/*
 * This Source Code is subject to the terms of the Mozilla Public License
 * version 2.0 (the "License"). You can obtain a copy of the License at
 * http://mozilla.org/MPL/2.0/.
 */

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

let {addonRoot, addonName} = require("info");
let branchName = "extensions." + addonName + ".";
let branch = Services.prefs.getBranch(branchName);
let ignorePrefChanges = false;

function init()
{
  // Load default preferences and set up properties for them
  let defaultBranch = Services.prefs.getDefaultBranch(branchName);
  let scope =
  {
    pref: function(pref, value)
    {
      if (pref.substr(0, branchName.length) != branchName)
      {
        Cu.reportError(new Error("Ignoring default preference " + pref + ", wrong branch."));
        return;
      }
      pref = pref.substr(branchName.length);

      let [getter, setter] = typeMap[typeof value];
      setter(defaultBranch, pref, value);
      defineProperty(pref, false, getter, setter);
    }
  };
  Services.scriptloader.loadSubScript(addonRoot + "defaults/prefs.js", scope);

  // Add preference change observer
  try
  {
    branch.QueryInterface(Ci.nsIPrefBranch2).addObserver("", Prefs, true);
    onShutdown.add(function() branch.removeObserver("", Prefs));
  }
  catch (e)
  {
    Cu.reportError(e);
  }
}

/**
 * Sets up getter/setter on Prefs object for preference.
 */
function defineProperty(/**String*/ name, defaultValue, /**Function*/ readFunc, /**Function*/ writeFunc)
{
  let value = defaultValue;
  Prefs["_update_" + name] = function()
  {
    try
    {
      value = readFunc(branch, name);
      triggerListeners(name);
    }
    catch(e)
    {
      Cu.reportError(e);
    }
  };
  Prefs.__defineGetter__(name, function() value);
  Prefs.__defineSetter__(name, function(newValue)
  {
    if (value == newValue)
      return value;

    try
    {
      ignorePrefChanges = true;
      writeFunc(branch, name, newValue);
      value = newValue;
      triggerListeners(name);
    }
    catch(e)
    {
      Cu.reportError(e);
    }
    finally
    {
      ignorePrefChanges = false;
    }
    return value;
  });
  Prefs["_update_" + name]();
}

let listeners = [];
function triggerListeners(/**String*/ name)
{
  for (let i = 0; i < listeners.length; i++)
  {
    try
    {
      listeners[i](name);
    }
    catch(e)
    {
      Cu.reportError(e);
    }
  }
}

/**
 * Manages the preferences for an extension, object properties corresponding
 * to extension's preferences are added automatically. Setting the property
 * will automatically change the preference, external preference changes are
 * also recognized automatically.
 */
let Prefs = exports.Prefs =
{
  /**
   * Migrates an old preference to a new name.
   */
  migrate: function(/**String*/ oldName, /**String*/ newName)
  {
    if (newName in this && Services.prefs.prefHasUserValue(oldName))
    {
      let [getter, setter] = typeMap[typeof this[newName]];
      try
      {
        this[newName] = getter(Services.prefs, oldName);
      } catch(e) {}
      Services.prefs.clearUserPref(oldName);
    }
  },

  /**
   * Adds a preferences listener that will be fired whenever a preference
   * changes.
   */
  addListener: function(/**Function*/ listener)
  {
    if (listeners.indexOf(listener) < 0)
      listeners.push(listener);
  },

  /**
   * Removes a preferences listener.
   */
  removeListener: function(/**Function*/ listener)
  {
    let index = listeners.indexOf(listener);
    if (index >= 0)
      listeners.splice(index, 1);
  },

  observe: function(subject, topic, data)
  {
    if (ignorePrefChanges || topic != "nsPref:changed")
      return;

    if ("_update_" + data in this)
      this["_update_" + data]();
  },

  QueryInterface: XPCOMUtils.generateQI([Ci.nsISupportsWeakReference, Ci.nsIObserver])
};

// Getter/setter functions for difference preference types
let typeMap =
{
  boolean: [getBoolPref, setBoolPref],
  number: [getIntPref, setIntPref],
  string: [getCharPref, setCharPref],
  object: [getJSONPref, setJSONPref]
};

function getIntPref(branch, pref) branch.getIntPref(pref)
function setIntPref(branch, pref, newValue) branch.setIntPref(pref, newValue)

function getBoolPref(branch, pref) branch.getBoolPref(pref)
function setBoolPref(branch, pref, newValue) branch.setBoolPref(pref, newValue)

function getCharPref(branch, pref) branch.getComplexValue(pref, Ci.nsISupportsString).data
function setCharPref(branch, pref, newValue)
{
  let str = Cc["@mozilla.org/supports-string;1"].createInstance(Ci.nsISupportsString);
  str.data = newValue;
  branch.setComplexValue(pref, Ci.nsISupportsString, str);
}

function getJSONPref(branch, pref) JSON.parse(getCharPref(branch, pref))
function setJSONPref(branch, pref, newValue) setCharPref(branch, pref, JSON.stringify(newValue))

init();
