/* 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";

this.EXPORTED_SYMBOLS = ["TabState"];

const Cu = Components.utils;

Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
Cu.import("resource://gre/modules/Promise.jsm", this);
Cu.import("resource://gre/modules/Task.jsm", this);

XPCOMUtils.defineLazyModuleGetter(this, "console",
  "resource://gre/modules/devtools/Console.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "PrivacyFilter",
  "resource:///modules/sessionstore/PrivacyFilter.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "TabStateCache",
  "resource:///modules/sessionstore/TabStateCache.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "TabAttributes",
  "resource:///modules/sessionstore/TabAttributes.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Utils",
  "resource:///modules/sessionstore/Utils.jsm");

/**
 * Module that contains tab state collection methods.
 */
this.TabState = Object.freeze({
  setSyncHandler: function (browser, handler) {
    TabStateInternal.setSyncHandler(browser, handler);
  },

  update: function (browser, data) {
    TabStateInternal.update(browser, data);
  },

  flush: function (browser) {
    TabStateInternal.flush(browser);
  },

  flushAsync: function (browser) {
    TabStateInternal.flushAsync(browser);
  },

  flushWindow: function (window) {
    TabStateInternal.flushWindow(window);
  },

  collect: function (tab) {
    return TabStateInternal.collect(tab);
  },

  clone: function (tab) {
    return TabStateInternal.clone(tab);
  }
});

let TabStateInternal = {
  // A map (xul:browser -> handler) that maps a tab to the
  // synchronous collection handler object for that tab.
  // See SyncHandler in content-sessionStore.js.
  _syncHandlers: new WeakMap(),

  // A map (xul:browser -> int) that maps a browser to the
  // last "SessionStore:update" message ID we received for it.
  _latestMessageID: new WeakMap(),

  /**
   * Install the sync handler object from a given tab.
   */
  setSyncHandler: function (browser, handler) {
    this._syncHandlers.set(browser.permanentKey, handler);
    this._latestMessageID.set(browser.permanentKey, 0);
  },

  /**
   * Processes a data update sent by the content script.
   */
  update: function (browser, {id, data}) {
    // Only ever process messages that have an ID higher than the last one we
    // saw. This ensures we don't use stale data that has already been received
    // synchronously.
    if (id > this._latestMessageID.get(browser.permanentKey)) {
      this._latestMessageID.set(browser.permanentKey, id);
      TabStateCache.update(browser, data);
    }
  },

  /**
   * Flushes all data currently queued in the given browser's content script.
   */
  flush: function (browser) {
    if (this._syncHandlers.has(browser.permanentKey)) {
      let lastID = this._latestMessageID.get(browser.permanentKey);
      this._syncHandlers.get(browser.permanentKey).flush(lastID);
    }
  },

  /**
   * DO NOT USE - DEBUGGING / TESTING ONLY
   *
   * This function is used to simulate certain situations where race conditions
   * can occur by sending data shortly before flushing synchronously.
   */
  flushAsync: function(browser) {
    if (this._syncHandlers.has(browser.permanentKey)) {
      this._syncHandlers.get(browser.permanentKey).flushAsync();
    }
  },

  /**
   * Flushes queued content script data for all browsers of a given window.
   */
  flushWindow: function (window) {
    for (let browser of window.gBrowser.browsers) {
      this.flush(browser);
    }
  },

  /**
   * Collect data related to a single tab, synchronously.
   *
   * @param tab
   *        tabbrowser tab
   *
   * @returns {TabData} An object with the data for this tab.  If the
   * tab has not been invalidated since the last call to
   * collect(aTab), the same object is returned.
   */
  collect: function (tab) {
    return this._collectBaseTabData(tab);
  },

  /**
   * Collect data related to a single tab, including private data.
   * Use with caution.
   *
   * @param tab
   *        tabbrowser tab
   *
   * @returns {object} An object with the data for this tab. This data is never
   *                   cached, it will always be read from the tab and thus be
   *                   up-to-date.
   */
  clone: function (tab) {
    return this._collectBaseTabData(tab, {includePrivateData: true});
  },

  /**
   * Collects basic tab data for a given tab.
   *
   * @param tab
   *        tabbrowser tab
   * @param options (object)
   *        {includePrivateData: true} to always include private data
   *
   * @returns {object} An object with the basic data for this tab.
   */
  _collectBaseTabData: function (tab, options) {
    let tabData = {entries: [], lastAccessed: tab.lastAccessed };
    let browser = tab.linkedBrowser;

    if (!browser || !browser.currentURI) {
      // can happen when calling this function right after .addTab()
      return tabData;
    }
    if (browser.__SS_data) {
      // Use the data to be restored when the tab hasn't been
      // completely loaded. We clone the data, since we're updating it
      // here and the caller may update it further.
      tabData = Utils.shallowCopy(browser.__SS_data);
      if (tab.pinned)
        tabData.pinned = true;
      else
        delete tabData.pinned;
      tabData.hidden = tab.hidden;

      // If __SS_extdata is set then we'll use that since it might be newer.
      if (tab.__SS_extdata)
        tabData.extData = tab.__SS_extdata;
      // If it exists but is empty then a key was likely deleted. In that case just
      // delete extData.
      if (tabData.extData && !Object.keys(tabData.extData).length)
        delete tabData.extData;
      return tabData;
    }

    // If there is a userTypedValue set, then either the user has typed something
    // in the URL bar, or a new tab was opened with a URI to load. userTypedClear
    // is used to indicate whether the tab was in some sort of loading state with
    // userTypedValue.
    if (browser.userTypedValue) {
      tabData.userTypedValue = browser.userTypedValue;
      tabData.userTypedClear = browser.userTypedClear;
    } else {
      delete tabData.userTypedValue;
      delete tabData.userTypedClear;
    }

    if (tab.pinned)
      tabData.pinned = true;
    else
      delete tabData.pinned;
    tabData.hidden = tab.hidden;

    // Save tab attributes.
    tabData.attributes = TabAttributes.get(tab);

    // Store the tab icon.
    let tabbrowser = tab.ownerDocument.defaultView.gBrowser;
    tabData.image = tabbrowser.getIcon(tab);

    if (tab.__SS_extdata)
      tabData.extData = tab.__SS_extdata;
    else if (tabData.extData)
      delete tabData.extData;

    // Copy data from the tab state cache only if the tab has fully finished
    // restoring. We don't want to overwrite data contained in __SS_data.
    this._copyFromCache(tab, tabData, options);

    return tabData;
  },

  /**
   * Copy tab data for the given |tab| from the cache to |tabData|.
   *
   * @param tab (xul:tab)
   *        The tab belonging to the given |tabData| object.
   * @param tabData (object)
   *        The tab data belonging to the given |tab|.
   * @param options (object)
   *        {includePrivateData: true} to always include private data
   */
  _copyFromCache: function (tab, tabData, options = {}) {
    let data = TabStateCache.get(tab.linkedBrowser);
    if (!data) {
      return;
    }

    // The caller may explicitly request to omit privacy checks.
    let includePrivateData = options && options.includePrivateData;

    for (let key of Object.keys(data)) {
      let value = data[key];

      // Filter sensitive data according to the current privacy level.
      if (!includePrivateData) {
        if (key === "storage") {
          value = PrivacyFilter.filterSessionStorageData(value, tab.pinned);
        } else if (key === "formdata") {
          value = PrivacyFilter.filterFormData(value, tab.pinned);
        }
      }

      if (key === "history") {
        tabData.entries = value.entries;

        if (value.hasOwnProperty("index")) {
          tabData.index = value.index;
        }
      } else if (value) {
        tabData[key] = value;
      }
    }
  }
};