using System.Threading;
using System.Threading.Tasks;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain.Filler;
using ErsatzTV.Infrastructure.Data;
using ErsatzTV.Infrastructure.Extensions;
using LanguageExt;
using MediatR;
using Microsoft.EntityFrameworkCore;
using Unit = LanguageExt.Unit;

namespace ErsatzTV.Application.Filler.Commands
{
    public class UpdateFillerPresetHandler : IRequestHandler<UpdateFillerPreset, Either<BaseError, Unit>>
    {
        private readonly IDbContextFactory<TvContext> _dbContextFactory;

        public UpdateFillerPresetHandler(IDbContextFactory<TvContext> dbContextFactory)
        {
            _dbContextFactory = dbContextFactory;
        }

        public async Task<Either<BaseError, Unit>> Handle(UpdateFillerPreset request, CancellationToken cancellationToken)
        {
            await using TvContext dbContext = _dbContextFactory.CreateDbContext();

            Validation<BaseError, FillerPreset> validation = await FillerPresetMustExist(dbContext, request);
            return await validation.Apply(ps => ApplyUpdateRequest(dbContext, ps, request));
        }

        private async Task<Unit> ApplyUpdateRequest(
            TvContext dbContext,
            FillerPreset existing,
            UpdateFillerPreset request)
        {
            existing.Name = request.Name;
            existing.FillerKind = request.FillerKind;
            existing.FillerMode = request.FillerMode;
            existing.Duration = request.Duration;
            existing.Count = request.Count;
            existing.PadToNearestMinute = request.PadToNearestMinute;
            existing.CollectionType = request.CollectionType;
            existing.CollectionId = request.CollectionId;
            existing.MediaItemId = request.MediaItemId;
            existing.MultiCollectionId = request.MultiCollectionId;
            existing.SmartCollectionId = request.SmartCollectionId;

            await dbContext.SaveChangesAsync();

            return Unit.Default;
        }

        private static Task<Validation<BaseError, FillerPreset>> FillerPresetMustExist(
            TvContext dbContext,
            UpdateFillerPreset request) =>
            dbContext.FillerPresets
                .SelectOneAsync(ps => ps.Id, ps => ps.Id == request.Id)
                .Map(o => o.ToValidation<BaseError>("FillerPreset does not exist"));
    }
}