ANTOOZA-BACKEND/Application/Features/Admin/Store/Coupon/Delete/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.Delete;

public sealed class Handler(IAppDbContext db) : ICommandHandler<Command, Result>
{
    public async Task<Result> Handle(Command request, CancellationToken ct)
    {
        if (request.IDs is null || request.IDs.Length == 0)
        {
            return Result.Failure(Error.Problem("Coupon.NoIDs", "삭제할 쿠폰을 선택해 주세요."));
        }

        // 발급(Issued)/사용(Used) 코드가 있으면 삭제 거부
        var issuedCodeCoupons = await db.CouponCode
            .Where(c => request.IDs.Contains(c.CouponID) && (c.Status == CouponCodeStatus.Issued || c.Status == CouponCodeStatus.Used))
            .Select(c => c.CouponID)
            .Distinct()
            .ToListAsync(ct);

        if (issuedCodeCoupons.Count > 0)
        {
            return Result.Failure(Error.Conflict("Coupon.InUse", $"이미 발급되거나 사용된 코드가 있는 쿠폰은 삭제할 수 없습니다. (쿠폰 ID: {string.Join(", ", issuedCodeCoupons)})"));
        }

        var coupons = await db.Coupon.Where(c => request.IDs.Contains(c.ID)).ToListAsync(ct);

        if (coupons.Count == 0)
        {
            return Result.Failure(Error.NotFound("Coupon.NotFound", "삭제할 쿠폰을 찾을 수 없습니다."));
        }

        // CouponCode 는 CASCADE 로 자동 삭제됨 (EF Configuration 에서 DeleteBehavior.Cascade)
        db.Coupon.RemoveRange(coupons);
        await db.SaveChangesAsync(ct);

        return Result.Success();
    }
}