/* 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/. */
"use strict";

ChromeUtils.import("resource://gre/modules/Services.jsm");

ChromeUtils.defineModuleGetter(this, "PrivateBrowsingUtils",
  "resource://gre/modules/PrivateBrowsingUtils.jsm");

/**
 * A Map from trigger IDs to singleton trigger listeners. Each listener must
 * have idempotent `init` and `uninit` methods.
 */
this.ASRouterTriggerListeners = new Map([

  /**
   * Attach listeners to every browser window to detect location changes, and
   * notify the trigger handler whenever we navigate to a URL with a hostname
   * we're looking for.
   */
  ["openURL", {
    _initialized: false,
    _triggerHandler: null,
    _hosts: null,

    /*
     * If the listener is already initialised, `init` will replace the trigger
     * handler and add any new hosts to `this._hosts`.
     */
    init(triggerHandler, hosts = []) {
      if (!this._initialized) {
        this.onLocationChange = this.onLocationChange.bind(this);

        // Listen for new windows being opened
        Services.ww.registerNotification(this);

        // Add listeners to all existing browser windows
        for (let win of Services.wm.getEnumerator("navigator:browser")) {
          if (win.closed || PrivateBrowsingUtils.isWindowPrivate(win)) {
            continue;
          }
          win.gBrowser.addTabsProgressListener(this);
        }

        this._initialized = true;
      }
      this._triggerHandler = triggerHandler;
      if (this._hosts) {
        hosts.forEach(h => this._hosts.add(h));
      } else {
        this._hosts = new Set(hosts); // Clone the hosts to avoid unexpected behaviour
      }
    },

    uninit() {
      if (this._initialized) {
        Services.ww.unregisterNotification(this);

        for (let win of Services.wm.getEnumerator("navigator:browser")) {
          if (win.closed || PrivateBrowsingUtils.isWindowPrivate(win)) {
            continue;
          }

          win.gBrowser.removeTabsProgressListener(this);
        }

        this._initialized = false;
        this._triggerHandler = null;
        this._hosts = null;
      }
    },

    onLocationChange(aBrowser, aWebProgress, aRequest, aLocationURI, aFlags) {
      const location = aLocationURI ? aLocationURI.spec : "";
      // Some websites trigger redirect events after they finish loading even
      // though the location remains the same. This results in onLocationChange
      // events to be fired twice.
      const isSameDocument = !!(aFlags & Ci.nsIWebProgressListener.LOCATION_CHANGE_SAME_DOCUMENT);
      if (location && aWebProgress.isTopLevel && !isSameDocument) {
        try {
          const host = (new URL(location)).hostname;
          if (this._hosts.has(host)) {
            this._triggerHandler(aBrowser, {id: "openURL", param: host});
          }
        } catch (e) {} // Couldn't parse location URL
      }
    },

    observe(win, topic, data) {
      let onLoad;

      switch (topic) {
        case "domwindowopened":
          if (!(win instanceof Ci.nsIDOMWindow) || win.closed || PrivateBrowsingUtils.isWindowPrivate(win)) {
            break;
          }
          onLoad = () => {
            // Ignore non-browser windows.
            if (win.document.documentElement.getAttribute("windowtype") === "navigator:browser") {
              win.gBrowser.addTabsProgressListener(this);
            }
          };
          win.addEventListener("load", onLoad, {once: true});
          break;

        case "domwindowclosed":
          if ((win instanceof Ci.nsIDOMWindow) &&
              win.document.documentElement.getAttribute("windowtype") === "navigator:browser") {
            win.gBrowser.removeTabsProgressListener(this);
          }
          break;
      }
    },
  }],
]);

const EXPORTED_SYMBOLS = ["ASRouterTriggerListeners"];