var app = window.app || {};

app.HeaderImage = qs.createObject();

app.HeaderImage.prototype = {
    container: null,
    options: {},
    currentImageKey: false,
    resizeTimer: false,
    resizeTimeout: 200,

    initialize: function (options) {
        this.container = $('#header-image');
        this.options = $.extend(options, {}); 

        if (navigator.userAgent.match(/MSIE 8/)) {
            this.updateBackgound(960);
        } else {
            var obj = this;
            $(window).resize(function() {
                if(obj.resizeTimer !== false) {
                    clearTimeout(obj.resizeTimer);
                    obj.resizeTimer = false;
                }
                obj.resizeTimer = setTimeout(function () { obj.updateBackgound() }, obj.resizeTimeout);
            });

            this.updateBackgound();
        }
    },

    getImageKey: function ()
    {
        var windowWidth = $(window).width();
        var imageKey = null;
        var lastKey = null;

        for (var key in this.options.images) {
            if (key < windowWidth) {
                imageKey = key;
            }
            lastKey = key;
        }

        if (null === imageKey) {
            imageKey = lastKey;
        }

        return imageKey;
    },

    updateBackgound: function (imageKey)
    {
        if (typeof imageKey == 'undefined') {
            imageKey = this.getImageKey();
        }
        if (imageKey !== this.currentImageKey) {
            this.currentImageKey = imageKey;
            this.container.css('background-image', 'url(' + this.options.images[imageKey] + ')');
        }
    }
};