using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Infrastructure.Data;
using Microsoft.EntityFrameworkCore;
using static ErsatzTV.Application.MediaCollections.Mapper;

namespace ErsatzTV.Application.MediaCollections;

public class CreateMultiCollectionHandler :
    IRequestHandler<CreateMultiCollection, Either<BaseError, MultiCollectionViewModel>>
{
    private readonly IDbContextFactory<TvContext> _dbContextFactory;

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

    public async Task<Either<BaseError, MultiCollectionViewModel>> Handle(
        CreateMultiCollection request,
        CancellationToken cancellationToken)
    {
        await using TvContext dbContext = _dbContextFactory.CreateDbContext();
        Validation<BaseError, MultiCollection> validation = await Validate(dbContext, request);
        return await validation.Apply(c => PersistCollection(dbContext, c));
    }

    private static async Task<MultiCollectionViewModel> PersistCollection(
        TvContext dbContext,
        MultiCollection multiCollection)
    {
        await dbContext.MultiCollections.AddAsync(multiCollection);
        await dbContext.SaveChangesAsync();
        await dbContext.Entry(multiCollection)
            .Collection(c => c.MultiCollectionItems)
            .Query()
            .Include(i => i.Collection)
            .LoadAsync();
        await dbContext.Entry(multiCollection)
            .Collection(c => c.MultiCollectionSmartItems)
            .Query()
            .Include(i => i.SmartCollection)
            .LoadAsync();
        return ProjectToViewModel(multiCollection);
    }

    private static Task<Validation<BaseError, MultiCollection>> Validate(
        TvContext dbContext,
        CreateMultiCollection request) =>
        ValidateName(dbContext, request).MapT(
            name => new MultiCollection
            {
                Name = name,
                MultiCollectionItems = request.Items.Bind(
                        i =>
                        {
                            if (i.CollectionId.HasValue)
                            {
                                return Some(
                                    new MultiCollectionItem
                                    {
                                        CollectionId = i.CollectionId.Value,
                                        ScheduleAsGroup = i.ScheduleAsGroup,
                                        PlaybackOrder = i.PlaybackOrder
                                    });
                            }

                            return Option<MultiCollectionItem>.None;
                        })
                    .ToList(),
                MultiCollectionSmartItems = request.Items.Bind(
                        i =>
                        {
                            if (i.SmartCollectionId.HasValue)
                            {
                                return Some(
                                    new MultiCollectionSmartItem
                                    {
                                        SmartCollectionId = i.SmartCollectionId.Value,
                                        ScheduleAsGroup = i.ScheduleAsGroup,
                                        PlaybackOrder = i.PlaybackOrder
                                    });
                            }

                            return Option<MultiCollectionSmartItem>.None;
                        })
                    .ToList()
            });

    private static async Task<Validation<BaseError, string>> ValidateName(
        TvContext dbContext,
        CreateMultiCollection createMultiCollection)
    {
        List<string> allNames = await dbContext.MultiCollections
            .Map(c => c.Name)
            .ToListAsync();

        Validation<BaseError, string> result1 = createMultiCollection.NotEmpty(c => c.Name)
            .Bind(_ => createMultiCollection.NotLongerThan(50)(c => c.Name));

        var result2 = Optional(createMultiCollection.Name)
            .Where(name => !allNames.Contains(name))
            .ToValidation<BaseError>("MultiCollection name must be unique");

        return (result1, result2).Apply((_, _) => createMultiCollection.Name);
    }
}