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

using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Domain.Entities.Store.ValueObject;
using Microsoft.EntityFrameworkCore;
using SharedKernel.Results;

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

public sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Result<Response>>
{
    public async Task<Result<Response>> Handle(Query request, CancellationToken ct)
    {
        var coupon = await db.Coupon
            .AsNoTracking()
            .Include(c => c.Product)
            .Include(c => c.Game)
            .Where(c => c.ID == request.ID)
            .Select(c => new Response(
                c.ID,
                c.ProductID,
                c.Product!.Name,
                c.GameID,
                c.Game!.KorName,
                c.Name,
                c.UsagePolicy,
                c.ExpiresAt,
                c.GeneratedCount,
                c.UsedCount,
                db.CouponCode.Count(cc => cc.CouponID == c.ID && cc.Status == CouponCodeStatus.Available),
                c.LowStockThreshold,
                c.CreatedAt,
                c.UpdatedAt
            ))
            .FirstOrDefaultAsync(ct);

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

        return Result.Success(coupon);
    }
}