<?php
namespace Ratchet\Application\WebSocket\Version;
use Ratchet\Application\WebSocket\Version\RFC6455\HandshakeVerifier;
use Guzzle\Http\Message\RequestInterface;

/**
 * @link http://www.rfc-editor.org/authors/rfc6455.txt
 */
class RFC6455 implements VersionInterface {
    const GUID = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11';

    /**
     * @var RFC6455\HandshakeVerifier
     */
    protected $_verifier;

    public function __construct() {
        $this->_verifier = new HandshakeVerifier;
    }

    /**
     * @todo Change the request to be a Guzzle RequestInterface
     */
    public static function isProtocol($headers) {
        if (isset($headers['Sec-WebSocket-Version'])) {
            if ((int)$headers['Sec-WebSocket-Version'] == 13) {
                return true;
            }
        }

        return false;
    }

    /**
     * @return array
     * I kept this as an array and combined in App for future considerations...easier to add a subprotol as a key value than edit a string
     * @todo Decide what to do on failure...currently throwing an exception and I think socket connection is closed.  Should be sending 40x error - but from where?
     */
    public function handshake($message) {
        $headers = $message->getHeaders();
        $key     = $this->sign($headers['Sec-WebSocket-Key']);

        if (true !== $this->_verifier->verifyAll($message)) {
            throw new \InvalidArgumentException('Invalid HTTP header');
        }

        return array(
            ''                     => 'HTTP/1.1 101 Switching Protocols'
          , 'Upgrade'              => 'websocket'
          , 'Connection'           => 'Upgrade'
          , 'Sec-WebSocket-Accept' => $this->sign($headers['Sec-WebSocket-Key'])
//          , 'Sec-WebSocket-Protocol' => ''
        );
   }

    /**
     * @return RFC6455\Message
     */
    public function newMessage() {
        return new RFC6455\Message;
    }

    /**
     * @return RFC6455\Frame
     */
    public function newFrame() {
        return new RFC6455\Frame;
    }

    /**
     * Thanks to @lemmingzshadow for the code on decoding a HyBi-10 frame
     * @link https://github.com/lemmingzshadow/php-websocket
     * @todo look into what happens when false is returned here
     * @param string
     * @return string
     */
    public function frame($message, $mask = true) {
        $payload = $message;
        $type    = 'text';
        $masked  = $mask;

        $frameHead = array();
        $frame = '';
        $payloadLength = strlen($payload);

        switch($type) {
            case 'text':
                // first byte indicates FIN, Text-Frame (10000001):
                $frameHead[0] = 129;                
            break;            

            case 'close':
                // first byte indicates FIN, Close Frame(10001000):
                $frameHead[0] = 136;
            break;

            case 'ping':
                // first byte indicates FIN, Ping frame (10001001):
                $frameHead[0] = 137;
            break;

            case 'pong':
                // first byte indicates FIN, Pong frame (10001010):
                $frameHead[0] = 138;
            break;
        }

        // set mask and payload length (using 1, 3 or 9 bytes) 
        if($payloadLength > 65535) {
            $payloadLengthBin = str_split(sprintf('%064b', $payloadLength), 8);
            $frameHead[1] = ($masked === true) ? 255 : 127;
            for($i = 0; $i < 8; $i++) {
                $frameHead[$i+2] = bindec($payloadLengthBin[$i]);
            }
            // most significant bit MUST be 0 (return false if to much data)
            if($frameHead[2] > 127) {
                return false;
            }
        } elseif($payloadLength > 125) {
            $payloadLengthBin = str_split(sprintf('%016b', $payloadLength), 8);
            $frameHead[1] = ($masked === true) ? 254 : 126;
            $frameHead[2] = bindec($payloadLengthBin[0]);
            $frameHead[3] = bindec($payloadLengthBin[1]);
        } else {
            $frameHead[1] = ($masked === true) ? $payloadLength + 128 : $payloadLength;
        }

        // convert frame-head to string:
        foreach(array_keys($frameHead) as $i) {
            $frameHead[$i] = chr($frameHead[$i]);
        } if($masked === true) {
            // generate a random mask:
            $mask = array();
            for($i = 0; $i < 4; $i++)
            {
                $mask[$i] = chr(rand(0, 255));
            }

            $frameHead = array_merge($frameHead, $mask);            
        }                        
        $frame = implode('', $frameHead);

        // append payload to frame:
        $framePayload = array();
        for($i = 0; $i < $payloadLength; $i++) {        
            $frame .= ($masked === true) ? $payload[$i] ^ $mask[$i % 4] : $payload[$i];
        }

        return $frame;
    }

    /**
     * Used when doing the handshake to encode the key, verifying client/server are speaking the same language
     * @param string
     * @return string
     * @internal
     */
    public function sign($key) {
        return base64_encode(sha1($key . static::GUID, 1));
    }
}