ANTOOZA-BACKEND/Application/Features/Api/ChannelTitle/SelectMyTitle/Handler.cs

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

namespace Application.Features.Api.ChannelTitle.SelectMyTitle;

internal sealed class Handler(IAppDbContext db) : ICommandHandler<Command, Result>
{
    public async Task<Result> Handle(Command request, CancellationToken ct)
    {
        if (request.TitleID.HasValue)
        {
            var title = await db.ChannelTitle.FirstOrDefaultAsync(t => t.ID == request.TitleID.Value, ct);
            if (title is null || title.ChannelID != request.ChannelID)
            {
                return Result.Failure(Error.NotFound("ChannelTitle.NotFound", "칭호를 찾을 수 없습니다."));
            }

            if (!title.IsActive)
            {
                return Result.Failure(Error.Problem("ChannelTitle.Inactive", "비활성화된 칭호는 선택할 수 없습니다."));
            }

            var stats = await db.DonorChannelStats.AsNoTracking()
                .FirstOrDefaultAsync(s => s.DonorMemberID == request.MemberID && s.ChannelID == request.ChannelID, ct);

            if (stats is null || stats.CumulativeAmount < title.MinAmount)
            {
                return Result.Failure(Error.Forbidden("ChannelTitle.NotAcquired", "아직 획득하지 못한 칭호입니다."));
            }
        }

        var selection = await db.DonorTitleSelection
            .FirstOrDefaultAsync(s => s.DonorMemberID == request.MemberID && s.ChannelID == request.ChannelID, ct);

        if (selection is null)
        {
            selection = DonorTitleSelection.Create(request.MemberID, request.ChannelID, request.TitleID);
            await db.DonorTitleSelection.AddAsync(selection, ct);
        }
        else
        {
            selection.Update(request.TitleID);
        }

        await db.SaveChangesAsync(ct);
        return Result.Success();
    }
}