<?php
/*
     Database.php, creates database connections and provides some basic
                   functions
     Copyright (C) 2004 Arend van Beelen, Auton Rijnsburg

     This program is free software; you can redistribute it and/or modify it
     under the terms of the GNU General Public License as published by the Free
     Software Foundation; either version 2 of the License, or (at your option)
     any later version.

     This program is distributed in the hope that it will be useful, but WITHOUT
     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
     more details.

     You should have received a copy of the GNU General Public License along
     with this program; if not, write to the Free Software Foundation, Inc.,
     59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

     For any questions, comments or whatever, you may mail me at: hide@address.com
*/

require_once('String.php');

/**
 * @brief Creates database connections and provides some basic functions
 *
 * This class can be used to create new database connections and to manage
 * existing connections.
 */
class Database
{
	/**
	 * Constructor.
	 *
	 * You do not have to instantiate this class yourself, instead you can
	 * use the static functions provided by this class.
	 */
	public function __construct()
	{
		$this->connections = array();
	}

	/**
	 * Destructor.
	 *
	 * Closes all managed database connections.
	 */
	public function __destruct()
	{
		foreach($this->connections as $connection)
		{
			$connection->disconnect();
		}
	}

	/**
	 * Selects a database connection.
	 *
	 * Returns the specified database connection. The function will check whether
	 * this connection already exists and if so, returns the connection. If the
	 * connection does not yet exist, it will try to establish it.
	 *
	 * @param type     The type of database to connect to, for example 'MySQL'. An
	 *                 appropriate DatabaseHandler needs to be installed to handle
	 *                 this type of database.
	 * @param server   The server on which the database is running. This can be an
	 *                 IP address or a hostname.
	 * @param database The name of the actual database to select on the server
	 *                 when connected.
	 * @param username Username used to authenticate to the database server.
	 * @param password The user's password to authenticate to the database server.
	 * @return A DatabaseHandler object with an established connection to the
	 *         specified database or @p false if no connection could be
	 *         established.
	 */
	public static function connection($type, $server, $database, $username, $password)
	{
		global $Database;

		foreach($Database->connections as $connection)
		{
			if($connection->type() == $type &&
			   $connection->server() == $server &&
			   $connection->database() == $database &&
			   $connection->username() == $username)
			{
				return $connection;
			}
		}

		$className = String::stripSpecialChars($type).'_DatabaseHandler';

		$include = include_once("DatabaseHandlers/$className.php");
		if($include == false ||
		   class_exists($className) == false)
		{
			return false;
		}

		$connection = new $className;
		if($connection->connect($server, $database, $username, $password) == false)
		{
			return false;
		}

		$Database->connections[] = $connection;

		return $connection;
	}

	private $connections;
}

// create one global instance of the class
global $Database;
$Database = new Database();

?>