ErsatzTV/ErsatzTV.Application/HDHR/Commands/UpdateHDHRTunerCountHandler.cs

using System.Threading;
using System.Threading.Tasks;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Repositories;
using LanguageExt;
using static LanguageExt.Prelude;

namespace ErsatzTV.Application.HDHR.Commands
{
    public class UpdateHDHRTunerCountHandler : MediatR.IRequestHandler<UpdateHDHRTunerCount, Either<BaseError, Unit>>
    {
        private readonly IConfigElementRepository _configElementRepository;

        public UpdateHDHRTunerCountHandler(IConfigElementRepository configElementRepository) =>
            _configElementRepository = configElementRepository;

        public Task<Either<BaseError, Unit>> Handle(
            UpdateHDHRTunerCount request,
            CancellationToken cancellationToken) =>
            Validate(request)
                .MapT(_ => _configElementRepository.Upsert(ConfigElementKey.HDHRTunerCount, request.TunerCount.ToString()))
                .Bind(v => v.ToEitherAsync());

        private static Task<Validation<BaseError, Unit>> Validate(UpdateHDHRTunerCount request) =>
            Optional(request.TunerCount)
                .Where(tc => tc > 0)
                .Map(_ => Unit.Default)
                .ToValidation<BaseError>("Tuner count must be greater than zero")
                .AsTask();
    }
}