<?php

class Database {
	static private $instance;

	private $dbh;
	private $stats;
	private $result;

	static function getInstance() {
		if (!isset(self::$instance))
			self::$instance = new Database();

		return self::$instance;
	}

	/*
	 * TODO: errorhandling?
	 */
	private function __construct() {
		$this->dbh = mysql_pconnect(DB_HOST, DB_USER, DB_PASS);
		mysql_select_db(DB_NAME, $this->dbh);

		$stats = array();
	}

	/*
	 * TODO: errorhandling?
	 */
	function query($sql) {
		$start = microtime(true);
		$this->result = mysql_query($sql, $this->dbh);
		$error = mysql_error($this->dbh);
		$end = microtime(true);
		$this->stats[] = array('query' => $sql, 'error' => $error, 'time' => $end - $start);
		return $this->result;
	}

	function fetch_assoc() {
		return mysql_fetch_assoc($this->result);
	}

	function fetch_array() {
		return mysql_fetch_array($this->result);
	}

	function fetch_row() {
		return mysql_fetch_row($this->result);
	}

	function num_rows() {
		return mysql_num_rows($this->result);
	}

	function insert_id() {
		return mysql_insert_id();
	}

	function affected_rows() {
		return mysql_affected_rows($this->result);
	}

	static function getQueryStats() {
		$sum = 0;
		$errors = 0;
		$stats = self::$instance->stats;
		unset($stats['last']);

		if (count($stats) > 0) {
			foreach ($stats as $key => $val) {
				$sum += $val['time'];

				if (!empty($val['error']))
					$errors++;
			}

			foreach ($stats as $key => $val)
				$stats[$key]['percent'] = round($val['time'] / $sum, 2);
		}

		$stats['last'] = array('count' => count($stats), 'errors' => $errors, 'sum' => round($sum, 4));
		return $stats;
	}

	static function resetQueryStats() {
		unset($instance->stats);
	}

	function close($force = false) {
		if ($force) {
			mysql_close($instance->dbh);
			unset($instance);
		}
	}
}

?>