LoggingHttpClientHandler

using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading;
using System.Threading.Tasks;

namespace MyNamespace
{
	public class LoggingHttpClientHandler : HttpClientHandler
	{
		public static int RequestId = 0;

		public LoggingHttpClientHandler()
		{
		}

		protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
		{
			var requestId = Interlocked.Increment(ref RequestId);
			var requestPrefix = $"  [REQ {requestId}] ";

			var requestUrl = request.RequestUri.ToString();
			this.Debug(requestPrefix + $"URL: {requestUrl}");

			this.Debug(requestPrefix + $"HDR:");
			foreach (var header in request.Headers)
			{
				this.Debug(requestPrefix + $"  {header.Key}: {String.Join(",", header.Value)}");
			}
			this.Debug(requestPrefix + $"CKK:");
			foreach (var cookie in CookieContainer.GetCookies(request.RequestUri))
			{
				this.Debug(requestPrefix + $"  {cookie.ToString()}");
			}
			this.Debug(requestPrefix + $"PRP:");
			foreach (var propertyKey in request.Properties.Keys)
			{
				this.Debug(requestPrefix + $"  {propertyKey}: {request.Properties[propertyKey].ToString()}");
			}
			if (request.Content != null)
			{
				foreach (var header in request.Content.Headers)
				{
					this.Debug(requestPrefix + $"  {header.Key}: {String.Join(",", header.Value)}");
				}
				this.Debug(requestPrefix + $"CNT:");
				this.Debug(requestPrefix + await request.Content.ReadAsStringAsync());
			}

			var sendTime = DateTimeOffset.Now;
			var response = await base.SendAsync(request, cancellationToken);
			var receiveTime = DateTimeOffset.Now;

			this.Debug(requestPrefix + $"TRN: {receiveTime - sendTime}s");

			var responsePrefix = $"  [REP {requestId}] ";

			this.Debug(responsePrefix + $"HDR:");
			foreach (var header in response.Headers)
			{
				this.Debug(responsePrefix + $"  {header.Key}: {String.Join(",", header.Value)}");
			}
			if (response.Content != null)
			{
				foreach (var header in response.Content.Headers)
				{
					this.Debug(responsePrefix + $"  {header.Key}: {String.Join(",", header.Value)}");
				}

				this.Debug(responsePrefix + $"CNT:");

				if (response.Content.Headers.ContentType.IsTextTypeMedia())
				{
					this.Debug(responsePrefix + await response.Content.ReadAsStringAsync());
				}
				else
				{
					this.Debug(responsePrefix + "  BINARY");
				}
			}

			return response;
		}
	}

	public static class MediaTypeExtensions
	{
		public static bool IsTextTypeMedia(this MediaTypeHeaderValue mediaTypeHeaderValue)
		{
			var mediaType = mediaTypeHeaderValue.MediaType;

			if (mediaType.StartsWith("text/", StringComparison.Ordinal))
			{
				return true;
			}

			if (mediaType == "application/json" ||
				mediaType.StartsWith("application.xhtml", StringComparison.Ordinal) ||
				mediaType.StartsWith("application.xml", StringComparison.Ordinal)
			   )
			{
				return true;
			}

			return false;
		}
	}
}