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

namespace HN.Application
{
  // public static class LinkQueriesExtensions
  // {
  //   public static IQueryable<LinkDto> AllAsDto(this DbSet<Link> links)
  //   {
  //     return from link in links
  //            select new LinkDto
  //            {
  //              Id = link.Id,
  //              Url = link.Url,
  //              CreatedAt = link.CreatedAt,
  //              UpVotes = link.Votes.Count(v => v.Type == VoteType.Up),
  //              DownVotes = link.Votes.Count(v => v.Type == VoteType.Down)
  //            };
  //   }

  //   public static IQueryable<LinkDto> ToLinkDto(this IQueryable<Link> links)
  //   {
  //     return links.Select(link => new LinkDto
  //     {
  //       Id = link.Id,
  //       Url = link.Url,
  //       CreatedAt = link.CreatedAt,
  //       UpVotes = link.Votes.Count(v => v.Type == VoteType.Up),
  //       DownVotes = link.Votes.Count(v => v.Type == VoteType.Down)
  //     });
  //   }
  // }

  public sealed class ListLinksQueryHandler : IRequestHandler<ListLinksQuery, LinkDto[]>
  {
    private readonly IHNContext _context;

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

    public Task<LinkDto[]> Handle(ListLinksQuery request, CancellationToken cancellationToken)
    {
      var links = from link in _context.Links
                  select new LinkDto
                  {
                    Id = link.Id,
                    Url = link.Url,
                    CreatedAt = link.CreatedAt,
                    UpVotes = link.Votes.Count(v => v.Type == VoteType.Up),
                    DownVotes = link.Votes.Count(v => v.Type == VoteType.Down)
                  };

      return Task.FromResult(links.OrderByDescending(l => l.CreatedAt).ToArray());
    }
  }
}