/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.*/
/*
 * Manifest obtainer frame script implementation of:
 * http://www.w3.org/TR/appmanifest/#obtaining
 *
 * It searches a top-level browsing context for
 * a <link rel=manifest> element. Then fetches
 * and processes the linked manifest.
 *
 * BUG: https://bugzilla.mozilla.org/show_bug.cgi?id=1083410
 */
/*globals Task, ManifestObtainer, ManifestFinder, content, sendAsyncMessage, addMessageListener, Components*/
'use strict';
const {
  utils: Cu,
} = Components;
Cu.import('resource://gre/modules/ManifestObtainer.jsm');
Cu.import('resource://gre/modules/ManifestFinder.jsm');
Cu.import('resource://gre/modules/Task.jsm');

const finder = new ManifestFinder();

const MessageHandler = {
  registerListeners() {
    addMessageListener(
      'DOM:WebManifest:hasManifestLink',
      this.hasManifestLink.bind(this)
    );
    addMessageListener(
      'DOM:ManifestObtainer:Obtain',
      this.obtainManifest.bind(this)
    );
  },

  /**
   * Check if the content document includes a link to a web manifest.
   * @param {Object} aMsg The IPC message.
   */
  hasManifestLink: Task.async(function* ({data: {id}}) {
    const response = this.makeMsgResponse(id);
    response.result = yield finder.hasManifestLink(content);
    response.success = true;
    sendAsyncMessage('DOM:WebManifest:hasManifestLink', response);
  }),

  /**
   * Obtains a web manifest from content by using the ManifestObtainer
   * and messages back the result.
   * @param {Object} aMsg The IPC message.
   */
  obtainManifest: Task.async(function* ({data: {id}}) {
    const obtainer = new ManifestObtainer();
    const response = this.makeMsgResponse(id);
    try {
      response.result = yield obtainer.obtainManifest(content);
      response.success = true;
    } catch (err) {
      response.result = this.serializeError(err);
    }
    sendAsyncMessage('DOM:ManifestObtainer:Obtain', response);
  }),

  makeMsgResponse(aId) {
    return {
      id: aId,
      success: false,
      result: undefined
    };
  },

  /**
   * Utility function to Serializes an JS Error, so it can be transferred over
   * the message channel.
   * FIX ME: https://bugzilla.mozilla.org/show_bug.cgi?id=1172586
   * @param  {Error} aError The error to serialize.
   * @return {Object} The serialized object.
   */
  serializeError(aError) {
    const clone = {
      'fileName': aError.fileName,
      'lineNumber': aError.lineNumber,
      'columnNumber': aError.columnNumber,
      'stack': aError.stack,
      'message': aError.message,
      'name': aError.name
    };
    return clone;
  },
};
MessageHandler.registerListeners();