FileShare/FileShare-Services/Services/FileLibrary/ThumbnailStreamService.cs

using FileShare_EFCore.Database;
using FileShare_Services.Core;
using Microsoft.EntityFrameworkCore;

namespace FileShare_Services.Services.FileLibrary
{
    public interface IThumbnailStreamService
    {
        Task<FileStreamResponse?> GetThumbnailAsync(int id, CancellationToken cancellationToken = default);
    }

    public sealed class ThumbnailStreamService(AppDataContext db, IVideoThumbnailService thumbnails) : IThumbnailStreamService
    {
        public async Task<FileStreamResponse?> GetThumbnailAsync(int id, CancellationToken cancellationToken = default)
        {
            var thumbnail = await db.ManagedThumbnailMaps
                .AsNoTracking()
                .FirstOrDefaultAsync(item => item.Id == id, cancellationToken);

            if (thumbnail is null)
            {
                return null;
            }

            var absolutePath = thumbnails.GetAbsolutePath(thumbnail.RelativePath);
            if (!File.Exists(absolutePath))
            {
                return null;
            }

            return new FileStreamResponse(
                absolutePath,
                Path.GetFileName(absolutePath),
                thumbnail.ContentType,
                File.GetLastWriteTimeUtc(absolutePath));
        }
    }
}