JiraOAuthDelegatingHandler.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading;
using System.Threading.Tasks;

namespace YourProject
{
	public class JiraOAuthDelegatingHandler : DelegatingHandler
	{
		private readonly IAtlassianOAuthCredentialsManager _manager;

		public JiraOAuthDelegatingHandler(
			IAtlassianOAuthCredentialsManager manager
		)
		{
			_manager = manager;
		}

		protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
		{
			var headers = request.Headers;
			if (string.IsNullOrWhiteSpace(headers.Authorization?.Parameter))
			{
				var jwt = await _manager.GetJwtAsync();
				headers.Authorization = new AuthenticationHeaderValue("Bearer", jwt);
			}

			var retries = 0;
			HttpResponseMessage response;
			do
			{
				response = await base.SendAsync(request, cancellationToken);

				//	unauthorized responses should have the JWT token refreshed and then try again.
				if (response.StatusCode == HttpStatusCode.Unauthorized)
				{
					await _manager.RefreshJwtAsync();
					var jwt = await _manager.GetJwtAsync();
					headers.Authorization = new AuthenticationHeaderValue("Bearer", jwt);
				}
				retries++;	// this could go in the if statement, but it works here too

			} while (response.StatusCode == HttpStatusCode.Unauthorized && retries < 2);

			if (!response.IsSuccessStatusCode)
			{
				var body = await response.Content.ReadAsStringAsync();
				var message = $"{(int)response.StatusCode} ({response.StatusCode}) - {body}";
				throw new HttpRequestException(message);
			}

			return response;
		}
	}
}