using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Repositories;
using LanguageExt;
using MediatR;
using static ErsatzTV.Application.Artists.Mapper;

namespace ErsatzTV.Application.Artists.Queries
{
    public class GetArtistByIdHandler : IRequestHandler<GetArtistById, Option<ArtistViewModel>>
    {
        private readonly IArtistRepository _artistRepository;
        private readonly ISearchRepository _searchRepository;

        public GetArtistByIdHandler(IArtistRepository artistRepository, ISearchRepository searchRepository)
        {
            _artistRepository = artistRepository;
            _searchRepository = searchRepository;
        }

        public async Task<Option<ArtistViewModel>> Handle(
            GetArtistById request,
            CancellationToken cancellationToken)
        {
            Option<Artist> maybeArtist = await _artistRepository.GetArtist(request.ArtistId);
            return await maybeArtist.Match<Task<Option<ArtistViewModel>>>(
                async artist =>
                {
                    List<string> languages = await _searchRepository.GetLanguagesForArtist(artist);
                    return ProjectToViewModel(artist, languages);
                },
                () => Task.FromResult(Option<ArtistViewModel>.None));
        }
    }
}