FileTransferStreamHandlerExtensions.cs

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using System;
using System.Linq;
using System.Net;
using System.Net.Mime;
using System.Threading;
using System.Threading.Tasks;
 
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Net.Http.Headers;
 
using Tgstation.Server.Api.Models;
using Tgstation.Server.Api.Models.Response;
using Tgstation.Server.Host.Controllers.Results;
using Tgstation.Server.Host.Transfer;
 
namespace Tgstation.Server.Host.Extensions
{
    static class FileTransferStreamHandlerExtensions
    {
        public static async ValueTask<IActionResult> GenerateDownloadResponse(
            this IFileTransferStreamHandler fileTransferService,
            ControllerBase controller,
            string ticket,
            CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(fileTransferService);
 
            ArgumentNullException.ThrowIfNull(controller);
 
            if (ticket == null)
                return controller.BadRequest(new ErrorMessageResponse(ErrorCode.ModelValidationFailure));
 
            var streamAccept = new MediaTypeHeaderValue(MediaTypeNames.Application.Octet);
            if (!controller.Request.GetTypedHeaders().Accept.Any(streamAccept.IsSubsetOf))
                return controller.StatusCode((int)HttpStatusCode.NotAcceptable, new ErrorMessageResponse(ErrorCode.BadHeaders)
                {
                    AdditionalData = $"File downloads must accept both {MediaTypeNames.Application.Octet} and {MediaTypeNames.Application.Json}!",
                });
 
            var fileTicketResult = new FileTicketResponse
            {
                FileTicket = ticket,
            };
 
            var (stream, errorMessage) = await fileTransferService.RetrieveDownloadStream(fileTicketResult, cancellationToken);
            try
            {
                if (errorMessage != null)
                    return controller.Conflict(errorMessage);
 
                if (stream == null)
                    return controller.Gone();
 
                return new LimitedStreamResult(stream);
            }
            catch
            {
                if (stream != null)
                    await stream.DisposeAsync();
 
                throw;
            }
        }
    }
}