peerjs/dist/peer.js

/*! peerjs.js build:0.1.0, development. Copyright(c) 2013 Michelle Bu <michelle@michellebu.com> */
(function(exports){
var binaryFeatures = {};
binaryFeatures.useBlobBuilder = (function(){
  try {
    new Blob([]);
    return false;
  } catch (e) {
    return true;
  }
})();

binaryFeatures.useArrayBufferView = !binaryFeatures.useBlobBuilder && (function(){
  try {
    return (new Blob([new Uint8Array([])])).size === 0;
  } catch (e) {
    return true;
  }
})();

exports.binaryFeatures = binaryFeatures;
exports.BlobBuilder = window.WebKitBlobBuilder || window.MozBlobBuilder || window.MSBlobBuilder || window.BlobBuilder;

function BufferBuilder(){
  this._pieces = [];
  this._parts = [];
}

BufferBuilder.prototype.append = function(data) {
  if(typeof data === 'number') {
    this._pieces.push(data);
  } else {
    this._flush();
    this._parts.push(data);
  }
};

BufferBuilder.prototype._flush = function() {
  if (this._pieces.length > 0) {    
    var buf = new Uint8Array(this._pieces);
    if(!binaryFeatures.useArrayBufferView) {
      buf = buf.buffer;
    }
    this._parts.push(buf);
    this._pieces = [];
  }
};

BufferBuilder.prototype.getBuffer = function() {
  this._flush();
  if(binaryFeatures.useBlobBuilder) {
    var builder = new BlobBuilder();
    for(var i = 0, ii = this._parts.length; i < ii; i++) {
      builder.append(this._parts[i]);
    }
    return builder.getBlob();
  } else {
    return new Blob(this._parts);
  }
};
exports.BinaryPack = {
  unpack: function(data){
    var unpacker = new Unpacker(data);
    return unpacker.unpack();
  },
  pack: function(data, utf8){
    var packer = new Packer(utf8);
    var buffer = packer.pack(data);
    return buffer;
  }
};

function Unpacker (data){
  // Data is ArrayBuffer
  this.index = 0;
  this.dataBuffer = data;
  this.dataView = new Uint8Array(this.dataBuffer);
  this.length = this.dataBuffer.byteLength;
}


Unpacker.prototype.unpack = function(){
  var type = this.unpack_uint8();
  if (type < 0x80){
    var positive_fixnum = type;
    return positive_fixnum;
  } else if ((type ^ 0xe0) < 0x20){
    var negative_fixnum = (type ^ 0xe0) - 0x20;
    return negative_fixnum;
  }
  var size;
  if ((size = type ^ 0xa0) <= 0x0f){
    return this.unpack_raw(size);
  } else if ((size = type ^ 0xb0) <= 0x0f){
    return this.unpack_string(size);
  } else if ((size = type ^ 0x90) <= 0x0f){
    return this.unpack_array(size);
  } else if ((size = type ^ 0x80) <= 0x0f){
    return this.unpack_map(size);
  }
  switch(type){
    case 0xc0:
      return null;
    case 0xc1:
      return undefined;
    case 0xc2:
      return false;
    case 0xc3:
      return true;
    case 0xca:
      return this.unpack_float();
    case 0xcb:
      return this.unpack_double();
    case 0xcc:
      return this.unpack_uint8();
    case 0xcd:
      return this.unpack_uint16();
    case 0xce:
      return this.unpack_uint32();
    case 0xcf:
      return this.unpack_uint64();
    case 0xd0:
      return this.unpack_int8();
    case 0xd1:
      return this.unpack_int16();
    case 0xd2:
      return this.unpack_int32();
    case 0xd3:
      return this.unpack_int64();
    case 0xd4:
      return undefined;
    case 0xd5:
      return undefined;
    case 0xd6:
      return undefined;
    case 0xd7:
      return undefined;
    case 0xd8:
      size = this.unpack_uint16();
      return this.unpack_string(size);
    case 0xd9:
      size = this.unpack_uint32();
      return this.unpack_string(size);
    case 0xda:
      size = this.unpack_uint16();
      return this.unpack_raw(size);
    case 0xdb:
      size = this.unpack_uint32();
      return this.unpack_raw(size);
    case 0xdc:
      size = this.unpack_uint16();
      return this.unpack_array(size);
    case 0xdd:
      size = this.unpack_uint32();
      return this.unpack_array(size);
    case 0xde:
      size = this.unpack_uint16();
      return this.unpack_map(size);
    case 0xdf:
      size = this.unpack_uint32();
      return this.unpack_map(size);
  }
}

Unpacker.prototype.unpack_uint8 = function(){
  var byte = this.dataView[this.index] & 0xff;
  this.index++;
  return byte;
};

Unpacker.prototype.unpack_uint16 = function(){
  var bytes = this.read(2);
  var uint16 =
    ((bytes[0] & 0xff) * 256) + (bytes[1] & 0xff);
  this.index += 2;
  return uint16;
}

Unpacker.prototype.unpack_uint32 = function(){
  var bytes = this.read(4);
  var uint32 =
     ((bytes[0]  * 256 +
       bytes[1]) * 256 +
       bytes[2]) * 256 +
       bytes[3];
  this.index += 4;
  return uint32;
}

Unpacker.prototype.unpack_uint64 = function(){
  var bytes = this.read(8);
  var uint64 =
   ((((((bytes[0]  * 256 +
       bytes[1]) * 256 +
       bytes[2]) * 256 +
       bytes[3]) * 256 +
       bytes[4]) * 256 +
       bytes[5]) * 256 +
       bytes[6]) * 256 +
       bytes[7];
  this.index += 8;
  return uint64;
}


Unpacker.prototype.unpack_int8 = function(){
  var uint8 = this.unpack_uint8();
  return (uint8 < 0x80 ) ? uint8 : uint8 - (1 << 8);
};

Unpacker.prototype.unpack_int16 = function(){
  var uint16 = this.unpack_uint16();
  return (uint16 < 0x8000 ) ? uint16 : uint16 - (1 << 16);
}

Unpacker.prototype.unpack_int32 = function(){
  var uint32 = this.unpack_uint32();
  return (uint32 < Math.pow(2, 31) ) ? uint32 :
    uint32 - Math.pow(2, 32);
}

Unpacker.prototype.unpack_int64 = function(){
  var uint64 = this.unpack_uint64();
  return (uint64 < Math.pow(2, 63) ) ? uint64 :
    uint64 - Math.pow(2, 64);
}

Unpacker.prototype.unpack_raw = function(size){
  if ( this.length < this.index + size){
    throw new Error('BinaryPackFailure: index is out of range'
      + ' ' + this.index + ' ' + size + ' ' + this.length);
  }
  var buf = this.dataBuffer.slice(this.index, this.index + size);
  this.index += size;
  
    //buf = util.bufferToString(buf);
  
  return buf;
}

Unpacker.prototype.unpack_string = function(size){
  var bytes = this.read(size);
  var i = 0, str = '', c, code;
  while(i < size){
    c = bytes[i];
    if ( c < 128){
      str += String.fromCharCode(c);
      i++;
    } else if ((c ^ 0xc0) < 32){
      code = ((c ^ 0xc0) << 6) | (bytes[i+1] & 63);
      str += String.fromCharCode(code);
      i += 2;
    } else {
      code = ((c & 15) << 12) | ((bytes[i+1] & 63) << 6) |
        (bytes[i+2] & 63);
      str += String.fromCharCode(code);
      i += 3;
    }
  }
  this.index += size;
  return str;
}

Unpacker.prototype.unpack_array = function(size){
  var objects = new Array(size);
  for(var i = 0; i < size ; i++){
    objects[i] = this.unpack();
  }
  return objects;
}

Unpacker.prototype.unpack_map = function(size){
  var map = {};
  for(var i = 0; i < size ; i++){
    var key  = this.unpack();
    var value = this.unpack();
    map[key] = value;
  }
  return map;
}

Unpacker.prototype.unpack_float = function(){
  var uint32 = this.unpack_uint32();
  var sign = uint32 >> 31;
  var exp  = ((uint32 >> 23) & 0xff) - 127;
  var fraction = ( uint32 & 0x7fffff ) | 0x800000;
  return (sign == 0 ? 1 : -1) *
    fraction * Math.pow(2, exp - 23);
}

Unpacker.prototype.unpack_double = function(){
  var h32 = this.unpack_uint32();
  var l32 = this.unpack_uint32();
  var sign = h32 >> 31;
  var exp  = ((h32 >> 20) & 0x7ff) - 1023;
  var hfrac = ( h32 & 0xfffff ) | 0x100000;
  var frac = hfrac * Math.pow(2, exp - 20) +
    l32   * Math.pow(2, exp - 52);
  return (sign == 0 ? 1 : -1) * frac;
}

Unpacker.prototype.read = function(length){
  var j = this.index;
  if (j + length <= this.length) {
    return this.dataView.subarray(j, j + length);
  } else {
    throw new Error('BinaryPackFailure: read index out of range');
  }
}
  
function Packer(utf8){
  this.utf8 = utf8;
  this.bufferBuilder = new BufferBuilder();
}

Packer.prototype.pack = function(value){
  var type = typeof(value);
  if (type == 'string'){
    this.pack_string(value);
  } else if (type == 'number'){
    if (Math.floor(value) === value){
      this.pack_integer(value);
    } else{
      this.pack_double(value);
    }
  } else if (type == 'boolean'){
    if (value === true){
      this.bufferBuilder.append(0xc3);
    } else if (value === false){
      this.bufferBuilder.append(0xc2);
    }
  } else if (type == 'undefined'){
    this.bufferBuilder.append(0xc0);
  } else if (type == 'object'){
    if (value === null){
      this.bufferBuilder.append(0xc0);
    } else {
      var constructor = value.constructor;
      if (constructor == Array){
        this.pack_array(value);
      } else if (constructor == Blob || constructor == File) {
        this.pack_bin(value);
      } else if (constructor == ArrayBuffer) {
        if(binaryFeatures.useArrayBufferView) {
          this.pack_bin(new Uint8Array(value));
        } else {
          this.pack_bin(value);
        }
      } else if ('BYTES_PER_ELEMENT' in value){
        if(binaryFeatures.useArrayBufferView) {
          this.pack_bin(value);
        } else {
          this.pack_bin(value.buffer);
        }
      } else if (constructor == Object){
        this.pack_object(value);
      } else if (constructor == Date){
        this.pack_string(value.toString());
      } else if (typeof value.toBinaryPack == 'function'){
        this.bufferBuilder.append(value.toBinaryPack());
      } else {
        throw new Error('Type "' + constructor.toString() + '" not yet supported');
      }
    }
  } else {
    throw new Error('Type "' + type + '" not yet supported');
  }
  return this.bufferBuilder.getBuffer();
}


Packer.prototype.pack_bin = function(blob){
  var length = blob.length || blob.byteLength || blob.size;
  if (length <= 0x0f){
    this.pack_uint8(0xa0 + length);
  } else if (length <= 0xffff){
    this.bufferBuilder.append(0xda) ;
    this.pack_uint16(length);
  } else if (length <= 0xffffffff){
    this.bufferBuilder.append(0xdb);
    this.pack_uint32(length);
  } else{
    throw new Error('Invalid length');
    return;
  }
  this.bufferBuilder.append(blob);
}

Packer.prototype.pack_string = function(str){
  var length;
  if (this.utf8) {
    var blob = new Blob([str]);
    length = blob.size;
  } else {
    length = str.length;
  }
  if (length <= 0x0f){
    this.pack_uint8(0xb0 + length);
  } else if (length <= 0xffff){
    this.bufferBuilder.append(0xd8) ;
    this.pack_uint16(length);
  } else if (length <= 0xffffffff){
    this.bufferBuilder.append(0xd9);
    this.pack_uint32(length);
  } else{
    throw new Error('Invalid length');
    return;
  }
  this.bufferBuilder.append(str);
}

Packer.prototype.pack_array = function(ary){
  var length = ary.length;
  if (length <= 0x0f){
    this.pack_uint8(0x90 + length);
  } else if (length <= 0xffff){
    this.bufferBuilder.append(0xdc)
    this.pack_uint16(length);
  } else if (length <= 0xffffffff){
    this.bufferBuilder.append(0xdd);
    this.pack_uint32(length);
  } else{
    throw new Error('Invalid length');
  }
  for(var i = 0; i < length ; i++){
    this.pack(ary[i]);
  }
}

Packer.prototype.pack_integer = function(num){
  if ( -0x20 <= num && num <= 0x7f){
    this.bufferBuilder.append(num & 0xff);
  } else if (0x00 <= num && num <= 0xff){
    this.bufferBuilder.append(0xcc);
    this.pack_uint8(num);
  } else if (-0x80 <= num && num <= 0x7f){
    this.bufferBuilder.append(0xd0);
    this.pack_int8(num);
  } else if ( 0x0000 <= num && num <= 0xffff){
    this.bufferBuilder.append(0xcd);
    this.pack_uint16(num);
  } else if (-0x8000 <= num && num <= 0x7fff){
    this.bufferBuilder.append(0xd1);
    this.pack_int16(num);
  } else if ( 0x00000000 <= num && num <= 0xffffffff){
    this.bufferBuilder.append(0xce);
    this.pack_uint32(num);
  } else if (-0x80000000 <= num && num <= 0x7fffffff){
    this.bufferBuilder.append(0xd2);
    this.pack_int32(num);
  } else if (-0x8000000000000000 <= num && num <= 0x7FFFFFFFFFFFFFFF){
    this.bufferBuilder.append(0xd3);
    this.pack_int64(num);
  } else if (0x0000000000000000 <= num && num <= 0xFFFFFFFFFFFFFFFF){
    this.bufferBuilder.append(0xcf);
    this.pack_uint64(num);
  } else{
    throw new Error('Invalid integer');
  }
}

Packer.prototype.pack_double = function(num){
  var sign = 0;
  if (num < 0){
    sign = 1;
    num = -num;
  }
  var exp  = Math.floor(Math.log(num) / Math.LN2);
  var frac0 = num / Math.pow(2, exp) - 1;
  var frac1 = Math.floor(frac0 * Math.pow(2, 52));
  var b32   = Math.pow(2, 32);
  var h32 = (sign << 31) | ((exp+1023) << 20) |
      (frac1 / b32) & 0x0fffff;
  var l32 = frac1 % b32;
  this.bufferBuilder.append(0xcb);
  this.pack_int32(h32);
  this.pack_int32(l32);
}

Packer.prototype.pack_object = function(obj){
  var keys = Object.keys(obj);
  var length = keys.length;
  if (length <= 0x0f){
    this.pack_uint8(0x80 + length);
  } else if (length <= 0xffff){
    this.bufferBuilder.append(0xde);
    this.pack_uint16(length);
  } else if (length <= 0xffffffff){
    this.bufferBuilder.append(0xdf);
    this.pack_uint32(length);
  } else{
    throw new Error('Invalid length');
  }
  for(var prop in obj){
    if (obj.hasOwnProperty(prop)){
      this.pack(prop);
      this.pack(obj[prop]);
    }
  }
}

Packer.prototype.pack_uint8 = function(num){
  this.bufferBuilder.append(num);
}

Packer.prototype.pack_uint16 = function(num){
  this.bufferBuilder.append(num >> 8);
  this.bufferBuilder.append(num & 0xff);
}

Packer.prototype.pack_uint32 = function(num){
  var n = num & 0xffffffff;
  this.bufferBuilder.append((n & 0xff000000) >>> 24);
  this.bufferBuilder.append((n & 0x00ff0000) >>> 16);
  this.bufferBuilder.append((n & 0x0000ff00) >>>  8);
  this.bufferBuilder.append((n & 0x000000ff));
}

Packer.prototype.pack_uint64 = function(num){
  var high = num / Math.pow(2, 32);
  var low  = num % Math.pow(2, 32);
  this.bufferBuilder.append((high & 0xff000000) >>> 24);
  this.bufferBuilder.append((high & 0x00ff0000) >>> 16);
  this.bufferBuilder.append((high & 0x0000ff00) >>>  8);
  this.bufferBuilder.append((high & 0x000000ff));
  this.bufferBuilder.append((low  & 0xff000000) >>> 24);
  this.bufferBuilder.append((low  & 0x00ff0000) >>> 16);
  this.bufferBuilder.append((low  & 0x0000ff00) >>>  8);
  this.bufferBuilder.append((low  & 0x000000ff));
}

Packer.prototype.pack_int8 = function(num){
  this.bufferBuilder.append(num & 0xff);
}

Packer.prototype.pack_int16 = function(num){
  this.bufferBuilder.append((num & 0xff00) >> 8);
  this.bufferBuilder.append(num & 0xff);
}

Packer.prototype.pack_int32 = function(num){
  this.bufferBuilder.append((num >>> 24) & 0xff);
  this.bufferBuilder.append((num & 0x00ff0000) >>> 16);
  this.bufferBuilder.append((num & 0x0000ff00) >>> 8);
  this.bufferBuilder.append((num & 0x000000ff));
}

Packer.prototype.pack_int64 = function(num){
  var high = Math.floor(num / Math.pow(2, 32));
  var low  = num % Math.pow(2, 32);
  this.bufferBuilder.append((high & 0xff000000) >>> 24);
  this.bufferBuilder.append((high & 0x00ff0000) >>> 16);
  this.bufferBuilder.append((high & 0x0000ff00) >>>  8);
  this.bufferBuilder.append((high & 0x000000ff));
  this.bufferBuilder.append((low  & 0xff000000) >>> 24);
  this.bufferBuilder.append((low  & 0x00ff0000) >>> 16);
  this.bufferBuilder.append((low  & 0x0000ff00) >>>  8);
  this.bufferBuilder.append((low  & 0x000000ff));
}
/**
 * Light EventEmitter. Ported from Node.js/events.js
 * Eric Zhang
 */

/**
 * EventEmitter class
 * Creates an object with event registering and firing methods
 */
function EventEmitter() {
  // Initialise required storage variables
  this._events = {};
}

var isArray = Array.isArray;


EventEmitter.prototype.addListener = function(type, listener, scope, once) {
  if ('function' !== typeof listener) {
    throw new Error('addListener only takes instances of Function');
  }
  
  // To avoid recursion in the case that type == "newListeners"! Before
  // adding it to the listeners, first emit "newListeners".
  this.emit('newListener', type, typeof listener.listener === 'function' ?
            listener.listener : listener);
            
  if (!this._events[type]) {
    // Optimize the case of one listener. Don't need the extra array object.
    this._events[type] = listener;
  } else if (isArray(this._events[type])) {

    // If we've already got an array, just append.
    this._events[type].push(listener);

  } else {
    // Adding the second element, need to change to array.
    this._events[type] = [this._events[type], listener];
  }
  return this;
};

EventEmitter.prototype.on = EventEmitter.prototype.addListener;

EventEmitter.prototype.once = function(type, listener, scope) {
  if ('function' !== typeof listener) {
    throw new Error('.once only takes instances of Function');
  }

  var self = this;
  function g() {
    self.removeListener(type, g);
    listener.apply(this, arguments);
  };

  g.listener = listener;
  self.on(type, g);

  return this;
};

EventEmitter.prototype.removeListener = function(type, listener, scope) {
  if ('function' !== typeof listener) {
    throw new Error('removeListener only takes instances of Function');
  }

  // does not use listeners(), so no side effect of creating _events[type]
  if (!this._events[type]) return this;

  var list = this._events[type];

  if (isArray(list)) {
    var position = -1;
    for (var i = 0, length = list.length; i < length; i++) {
      if (list[i] === listener ||
          (list[i].listener && list[i].listener === listener))
      {
        position = i;
        break;
      }
    }

    if (position < 0) return this;
    list.splice(position, 1);
    if (list.length == 0)
      delete this._events[type];
  } else if (list === listener ||
             (list.listener && list.listener === listener))
  {
    delete this._events[type];
  }

  return this;
};


EventEmitter.prototype.off = EventEmitter.prototype.removeListener;


EventEmitter.prototype.removeAllListeners = function(type) {
  if (arguments.length === 0) {
    this._events = {};
    return this;
  }

  // does not use listeners(), so no side effect of creating _events[type]
  if (type && this._events && this._events[type]) this._events[type] = null;
  return this;
};

EventEmitter.prototype.listeners = function(type) {
  if (!this._events[type]) this._events[type] = [];
  if (!isArray(this._events[type])) {
    this._events[type] = [this._events[type]];
  }
  return this._events[type];
};

EventEmitter.prototype.emit = function(type) {
  var type = arguments[0];
  var handler = this._events[type];
  if (!handler) return false;

  if (typeof handler == 'function') {
    switch (arguments.length) {
      // fast cases
      case 1:
        handler.call(this);
        break;
      case 2:
        handler.call(this, arguments[1]);
        break;
      case 3:
        handler.call(this, arguments[1], arguments[2]);
        break;
      // slower
      default:
        var l = arguments.length;
        var args = new Array(l - 1);
        for (var i = 1; i < l; i++) args[i - 1] = arguments[i];
        handler.apply(this, args);
    }
    return true;

  } else if (isArray(handler)) {
    var l = arguments.length;
    var args = new Array(l - 1);
    for (var i = 1; i < l; i++) args[i - 1] = arguments[i];

    var listeners = handler.slice();
    for (var i = 0, l = listeners.length; i < l; i++) {
      listeners[i].apply(this, args);
    }
    return true;
  } else {
    return false;
  }
};



var util = {
  
  debug: false,
  browserisms: '',
  
  inherits: function(ctor, superCtor) {
    ctor.super_ = superCtor;
    ctor.prototype = Object.create(superCtor.prototype, {
      constructor: {
        value: ctor,
        enumerable: false,
        writable: true,
        configurable: true
      }
    });
  },
  extend: function(dest, source) {
    for(var key in source) {
      if(source.hasOwnProperty(key)) {
        dest[key] = source[key];
      }
    }
    return dest;
  },
  pack: BinaryPack.pack,
  unpack: BinaryPack.unpack,
  randomPort: function() {
    return Math.round(Math.random() * 60535) + 5000;
  },
  
  log: function () {
    if (util.debug) {
      var err = false;
      var copy = Array.prototype.slice.call(arguments);
      copy.unshift('PeerJS: ');
      for (var i = 0, l = copy.length; i < l; i++){
        if (copy[i] instanceof Error) {
          copy[i] = '(' + copy[i].name + ') ' + copy[i].message;
          err = true;
        }
      }
      err ? console.error.apply(console, copy) : console.log.apply(console, copy);
    }
  },

  setZeroTimeout: (function(global) {
    var timeouts = [];
    var messageName = 'zero-timeout-message';

    // Like setTimeout, but only takes a function argument.	 There's
    // no time argument (always zero) and no arguments (you have to
    // use a closure).
    function setZeroTimeoutPostMessage(fn) {
      timeouts.push(fn);
      global.postMessage(messageName, '*');
    }		

    function handleMessage(event) {
      if (event.source == global && event.data == messageName) {
        if (event.stopPropagation) {
          event.stopPropagation();
        }
        if (timeouts.length) {
          timeouts.shift()();
        }
      }
    }
    if (global.addEventListener) {
      global.addEventListener('message', handleMessage, true);
    } else if (global.attachEvent) {
      global.attachEvent('onmessage', handleMessage);
    }
    return setZeroTimeoutPostMessage;
  }(this)),
  
  blobToArrayBuffer: function(blob, cb){
    var fr = new FileReader();
    fr.onload = function(evt) {
      cb(evt.target.result);
    };
    fr.readAsArrayBuffer(blob);
  },
  blobToBinaryString: function(blob, cb){
    var fr = new FileReader();
    fr.onload = function(evt) {
      cb(evt.target.result);
    };
    fr.readAsBinaryString(blob);
  },
  binaryStringToArrayBuffer: function(binary) {
    var byteArray = new Uint8Array(binary.length);
    for (var i = 0; i < binary.length; i++) {
      byteArray[i] = binary.charCodeAt(i) & 0xff;
    }
    return byteArray.buffer;
  },
  randomToken: function () {
    return Math.random().toString(36).substr(2);
  }
};
/**
 * Reliable transfer for Chrome Canary DataChannel impl.
 * Author: @michellebu
 */
function Reliable(dc, debug) {
  if (!(this instanceof Reliable)) return new Reliable(dc);
  this._dc = dc;

  util.debug = debug;

  // Messages sent/received so far.
  // id: { ack: n, chunks: [...] }
  this._outgoing = {};
  // id: { ack: ['ack', id, n], chunks: [...] }
  this._incoming = {};
  this._received = {};

  // Window size.
  this._window = 20;
  // MTU.
  this._mtu = 500;
  // Interval for setInterval. In ms.
  this._interval = 30;
  /**
   * TIMES for 5KB:
   * Time - wi | mtu | interval
   * 4441 - 20 | 500 | 50
   * 4317 - 100| 600 | 20
   * 4158 - 50 | 600 | 100
   * 4151 - 20 | 500 | 30
   * 4086 - 20 | 600 | 20
   * 4080 - 50 | 600 | 20
   * 4049 - 50 | 600 | 10
   * 3561 - 50 | 600 | 50
   * 2198 - 20 | 800 | 50 - Breaks for bigger files.
   *              800 MTU seems to throttle even at 200ms for larger files
   *
   * TIMES for 23KB:
   * 38421 - 20 | 600 | 50
   * 29904 - 20 | 500 | 30
   * 37906 - 50 | 500 | 30
   */

  // Messages sent.
  this._count = 0;

  // Outgoing message queue.
  this._queue = [];

  this._setupDC();
};

// Send a message reliably.
Reliable.prototype.send = function(msg) {
  // Determine if chunking is necessary.
  var bl = util.pack(msg);
  if (bl.size < this._mtu) {
    this._handleSend(['no', bl]);
    return;
  }

  this._outgoing[this._count] = {
    ack: 0,
    chunks: this._chunk(bl)
  };

  if (util.debug) {
    this._outgoing[this._count].timer = new Date();
  }

  // Send prelim window.
  this._sendWindowedChunks(this._count);
  this._count += 1;
};

// Overwritten, typically.
Reliable.prototype.onmessage = function(msg) {};

// Set up interval for processing queue.
Reliable.prototype._setupInterval = function() {
  var self = this;
  this._timeout = setInterval(function() {
    // FIXME: String stuff makes things terribly async.
    var msg = self._queue.shift();
    util.log('Sending...', msg);
    msg = util.pack(msg);
    util.blobToBinaryString(msg, function(str) {
      self._dc.send(str);
      if (self._queue.length === 0) {
        clearTimeout(self._timeout);
        self._timeout = null;
        self._processAcks();
      }
    });
  }, this._interval);
};

// Go through ACKs to send missing pieces.
Reliable.prototype._processAcks = function() {
  for (var id in this._outgoing) {
    if (this._outgoing.hasOwnProperty(id)) {
      this._sendWindowedChunks(id);
    }
  }
};

// Handle sending a message.
// FIXME: Don't wait for interval time for all messages...
Reliable.prototype._handleSend = function(msg) {
  if (this._queue.indexOf(msg) === -1) {
    this._queue.push(msg);
    if (!this._timeout) {
      this._setupInterval();
    }
  }
};

// Set up DataChannel handlers.
Reliable.prototype._setupDC = function() {
  // Handle various message types.
  var self = this;
  this._dc.onmessage = function(e) {
    var msg = e.data;
    var datatype = msg.constructor;
    // FIXME: msg is String until binary is supported.
    // Once that happens, this will have to be smarter.
    if (datatype === String) {
      var ab = util.binaryStringToArrayBuffer(msg);
      msg = util.unpack(ab);
      self._handleMessage(msg);
    }
  };
};

// Handles an incoming message.
Reliable.prototype._handleMessage = function(msg) {
  util.log('handleMessage: ', msg);
  var id = msg[1];
  var idata = this._incoming[id];
  var odata = this._outgoing[id];
  var data;
  switch (msg[0]) {
    // No chunking was done.
    case 'no':
      var message = id;
      if (!!message) {
        // TODO: What fancy timeout stuff to do with ACK?
        this.onmessage(util.unpack(message));
      }
      break;
    // Reached the end of the message.
    case 'end':
      // What if 'end' is sent out of order? Eventually we will ACK for
      // and receive it, so shouldn't be a problem.
      data = idata;
      if (!!data && data.ack[2] === msg[2]) {
        this._complete(id);
        this._received[id] = true;
      } else if (!!data) {
        this._ack(id, data.ack);
      }
      break;
    case 'ack':
      data = odata;
      if (!!data) {
        // TODO: more optimization for window size & data sent.
        // TODO: possibly process ACKs only after queue cleared to avoid dups?
        var ack = msg[2];
        // Take the larger ACK, for out of order messages.
        data.ack = Math.max(ack, data.ack);

        // Clean up when all chunks are ACKed.
        if (data.ack >= data.chunks.length) {
          util.log('Time: ', new Date() - data.timer);
          delete this._outgoing[id];
        }
      }
      // If !data, just ignore.
      break;
    // Received a chunk of data.
    case 'chunk':
      // Create a new entry if none exists.
      data = idata;
      if (!data) {
        if (this._received[id] !== undefined) {
          break;
        }
        data = {
          ack: ['ack', id, 0],
          chunks: []
        };
        this._incoming[id] = data;
      }

      var n = msg[2];
      var chunk = msg[3];
      data.chunks[n] = chunk;

      // If we get the chunk we're looking for, ACK for next missing.
      // Otherwise, ACK the same N again.
      if (n === data.ack[2]) {
        this._calculateNextAck(id);
      }
      this._ack(id);
      break;
    default:
      // Shouldn't happen, but would make sense for message to just go
      // through as is.
      this._handleSend(msg);
      break;
  }
};

// Chunks BL into smaller messages.
Reliable.prototype._chunk = function(bl) {
  var chunks = [];
  var size = bl.size;
  var start = 0;
  while (start < size) {
    var end = Math.min(size, start + this._mtu);
    var b = bl.slice(start, end);
    var chunk = {
      payload: b
    }
    chunks.push(chunk);
    start = end;
  }
  return chunks;
};

// Sends ACK N, expecting Nth blob chunk for message ID.
Reliable.prototype._ack = function(id, n) {
  var ack = this._incoming[id].ack;
  this._handleSend(ack);
};

// Sends END.
Reliable.prototype._end = function(id, n) {
  this._handleSend(['end', id, n]);
};

// Calculates the next ACK number, given chunks.
Reliable.prototype._calculateNextAck = function(id) {
  var data = this._incoming[id];
  var chunks = data.chunks;
  for (var i = 0, ii = chunks.length; i < ii; i += 1) {
    // This chunk is missing!!! Better ACK for it.
    if (chunks[i] === undefined) {
      data.ack[2] = i;
      return;
    }
  }
  data.ack[2] = chunks.length;
};

// Sends the next window of chunks.
Reliable.prototype._sendWindowedChunks = function(id) {
  util.log('sendWindowedChunks for: ', id);
  var data = this._outgoing[id];
  var ch = data.chunks;
  var limit = Math.min(data.ack + this._window, ch.length);
  var timeout = 0;
  for (var i = data.ack; i < limit; i += 1) {
    if (!ch[i].sent || i === data.ack) {
      ch[i].sent = true;
      // TODO: set timer.
      this._sendChunk(id, i, ch[i].payload);
    }
  }
  if (data.ack + this._window >= ch.length) {
    this._end(id, ch.length);
  }
  // TODO: set retry timer.
};

// Sends one chunk.
Reliable.prototype._sendChunk = function(id, n, payload) {
  util.log('sendChunk', payload);
  this._handleSend(['chunk', id, n, payload]);
};

// Puts together a message from chunks.
Reliable.prototype._complete = function(id) {
  util.log('complete', id);
  // FIXME: handle errors.
  var self = this;
  var chunks = this._incoming[id].chunks;
  var bl = new Blob(chunks);
  util.blobToArrayBuffer(bl, function(ab) {
    self.onmessage(util.unpack(ab));
  });
  delete this._incoming[id];
};

exports.Reliable = Reliable;
var RTCPeerConnection = null;
var getUserMedia = null;
var attachMediaStream = null;

if (navigator.mozGetUserMedia) {
  util.browserisms = 'Firefox';

  RTCSessionDescription = window.mozRTCSessionDescription;
  RTCPeerConnection = window.mozRTCPeerConnection;
  getUserMedia = navigator.mozGetUserMedia.bind(navigator);
} else if (navigator.webkitGetUserMedia) {
  util.browserisms = 'Webkit';

  RTCPeerConnection = window.webkitRTCPeerConnection;
  getUserMedia = navigator.webkitGetUserMedia.bind(navigator);
}

exports.RTCSessionDescription = RTCSessionDescription;
exports.RTCPeerConnection = RTCPeerConnection;
exports.getUserMedia = getUserMedia;
/**
 * A peer who can initiate connections with other peers.
 */
function Peer(id, options) {
  if (id && id.constructor == Object) {
    options = id;
    id = undefined;
  }
  if (!(this instanceof Peer)) return new Peer(id, options);
  EventEmitter.call(this);

  // Detect relative URL host.
  if (options.host === '/') {
    options.host = window.location.hostname;
  }

  options = util.extend({
    debug: false,
    host: '0.peerjs.com',
    port: 9000,
    key: 'peerjs',
    config: { 'iceServers': [{ 'url': 'stun:stun.l.google.com:19302' }] }
  }, options);
  this._options = options;
  util.debug = options.debug;

  // Ensure alphanumeric_-
  var self = this;
  if (id && !/^[A-Za-z0-9]+(?:[ _-][A-Za-z0-9]+)*$/.exec(id)) {
    util.setZeroTimeout(function() {
      self._abort('invalid-id', 'ID "' + id + '" is invalid');
    });
    return
  }
  if (options.key && !/^[A-Za-z0-9]+(?:[ _-][A-Za-z0-9]+)*$/.exec(options.key)) {
    util.setZeroTimeout(function() {
      self._abort('invalid-key', 'API KEY "' + options.key + '" is invalid');
    });
    return
  }

  // Connections for this peer.
  this.connections = {};

  // Queued connections to make.
  this._queued = [];

  // Init immediately if ID is given, otherwise ask server for ID
  if (id) {
    this.id = id;
    this._init();
  } else {
    this._getId();
  }
};

util.inherits(Peer, EventEmitter);

Peer.prototype._getId = function(cb) {  
  var self = this;
  try {
    var http = new XMLHttpRequest();
    var url = 'http://' + this._options.host + ':' + this._options.port + '/' + this._options.key + '/id';
    var queryString = '?ts=' + new Date().getTime() + '' + Math.random();
    url += queryString;
    // If there's no ID we need to wait for one before trying to init socket.
    http.open('get', url, true);
    http.onreadystatechange = function() {
      if (http.readyState === 4) {
        self.id = http.responseText;
        self._init();
      }
    };
    http.send(null);
  } catch(e) {
    this._abort('server-error', 'Could not get an ID from the server');
  }
};


Peer.prototype._init = function() {
  var self = this;
  this._socket = new Socket(this._options.host, this._options.port, this._options.key, this.id);
  this._socket.on('message', function(data) {
    self._handleServerJSONMessage(data);
  });
  this._socket.on('error', function(error) {
    util.log(error);
    self._abort('socket-error', error);
  });
  this._socket.on('close', function() {
    var msg = 'Underlying socket has closed';
    util.log('error', msg);
    self._abort('socket-closed', msg);
  });
  this._socket.start();
}


Peer.prototype._handleServerJSONMessage = function(message) {
  var peer = message.src;
  var connection = this.connections[peer];
  var payload = message.payload;
  switch (message.type) {
    case 'OPEN':
      this._processQueue();
      this.emit('open', this.id);
      break;
    case 'ERROR':
      util.log(payload.msg);
      this._abort('server-error', payload.msg);
      break;
    case 'ID-TAKEN':
      this._abort('unavailable-id', 'ID `'+this.id+'` is taken');
      break;
    case 'OFFER':
      var options = {
        metadata: payload.metadata,
        serialization: payload.serialization,
        sdp: payload.sdp,
        reliable: payload.reliable,
        config: this._options.config
      };
      var connection = new DataConnection(this.id, peer, this._socket, options);
      this._attachConnectionListeners(connection);
      this.connections[peer] = connection;
      this.emit('connection', connection, payload.metadata);
      break;
    case 'EXPIRE':
      connection = this.connections[peer];
      if (connection) {
        connection.close();
        connection.emit('error', new Error('Could not connect to peer ' + connection.peer));
      }
      break;
    case 'ANSWER':
      if (connection) {
        connection.handleSDP(payload.sdp, message.type);
      }
      break;
    case 'CANDIDATE':
      if (connection) {
        connection.handleCandidate(payload);
      }
      break;
    case 'LEAVE':
      if (connection) {
        connection.handleLeave();
      }
      break;
    case 'INVALID-KEY':
      this._abort('invalid-key', 'API KEY "' + this._key + '" is invalid');
      break;
    case 'PORT':
      //if (util.browserisms === 'Firefox') {
      //  connection.handlePort(payload);
      //  break;
      //}
    default:
      util.log('Unrecognized message type:', message.type);
      break;
  }
};

/** Process queued calls to connect. */
Peer.prototype._processQueue = function() {
  while (this._queued.length > 0) {
    var conn = this._queued.pop();
    conn.initialize(this.id, this._socket);
  }
};

/** Destroys the Peer and emits an error message. */
Peer.prototype._abort = function(type, message) {
  var err = new Error(message);
  err.type = type;
  this.destroy();
  this.emit('error', err);
};

Peer.prototype._cleanup = function() {
  var self = this;
  if (!!this.connections) {
    var peers = Object.keys(this.connections);
    for (var i = 0, ii = peers.length; i < ii; i++) {
      this.connections[peers[i]].close();
    }
    util.setZeroTimeout(function(){
      self._socket.close();
    });
  }
  this.emit('close');
};

/** Listeners for DataConnection events. */
Peer.prototype._attachConnectionListeners = function(connection) {
  var self = this;
  connection.on('close', function(peer) {
    if (self.connections[peer]) { 
      delete self.connections[peer]; 
    }
  });
};



/** Exposed connect function for users. Will try to connect later if user
 * is waiting for an ID. */
// TODO: pause XHR streaming when not in use and start again when this is
// called.
Peer.prototype.connect = function(peer, options) {
  if (this.destroyed) {
    this._abort('peer-destroyed', 'This Peer has been destroyed and is no longer able to make connections.');
    return;
  }

  options = util.extend({
    config: this._options.config
  }, options);

  var connection = new DataConnection(this.id, peer, this._socket, options);
  this._attachConnectionListeners(connection);

  this.connections[peer] = connection;
  if (!this.id) {
    this._queued.push(connection);
  }
  return connection;
};

Peer.prototype.destroy = function() {
  if (!this.destroyed) {
    this._cleanup();
    this.destroyed = true;
  }
};


exports.Peer = Peer;
/**
 * A DataChannel|PeerConnection between two Peers.
 */
function DataConnection(id, peer, socket, options) {
  if (!(this instanceof DataConnection)) return new DataConnection(options);
  EventEmitter.call(this);

  options = util.extend({
    config: { 'iceServers': [{ 'url': 'stun:stun.l.google.com:19302' }] },
    reliable: false,
    serialization: 'binary'
  }, options);
  this._options = options;

  // Connection is not open yet.
  this.open = false;

  this.id = id;
  this.peer = peer;
  this.metadata = options.metadata;
  this.serialization = options.serialization;

  this._originator = (options.sdp === undefined);
  this._socket = socket;
  this._sdp = options.sdp;

  if (!!this.id) {
    this.initialize();
  }
};

util.inherits(DataConnection, EventEmitter);

DataConnection.prototype.initialize = function(id, socket) {
  if (!!id) {
    this.id = id;
  }
  if (!!socket) {
    this._socket = socket;
  }
  // Firefoxism: connectDataConnection ports.
  /*if (util.browserisms === 'Firefox') {
    this._firefoxPortSetup();
  }*/

  // Set up PeerConnection.
  this._startPeerConnection();

  // Listen for ICE candidates
  this._setupIce();

  // Listen for negotiation needed
  // ** Chrome only.
  if (util.browserisms !== 'Firefox' && !!this.id) {
    this._setupOffer();
  }

  // Listen for or create a data channel
  this._setupDataChannel();

  var self = this;
  if (!!this._sdp) {
    this.handleSDP(this._sdp, 'OFFER');
  }

  // Makes offer if Firefox
  /*if (util.browserisms === 'Firefox') {
    this._firefoxAdditional();
  }*/

  // No-op this.
  this.initialize = function() {};
};


DataConnection.prototype._setupOffer = function() {
  var self = this;
  util.log('Listening for `negotiationneeded`');
  this._pc.onnegotiationneeded = function() {
    util.log('`negotiationneeded` triggered');
    self._makeOffer();
  };
};


DataConnection.prototype._setupDataChannel = function() {
  var self = this;
  if (this._originator) {
    util.log('Creating data channel');
    // FOR NOW: reliable DC is not supported.
    this._dc = this._pc.createDataChannel(this.peer, { reliable: false });
    // Experimental reliable wrapper.
    if (this._options.reliable) {
      this._reliable = new Reliable(this._dc, util.debug);
    }
    this._configureDataChannel();
  } else {
    util.log('Listening for data channel');
    this._pc.ondatachannel = function(evt) {
      util.log('Received data channel');
      self._dc = evt.channel;
      // Experimental reliable wrapper.
      if (self._options.reliable) {
        self._reliable = new Reliable(self._dc, util.debug);
      }
      self._configureDataChannel();
    };
  }
};


/** Starts a PeerConnection and sets up handlers. */
DataConnection.prototype._startPeerConnection = function() {
  util.log('Creating RTCPeerConnection');
  this._pc = new RTCPeerConnection(this._options.config, { optional:[ { RtpDataChannels: true } ]});
};


/** Takes care of ice handlers. */
DataConnection.prototype._setupIce = function() {
  util.log('Listening for ICE candidates');
  var self = this;
  this._pc.onicecandidate = function(evt) {
    if (evt.candidate) {
      util.log('Received ICE candidates');
      self._socket.send({
        type: 'CANDIDATE',
        payload: {
          candidate: evt.candidate
        },
        dst: self.peer
      });
    }
  };
};


/*DataConnection.prototype._firefoxPortSetup = function() {
  if (!DataConnection.usedPorts) {
    DataConnection.usedPorts = [];
  }
  this.localPort = util.randomPort();
  while (DataConnection.usedPorts.indexOf(this.localPort) != -1) {
    this.localPort = util.randomPort();
  }
  this.remotePort = util.randomPort();
  while (this.remotePort === this.localPort ||
      DataConnection.usedPorts.indexOf(this.localPort) != -1) {
    this.remotePort = util.randomPort();
  }
  DataConnection.usedPorts.push(this.remotePort);
  DataConnection.usedPorts.push(this.localPort);
}*/

DataConnection.prototype._configureDataChannel = function() {
  var self = this;
  
  if (util.browserisms !== 'Webkit') {
    this._dc.binaryType = 'arraybuffer';
  }
  this._dc.onopen = function() {
    util.log('Data channel connection success');
    self.open = true;
    self.emit('open');
  };
  if (this._reliable) {
    this._reliable.onmessage = function(msg) {
      self.emit('data', msg);
    };
  } else {
    this._dc.onmessage = function(e) {
      self._handleDataMessage(e);
    };
  }
  this._dc.onclose = function(e) {
    self.emit('close');
  };
};


/** Decide whether to handle Firefoxisms. */
/*DataConnection.prototype._firefoxAdditional = function() {
  var self = this;
  getUserMedia({ audio: true, fake: true }, function(s) {
    self._pc.addStream(s);
    if (self._originator) {
      self._makeOffer();
    }
  }, function(err) { util.log('Could not getUserMedia'); });
};*/

DataConnection.prototype._makeOffer = function() {
  var self = this;
  this._pc.createOffer(function(offer) {
    util.log('Created offer');
    self._pc.setLocalDescription(offer, function() {
      util.log('Set localDescription to offer');
      self._socket.send({
        type: 'OFFER',
        payload: {
          sdp: offer,
          serialization: self.serialization,
          metadata: self.metadata,
          reliable: self._options.reliable
        },
        dst: self.peer
      });
    }, function(err) {
      self.emit('error', err);
      util.log('Failed to setLocalDescription, ', err);
    });
  });
};

/** Create an answer for PC. */
DataConnection.prototype._makeAnswer = function() {
  var self = this;
  this._pc.createAnswer(function(answer) {
    util.log('Created answer');
    self._pc.setLocalDescription(answer, function() {
      util.log('Set localDescription to answer');
      self._socket.send({
        type: 'ANSWER',
        payload: {
          sdp: answer
        },
        dst: self.peer
      });
    }, function(err) {
      self.emit('error', err);
      util.log('Failed to setLocalDescription, ', err)
    });
  }, function(err) {
    self.emit('error', err);
    util.log('Failed to create answer, ', err)
  });
};


DataConnection.prototype._cleanup = function() {
  if (!!this._dc && this._dc.readyState != 'closed') {
    this._dc.close();
    this._dc = null;
  }
  if (!!this._pc && this._pc.readyState != 'closed') {
    this._pc.close();
    this._pc = null;
  }
};


// Handles a DataChannel message.
DataConnection.prototype._handleDataMessage = function(e) {
  var self = this;
  var data = e.data;
  var datatype = data.constructor;
  if (this.serialization === 'binary' || this.serialization === 'binary-utf8') {
    if (datatype === Blob) {
      util.blobToArrayBuffer(data, function(ab) {
        data = util.unpack(ab);
        self.emit('data', data);
      });
      return;
    } else if (datatype === ArrayBuffer) {
      data = util.unpack(data);
    } else if (datatype === String) {
      var ab = util.binaryStringToArrayBuffer(data);
      data = util.unpack(ab);
    }
  } else if (this.serialization === 'json') {
    data = JSON.parse(data);
  }
  this.emit('data', data);
};


/**
 * Exposed functionality for users.
 */

/** Allows user to close connection. */
DataConnection.prototype.close = function() {
  this._cleanup();
  var self = this;
  if (this.open) {
    this._socket.send({
      type: 'LEAVE',
      dst: self.peer
    });
  }
  this.open = false;
  this.emit('close', this.peer);
};


/** Allows user to send data. */
DataConnection.prototype.send = function(data) {
  if (this._reliable) {
    // Note: reliable sending will make it so that you cannot customize
    // serialization.
    this._reliable.send(data);
    return;
  }
  var self = this;
  if (this.serialization === 'none') {
    this._dc.send(data);
  } else if (this.serialization === 'json') {
    this._dc.send(JSON.stringify(data));
  } else {
    var utf8 = (this.serialization === 'binary-utf8');
    var blob = util.pack(data, utf8);
    // DataChannel currently only supports strings.
    if (util.browserisms === 'Webkit') {
      util.blobToBinaryString(blob, function(str){
        self._dc.send(str);
      });
    } else {
      this._dc.send(blob);
    }
  }
};

DataConnection.prototype.handleSDP = function(sdp, type) {
  if (util.browserisms != 'Firefox') {
    sdp = new RTCSessionDescription(sdp);
  }
  var self = this;
  this._pc.setRemoteDescription(sdp, function() {
    util.log('Set remoteDescription: ' + type);
    // Firefoxism
    /**if (type === 'ANSWER' && util.browserisms === 'Firefox') {
      self._pc.connectDataConnection(self.localPort, self.remotePort);
      self._socket.send({
        type: 'PORT',
        dst: self.peer,
        payload: {
          remote: self.localPort,
          local: self.remotePort
        }
      });
    } else*/ if (type === 'OFFER') {
      self._makeAnswer();
    }
  }, function(err) {
    self.emit('error', err);
    util.log('Failed to setRemoteDescription, ', err);
  });
};


DataConnection.prototype.handleCandidate = function(message) {
  var candidate = new RTCIceCandidate(message.candidate);
  this._pc.addIceCandidate(candidate);
  util.log('Added ice candidate');
};


DataConnection.prototype.handleLeave = function() {
  util.log('Peer ' + this.peer + ' disconnected');
  this.close();
};

/*
DataConnection.prototype.handlePort = function(message) {
  if (!DataConnection.usedPorts) {
    DataConnection.usedPorts = [];
  }
  DataConnection.usedPorts.push(message.local);
  DataConnection.usedPorts.push(message.remote);
  this._pc.connectDataConnection(message.local, message.remote);
};
*/

/**
 * An abstraction on top of WebSockets and XHR streaming to provide fastest
 * possible connection for peers.
 */
function Socket(host, port, key, id) {
  if (!(this instanceof Socket)) return new Socket(server, id, key);
  EventEmitter.call(this);
  
  this._id = id;
  var token = util.randomToken();
  
  this._httpUrl = 'http://' + host + ':' + port + '/' + key + '/' + id + '/' + token;
  this._wsUrl = 'ws://' + host + ':' + port + '/peerjs?key='+key+'&id='+id+'&token='+token;
};

util.inherits(Socket, EventEmitter);


/** Check in with ID or get one from server. */
Socket.prototype.start = function() {  
  this._startXhrStream();
  this._startWebSocket();
};


/** Start up websocket communications. */
Socket.prototype._startWebSocket = function() {
  var self = this;

  if (!!this._socket) {
    return;
  }

  this._socket = new WebSocket(this._wsUrl);
  
  this._socket.onmessage = function(event) {
    var data;
    try {
      data = JSON.parse(event.data);
    } catch(e) {
      util.log('Invalid server message', event.data);
      return;
    }
    self.emit('message', data);
  };

  // Take care of the queue of connections if necessary and make sure Peer knows
  // socket is open.
  this._socket.onopen = function() {
    if (!!self._timeout) {
      clearTimeout(self._timeout);
      setTimeout(function(){
        self._http.abort();
        self._http = null;
      }, 5000);
    }
    util.log('Socket open');
  };
};

/** Start XHR streaming. */
Socket.prototype._startXhrStream = function(n) {
  try {
    var self = this;
    this._http = new XMLHttpRequest();
    this._http._index = 1;
    this._http._streamIndex = n || 0;
    this._http.open('post', this._httpUrl + '/id?i=' + this._http._streamIndex, true);
    this._http.onreadystatechange = function() {
      if (this.readyState == 2 && !!this.old) {
        this.old.abort();
        delete this.old;
      }
      if (this.readyState > 2 && this.status == 200 && !!this.responseText) {
        self._handleStream(this);
      }
    };
    this._http.send(null);
    this._setHTTPTimeout();
  } catch(e) {
    util.log('XMLHttpRequest not available; defaulting to WebSockets');
  }
};


/** Handles onreadystatechange response as a stream. */
Socket.prototype._handleStream = function(http) {
  var self = this;
  // 3 and 4 are loading/done state. All others are not relevant.
  var message = http.responseText.split('\n')[http._index];
  if (!!message) {
    http._index += 1;
    try {
      message = JSON.parse(message);
    } catch(e) {
      util.log('Invalid server message', message);
      return;
    }
    self.emit('message', message);
  }
};

Socket.prototype._setHTTPTimeout = function() {
  var self = this;
  this._timeout = setTimeout(function() {
    var old = self._http;
    if (!self._wsOpen()) {
      self._startXhrStream(old._streamIndex + 1);
      self._http.old = old;        
    } else {
      old.abort();
    }
  }, 25000);
};

/** Exposed send for DC & Peer. */
Socket.prototype.send = function(data) {
  if (!data.type) {
    this.emit('error', 'Invalid message');
    return;
  }
  
  var message = JSON.stringify(data);
  if (this._wsOpen()) {
    this._socket.send(message);
  } else {
    var http = new XMLHttpRequest();
    var url = this._httpUrl + '/' + data.type.toLowerCase();
    http.open('post', url, true);
    http.setRequestHeader('Content-Type', 'application/json');
    http.send(message);
  }
};

Socket.prototype.close = function() {
  if (!!this._wsOpen()) {
    this._socket.close();
  }
};

Socket.prototype._wsOpen = function() {
  return !!this._socket && this._socket.readyState == 1;
};


})(this);