bitforum-backend/Application/Features/Api/Forum/Comment/Create/Handler.cs

using Application.Abstractions.Messaging;
using Application.Abstractions.Data;
using Microsoft.EntityFrameworkCore;
using SharedKernel.Results;

namespace Application.Features.Api.Forum.Comment.Create;

public sealed class Handler(IAppDbContext db) : ICommandHandler<Command, Result<int>>
{
    public async Task<Result<int>> Handle(Command request, CancellationToken ct)
    {
        if (string.IsNullOrWhiteSpace(request.Content))
        {
            return Result.Failure<int>(Error.Problem("Comment.ContentRequired", "내용을 입력해주세요."));
        }

        var post = await db.Post.FirstOrDefaultAsync(x => x.ID == request.PostID, ct);
        if (post is null)
        {
            return Result.Failure<int>(Error.NotFound("Comment.PostNotFound", "게시글을 찾을 수 없습니다."));
        }

        var member = await db.Member.AsNoTracking().FirstOrDefaultAsync(x => x.ID == request.MemberID, ct);
        if (member is null)
        {
            return Result.Failure<int>(Error.NotFound("Comment.MemberNotFound", "회원 정보를 찾을 수 없습니다."));
        }

        sbyte depth = 0;
        var isReply = false;

        if (request.ParentID.HasValue)
        {
            var parent = await db.Comment.AsNoTracking().FirstOrDefaultAsync(x => x.ID == request.ParentID.Value, ct);
            if (parent is null)
            {
                return Result.Failure<int>(Error.NotFound("Comment.ParentNotFound", "상위 댓글을 찾을 수 없습니다."));
            }

            depth = (sbyte)(parent.Depth + 1);
            isReply = true;

            // 부모 댓글 답글 수 증가
            var parentEntity = await db.Comment.FirstOrDefaultAsync(x => x.ID == request.ParentID.Value, ct);
            if (parentEntity is not null)
            {
                parentEntity.Replies++;
            }
        }

        var comment = new Domain.Entities.Forum.Comments.Comment
        {
            BoardID = request.BoardID,
            PostID = request.PostID,
            MemberID = request.MemberID,
            ParentID = request.ParentID,
            Depth = depth,
            Content = request.Content.Trim(),
            IsReply = isReply,
            IsSecret = request.IsSecret,
            Name = member.Name,
            SID = member.SID,
            Email = member.Email
        };

        await db.Comment.AddAsync(comment, ct);

        // Post 댓글 카운트 증가
        post.Comments++;
        post.LastCommentUpdatedAt = DateTime.UtcNow;

        // Board 댓글 카운트 증가
        var board = await db.Board.FirstOrDefaultAsync(x => x.ID == request.BoardID, ct);
        if (board is not null)
        {
            board.Comments++;
            board.UpdatedAt = DateTime.UtcNow;
        }

        // MemberStats 댓글 수 증가
        var memberStats = await db.MemberStats.FirstOrDefaultAsync(x => x.MemberID == request.MemberID, ct);
        if (memberStats is not null)
        {
            memberStats.CommentCount++;
        }

        await db.SaveChangesAsync(ct);

        return comment.ID;
    }
}