ersatztv/ErsatzTV.Application/Watermarks/Commands/CreateWatermarkHandler.cs

using System.Threading;
using System.Threading.Tasks;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Infrastructure.Data;
using LanguageExt;
using MediatR;
using Microsoft.EntityFrameworkCore;

namespace ErsatzTV.Application.Watermarks.Commands
{
    public class CreateWatermarkHandler : IRequestHandler<CreateWatermark, Either<BaseError, CreateWatermarkResult>>
    {
        private readonly IDbContextFactory<TvContext> _dbContextFactory;

        public CreateWatermarkHandler(IDbContextFactory<TvContext> dbContextFactory) =>
            _dbContextFactory = dbContextFactory;

        public async Task<Either<BaseError, CreateWatermarkResult>> Handle(
            CreateWatermark request,
            CancellationToken cancellationToken)
        {
            await using TvContext dbContext = _dbContextFactory.CreateDbContext();
            Validation<BaseError, ChannelWatermark> validation = Validate(request);
            return await validation.Apply(profile => PersistChannelWatermark(dbContext, profile));
        }

        private static async Task<CreateWatermarkResult> PersistChannelWatermark(
            TvContext dbContext,
            ChannelWatermark watermark)
        {
            await dbContext.ChannelWatermarks.AddAsync(watermark);
            await dbContext.SaveChangesAsync();
            return new CreateWatermarkResult(watermark.Id);
        }

        private static Validation<BaseError, ChannelWatermark> Validate(CreateWatermark request) =>
            ValidateName(request)
                .Map(
                    _ => new ChannelWatermark
                    {
                        Name = request.Name,
                        Image = request.ImageSource == ChannelWatermarkImageSource.Custom ? request.Image : null,
                        Mode = request.Mode,
                        ImageSource = request.ImageSource,
                        Location = request.Location,
                        Size = request.Size,
                        WidthPercent = request.Width,
                        HorizontalMarginPercent = request.HorizontalMargin,
                        VerticalMarginPercent = request.VerticalMargin,
                        FrequencyMinutes = request.FrequencyMinutes,
                        DurationSeconds = request.DurationSeconds,
                        Opacity = request.Opacity
                    });

        private static Validation<BaseError, string> ValidateName(CreateWatermark request) =>
            request.NotEmpty(x => x.Name)
                .Bind(_ => request.NotLongerThan(50)(x => x.Name));
    }
}