/* -*- mode: js; indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* 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";

var EXPORTED_SYMBOLS = ["BrowserUtils"];

const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
const { XPCOMUtils } = ChromeUtils.import(
  "resource://gre/modules/XPCOMUtils.jsm"
);

var BrowserUtils = {
  /**
   * Return or create a principal with the content of one, and the originAttributes
   * of an existing principal (e.g. on a docshell, where the originAttributes ought
   * not to change, that is, we should keep the userContextId, privateBrowsingId,
   * etc. the same when changing the principal).
   *
   * @param principal
   *        The principal whose content/null/system-ness we want.
   * @param existingPrincipal
   *        The principal whose originAttributes we want, usually the current
   *        principal of a docshell.
   * @return an nsIPrincipal that matches the content/null/system-ness of the first
   *         param, and the originAttributes of the second.
   */
  principalWithMatchingOA(principal, existingPrincipal) {
    // Don't care about system principals:
    if (principal.isSystemPrincipal) {
      return principal;
    }

    // If the originAttributes already match, just return the principal as-is.
    if (existingPrincipal.originSuffix == principal.originSuffix) {
      return principal;
    }

    let secMan = Services.scriptSecurityManager;
    if (principal.isContentPrincipal) {
      return secMan.principalWithOA(
        principal,
        existingPrincipal.originAttributes
      );
    }

    if (principal.isNullPrincipal) {
      return secMan.createNullPrincipal(existingPrincipal.originAttributes);
    }
    throw new Error(
      "Can't change the originAttributes of an expanded principal!"
    );
  },

  onBeforeLinkTraversal(originalTarget, linkURI, linkNode, isAppTab) {
    // Don't modify non-default targets or targets that aren't in top-level app
    // tab docshells (isAppTab will be false for app tab subframes).
    if (originalTarget != "" || !isAppTab) {
      return originalTarget;
    }

    // External links from within app tabs should always open in new tabs
    // instead of replacing the app tab's page (Bug 575561)
    let linkHost;
    let docHost;
    try {
      linkHost = linkURI.host;
      docHost = linkNode.ownerDocument.documentURIObject.host;
    } catch (e) {
      // nsIURI.host can throw for non-nsStandardURL nsIURIs.
      // If we fail to get either host, just return originalTarget.
      return originalTarget;
    }

    if (docHost == linkHost) {
      return originalTarget;
    }

    // Special case: ignore "www" prefix if it is part of host string
    let [longHost, shortHost] =
      linkHost.length > docHost.length
        ? [linkHost, docHost]
        : [docHost, linkHost];
    if (longHost == "www." + shortHost) {
      return originalTarget;
    }

    return "_blank";
  },

  /**
   * Returns true if |mimeType| is text-based, or false otherwise.
   *
   * @param mimeType
   *        The MIME type to check.
   */
  mimeTypeIsTextBased(mimeType) {
    return (
      mimeType.startsWith("text/") ||
      mimeType.endsWith("+xml") ||
      mimeType == "application/x-javascript" ||
      mimeType == "application/javascript" ||
      mimeType == "application/json" ||
      mimeType == "application/xml"
    );
  },

  /**
   * Returns true if we can show a find bar, including FAYT, for the specified
   * document location. The location must not be in a blacklist of specific
   * "about:" pages for which find is disabled.
   *
   * This can be called from the parent process or from content processes.
   */
  canFindInPage(location) {
    return (
      !location.startsWith("about:addons") &&
      !location.startsWith(
        "chrome://mozapps/content/extensions/aboutaddons.html"
      ) &&
      !location.startsWith("about:preferences")
    );
  },

  isFindbarVisible(docShell) {
    const FINDER_JSM = "resource://gre/modules/Finder.jsm";
    return (
      Cu.isModuleLoaded(FINDER_JSM) &&
      ChromeUtils.import(FINDER_JSM).Finder.isFindbarVisible(docShell)
    );
  },

  /**
   * Returns a Promise which resolves when the given observer topic has been
   * observed.
   *
   * @param {string} topic
   *        The topic to observe.
   * @param {function(nsISupports, string)} [test]
   *        An optional test function which, when called with the
   *        observer's subject and data, should return true if this is the
   *        expected notification, false otherwise.
   * @returns {Promise<object>}
   */
  promiseObserved(topic, test = () => true) {
    return new Promise(resolve => {
      let observer = (subject, topic, data) => {
        if (test(subject, data)) {
          Services.obs.removeObserver(observer, topic);
          resolve({ subject, data });
        }
      };
      Services.obs.addObserver(observer, topic);
    });
  },
};

XPCOMUtils.defineLazyPreferenceGetter(
  BrowserUtils,
  "navigationRequireUserInteraction",
  "browser.navigation.requireUserInteraction",
  false
);