using Dapper;
using Femto.Modules.Blog.Contracts.Dto;
using Femto.Modules.Blog.Infrastructure.DbConnection;
using MediatR;
using Microsoft.Data.SqlClient;

namespace Femto.Modules.Blog.Domain.Posts.Commands.GetAuthorPosts;

public class GetAuthorPostsQueryHandler(IDbConnectionFactory connectionFactory)
    : IRequestHandler<GetAuthorPostsQuery, IList<GetAuthorPostsDto>>
{
    public async Task<IList<GetAuthorPostsDto>> Handle(
        GetAuthorPostsQuery query,
        CancellationToken cancellationToken
    )
    {
        using var conn = connectionFactory.GetConnection();

        var sql = $$"""
            with post_page as (
                select * from blog.post
                where blog.post.author_id = @authorId
                and (@cursor is null or blog.post.id < @cursor)
                order by blog.post.id desc
                limit @count
            )
            select
                p.id as PostId,
                p.content as Content,
                pm.url as MediaUrl
                from post_page p
            left join blog.post_media pm on pm.post_id = p.id
            order by p.id desc
            """;

        var result = await conn.QueryAsync<QueryResult>(
            sql,
            new { authorId = query.AuthorId, cursor = query.Cursor, count = query.Count }
        );

        return result
            .GroupBy(row => row.PostId)
            .Select(group => new GetAuthorPostsDto(
                group.Key,
                group.First().Content,
                group
                    .Select(row => row.MediaUrl)
                    .OfType<string>()
                    .Select(url => new GetAuthorPostsMediaDto(new Uri(url)))
                    .ToList()
            ))
            .ToList();
    }

    internal class QueryResult
    {
        public Guid PostId { get; set; }
        public string Content { get; set; }
        public string? MediaUrl { get; set; }
    }
}