/* 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/. */

const lazy = {};

ChromeUtils.defineESModuleGetters(lazy, {
  AppInfo: "chrome://remote/content/shared/AppInfo.sys.mjs",
  EventPromise: "chrome://remote/content/shared/Sync.sys.mjs",
  generateUUID: "chrome://remote/content/shared/UUID.sys.mjs",
  MobileTabBrowser: "chrome://remote/content/shared/MobileTabBrowser.sys.mjs",
});

// Maps browser's permanentKey to uuid: WeakMap.<Object, string>
const browserUniqueIds = new WeakMap();

export var TabManager = {
  /**
   * Retrieve all the browser elements from tabs as contained in open windows.
   *
   * @returns {Array<XULBrowser>}
   *     All the found <xul:browser>s. Will return an empty array if
   *     no windows and tabs can be found.
   */
  get browsers() {
    const browsers = [];

    for (const win of this.windows) {
      const tabBrowser = this.getTabBrowser(win);

      if (tabBrowser && tabBrowser.tabs) {
        const contentBrowsers = tabBrowser.tabs.map(tab => {
          return this.getBrowserForTab(tab);
        });
        browsers.push(...contentBrowsers);
      }
    }

    return browsers;
  },

  get windows() {
    return Services.wm.getEnumerator(null);
  },

  /**
   * Array of unique browser ids (UUIDs) for all content browsers of all
   * windows.
   *
   * TODO: Similarly to getBrowserById, we should improve the performance of
   * this getter in Bug 1750065.
   *
   * @returns {Array<string>}
   *     Array of UUIDs for all content browsers.
   */
  get allBrowserUniqueIds() {
    const browserIds = [];

    for (const win of this.windows) {
      const tabBrowser = this.getTabBrowser(win);

      // Only return handles for browser windows
      if (tabBrowser && tabBrowser.tabs) {
        for (const tab of tabBrowser.tabs) {
          const contentBrowser = this.getBrowserForTab(tab);
          const winId = this.getIdForBrowser(contentBrowser);
          if (winId !== null) {
            browserIds.push(winId);
          }
        }
      }
    }

    return browserIds;
  },

  /**
   * Get the <code>&lt;xul:browser&gt;</code> for the specified tab.
   *
   * @param {Tab} tab
   *     The tab whose browser needs to be returned.
   *
   * @returns {XULBrowser}
   *     The linked browser for the tab or null if no browser can be found.
   */
  getBrowserForTab(tab) {
    if (tab && "linkedBrowser" in tab) {
      return tab.linkedBrowser;
    }

    return null;
  },

  /**
   * Return the tab browser for the specified chrome window.
   *
   * @param {ChromeWindow} win
   *     Window whose <code>tabbrowser</code> needs to be accessed.
   *
   * @returns {Tab}
   *     Tab browser or null if it's not a browser window.
   */
  getTabBrowser(win) {
    if (lazy.AppInfo.isAndroid) {
      return new lazy.MobileTabBrowser(win);
    } else if (lazy.AppInfo.isFirefox) {
      return win.gBrowser;
    }

    return null;
  },

  /**
   * Create a new tab.
   *
   * @param {object} options
   * @param {boolean=} options.focus
   *     Set to true if the new tab should be focused (selected). Defaults to
   *     false.
   * @param {Tab=} options.referenceTab
   *     The reference tab after which the new tab will be added. If no
   *     reference tab is provided, the new tab will be added after all the
   *     other tabs.
   * @param {number} options.userContextId
   *     The user context (container) id.
   * @param {window=} options.window
   *     The window where the new tab will open. Defaults to Services.wm.getMostRecentWindow
   *     if no window is provided. Will be ignored if referenceTab is provided.
   */
  async addTab(options = {}) {
    let {
      focus = false,
      referenceTab = null,
      userContextId,
      window = Services.wm.getMostRecentWindow(null),
    } = options;

    let index;
    if (referenceTab != null) {
      // If a reference tab was specified, the window should be the window
      // owning the reference tab.
      window = this._getWindowForTab(referenceTab);
    }

    const tabBrowser = this.getTabBrowser(window);
    if (referenceTab != null) {
      index = tabBrowser.tabs.indexOf(referenceTab) + 1;
    }

    const tab = await tabBrowser.addTab("about:blank", {
      index,
      triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
      userContextId,
    });

    if (focus) {
      await this.selectTab(tab);
    }

    return tab;
  },

  /**
   * Retrieve the browser element corresponding to the provided unique id,
   * previously generated via getIdForBrowser.
   *
   * TODO: To avoid creating strong references on browser elements and
   * potentially leaking those elements, this method loops over all windows and
   * all tabs. It should be replaced by a faster implementation in Bug 1750065.
   *
   * @param {string} id
   *     A browser unique id created by getIdForBrowser.
   * @returns {XULBrowser}
   *     The <xul:browser> corresponding to the provided id. Will return null if
   *     no matching browser element is found.
   */
  getBrowserById(id) {
    for (const win of this.windows) {
      const tabBrowser = this.getTabBrowser(win);
      if (tabBrowser && tabBrowser.tabs) {
        for (let i = 0; i < tabBrowser.tabs.length; ++i) {
          const contentBrowser = this.getBrowserForTab(tabBrowser.tabs[i]);
          if (this.getIdForBrowser(contentBrowser) == id) {
            return contentBrowser;
          }
        }
      }
    }
    return null;
  },

  /**
   * Retrieve the browsing context corresponding to the provided unique id.
   *
   * @param {string} id
   *     A browsing context unique id (created by getIdForBrowsingContext).
   * @returns {BrowsingContext=}
   *     The browsing context found for this id, null if none was found.
   */
  getBrowsingContextById(id) {
    const browser = this.getBrowserById(id);
    if (browser) {
      return browser.browsingContext;
    }

    return BrowsingContext.get(id);
  },

  /**
   * Retrieve the unique id for the given xul browser element. The id is a
   * dynamically generated uuid associated with the permanentKey property of the
   * given browser element. This method is preferable over getIdForBrowsingContext
   * in case of working with browser element of a tab, since we can not guarantee
   * that browsing context is attached to it.
   *
   * @param {XULBrowser} browserElement
   *     The <xul:browser> for which we want to retrieve the id.
   * @returns {string} The unique id for this browser.
   */
  getIdForBrowser(browserElement) {
    if (browserElement === null) {
      return null;
    }

    const key = browserElement.permanentKey;
    if (!browserUniqueIds.has(key)) {
      browserUniqueIds.set(key, lazy.generateUUID());
    }
    return browserUniqueIds.get(key);
  },

  /**
   * Retrieve the id of a Browsing Context.
   *
   * For a top-level browsing context a custom unique id will be returned.
   *
   * @param {BrowsingContext=} browsingContext
   *     The browsing context to get the id from.
   *
   * @returns {string}
   *     The id of the browsing context.
   */
  getIdForBrowsingContext(browsingContext) {
    if (!browsingContext) {
      return null;
    }

    if (!browsingContext.parent) {
      // Top-level browsing contexts have their own custom unique id.
      return this.getIdForBrowser(browsingContext.embedderElement);
    }

    return browsingContext.id.toString();
  },

  getTabCount() {
    let count = 0;
    for (const win of this.windows) {
      // For browser windows count the tabs. Otherwise take the window itself.
      const tabbrowser = this.getTabBrowser(win);
      if (tabbrowser?.tabs) {
        count += tabbrowser.tabs.length;
      } else {
        count += 1;
      }
    }
    return count;
  },

  /**
   * Retrieve the tab owning a Browsing Context.
   *
   * @param {BrowsingContext=} browsingContext
   *     The browsing context to get the tab from.
   *
   * @returns {Tab|null}
   *     The tab owning the Browsing Context.
   */
  getTabForBrowsingContext(browsingContext) {
    const browser = browsingContext?.top.embedderElement;
    if (!browser) {
      return null;
    }

    const tabBrowser = this.getTabBrowser(browser.ownerGlobal);
    return tabBrowser.getTabForBrowser(browser);
  },

  /**
   * Remove the given tab.
   *
   * @param {Tab} tab
   *     Tab to remove.
   */
  async removeTab(tab) {
    if (!tab) {
      return;
    }

    const ownerWindow = this._getWindowForTab(tab);
    const tabBrowser = this.getTabBrowser(ownerWindow);
    await tabBrowser.removeTab(tab);
  },

  /**
   * Select the given tab.
   *
   * @param {Tab} tab
   *     Tab to select.
   *
   * @returns {Promise}
   *     Promise that resolves when the given tab has been selected.
   */
  selectTab(tab) {
    if (!tab) {
      return Promise.resolve();
    }

    const ownerWindow = this._getWindowForTab(tab);
    const tabBrowser = this.getTabBrowser(ownerWindow);

    if (tab === tabBrowser.selectedTab) {
      return Promise.resolve();
    }

    const selected = new lazy.EventPromise(ownerWindow, "TabSelect");
    tabBrowser.selectedTab = tab;
    return selected;
  },

  supportsTabs() {
    return lazy.AppInfo.isAndroid || lazy.AppInfo.isFirefox;
  },

  _getWindowForTab(tab) {
    // `.linkedBrowser.ownerGlobal` works both with Firefox Desktop and Mobile.
    // Other accessors (eg `.ownerGlobal` or `.browser.ownerGlobal`) fail on one
    // of the platforms.
    return tab.linkedBrowser.ownerGlobal;
  },
};