1function Uploader(url, cb) {
 2  this.ws = new WebSocket(url);
 3  if (cb) this.ws.onopen = cb;
 4  this.sendQueue = [];
 5  this.sending = null;
 6  this.sendCallback = null;
 7  this.ondone = null;
 8  var self = this;
 9  this.ws.onmessage = function(event) {
10    var data = JSON.parse(event.data);
11    if (data.event == 'complete') {
12      if (data.path != self.sending.path) {
13        self.sendQueue = [];
14        self.sending = null;
15        self.sendCallback = null;
16        throw new Error('Got message for wrong file!');
17      }
18      self.sending = null;
19      var callback = self.sendCallback;
20      self.sendCallback = null;
21      if (callback) callback();
22      if (self.sendQueue.length === 0 && self.ondone) self.ondone(null);
23      if (self.sendQueue.length > 0) {
24        var args = self.sendQueue.pop();
25        setTimeout(function() { self.sendFile.apply(self, args); }, 0);
26      }
27    }
28    else if (data.event == 'error') {
29      self.sendQueue = [];
30      self.sending = null;
31      var callback = self.sendCallback;
32      self.sendCallback = null;
33      var error = new Error('Server reported send error for file ' + data.path);
34      if (callback) callback(error);
35      if (self.ondone) self.ondone(error);
36    }
37  }
38}
39
40Uploader.prototype.sendFile = function(file, cb) {
41  if (this.ws.readyState != WebSocket.OPEN) throw new Error('Not connected');
42  if (this.sending) {
43    this.sendQueue.push(arguments);
44    return;
45  }
46  var fileData = { name: file.name, path: file.webkitRelativePath };
47  this.sending = fileData;
48  this.sendCallback = cb;
49  this.ws.send(JSON.stringify(fileData));
50  this.ws.send(file);
51}
52
53Uploader.prototype.close = function() {
54  this.ws.close();
55}