using ErsatzTV.Core;
using ErsatzTV.Core.Api.Artwork;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Images;

namespace ErsatzTV.Application.Artworks;

public class UploadArtworkHandler : IRequestHandler<UploadArtwork, Either<BaseError, ArtworkUploadResponseModel>>
{
    // png/jpeg/gif/webp are all decoded by SkiaSharp and read by FFmpeg, matching the
    // formats the Blazor logo/watermark upload already accepts. Format expansion is ersatztv#66.
    private static readonly System.Collections.Generic.HashSet<string> AcceptedContentTypes = new(StringComparer.OrdinalIgnoreCase)
    {
        "image/png",
        "image/jpeg",
        "image/gif",
        "image/webp"
    };

    private readonly IImageCache _imageCache;

    public UploadArtworkHandler(IImageCache imageCache) => _imageCache = imageCache;

    public async Task<Either<BaseError, ArtworkUploadResponseModel>> Handle(
        UploadArtwork request,
        CancellationToken cancellationToken)
    {
        string contentType = (request.ContentType ?? string.Empty).Trim();
        if (!AcceptedContentTypes.Contains(contentType))
        {
            return BaseError.New(
                $"Unsupported image content type '{contentType}'; supported types are: {string.Join(", ", AcceptedContentTypes)}");
        }

        Either<BaseError, string> maybeFileName = await _imageCache.SaveArtworkToCache(
            request.Stream,
            request.ArtworkKind);

        return maybeFileName.Map(fileName => new ArtworkUploadResponseModel(
            BuildPath(request.ArtworkKind, fileName),
            contentType));
    }

    // Mirror the on-disk conventions the Blazor editors use so the returned path is a drop-in
    // for ArtworkContentTypeModel.Path: channel logos are addressed as "iptv/logos/{file}"
    // (see ChannelEditor.UploadLogo), watermarks by the bare cache file name (see WatermarkEditor).
    private static string BuildPath(ArtworkKind artworkKind, string fileName) =>
        artworkKind switch
        {
            ArtworkKind.Logo => $"iptv/logos/{fileName}",
            _ => fileName
        };
}