var EXPORTED_SYMBOLS = ["init"];

const Cc = Components.classes;
const Ci = Components.interfaces;
const Cu = Components.utils;

const REQUEST_BOX_NAME = "powerbox_superpower_request";
const REQUEST_BOX_TEXT = "This web page wants superpowers.";
const REQUEST_BOX_BUTTON_TEXT = "Huh?";

Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");

function getParentChromeWindow(window) {
  var mainWindow = window.QueryInterface(Ci.nsIInterfaceRequestor)
                   .getInterface(Ci.nsIWebNavigation)
                   .QueryInterface(Ci.nsIDocShellTreeItem)
                   .rootTreeItem
                   .QueryInterface(Ci.nsIInterfaceRequestor)
                   .getInterface(Ci.nsIDOMWindow);
  return mainWindow.wrappedJSObject;
}

function showRequestNotificationBox(window, caps, callback) {
  var tabbrowser = getParentChromeWindow(window).getBrowser();
  var browser = tabbrowser.getBrowserForDocument(window.document);

  if (browser) {
    var nBox = tabbrowser.getNotificationBox(browser);

    var oldNotification = nBox.getNotificationWithValue(REQUEST_BOX_NAME);
    if (oldNotification)
      nBox.removeNotification(oldNotification);

    function onClickButton() {
      // TODO: Implement a real callback.
      const CAP_URI = "chrome://powerbox/content/request.html";
      tabbrowser.selectedTab = tabbrowser.addTab(CAP_URI);
    }

    nBox.appendNotification(REQUEST_BOX_TEXT,
                            REQUEST_BOX_NAME,
                            null,
                            nBox.PRIORITY_INFO_MEDIUM,
                            [{accessKey: null,
                              callback: onClickButton,
                              label: REQUEST_BOX_BUTTON_TEXT,
                              popup: null}]);
  }
}

function buildRequestor(window) {
  return function request(caps, callback) {
    if (!(typeof(caps) == "object" ||
          typeof(caps) == "string"))
      throw new Error("Must provide capabilities as first parameter.");

    if (typeof(callback) != "function")
      throw new Error("Must provide callback as second parameter");

    if (typeof(caps) == "object")
      caps = new XPCSafeJSObjectWrapper(caps);
    callback = new XPCSafeJSObjectWrapper(callback);

    showRequestNotificationBox(window, caps, callback);
  };
}

// Taken from Firebug's content/firebug/tabWatcher.js.
function safeGetName(request) {
    try {
      return request.name;
    } catch (exc) {
      return null;
    }
}

var listener = {
  QueryInterface : XPCOMUtils.generateQI([Ci.nsIWebProgressListener,
                                          Ci.nsISupportsWeakReference]),

  // Much of this is taken from Firebug's content/firebug/tabWatcher.js,
  // specifically the FrameProgressListener object.
  onStateChange : function (aWebProgress, aRequest,
                            aStateFlags,  aStatus) {
    if (aStateFlags & Ci.nsIWebProgressListener.STATE_IS_REQUEST &&
        aStateFlags & Ci.nsIWebProgressListener.STATE_START) {
      // We need to get the hook in as soon as the new DOMWindow is
      // created, but before it starts executing any scripts in the
      // page.  After lengthy analysis, it seems that the start of
      // these "dummy" requests is the only state that works.

      // TODO: Firebug's code mentions that XHTML doesn't dispatch
      // any of these dummy requests, so we should probably use the
      // Firebug's XHTML workaround here.
      var safeName = safeGetName(aRequest);
      var window = aWebProgress.DOMWindow;
      if (window && window.wrappedJSObject &&
          (safeName == "about:layout-dummy-request" ||
           safeName == "about:document-onload-blocker")) {
        // TODO: Firebug's code mentions that about:blank causes strange
        // behavior here; I don't think it should apply to our use case,
        // though.
        var sandbox = Cu.Sandbox(window);
        sandbox.importFunction(buildRequestor(window));
        sandbox.window = window.wrappedJSObject;

        function setupPowerbox() {
          window.powerbox = {request: request};
        }

        Cu.evalInSandbox("(" + setupPowerbox.toString() + ")();", sandbox);
      }
    }
  },

  // Stubs for the nsIWebProgressListener interfaces which we don't use.
  onProgressChange : function() { },
  onLocationChange : function() { },
  onStatusChange   : function() { },
  onSecurityChange : function() { }
};

function init(window) {
  var tabbrowser = window.getBrowser();

  function addListener(browser) {
    browser.addProgressListener(listener,
                                Ci.nsIWebProgress.NOTIFY_STATE_DOCUMENT);
  }

  tabbrowser.tabContainer.addEventListener(
    "TabOpen",
    function onTabOpen(event) { addListener(event.target.linkedBrowser); },
    false
  );

  tabbrowser.browsers.forEach(function(browser) { addListener(browser); });
}