TinfoilVibeServer/TinfoilVibeServer/Controllers/CancelableFileResult.cs

using Microsoft.AspNetCore.Mvc;

namespace TinfoilVibeServer.Controllers;

public class CancelableFileResult : FileResult
{
    private readonly Stream _fileStream;

    public CancelableFileResult(string contentType, Stream fileStream)
        : base(contentType)
    {
        _fileStream = fileStream ?? throw new ArgumentNullException(nameof(fileStream));
    }

    /// <summary>
    /// Allows you to set a suggested download name.  
    /// It will be sent in a “Content‑Disposition” header.
    /// </summary>
    public new string? FileDownloadName { get; set; }

    public override async Task ExecuteResultAsync(ActionContext context)
    {
        var response = context.HttpContext.Response;

        if (!string.IsNullOrEmpty(FileDownloadName))
        {
            // Typical “attachment” disposition – most browsers honour it.
            response.Headers.Append("Content-Disposition",
                $"attachment; filename=\"{FileDownloadName}\"");
        }

        // The request‑aborted token tells the stream copy to stop ASAP
        var cancellationToken = context.HttpContext.RequestAborted;

        try
        {
            // Copy the file to the response body in 8 KiB chunks
            await _fileStream.CopyToAsync(
                response.Body,
                bufferSize: 81920,   // 80 KiB – default for Stream.CopyToAsync
                cancellationToken);
        }
        catch (OperationCanceledException)
        {
            // The client disconnected – nothing to do.  
            // Swallowing keeps the API from returning a 500 error.
        }
        finally
        {
            await _fileStream.DisposeAsync();
        }
    }
}