using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Application.Features.Api.Feed.Shared;
using Microsoft.EntityFrameworkCore;

namespace Application.Features.Api.Feed.GetTimeline;

public sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Response>
{
    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var followingIDs = await db.MemberFollow.AsNoTracking()
            .Where(f => f.FollowerMemberID == request.MemberID && !f.IsMuted)
            .Select(f => f.FolloweeMemberID)
            .ToListAsync(ct);

        if (followingIDs.Count == 0)
        {
            return new Response { Total = 0, List = [] };
        }

        var query = db.FeedPost.AsNoTracking().Where(p => !p.IsDeleted && followingIDs.Contains(p.MemberID));

        var total = await query.LongCountAsync(ct);
        var skip = (request.Page - 1) * request.PerPage;

        var rows = await query
            .OrderByDescending(p => p.CreatedAt)
            .Skip(skip)
            .Take(request.PerPage)
            .Select(p => new
            {
                p.ID,
                AuthorSID = p.Member.SID,
                AuthorName = p.Member.Name,
                AuthorThumb = p.Member.Thumb,
                AuthorSummary = p.Member.Summary,
                IsCreator = p.Member.IsCreator,
                ChannelSID = p.Member.Channel != null ? p.Member.Channel.SID : null,
                p.Content,
                p.Thumbnail,
                p.Images,
                p.Medias,
                p.Likes,
                p.Comments,
                p.Bookmarks,
                p.Views,
                Tags = p.FeedPostTag.Select(pt => new { pt.FeedTag.Name, pt.FeedTag.Slug }).ToList(),
                p.CreatedAt
            })
            .ToListAsync(ct);

        return new Response
        {
            Total = total,
            List = [..rows.Select(r => new FeedCardRow
            {
                PostID = r.ID,
                AuthorSID = r.AuthorSID,
                AuthorName = r.AuthorName,
                AuthorThumb = r.AuthorThumb,
                AuthorSummary = r.AuthorSummary,
                IsCreator = r.IsCreator,
                ChannelSID = r.ChannelSID,
                Subject = FeedContent.Excerpt(r.Content, 60),
                ContentExcerpt = FeedContent.Excerpt(r.Content, 200),
                Thumbnail = r.Thumbnail,
                Images = r.Images,
                Medias = r.Medias,
                Likes = r.Likes,
                Comments = r.Comments,
                Bookmarks = r.Bookmarks,
                Views = r.Views,
                Tags = [..r.Tags.Select(t => new FeedCardRow.TagRef { Name = t.Name, Slug = t.Slug })],
                CreatedAt = r.CreatedAt
            })]
        };
    }
}