</td>';
				}
				$this->explain_hold .= '</tr>';

				return $html_table;
				break;

			case 'display':
				echo '<a name="explain"></a><div class="med">'. $this->explain_out .'</div>';
				break;

			default:
				die("Invalid {$this->engine} explain mode");
				break;
		}
		return false;
	}
}