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

namespace ErsatzTV
{
    namespace wms_xamarin
    {
        public class HttpLoggingHandler : DelegatingHandler
        {
            private readonly string[] types = { "html", "text", "xml", "json", "txt", "x-www-form-urlencoded" };

            public HttpLoggingHandler(HttpMessageHandler innerHandler = null) : base(
                innerHandler ?? new HttpClientHandler())
            {
            }

            protected override async Task<HttpResponseMessage> SendAsync(
                HttpRequestMessage request,
                CancellationToken cancellationToken)
            {
                await Task.Delay(1, cancellationToken).ConfigureAwait(false);
                DateTime start = DateTime.Now;
                HttpRequestMessage req = request;
                var msg = $"[{req.RequestUri.PathAndQuery} -  Request]";

                Debug.WriteLine($"{msg}========Request Start==========");
                Debug.WriteLine(
                    $"{msg} {req.Method} {req.RequestUri.PathAndQuery} {req.RequestUri.Scheme}/{req.Version}");
                Debug.WriteLine($"{msg} Host: {req.RequestUri.Scheme}://{req.RequestUri.Host}");

                foreach (KeyValuePair<string, IEnumerable<string>> header in req.Headers)
                {
                    Debug.WriteLine($"{msg} {header.Key}: {string.Join(", ", header.Value)}");
                }

                if (req.Content != null)
                {
                    foreach (KeyValuePair<string, IEnumerable<string>> header in req.Content.Headers)
                    {
                        Debug.WriteLine($"{msg} {header.Key}: {string.Join(", ", header.Value)}");
                    }

                    Debug.WriteLine($"{msg} Content:");

                    if (req.Content is StringContent || IsTextBasedContentType(req.Headers) ||
                        IsTextBasedContentType(req.Content.Headers))
                    {
                        string result = await req.Content.ReadAsStringAsync();

                        Debug.WriteLine($"{msg} {string.Join("", result.Take(256))}...");
                    }
                }

                HttpResponseMessage response = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);

                Debug.WriteLine($"{msg}==========Request End==========");

                msg = $"[{req.RequestUri.PathAndQuery} - Response]";

                Debug.WriteLine($"{msg}=========Response Start=========");

                HttpResponseMessage resp = response;

                Debug.WriteLine(
                    $"{msg} {req.RequestUri.Scheme.ToUpper()}/{resp.Version} {(int) resp.StatusCode} {resp.ReasonPhrase}");

                foreach (KeyValuePair<string, IEnumerable<string>> header in resp.Headers)
                {
                    Debug.WriteLine($"{msg} {header.Key}: {string.Join(", ", header.Value)}");
                }

                if (resp.Content != null)
                {
                    foreach (KeyValuePair<string, IEnumerable<string>> header in resp.Content.Headers)
                    {
                        Debug.WriteLine($"{msg} {header.Key}: {string.Join(", ", header.Value)}");
                    }

                    Debug.WriteLine($"{msg} Content:");

                    if (resp.Content is StringContent || IsTextBasedContentType(resp.Headers) ||
                        IsTextBasedContentType(resp.Content.Headers))
                    {
                        string result = await resp.Content.ReadAsStringAsync();

                        Debug.WriteLine($"{msg} {string.Join("", result.Take(256))}...");
                    }
                }

                Debug.WriteLine($"{msg} Duration: {DateTime.Now - start}");
                Debug.WriteLine($"{msg}==========Response End==========");
                return response;
            }

            private bool IsTextBasedContentType(HttpHeaders headers)
            {
                IEnumerable<string> values;
                if (!headers.TryGetValues("Content-Type", out values))
                {
                    return false;
                }

                string header = string.Join(" ", values).ToLowerInvariant();

                return types.Any(t => header.Contains(t));
            }
        }
    }
}