// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

'use strict';

/** @suppress {duplicate} */
var remoting = remoting || {};

/**
 * A connection to an XMPP server.
 *
 * TODO(sergeyu): Chrome provides two APIs for TCP sockets: chrome.socket and
 * chrome.sockets.tcp . chrome.socket is deprecated but it's still used here
 * because TLS support in chrome.sockets.tcp is currently broken, see
 * crbug.com/403076 .
 *
 * @param {function(remoting.XmppConnection.State):void} onStateChangedCallback
 *   Callback to call on state change.
 * @param {function(Element):void} onIncomingStanzaCallback Callback to call to
 *   handle incoming messages.
 * @constructor
 * @implements {base.Disposable}
 */
remoting.XmppConnection =
    function(onStateChangedCallback, onIncomingStanzaCallback) {
  /** @private */
  this.server_ = '';
  /** @private */
  this.port_ = 0;
  /** @private */
  this.onStateChangedCallback_ = onStateChangedCallback;
  /** @private */
  this.onIncomingStanzaCallback_ = onIncomingStanzaCallback;
  /** @private */
  this.socketId_ = -1;
  /** @private */
  this.state_ = remoting.XmppConnection.State.NOT_CONNECTED;
  /** @private */
  this.readPending_ = false;
  /** @private */
  this.sendPending_ = false;
  /** @private */
  this.startTlsPending_ = false;
  /** @type {Array.<ArrayBuffer>} @private */
  this.sendQueue_ = [];
  /** @type {remoting.XmppLoginHandler} @private*/
  this.loginHandler_ = null;
  /** @type {remoting.XmppStreamParser} @private*/
  this.streamParser_ = null;
  /** @private */
  this.jid_ = '';
  /** @private */
  this.error_ = remoting.Error.NONE;
};

/**
 * @enum {number} XmppConnection states. Possible state transitions:
 *    NOT_CONNECTED -> CONNECTING (connect() called).
 *    CONNECTING -> HANDSHAKE (connected successfully).
 *    HANDSHAKE -> CONNECTED (authenticated successfully).
 *    CONNECTING -> FAILED (connection failed).
 *    HANDSHAKE -> FAILED (authentication failed).
 *    * -> CLOSED (dispose() called).
 */
remoting.XmppConnection.State = {
  NOT_CONNECTED: 0,
  CONNECTING: 1,
  HANDSHAKE: 2,
  CONNECTED: 3,
  FAILED: 4,
  CLOSED: 5
};

/**
 * @param {string} server
 * @param {string} username
 * @param {string} authToken
 */
remoting.XmppConnection.prototype.connect =
    function(server, username, authToken) {
  base.debug.assert(this.state_ == remoting.XmppConnection.State.NOT_CONNECTED);

  this.error_ = remoting.Error.NONE;
  var hostnameAndPort = server.split(':', 2);
  this.server_ = hostnameAndPort[0];
  this.port_ =
      (hostnameAndPort.length == 2) ? parseInt(hostnameAndPort[1], 10) : 5222;

  // The server name is passed as to attribute in the <stream>. When connecting
  // to talk.google.com it affects the certificate the server will use for TLS:
  // talk.google.com uses gmail certificate when specified server is gmail.com
  // or googlemail.com and google.com cert otherwise. In the same time it
  // doesn't accept talk.google.com as target server. Here we use google.com
  // server name when authenticating to talk.google.com. This ensures that the
  // server will use google.com cert which will be accepted by the TLS
  // implementation in Chrome (TLS API doesn't allow specifying domain other
  // than the one that was passed to connect()).
  var xmppServer = this.server_;
  if (xmppServer == 'talk.google.com')
    xmppServer = 'google.com';

  /** @type {remoting.XmppLoginHandler} */
  this.loginHandler_ =
      new remoting.XmppLoginHandler(xmppServer, username, authToken,
                                    this.sendInternal_.bind(this),
                                    this.startTls_.bind(this),
                                    this.onHandshakeDone_.bind(this),
                                    this.onError_.bind(this));
  chrome.socket.create("tcp", {}, this.onSocketCreated_.bind(this));
  this.setState_(remoting.XmppConnection.State.CONNECTING);
};

/** @param {string} message */
remoting.XmppConnection.prototype.sendMessage = function(message) {
  base.debug.assert(this.state_ == remoting.XmppConnection.State.CONNECTED);
  this.sendInternal_(message);
};

/** @return {remoting.XmppConnection.State} Current state */
remoting.XmppConnection.prototype.getState = function() {
  return this.state_;
};

/** @return {remoting.Error} Error when in FAILED state. */
remoting.XmppConnection.prototype.getError = function() {
  return this.error_;
};

/** @return {string} Current JID when in CONNECTED state. */
remoting.XmppConnection.prototype.getJid = function() {
  return this.jid_;
};

remoting.XmppConnection.prototype.dispose = function() {
  this.closeSocket_();
  this.setState_(remoting.XmppConnection.State.CLOSED);
};

/**
 * @param {chrome.socket.CreateInfo} createInfo
 * @private
 */
remoting.XmppConnection.prototype.onSocketCreated_ = function(createInfo) {
  // Check if connection was destroyed.
  if (this.state_ != remoting.XmppConnection.State.CONNECTING) {
    chrome.socket.destroy(createInfo.socketId);
    return;
  }

  this.socketId_ = createInfo.socketId;

  chrome.socket.connect(this.socketId_,
                        this.server_,
                        this.port_,
                        this.onSocketConnected_.bind(this));
};

/**
 * @param {number} result
 * @private
 */
remoting.XmppConnection.prototype.onSocketConnected_ = function(result) {
  // Check if connection was destroyed.
  if (this.state_ != remoting.XmppConnection.State.CONNECTING) {
    return;
  }

  if (result != 0) {
    this.onError_(remoting.Error.NETWORK_FAILURE,
                  'Failed to connect to ' + this.server_ + ': ' +  result);
    return;
  }

  this.setState_(remoting.XmppConnection.State.HANDSHAKE);

  this.tryRead_();
  this.loginHandler_.start();
};

/**
 * @private
 */
remoting.XmppConnection.prototype.tryRead_ = function() {
  base.debug.assert(!this.readPending_);
  base.debug.assert(this.state_ == remoting.XmppConnection.State.HANDSHAKE ||
                    this.state_ == remoting.XmppConnection.State.CONNECTED);
  base.debug.assert(!this.startTlsPending_);

  this.readPending_ = true;
  chrome.socket.read(this.socketId_, this.onRead_.bind(this));
};

/**
 * @param {chrome.socket.ReadInfo} readInfo
 * @private
 */
remoting.XmppConnection.prototype.onRead_ = function(readInfo) {
  base.debug.assert(this.readPending_);
  this.readPending_ = false;

  // Check if the socket was closed while reading.
  if (this.state_ != remoting.XmppConnection.State.HANDSHAKE &&
      this.state_ != remoting.XmppConnection.State.CONNECTED) {
    return;
  }

  if (readInfo.resultCode < 0) {
    this.onError_(remoting.Error.NETWORK_FAILURE,
                  'Failed to receive from XMPP socket: ' + readInfo.resultCode);
    return;
  }

  if (this.state_ == remoting.XmppConnection.State.HANDSHAKE) {
    this.loginHandler_.onDataReceived(readInfo.data);
  } else if (this.state_ == remoting.XmppConnection.State.CONNECTED) {
    this.streamParser_.appendData(readInfo.data);
  }

  if (!this.startTlsPending_) {
    this.tryRead_();
  }
};

/**
 * @param {string} text
 * @private
 */
remoting.XmppConnection.prototype.sendInternal_ = function(text) {
  this.sendQueue_.push(base.encodeUtf8(text));
  this.doSend_();
};

/**
 * @private
 */
remoting.XmppConnection.prototype.doSend_ = function() {
  if (this.sendPending_ || this.sendQueue_.length == 0) {
    return;
  }

  var data = this.sendQueue_[0]
  this.sendPending_ = true;
  chrome.socket.write(this.socketId_, data, this.onWrite_.bind(this));
};

/**
 * @param {chrome.socket.WriteInfo} writeInfo
 * @private
 */
remoting.XmppConnection.prototype.onWrite_ = function(writeInfo) {
  base.debug.assert(this.sendPending_);
  this.sendPending_ = false;

  // Ignore write() result if the socket was closed.
  if (this.state_ != remoting.XmppConnection.State.HANDSHAKE &&
      this.state_ != remoting.XmppConnection.State.CONNECTED) {
    return;
  }

  if (writeInfo.bytesWritten < 0) {
    this.onError_(remoting.Error.NETWORK_FAILURE,
                  'TCP write failed with error ' + writeInfo.bytesWritten);
    return;
  }

  base.debug.assert(this.sendQueue_.length > 0);

  var data = this.sendQueue_[0]
  base.debug.assert(writeInfo.bytesWritten <= data.byteLength);
  if (writeInfo.bytesWritten == data.byteLength) {
    this.sendQueue_.shift();
  } else {
    this.sendQueue_[0] = data.slice(data.byteLength - writeInfo.bytesWritten);
  }

  this.doSend_();
};

/**
 * @private
 */
remoting.XmppConnection.prototype.startTls_ = function() {
  base.debug.assert(!this.readPending_);
  base.debug.assert(!this.startTlsPending_);

  this.startTlsPending_ = true;
  chrome.socket.secure(
      this.socketId_, {}, this.onTlsStarted_.bind(this));
}

/**
 * @param {number} resultCode
 * @private
 */
remoting.XmppConnection.prototype.onTlsStarted_ = function(resultCode) {
  base.debug.assert(this.startTlsPending_);
  this.startTlsPending_ = false;

  if (resultCode < 0) {
    this.onError_(remoting.Error.NETWORK_FAILURE,
                  'Failed to start TLS: ' + resultCode);
    return;
  }

  this.tryRead_();
  this.loginHandler_.onTlsStarted();
};

/**
 * @param {string} jid
 * @param {remoting.XmppStreamParser} streamParser
 * @private
 */
remoting.XmppConnection.prototype.onHandshakeDone_ =
    function(jid, streamParser) {
  this.jid_ = jid;
  this.streamParser_ = streamParser;
  this.streamParser_.setCallbacks(this.onIncomingStanzaCallback_,
                                  this.onParserError_.bind(this));
  this.setState_(remoting.XmppConnection.State.CONNECTED);
};

/**
 * @param {string} text
 * @private
 */
remoting.XmppConnection.prototype.onParserError_ = function(text) {
  this.onError_(remoting.Error.UNEXPECTED, text);
}

/**
 * @param {remoting.Error} error
 * @param {string} text
 * @private
 */
remoting.XmppConnection.prototype.onError_ = function(error, text) {
  console.error(text);
  this.error_ = error;
  this.closeSocket_();
  this.setState_(remoting.XmppConnection.State.FAILED);
};

/**
 * @private
 */
remoting.XmppConnection.prototype.closeSocket_ = function() {
  if (this.socketId_ != -1) {
    chrome.socket.destroy(this.socketId_);
    this.socketId_ = -1;
  }
};

/**
 * @param {remoting.XmppConnection.State} newState
 * @private
 */
remoting.XmppConnection.prototype.setState_ = function(newState) {
  if (this.state_ != newState) {
    this.state_ = newState;
    this.onStateChangedCallback_(this.state_);
  }
};