/* vim:ts=4:sts=4:sw=4:
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Ajax.org Code Editor (ACE).
 *
 * The Initial Developer of the Original Code is
 * Ajax.org B.V.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *      Fabian Jakobs <fabian AT ajax DOT org>
 *      Irakli Gozalishvili <rfobic@gmail.com> (http://jeditoolkit.com)
 *      Julian Viereck <julian.viereck@gmail.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

define(function(require, exports, module) {
"use strict";

var oop = require("./oop");
var event = require("./event");
var EventEmitter = require("./event_emitter").EventEmitter;

/*
 * This class keeps track of the focus state of the given window.
 * Focus changes for example when the user switches a browser tab,
 * goes to the location bar or switches to another application.
 */ 
var BrowserFocus = function(win) {
    win = win || window;
    
    this.lastFocus = new Date().getTime();
    this._isFocused = true;
    
    var _self = this;

    // IE < 9 supports focusin and focusout events
    if ("onfocusin" in win.document) {
        event.addListener(win.document, "focusin", function(e) {
            _self._setFocused(true);
        });

        event.addListener(win.document, "focusout", function(e) {
            _self._setFocused(!!e.toElement);
        });
    }
    else {
        event.addListener(win, "blur", function(e) {
            _self._setFocused(false);
        });

        event.addListener(win, "focus", function(e) {
            _self._setFocused(true);
        });
    }
};

(function(){

    oop.implement(this, EventEmitter);
    
    this.isFocused = function() {
        return this._isFocused;
    };
    
    this._setFocused = function(isFocused) {
        if (this._isFocused == isFocused)
            return;
            
        if (isFocused)
            this.lastFocus = new Date().getTime();
            
        this._isFocused = isFocused;
        this._emit("changeFocus");
    };

}).call(BrowserFocus.prototype);


exports.BrowserFocus = BrowserFocus;
});