<?php
class MinecraftQueryException extends Exception
{
    // Exception thrown by MinecraftQuery class
}

class MinecraftQuery
{


    const STATISTIC = 0x00;
    const HANDSHAKE = 0x09;

    private $Socket;
    private $Players;
    private $Info;

    public function Connect( $Ip, $Port = 25565, $Timeout = 3 )
    {
        if( !is_int( $Timeout ) || $Timeout < 0 )
        {
            throw new InvalidArgumentException( 'Timeout must be an integer.' );
        }

        $this->Socket = @FSockOpen( 'udp://' . $Ip, (int)$Port, $ErrNo, $ErrStr, $Timeout );

        if( $ErrNo || $this->Socket === false )
        {
            throw new MinecraftQueryException( 'Could not create socket: ' . $ErrStr );
        }

        Stream_Set_Timeout( $this->Socket, $Timeout );
        Stream_Set_Blocking( $this->Socket, true );

        try
        {
            $Challenge = $this->GetChallenge( );

            $this->GetStatus( $Challenge );
        }
        // We catch this because we want to close the socket, not very elegant
        catch( MinecraftQueryException $e )
        {
            FClose( $this->Socket );

            throw new MinecraftQueryException( $e->getMessage( ) );
        }

        FClose( $this->Socket );
    }

    public function GetInfo( )
    {
        return isset( $this->Info ) ? $this->Info : false;
    }

    public function GetPlayers( )
    {
        return isset( $this->Players ) ? $this->Players : false;
    }

    private function GetChallenge( )
    {
        $Data = $this->WriteData( self :: HANDSHAKE );

        if( $Data === false )
        {
            throw new MinecraftQueryException( 'Failed to receive challenge.' );
        }

        return Pack( 'N', $Data );
    }

    private function GetStatus( $Challenge )
    {
        $Data = $this->WriteData( self :: STATISTIC, $Challenge . Pack( 'c*', 0x00, 0x00, 0x00, 0x00 ) );

        if( !$Data )
        {
            throw new MinecraftQueryException( 'Failed to receive status.' );
        }

        $Last = '';
        $Info = Array( );

        $Data    = SubStr( $Data, 11 ); // splitnum + 2 int
        $Data    = Explode( "\x00\x00\x01player_\x00\x00", $Data );

        if( Count( $Data ) !== 2 )
        {
            throw new MinecraftQueryException( 'Failed to parse server\'s response.' );
        }

        $Players = SubStr( $Data[ 1 ], 0, -2 );
        $Data    = Explode( "\x00", $Data[ 0 ] );

        // Array with known keys in order to validate the result
        // It can happen that server sends custom strings containing bad things (who can know!)
        $Keys = Array(
            'hostname'   => 'HostName',
            'gametype'   => 'GameType',
            'version'    => 'Version',
            'plugins'    => 'Plugins',
            'map'        => 'Map',
            'numplayers' => 'Players',
            'maxplayers' => 'MaxPlayers',
            'hostport'   => 'HostPort',
            'hostip'     => 'HostIp'
        );

        foreach( $Data as $Key => $Value )
        {
            if( ~$Key & 1 )
            {
                if( !Array_Key_Exists( $Value, $Keys ) )
                {
                    $Last = false;
                    continue;
                }

                $Last = $Keys[ $Value ];
                $Info[ $Last ] = '';
            }
            else if( $Last != false )
            {
                $Info[ $Last ] = $Value;
            }
        }

        // Ints
        $Info[ 'Players' ]    = IntVal( $Info[ 'Players' ] );
        $Info[ 'MaxPlayers' ] = IntVal( $Info[ 'MaxPlayers' ] );
        $Info[ 'HostPort' ]   = IntVal( $Info[ 'HostPort' ] );

        // Parse "plugins", if any
        if( $Info[ 'Plugins' ] )
        {
            $Data = Explode( ": ", $Info[ 'Plugins' ], 2 );

            $Info[ 'RawPlugins' ] = $Info[ 'Plugins' ];
            $Info[ 'Software' ]   = $Data[ 0 ];

            if( Count( $Data ) == 2 )
            {
                $Info[ 'Plugins' ] = Explode( "; ", $Data[ 1 ] );
            }
        }
        else
        {
            $Info[ 'Software' ] = 'Vanilla';
        }

        $this->Info = $Info;

        if( $Players )
        {
            $this->Players = Explode( "\x00", $Players );
        }
    }

    private function WriteData( $Command, $Append = "" )
    {
        $Command = Pack( 'c*', 0xFE, 0xFD, $Command, 0x01, 0x02, 0x03, 0x04 ) . $Append;
        $Length  = StrLen( $Command );

        if( $Length !== FWrite( $this->Socket, $Command, $Length ) )
        {
            throw new MinecraftQueryException( "Failed to write on socket." );
        }

        $Data = FRead( $this->Socket, 2048 );

        if( $Data === false )
        {
            throw new MinecraftQueryException( "Failed to read from socket." );
        }

        if( StrLen( $Data ) < 5 || $Data[ 0 ] != $Command[ 2 ] )
        {
            return false;
        }

        return SubStr( $Data, 5 );
    }
}