/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Ambient News.
 *
 * The Initial Developer of the Original Code is Mozilla.
 * Portions created by the Initial Developer are Copyright (C) 2007
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *  Atul Varma <avarma@mozilla.com>
 *  Ben Basson <ben@basson.at>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

var AmbNews = {
  url: function url(spec) {
    if (typeof(spec) != "string")
      // Assume that a URI object was passed in, so just return it back.
      return spec;
    var classObj = Components.classes["@mozilla.org/network/io-service;1"];
    var ios = classObj.getService(Components.interfaces.nsIIOService);
    return ios.newURI(spec, null, null);
  },
  getFeed: function AmbNews_getFeed(url, callback) {
    function onXml(text) {
      var feed = null;
      if (text) {
        var resultListener = {
          handleResult: function resultListener_handleResult(aResult) {
            var nsIFeed = aResult.doc;
            if (!nsIFeed)
              return;
            feed = {};
            var Ci = Components.interfaces;
            nsIFeed.QueryInterface(Ci.nsIFeed);
            feed.link = nsIFeed.link;
            feed.title = nsIFeed.title;
            feed.entries = [];
            for (var i = 0; i < nsIFeed.items.length; i++) {
              var item = nsIFeed.items.queryElementAt(i, Ci.nsIFeedEntry);
              feed.entries.push(item);
            }
          }
        };
        var fp = AmbNews.__getFeedProcessor();
        fp.listener = resultListener;
        fp.parseFromString(text, AmbNews.url(url));
      }
      callback(feed);
    }
    AmbNews.__getXml(url, onXml);
  },
  __getXml: function AmbNews_getXml(url, callback) {
    var feedUrl = AmbNews.url(url);
    var annSvc = AmbNews.__getAnnSvc();

    if (annSvc.pageHasAnnotation(feedUrl, "ambnews/feed-xml")) {
      var xml = annSvc.getPageAnnotation(feedUrl, "ambnews/feed-xml");
      // TODO: Perhaps re-enable this, but only let it live for a
      // few minutes?
      //callback(xml);
      //return;
    }

    var request = new XMLHttpRequest();
    request.mozBackgroundRequest = true;
    request.open("GET", url, true);

    var onRscFunc = function getXml_onReadyStateChange() {
      if (request.readyState == 4) {
        if (request.status == 200) {
          if (request.responseText) {
            annSvc.setPageAnnotation(feedUrl,
                                     "ambnews/feed-xml",
                                     request.responseText,
                                     0,
                                     annSvc.EXPIRE_DAYS);
            callback(request.responseText);
          } else
            callback("");
        } else
          callback("");
      }
    };

    request.onreadystatechange = onRscFunc;
    request.send(null);
  },
  __getFeedProcessor: function AmbNews_getFeedProcessor() {
    var Cc = Components.classes;
    var Ci = Components.interfaces;
    var fp = Cc["@mozilla.org/feed-processor;1"]
             .createInstance(Ci.nsIFeedProcessor);
    return fp;
  },
  __getAnnSvc: function AmbNews_getAnnSvc() {
    var Cc = Components.classes;
    var annSvc = Cc["@mozilla.org/browser/annotation-service;1"]
                 .getService(Components.interfaces.nsIAnnotationService);
    return annSvc;
  },
  onLinkAdded: function AmbNews_onLinkAdded(aEvent) {
    if (aEvent.target.rel == "alternate" &&
        (aEvent.target.type == "application/rss+xml" ||
         aEvent.target.type == "application/atom+xml")) {
      var annSvc = AmbNews.__getAnnSvc();
      var page = AmbNews.url(aEvent.target.baseURI);
      var feed = AmbNews.url(aEvent.target.href);
      annSvc.setPageAnnotation(page, "ambnews/feed",
                               feed.spec, 0, annSvc.EXPIRE_WEEKS);
    }
  },
  initBrowser: function AmbNews_initBrowser() {
    // Listen for the addition of new <link> elements on pages.
    window.addEventListener("DOMLinkAdded", AmbNews.onLinkAdded, false);

    // Whenever the user opens a new tab, have it point to
    // about:news by default, and select the URL.

    // The following code was taken from the "New Tab Homepage 0.4"
    // extension's 'chrome/content/tabhomepage.js' file. Thanks,
    // Ben Basson, for figuring this out for me.
    gBrowser.removeEventListener("NewTab", BrowserOpenTab, false);
    function onOpenTab(aEvent) {
      var newTab = gBrowser.addTab("about:news");
      gBrowser.selectedTab = newTab;
      if (gURLBar)
        setTimeout(function() { gURLBar.select(); }, 0);
      if (aEvent)
        aEvent.stopPropagation();

      return newTab;
    }
    window.BrowserOpenTab = onOpenTab;
    gBrowser.addEventListener("NewTab", onOpenTab, false);
  }
};