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 // -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; js2-basic-offset: 2; js2-skip-preprocessor-directives: t; -*-

 /* 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 = ["SharedPreferences"];

 const { classes: Cc, interfaces: Ci, utils: Cu } = Components;

 // For adding observers.

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

 Cu.import("resource://gre/modules/Messaging.jsm");

 /**

  * Create an interface to an Android SharedPreferences branch.

  *

  * branch {String} should be a string describing a preferences branch,

  * like "UpdateService" or "background.data", or null to access the

  * default preferences branch for the application.

  */

 function SharedPreferences(branch) {

   if (!(this instanceof SharedPreferences)) {

     return new SharedPreferences(branch);

   }

   this._branch = branch || null;

   this._observers = {};

 };

 SharedPreferences.prototype = Object.freeze({

   _set: function _set(prefs) {

     sendMessageToJava({

       type: "SharedPreferences:Set",

       preferences: prefs,

       branch: this._branch,

     });

   },

   _setOne: function _setOne(prefName, value, type) {

     let prefs = [];

     prefs.push({

       name: prefName,

       value: value,

       type: type,

     });

     this._set(prefs);

   },

   setBoolPref: function setBoolPref(prefName, value) {

     this._setOne(prefName, value, "bool");

   },

   setCharPref: function setCharPref(prefName, value) {

     this._setOne(prefName, value, "string");

   },

   setIntPref: function setIntPref(prefName, value) {

     this._setOne(prefName, value, "int");

   },

   _get: function _get(prefs, callback) {

     let result = null;

     sendMessageToJava({

       type: "SharedPreferences:Get",

       preferences: prefs,

       branch: this._branch,

     }, (data) => {

       result = data.values;

     });

     let thread = Services.tm.currentThread;

     while (result == null)

       thread.processNextEvent(true);

     return result;

   },

   _getOne: function _getOne(prefName, type) {

     let prefs = [];

     prefs.push({

       name: prefName,

       type: type,

     });

     let values = this._get(prefs);

     if (values.length != 1) {

       throw new Error("Got too many values: " + values.length);

     }

     return values[0].value;

   },

   getBoolPref: function getBoolPref(prefName) {

     return this._getOne(prefName, "bool");

   },

   getCharPref: function getCharPref(prefName) {

     return this._getOne(prefName, "string");

   },

   getIntPref: function getIntPref(prefName) {

     return this._getOne(prefName, "int");

   },

   /**

    * Invoke `observer` after a change to the preference `domain` in

    * the current branch.

    *

    * `observer` should implement the nsIObserver.observe interface.

    */

   addObserver: function addObserver(domain, observer, holdWeak) {

     if (!domain)

       throw new Error("domain must not be null");

     if (!observer)

       throw new Error("observer must not be null");

     if (holdWeak)

       throw new Error("Weak references not yet implemented.");

     if (!this._observers.hasOwnProperty(domain))

       this._observers[domain] = [];

     if (this._observers[domain].indexOf(observer) > -1)

       return;

     this._observers[domain].push(observer);

     this._updateAndroidListener();

   },

   /**

    * Do not invoke `observer` after a change to the preference

    * `domain` in the current branch.

    */

   removeObserver: function removeObserver(domain, observer) {

     if (!this._observers.hasOwnProperty(domain))

       return;

     let index = this._observers[domain].indexOf(observer);

     if (index < 0)

       return;

     this._observers[domain].splice(index, 1);

     if (this._observers[domain].length < 1)

       delete this._observers[domain];

     this._updateAndroidListener();

   },

   _updateAndroidListener: function _updateAndroidListener() {

     if (this._listening && Object.keys(this._observers).length < 1)

       this._uninstallAndroidListener();

     if (!this._listening && Object.keys(this._observers).length > 0)

       this._installAndroidListener();

   },

   _installAndroidListener: function _installAndroidListener() {

     if (this._listening)

       return;

     this._listening = true;

     Services.obs.addObserver(this, "SharedPreferences:Changed", false);

     sendMessageToJava({

       type: "SharedPreferences:Observe",

       enable: true,

       branch: this._branch,

     });

   },

   observe: function observe(subject, topic, data) {

     if (topic != "SharedPreferences:Changed") {

       return;

     }

     let msg = JSON.parse(data);

     if (msg.branch != this._branch) {

       return;

     }

     if (!this._observers.hasOwnProperty(msg.key)) {

       return;

     }

     let observers = this._observers[msg.key];

     for (let obs of observers) {

       obs.observe(obs, msg.key, msg.value);

     }

   },

   _uninstallAndroidListener: function _uninstallAndroidListener() {

     if (!this._listening)

       return;

     this._listening = false;

     Services.obs.removeObserver(this, "SharedPreferences:Changed");

     sendMessageToJava({

       type: "SharedPreferences:Observe",

       enable: false,

       branch: this._branch,

     });

   },

 });