dpot-backend/Application/Features/Api/Forum/CommentFile/Download/Handler.cs

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

namespace Application.Features.Api.Forum.CommentFile.Download;

public sealed class Handler(IAppDbContext db, IBoardPermissionService permissionService) : ICommandHandler<Command, Result<Response>>
{
    public async Task<Result<Response>> Handle(Command request, CancellationToken ct)
    {
        var file = await db.CommentFile.FirstOrDefaultAsync(x => x.UUID == request.CommentFileUUID && !x.IsDisabled, ct);
        if (file is null)
        {
            return Result.Failure<Response>(Error.NotFound("CommentFile.NotFound", "파일을 찾을 수 없습니다."));
        }

        // 파일 다운로드 권한 확인
        var boardMeta = await db.BoardMeta.AsNoTracking().FirstOrDefaultAsync(x => x.BoardID == file.BoardID, ct);
        if (boardMeta is not null && boardMeta.Permission.FileDownload > -1)
        {
            if (!request.MemberID.HasValue)
            {
                return Result.Failure<Response>(Error.Forbidden("CommentFile.PermissionDenied", "파일 다운로드 권한이 없습니다."));
            }

            var member = await db.Member.AsNoTracking().FirstOrDefaultAsync(x => x.ID == request.MemberID.Value, ct);
            if (member is null || !await permissionService.HasPermissionAsync(member, file.BoardID, boardMeta.Permission.FileDownload, ct))
            {
                return Result.Failure<Response>(Error.Forbidden("CommentFile.PermissionDenied", "파일 다운로드 권한이 없습니다."));
            }
        }

        file.Downloads++;

        var log = new CommentFileDownLog
        {
            CommentID = file.CommentID,
            CommentFileID = file.ID,
            MemberID = request.MemberID,
            IpAddress = request.IpAddress,
            UserAgent = request.UserAgent
        };

        await db.CommentFileDownLog.AddAsync(log, ct);
        await db.SaveChangesAsync(ct);

        return new Response(file.Url, file.FileName);
    }
}