Implemented order ui and validation. Added coupon handling

Moonlight/App/Services/Store/StoreOrderService.cs

@@ -0,0 +1,87 @@
+using Microsoft.EntityFrameworkCore;
+using Moonlight.App.Database.Entities;
+using Moonlight.App.Database.Entities.Store;
+using Moonlight.App.Exceptions;
+using Moonlight.App.Repositories;
+
+namespace Moonlight.App.Services.Store;
+
+public class StoreOrderService
+{
+    private readonly IServiceScopeFactory ServiceScopeFactory;
+
+    public StoreOrderService(IServiceScopeFactory serviceScopeFactory)
+    {
+        ServiceScopeFactory = serviceScopeFactory;
+    }
+
+    public Task Validate(User u, Product p, int durationMultiplier, Coupon? c)
+    {
+        using var scope = ServiceScopeFactory.CreateScope();
+        var productRepo = scope.ServiceProvider.GetRequiredService<Repository<Product>>();
+        var userRepo = scope.ServiceProvider.GetRequiredService<Repository<User>>();
+        var serviceRepo = scope.ServiceProvider.GetRequiredService<Repository<Service>>();
+        var couponRepo = scope.ServiceProvider.GetRequiredService<Repository<Coupon>>();
+        
+        // Ensure the values are safe and loaded by using the created scope to bypass the cache
+        
+        var user = userRepo
+            .Get()
+            .Include(x => x.CouponUses)
+            .ThenInclude(x => x.Coupon)
+            .FirstOrDefault(x => x.Id == u.Id);
+
+        if (user == null)
+            throw new DisplayException("Unsafe value detected. Please reload the page to proceed");
+
+        
+        var product = productRepo
+            .Get()
+            .FirstOrDefault(x => x.Id == p.Id);
+        
+        if (product == null)
+            throw new DisplayException("Unsafe value detected. Please reload the page to proceed");
+
+
+        Coupon? coupon = c;
+
+        if (coupon != null) // Only check if the coupon actually has a value
+        {
+            coupon = couponRepo
+                .Get()
+                .FirstOrDefault(x => x.Id == coupon.Id);
+            
+            if(coupon == null)
+                    throw new DisplayException("Unsafe value detected. Please reload the page to proceed");
+        }
+        
+        // Perform checks on selected order
+
+        if (coupon != null && user.CouponUses.Any(x => x.Coupon.Id == coupon.Id))
+            throw new DisplayException("Coupon already used");
+
+        if (coupon != null && coupon.Amount == 0)
+            throw new DisplayException("No coupon uses left");
+        
+        var price = product.Price * durationMultiplier;
+
+        if (coupon != null)
+            price = Math.Round(price * coupon.Percent / 100, 2);
+
+        if (user.Balance < price)
+            throw new DisplayException("Order is too expensive");
+
+        var userServices = serviceRepo
+            .Get()
+            .Where(x => x.Product.Id == product.Id)
+            .Count(x => x.Owner.Id == user.Id);
+
+        if (userServices >= product.MaxPerUser)
+            throw new DisplayException("The limit of this product on your account has been reached");
+
+        if (product.Stock < 1)
+            throw new DisplayException("The product is out of stock");
+        
+        return Task.CompletedTask;
+    }
+}