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

namespace Application.Features.Api.Member.Profile;

public sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Result<Response>>
{
    private const string FeedBoardCode = "feed";

    public async Task<Result<Response>> Handle(Query request, CancellationToken ct)
    {
        var member = await db.Member.AsNoTracking()
            .Where(m => m.SID == request.MemberSID && !m.IsWithdraw && !m.IsDenied)
            .Select(m => new
            {
                m.ID,
                m.SID,
                m.Name,
                m.Thumb,
                m.BannerUrl,
                m.Summary,
                m.Intro,
                m.IsCreator,
                m.IsAdmin,
                m.IsAuthCertified,
                JoinedAt = m.CreatedAt,
                m.LastLoginAt,
                ChannelSID = m.Channel != null ? m.Channel.SID : null,
                ChannelHandle = m.Channel != null ? m.Channel.Handle : null,
                Stats = m.MemberStats == null ? null : new
                {
                    m.MemberStats.FollowerCount,
                    m.MemberStats.FollowingCount,
                    m.MemberStats.PostCount,
                    m.MemberStats.CommentCount,
                    m.MemberStats.AttendanceCount,
                    m.MemberStats.Exp,
                    m.MemberStats.LikeReceivedCount
                }
            })
            .FirstOrDefaultAsync(ct);

        if (member is null)
        {
            return Result.Failure<Response>(Error.NotFound("Member.ProfileNotFound", "회원을 찾을 수 없습니다."));
        }

        var feedBoardID = await db.Board.AsNoTracking().Where(b => b.Code == FeedBoardCode).Select(b => (int?)b.ID).FirstOrDefaultAsync(ct);

        var feedPostCount = feedBoardID is int fid
            ? await db.Post.AsNoTracking().LongCountAsync(p => p.BoardID == fid && p.MemberID == member.ID && !p.IsDeleted, ct)
            : 0;

        var consecutiveDays = await db.Attendance.AsNoTracking()
            .Where(a => a.MemberID == member.ID)
            .OrderByDescending(a => a.CreatedAt)
            .Select(a => (int?)a.ConsecutiveDays)
            .FirstOrDefaultAsync(ct) ?? 0;

        var viewerID = request.ViewerMemberID ?? 0;
        var isSelf = viewerID > 0 && viewerID == member.ID;

        var isFollowing = false;
        if (viewerID > 0 && !isSelf)
        {
            isFollowing = await db.MemberFollow.AsNoTracking().AnyAsync(f => f.FollowerMemberID == viewerID && f.FolloweeMemberID == member.ID, ct);
        }

        return new Response
        {
            MemberID = member.ID,
            MemberSID = member.SID,
            Name = member.Name,
            Thumb = member.Thumb,
            BannerUrl = member.BannerUrl,
            Summary = member.Summary,
            Intro = member.Intro,
            IsCreator = member.IsCreator,
            IsAdmin = member.IsAdmin,
            IsAuthCertified = member.IsAuthCertified,
            JoinedAt = member.JoinedAt,
            LastLoginAt = member.LastLoginAt,
            ChannelSID = member.ChannelSID,
            ChannelHandle = member.ChannelHandle,
            FollowerCount = member.Stats?.FollowerCount ?? 0,
            FollowingCount = member.Stats?.FollowingCount ?? 0,
            PostCount = member.Stats?.PostCount ?? 0,
            CommentCount = member.Stats?.CommentCount ?? 0,
            FeedPostCount = feedPostCount,
            AttendanceCount = member.Stats?.AttendanceCount ?? 0,
            ConsecutiveDays = consecutiveDays,
            Exp = member.Stats?.Exp ?? 0,
            LikeReceivedCount = member.Stats?.LikeReceivedCount ?? 0,
            IsFollowing = isFollowing,
            IsSelf = isSelf
        };
    }
}