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

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

namespace Application.Features.Api.ChannelTitle.CreateChannelTitle;

internal sealed class Handler(IAppDbContext db) : ICommandHandler<Command, Result<int>>
{
    public async Task<Result<int>> Handle(Command request, CancellationToken ct)
    {
        var channel = await db.Channel.FirstOrDefaultAsync(c => c.ID == request.ChannelID, ct);
        if (channel is null)
        {
            return Result.Failure<int>(Error.NotFound("ChannelTitle.ChannelNotFound", "채널을 찾을 수 없습니다."));
        }

        if (channel.MemberID != request.MemberID)
        {
            return Result.Failure<int>(Error.Forbidden("ChannelTitle.Forbidden", "본인 채널만 수정할 수 있습니다."));
        }

        var count = await db.ChannelTitle.CountAsync(t => t.ChannelID == request.ChannelID, ct);
        if (count >= DonationConstants.Title.MaxTitlesPerChannel)
        {
            return Result.Failure<int>(Error.Problem("ChannelTitle.TooMany", $"칭호는 최대 {DonationConstants.Title.MaxTitlesPerChannel}개까지 등록할 수 있습니다."));
        }

        if (string.IsNullOrWhiteSpace(request.Name))
        {
            return Result.Failure<int>(Error.Problem("ChannelTitle.NameRequired", "칭호 이름을 입력해 주세요."));
        }

        if (request.Name.Length > 20)
        {
            return Result.Failure<int>(Error.Problem("ChannelTitle.NameTooLong", "칭호 이름은 20자 이내여야 합니다."));
        }

        if (request.MinAmount < 0)
        {
            return Result.Failure<int>(Error.Problem("ChannelTitle.InvalidAmount", "최소 금액은 0원 이상이어야 합니다."));
        }

        var duplicateAmount = await db.ChannelTitle.AnyAsync(t => t.ChannelID == request.ChannelID && t.MinAmount == request.MinAmount, ct);
        if (duplicateAmount)
        {
            return Result.Failure<int>(Error.Conflict("ChannelTitle.DuplicateAmount", "같은 최소 금액의 칭호가 이미 존재합니다."));
        }

        var entity = Domain.Entities.Donations.ChannelTitle.Create(request.ChannelID, request.Name, request.MinAmount, request.Color);
        entity.Update(request.Name, request.Description, request.MinAmount, request.Color, request.IconUrl, true);
        entity.SetOrder(count);

        await db.ChannelTitle.AddAsync(entity, ct);
        await db.SaveChangesAsync(ct);

        return Result.Success(entity.ID);
    }
}