ErsatzTV/ErsatzTV.Application/Channels/Commands/DeleteChannelHandler.cs

using ErsatzTV.Core;
using ErsatzTV.Core.Interfaces.Repositories;

namespace ErsatzTV.Application.Channels;

public class DeleteChannelHandler : IRequestHandler<DeleteChannel, Either<BaseError, Task>>
{
    private readonly IChannelRepository _channelRepository;

    public DeleteChannelHandler(IChannelRepository channelRepository) => _channelRepository = channelRepository;

    public async Task<Either<BaseError, Task>> Handle(DeleteChannel request, CancellationToken cancellationToken) =>
        (await ChannelMustExist(request))
        .Map(DoDeletion)
        .ToEither<Task>();

    private Task DoDeletion(int channelId) => _channelRepository.Delete(channelId);

    private async Task<Validation<BaseError, int>> ChannelMustExist(DeleteChannel deleteChannel) =>
        (await _channelRepository.Get(deleteChannel.ChannelId))
        .ToValidation<BaseError>($"Channel {deleteChannel.ChannelId} does not exist.")
        .Map(c => c.Id);
}