(function (ns) {

    ns.Gtm = function (options) {
        this.construct.apply(this, arguments);
    };

    ns.Gtm.prototype.construct = function (options) {
        this.namespace = 'gtm';
        this.options = $.extend({
            cartItems: {},
            products: {},
            actionField: {}
        },
        options);

        this.initProductClicks();
        this.initRemovingFromCart();
    };

    ns.Gtm.prototype.initProductClicks = function () {
        for (var productId in this.options.products) {
            $('[data-product-id=' + productId + ']').bind(
                'click.' + this.namespace,
                _.bind(this.onProductClick, this, productId)
            );
        }
    };

    ns.Gtm.prototype.onProductClick = function (productId, ev) {
        ev.preventDefault();

        var data = {
            'event': 'productClick',
            'ecommerce': {
                'click': {
                    'actionField': this.options.actionField,
                    'products': [this.options.products[productId]]
                }
            },
            'eventCallback': function() {
                document.location = $('[data-product-id=' + productId + ']').prop('href');
            }
        };

        dataLayer.push(data);
        ns.Gtm._debug(data);
    };

    ns.Gtm.prototype.initRemovingFromCart = function () {
        for (var itemId in this.options.cartItems) {
            $('[data-cartitem-id=' + itemId + ']').bind(
                'click.' + this.namespace,
                _.bind(this.onRemoveFromCart, this, itemId)
            );
        }
    };

    ns.Gtm.prototype.onRemoveFromCart = function (itemId, ev) {
        var defaultPrevented;
        if (-1 != navigator.userAgent.indexOf('MSIE 8')) {
            defaultPrevented = ('1' == $('[data-cartitem-id=' + itemId + ']').data('default-prevented'));
        } else {
            defaultPrevented = ev.isDefaultPrevented();
        }
        if (false == defaultPrevented) {
            ev.preventDefault();
            var product = this.options.cartItems[itemId];
            var quantity = '' + $('[data-cartitem-id=' + itemId + ']').closest('div').find('input[name^=quantity]').val();
            if (!isNaN(parseInt(quantity))) {
                product.quantity = quantity;
            }
            var data = {
                'event': 'removeFromCart',
                'ecommerce': {
                    'remove': {
                        'products': [product]
                    }
                },
                'eventCallback': function() {
                    document.location = $('[data-cartitem-id=' + itemId + ']').prop('href');
                }
            };

            dataLayer.push(data);
            ns.Gtm._debug(data);
        }
    };

    ns.Gtm.onAddToCart = function (product) {
        var data = {
            'event': 'addToCart',
            'ecommerce': {
                'add': {
                    'products': [product]
                }
            }
        };

        dataLayer.push(data);
        ns.Gtm._debug(data);
    };

    ns.Gtm.onCheckout = function (step, products, callback) {
        var data = {
            'event': 'checkout',
            'ecommerce': {
                'checkout': {
                    'actionField': {'step': step},
                    'products': products
                }
            }
        };
        if (undefined != callback) {
            data['eventCallback'] = callback;
        }

        dataLayer.push(data);
        ns.Gtm._debug(data);
    };

    ns.Gtm.onCheckoutOption = function (step, checkoutOption) {
        var data = {
            'event': 'checkoutOption',
            'ecommerce': {
                'checkout_option': {
                    'actionField': {'step': step, 'option': checkoutOption}
                }
            }
        };

        dataLayer.push(data);
        ns.Gtm._debug(data);
    };

    ns.Gtm._debug = function (data) {
        if (false == qs.constant('SITE_LIVE')) {
            if (true == qs.constant('DEBUG')) {
                alert(JSON.stringify(data, undefined, 4));
            }
            if (undefined != data.eventCallback) {
                data.eventCallback();
            }
        }
    };

})(qs.defineNS('lib'));