<?php
/**
 * Database Wrapper
 * @version $Id$
 * @author Moazzam Khan <mkhan@talkpoint.com>
 * @package TPFramework
 */

/**
 * Database wrapper (singleton)
 *
 * @author Moazzam Khan <mkhan@talkpoint.com>
 * @package TPFramework
 */
class database {
	/** @var DB connection resource handle */
	private $_resource;
	/** @var string Internal variable to hold SQL */
	private $_sql;
	/** @var Internal variable to hold last query cursor */
	private $_cursor;
	/** @var Array Log of queries */
	private $_log = array();
	/** @var int Internal variable to hold the error number of last error */
	private $_errorNum;
	/** @var string Internal variable to hold the error number of last error */
	private $_errorMsg;
	/** @var debugging flag */
	public $debug = 0;

	/**
	 * Constructor
	 *
	 * @param string $host
	 * @param string $user
	 * @param string $pass
	 * @param string $name
	 * @return database
	 */
	private function database($host, $user, $pass, $name)
	{
		if (!($this->_resource = @mysql_pconnect($host, $user, $pass))) {
			trigger_error(mysql_error(), E_USER_ERROR);
			return;
		}
		if (!mysql_select_db($name)) {
			trigger_error("Database Selection failed", E_USER_ERROR);
		}
	}

	/**
	 * @param string $host DB Hostname/IP
	 * @param string $user DB Username
	 * @param string $pass DB User's password
	 * @param string $name DB Name
	 * @return object
	 */
	static function &getInstance($host='', $user='', $pass='', $name='')
	{
		static $db;
		if (!is_object($db))
			$db = new database($host, $user, $pass, $name);
		return $db;
	}


	function execute($sql)
	{
		if (!$this->query($sql)) return false;
		return true;
	}

	/**
	 * @param string $sql SQL statement
	 * @return Array of rows returned by the query
	 */
	function getAll($sql)
	{
		$this->_sql = $sql;
		$ret =& $this->retrieveResults('', 0, 'assoc');
		return $ret;
	}

	/**
	 * Returns an array of row objects
	 * @param string $sql
	 * @see retrieveResults
	 */
	function loadObjectList($sql)
	{
		return $this->retrieveResults('', 0, 'object');
	}


	/**
	 * Load an array of retrieved database objects or values
	 * @param int Database cursor
	 * @param string The field name of a primary key
	 * @return array If <var>key</var> is empty as sequential list of returned records.
	 * If <var>key</var> is not empty then the returned array is indexed by the value
	 * the database key.  Returns <var>null</var> if the query fails.
	 */
	function &retrieveResults ($key='', $max=0, $result_type='row')
	{
		$results = array();
		$sql_function = 'mysql_fetch_'.$result_type;
		if ($cur = $this->query()) {
			while ($row = $sql_function($cur)) {
				if ($key != '') $results[$row->$key] = $row;
				else $results[] = $row;
				if ($max AND count($results) >= $max) break;
			}
			mysql_free_result($cur);
		}
		return $results;
	}

	/**
	 * Execute the query
	 * @return mixed A database resource if successful, FALSE if not.
	 */
	function query($sql = '')
	{
		$this->_errorNum = 0;
		$this->_errorMsg = '';
		if ($sql == '') $sql = $this->_sql;
		if ($this->debug) $this->_log[] = $sql;
		if ($this->_cursor = mysql_query($sql, $this->_resource)) {
			$this->_errorNum = 0;
			$this->_errorMsg = '';
			return $this->_cursor;
		} else {
			$this->_errorNum = mysql_errno( $this->_resource );
			$this->_errorMsg = mysql_error( $this->_resource )." SQL=$sql";
			//if ($this->_debug) $this->debug_trace();
			return false;
		}
	}

	function errorMsg() {return $this->_errorMsg;}


	/** Closes the db connection */
	function close()
	{
		@mysql_close($this->_resource);
		$this->_resource = NULL;
	}

}