/*
 * Copyright 2011 Andrey “A.I.” Sitnik <andrey@sitnik.ru>,
 * sponsored by Evil Martians.
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

// Add Page Visibility API support to old browsers by focus/blur hack.
//
// Include this script _before_ Visibility.js.
//
// Note, that this hack doesn’t correctly emulate Page Visibility API:
// when user change focus from browser to another window (browser and your
// page may stay visible), this hack will decide, that you page is hidden.
//
// For Firefox 5 it will be better to use MozVisibility hack without this issue.
// See <https://github.com/private-face/mozvisibility>.
;(function() {
    "use strict";

    if ( document.visibilityState   || document.webkitVisibilityState ||
         document.msVisibilityState || document.mozVisibilityState    ||
         document.oVisibilityState ) {
         return;
    }

    document.hidden = false;
    document.visibilityState = 'visible';

    var event = null
    var i = 0
    var fireEvent = function () {
        if( document.createEvent ) {
            if ( !event ) {
                event = document.createEvent('HTMLEvents');
                event.initEvent('visibilitychange', true, true);
            }
            document.dispatchEvent(event);
        } else {
            if ( typeof(Visibility) == 'object' ) {
                Visibility._onVisibilityChange.call(Visibility, { })
            }
        }
    }

    var onfocus = function () {
        document.hidden = false;
        document.visibilityState = 'visible';
        fireEvent();
    };
    var onblur  = function () {
        document.hidden = true;
        document.visibilityState = 'hidden';
        fireEvent();
    }

    if ( document.addEventListener ) {
        window.addEventListener('focus', onfocus, true);
        window.addEventListener('blur',  onblur,  true);
    } else {
        document.attachEvent('onfocusin',  onfocus);
        document.attachEvent('onfocusout', onblur);
    }
})();