components/LiteCharms.Features/ShoppingCarts/Commands/Handlers/AddPackageToShoppingCartCommandHandler.cs

using LiteCharms.Infrastructure.Database;

namespace LiteCharms.Features.ShoppingCarts.Commands.Handlers;

public class AddPackageToShoppingCartCommandHandler(IDbContextFactory<ShopDbContext> contextFactory) : IRequestHandler<AddPackageToShoppingCartCommand, Result>
{
    public async ValueTask<Result> Handle(AddPackageToShoppingCartCommand request, CancellationToken cancellationToken)
    {
        try
        {
            using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Packages.AnyAsync(p => p.Id == request.PackageId, cancellationToken))
                return Result.Fail($"Package cold not be found by ID {request.PackageId}");

            var shoppingCart = await context.ShoppingCarts.FirstOrDefaultAsync(c => c.Id == request.ShoppingCartId, cancellationToken);

            if (shoppingCart is null)
                return Result.Fail($"Shopping cart could not be found by ID {request.ShoppingCartId}");

            if (!await context.ShoppingCartPackages.AnyAsync(cp => cp.ShoppingCartId == request.ShoppingCartId, cancellationToken))
                return Result.Fail($"Package {request.PackageId} is already in the cart");

            var newShoppingCartPackage = context.ShoppingCartPackages.Add(new Entities.ShoppingCartPackage
            {
                ShoppingCartId = request.ShoppingCartId,
                PackageId = request.PackageId
            });

            return await context.SaveChangesAsync(cancellationToken) > 0
                ? Result.Ok()
                : Result.Fail($"Could not add package of id {request.PackageId} to shopping cart {request.ShoppingCartId}");
        }
        catch (Exception ex)
        {
            return Result.Fail(new Error(ex.Message).CausedBy(ex));
        }
    }
}