ANTOOZA-BACKEND/Application/Features/Admin/Store/Coupon/Update/Handler.cs

using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Microsoft.EntityFrameworkCore;
using SharedKernel.Results;

namespace Application.Features.Admin.Store.Coupon.Update;

public sealed class Handler(IAppDbContext db) : ICommandHandler<Command, Result>
{
    public async Task<Result> Handle(Command request, CancellationToken ct)
    {
        var coupon = await db.Coupon.FirstOrDefaultAsync(c => c.ID == request.ID, ct);

        if (coupon is null)
        {
            return Result.Failure(Error.NotFound("Coupon.NotFound", "쿠폰을 찾을 수 없습니다."));
        }

        if (request.LowStockThreshold < 0)
        {
            return Result.Failure(Error.Problem("Coupon.InvalidThreshold", "재고 부족 임계치는 0 이상이어야 합니다."));
        }

        coupon.Update(request.Name, request.ExpiresAt, request.LowStockThreshold);
        await db.SaveChangesAsync(ct);

        return Result.Success();
    }
}