using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using HN.Domain;
using MediatR;

namespace HN.Application
{
  public sealed class GetLinkCommentsQueryHandler : IRequestHandler<GetLinkCommentsQuery, CommentDto[]>
  {
    private readonly IHNContext _context;

    public GetLinkCommentsQueryHandler(IHNContext context)
    {
      _context = context;
    }

    public Task<CommentDto[]> Handle(GetLinkCommentsQuery request, CancellationToken cancellationToken)
    {
      var comments = from comment in _context.Comments
                     join user in _context.Users on comment.CreatedBy equals user.Id
                     where comment.LinkId == request.LinkId
                     select new CommentDto
                     {
                       Id = comment.Id,
                       CreatedAt = comment.CreatedAt,
                       CreatedByName = user.UserName,
                       Content = comment.Content,
                       UpVotes = comment.Votes.Count(c => c.Type == VoteType.Up),
                       DownVotes = comment.Votes.Count(c => c.Type == VoteType.Down)
                     };

      return Task.FromResult(comments.OrderBy(c => c.CreatedAt).ToArray());
    }
  }
}