<?php
/**
 * Connects to a minecraft server using the [Gamespy?] Query protocol.
 * more info on the protocol can be found at
 * http://wiki.vg/Query
 *
 * @copyright 2013 Chris Churchwell
 *
 */
class Query {
	
	private $host;
	private $port;
	private $timeout; 
	
	private $token = null;
	
	private $socket;
	
	private $errstr = "";
	
	const SESSION_ID = 2;
	
	const TYPE_HANDSHAKE = 0x09;
	const TYPE_STAT = 0x00;
	
	public function __construct($host, $port=25565, $timeout=3, $auto_connect = false) {
		
		$this->host = $host;
		$this->port = $port;
		$this->timeout = $timeout;
		
		if (is_array($host))
		{
		  $this->host = $host['host'];
		  $this->port = empty($host['port'])?$port:$host['port'];
		  $this->timeout = empty($host['timeout'])?$timeout:$host['timeout'];
		  $auto_connect = empty($host['auto_connect'])?$auto_connect:$host['auto_connect'];
		} 
		
		if ($auto_connect === true) {
			$this->connect();
		}
		
	}
	
	/**
	 * Returns the description of the last error produced.
	 * 
	 * @return String - Last error string.
	 */
	public function get_error() {
		return $this->errstr;
	}
	
	/**
	 * Checks whether or not the current connection is established.
	 * 
	 * @return boolean - True if connected; false otherwise.
	 */
	public function is_connected() {
		if (empty($this->token)) return false;
		return true;
	}
	
	/**
	 * Disconnects!
	 * duh
	 */
	public function disconnect() {
		if ($this->socket) {
			fclose($this->socket);
		}
	}
	
	/**
	 * Connects to the host via UDP with the provided credentials.
	 * @return boolean - true if successful, false otherwise.
	 */
	public function connect()
	{
		$this->socket = fsockopen( 'udp://' . $this->host, $this->port, $errno, $errstr, $this->timeout );
		
		if (!$this->socket)
		{
			$this->errstr = $errstr;
			return false;
		}
		
		stream_set_timeout( $this->socket, $this->timeout );
		stream_set_blocking( $this->socket, true );
		
		return $this->get_challenge();
		
	}
	
	/**
	 * Authenticates with the host server and saves the authentication token to a class var.
	 * 
	 * @return boolean - True if succesfull; false otherwise.
	 */
	private function get_challenge()
	{
		if (!$this->socket)
		{
			return false;
		}
		
		//build packet to get challenge.
		$packet = pack("c3N", 0xFE, 0xFD, Query::TYPE_HANDSHAKE, Query::SESSION_ID);
		
		//write packet
		if ( fwrite($this->socket, $packet, strlen($packet)) === FALSE) {
			$this->errstr = "Unable to write to socket";
			return false;
		}
		
		//read packet.
		$response = fread($this->socket, 2056);
		
		if (empty($response)) {
			$this->errstr = "Unable to authenticate connection";
			return false;
		}
		
		$response_data = unpack("c1type/N1id/a*token", $response);
		
		if (!isset($response_data['token']) || empty($response_data['token'])) {
			$this->errstr = "Unable to authenticate connection.";
			return false;
		}
		
		$this->token = $response_data['token'];
		
		return true;
		
	}
	
	/**
	 * Gets all the info from the server.
	 * 
	 * @return boolean|array - Returns the data in an array, or false if there was an error.
	 */
	public function get_info()
	{
		if (!$this->is_connected()) {
			$this->errstr = "Not connected to host";
			return false;
		}
		//build packet to get info
		$packet = pack("c3N2", 0xFE, 0xFD, Query::TYPE_STAT, Query::SESSION_ID, $this->token);
		
		//add the full stat thingy.
		$packet = $packet . pack("c4", 0x00, 0x00, 0x00, 0x00);
		
		//write packet
		if (!fwrite($this->socket, $packet, strlen($packet))) {
			$this->errstr = "Unable to write to socket.";
			return false;
		}
		
		//read packet header
		$response = fread($this->socket, 16);
		//$response = stream_get_contents($this->socket);
		
		// first byte is type. next 4 are id. dont know what the last 11 are for.
		$response_data = unpack("c1type/N1id", $response);
		
		//read the rest of the stream.
		$response = fread($this->socket, 2056);
		
		//split the response into 2 parts.
		$payload = explode ( "\x00\x01player_\x00\x00" , $response);
		
		$info_raw = explode("\x00",  rtrim($payload[0], "\x00"));
		
		//extract key->value chunks from info
		$info = array();
		foreach (array_chunk($info_raw, 2) as $pair) {
			list($key, $value) = $pair;
			//strip possible color format codes from hostname
			if ($key == "hostname") {
				$value = $this->strip_color_codes($value);
			}
			$info[$key] = $value;
		}
		
		//get player data.
		$players_raw = rtrim($payload[1], "\x00");
		$players = array();
		if (!empty($players_raw)) {
			$players = explode("\x00", $players_raw);
		}
		
		//attach player data to info for simplicity
		$info['players'] = $players;
		
		return $info;
	}
	
	/**
	 * Clears Minecraft color codes from a string.
	 * 
	 * @param String $string - the string to remove the codes from
	 * @return String - a clean string.
	 */
	public function strip_color_codes($string) {
		return preg_replace('/[\x00-\x1F\x80-\xFF]./', '', $string);
	}
	
}