groupBy(x=>x.Cart)
    .aggregate(g => {
        var products = g.values.reduce((agg, item) => {
            for (var key in item.Products) {
                var p = item.Products[key];
                var existing = agg[key];
                if (!existing) {
                    agg[key] = { Quantity: p.Quantity, Price: p.Price };
                }
                else {
                    existing.Quantity += p.Quantity;
                    if(p.Price > 0)
                        existing.Price = Math.min(p.Price, existing.Price);
                }
            }
            return agg;
        }, {});

        for (var key in products) {
            if(products[key].Quantity == 0)
                delete products[key];
        }

        return {
            Cart: g.key,
            Products: products
        };
    })