Added CartService and LocalStorageService (browser)

LiteCharms.Features.MidrandBooks/Orders/CartService.cs

@@ -0,0 +1,128 @@
+using LiteCharms.Features.Abstractions;
+using LiteCharms.Features.MidrandBooks.Orders.Models;
+using LiteCharms.Features.MidrandBooks.Products.Models;
+
+namespace LiteCharms.Features.MidrandBooks.Orders;
+
+public sealed class CartService : IService
+{
+    private Cart cart = new();
+
+    public Cart GetCart() => cart;
+
+    public void LoadCart(Cart savedCart) => cart = savedCart;
+
+    public void AddItem(ProductPrice productPrice)
+    {
+        var itemExists = false;
+
+        for (var i = 0; i < cart.Items.Count; i++)
+        {
+            if (cart.Items[i].Price!.Id == productPrice.Id)
+            {
+                cart.Items[i].Quantity++;
+                cart.Items[i].Amount += productPrice.Amount;
+
+                itemExists = true;
+
+                break;
+            }
+        }
+
+        if (!itemExists)
+            cart.Items.Add(new CartItem
+            {
+                Price = productPrice,
+                Amount = productPrice.Amount,
+                Quantity = 1,
+            });
+
+        CalculateTotalPrice();
+    }
+
+    public void UpdateQuantity(long productPriceId, int newQuantity)
+    {
+        if (newQuantity <= 0)
+        {
+            RemoveAllSameItem(productPriceId);
+
+            return;
+        }
+
+        for (var i = 0; i < cart.Items.Count; i++)
+        {
+            if (cart.Items[i].Price!.Id == productPriceId)
+            {
+                var oldQuantity = cart.Items[i].Quantity;
+                var pricePerUnit = cart.Items[i].Price!.Amount;
+
+                cart.Items[i].Quantity = newQuantity;
+                cart.Items[i].Amount = pricePerUnit * newQuantity;
+                break;
+            }
+        }
+
+        CalculateTotalPrice();
+    }
+
+    public void RemoveOneItem(long productPriceId)
+    {
+        for (var i = 0; i < cart.Items.Count; i++)
+        {
+            if (cart.Items[i].Price!.Id == productPriceId)
+            {
+                if (cart.Items[i].Quantity <= 1)
+                {
+                    cart.Items.RemoveAt(i);
+                }
+                else
+                {
+                    cart.Items[i].Quantity--;
+                    cart.Items[i].Amount -= cart.Items[i].Price!.Amount;
+                }
+
+                break;
+            }
+        }
+
+        CalculateTotalPrice();
+    }
+
+    public void RemoveAllSameItem(long productPriceId)
+    {
+        if (cart.Items.Count == 0) return;
+
+        var item = cart.Items.FirstOrDefault(i => i.Price?.Id == productPriceId);
+
+        if (item is not null) cart.Items.Remove(item);
+
+        CalculateTotalPrice();
+    }
+
+    public void Clear()
+    {
+        if(cart.CustomerId is not null || cart.OrderId is not null)
+        {
+            cart.TotalPrice = 0;
+            cart.TotalVat = 0;
+            cart.Items.Clear();
+
+            return;
+        }
+
+        cart = new Cart();
+    }
+
+    public decimal CalculateTotalPrice()
+    {
+        if (cart.Items.Count == 0) return 0;
+
+        var gross = cart.Items.Sum(i => i.Amount);
+
+        if (!cart.IsVatInclusive) cart.TotalVat = gross * cart.VatRate;
+
+        cart.TotalPrice = gross + cart.TotalVat;
+
+        return cart.TotalPrice;
+    }
+}

LiteCharms.Features.MidrandBooks/Orders/Models/Cart.cs

@@ -0,0 +1,18 @@
+namespace LiteCharms.Features.MidrandBooks.Orders.Models;
+
+public sealed class Cart
+{
+    public long? CustomerId { get; set; }
+
+    public long? OrderId { get; set; }
+
+    public decimal TotalPrice { get; set; }
+
+    public decimal TotalVat { get; set; }
+
+    public decimal VatRate { get; set; } = 0.15m;
+
+    public bool IsVatInclusive { get; set; } = true;
+
+    public IList<CartItem> Items { get; set; } = [];
+}

LiteCharms.Features.MidrandBooks/Orders/Models/CartItem.cs

@@ -0,0 +1,12 @@
+using LiteCharms.Features.MidrandBooks.Products.Models;
+
+namespace LiteCharms.Features.MidrandBooks.Orders.Models;
+
+public sealed class CartItem
+{
+    public ProductPrice? Price { get; set; }
+
+    public long Quantity { get; set; }
+
+    public decimal Amount { get; set; }
+}