FileShare/FileShare-Services/Services/FileLibrary/FileStreamService.cs

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

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

    public sealed class FileStreamService(AppDataContext db) : IFileStreamService
    {
        public async Task<FileStreamResponse?> GetFileStreamAsync(int id, CancellationToken cancellationToken = default)
        {
            var file = await db.ManagedFileRecords
                .AsNoTracking()
                .Include(item => item.LibraryRoot)
                .FirstOrDefaultAsync(item =>
                    item.Id == id
                    && item.Exists
                    && item.LibraryRoot != null
                    && item.LibraryRoot.IsAvailable,
                    cancellationToken);

            if (file is null || !System.IO.File.Exists(file.AbsolutePath))
                return null;

            return new FileStreamResponse(
                file.AbsolutePath,
                file.FileName,
                file.ContentType,
                file.LastWriteTimeUtc);
        }
    }
}