using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Repositories;
using static ErsatzTV.Application.Libraries.Mapper;

namespace ErsatzTV.Application.Libraries;

public class CreateLocalLibraryPathHandler : IRequestHandler<CreateLocalLibraryPath,
    Either<BaseError, LocalLibraryPathViewModel>>
{
    private readonly ILibraryRepository _libraryRepository;

    public CreateLocalLibraryPathHandler(ILibraryRepository libraryRepository) =>
        _libraryRepository = libraryRepository;

    public Task<Either<BaseError, LocalLibraryPathViewModel>> Handle(
        CreateLocalLibraryPath request,
        CancellationToken cancellationToken) =>
        Validate(request).MapT(PersistLocalLibraryPath).Bind(v => v.ToEitherAsync());

    private Task<LocalLibraryPathViewModel> PersistLocalLibraryPath(LibraryPath p) =>
        _libraryRepository.Add(p).Map(ProjectToViewModel);

    private Task<Validation<BaseError, LibraryPath>> Validate(CreateLocalLibraryPath request) =>
        ValidateFolder(request)
            .MapT(
                folder =>
                    new LibraryPath
                    {
                        LibraryId = request.LibraryId,
                        Path = folder
                    });

    private async Task<Validation<BaseError, string>> ValidateFolder(CreateLocalLibraryPath request)
    {
        List<string> allPaths = await _libraryRepository.GetLocalPaths(request.LibraryId)
            .Map(list => list.Map(c => c.Path).ToList());

        return Optional(request.Path)
            .Where(folder => allPaths.ForAll(f => !AreSubPaths(f, folder)))
            .ToValidation<BaseError>("Path must not belong to another library path");
    }

    private static bool AreSubPaths(string path1, string path2)
    {
        string one = path1 + Path.DirectorySeparatorChar;
        string two = path2 + Path.DirectorySeparatorChar;
        return one == two || one.StartsWith(two, StringComparison.OrdinalIgnoreCase) ||
               two.StartsWith(one, StringComparison.OrdinalIgnoreCase);
    }
}