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

namespace Application.Features.Api.Feed.GetPost;

public sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Result<Response>>
{
    public async Task<Result<Response>> Handle(Query request, CancellationToken ct)
    {
        var post = await db.FeedPost.AsNoTracking()
            .Where(p => p.ID == request.PostID && !p.IsDeleted)
            .Select(p => new
            {
                p.ID,
                p.MemberID,
                AuthorSID = p.Member.SID,
                AuthorName = p.Member.Name,
                AuthorThumb = p.Member.Thumb,
                IsCreator = p.Member.IsCreator,
                ChannelSID = p.Member.Channel != null ? p.Member.Channel.SID : null,
                p.Content,
                Images = p.FeedPostImage.OrderBy(i => i.ID).Select(i => new { i.Url, i.Width, i.Height }).ToList(),
                Medias = p.FeedPostMedia.OrderBy(m => m.ID).Select(m => m.Url).ToList(),
                p.Likes,
                p.Comments,
                p.Bookmarks,
                p.Views,
                Tags = p.FeedPostTag.Select(pt => new { pt.FeedTag.Name, pt.FeedTag.Slug }).ToList(),
                p.CreatedAt
            })
            .FirstOrDefaultAsync(ct);

        if (post is null)
        {
            return Result.Failure<Response>(Error.NotFound("Feed.PostNotFound", "게시글을 찾을 수 없습니다."));
        }

        var hasLike = false;
        var hasBookmark = false;

        if (request.ViewerMemberID is int viewerID && viewerID > 0)
        {
            hasLike = await db.FeedLike.AsNoTracking().AnyAsync(l => l.FeedPostID == post.ID && l.MemberID == viewerID, ct);
            hasBookmark = await db.FeedBookmark.AsNoTracking().AnyAsync(b => b.FeedPostID == post.ID && b.MemberID == viewerID, ct);
        }

        return new Response
        {
            PostID = post.ID,
            AuthorSID = post.AuthorSID,
            AuthorName = post.AuthorName,
            AuthorThumb = post.AuthorThumb,
            IsCreator = post.IsCreator,
            ChannelSID = post.ChannelSID,
            Content = post.Content,
            Images = [..post.Images.Select(i => new Response.ImageItem { Url = i.Url, Width = i.Width, Height = i.Height })],
            Medias = [..post.Medias],
            Likes = post.Likes,
            Comments = post.Comments,
            Bookmarks = post.Bookmarks,
            Views = post.Views,
            Tags = [..post.Tags.Select(t => new Response.TagRef { Name = t.Name, Slug = t.Slug })],
            CreatedAt = post.CreatedAt,
            HasLike = hasLike,
            HasBookmark = hasBookmark,
            IsOwner = request.ViewerMemberID is int vID && vID > 0 && post.MemberID == vID
        };
    }
}