using System.Net;
using System.Text;
using System;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Threading.Tasks;

namespace SpotifyAPI.Web.Http
{
  public class NetHttpClient : IHTTPClient
  {
    private readonly HttpMessageHandler _httpMessageHandler;
    private readonly HttpClient _httpClient;

    public NetHttpClient()
    {
      _httpClient = new HttpClient();
    }

    public NetHttpClient(IProxyConfig proxyConfig)
    {
      Ensure.ArgumentNotNull(proxyConfig, nameof(proxyConfig));

      _httpMessageHandler = CreateMessageHandler(proxyConfig);
      _httpClient = new HttpClient(_httpMessageHandler);
    }

    public async Task<IResponse> DoRequest(IRequest request)
    {
      Ensure.ArgumentNotNull(request, nameof(request));

      using HttpRequestMessage requestMsg = BuildRequestMessage(request);
      var responseMsg = await _httpClient
        .SendAsync(requestMsg, HttpCompletionOption.ResponseContentRead)
        .ConfigureAwait(false);

      return await BuildResponse(responseMsg).ConfigureAwait(false);
    }

    private static async Task<IResponse> BuildResponse(HttpResponseMessage responseMsg)
    {
      Ensure.ArgumentNotNull(responseMsg, nameof(responseMsg));

      // We only support text stuff for now
      using var content = responseMsg.Content;
      var headers = responseMsg.Headers.ToDictionary(header => header.Key, header => header.Value.First());
      var body = await responseMsg.Content.ReadAsStringAsync().ConfigureAwait(false);
      var contentType = content.Headers?.ContentType?.MediaType;

      return new Response(headers)
      {
        ContentType = contentType,
        StatusCode = responseMsg.StatusCode,
        Body = body
      };
    }

    private static HttpRequestMessage BuildRequestMessage(IRequest request)
    {
      Ensure.ArgumentNotNull(request, nameof(request));

      var fullUri = new Uri(request.BaseAddress, request.Endpoint).ApplyParameters(request.Parameters);
      var requestMsg = new HttpRequestMessage(request.Method, fullUri);
      foreach (var header in request.Headers)
      {
        requestMsg.Headers.Add(header.Key, header.Value);
      }

      switch (request.Body)
      {
        case HttpContent body:
          requestMsg.Content = body;
          break;
        case string body:
          requestMsg.Content = new StringContent(body, Encoding.UTF8, "application/json");
          break;
        case Stream body:
          requestMsg.Content = new StreamContent(body);
          break;
      }

      return requestMsg;
    }

    public void Dispose()
    {
      Dispose(true);
      GC.SuppressFinalize(this);
    }

    protected virtual void Dispose(bool disposing)
    {
      if (disposing)
      {
        _httpClient?.Dispose();
        _httpMessageHandler?.Dispose();
      }
    }

    public void SetRequestTimeout(TimeSpan timeout)
    {
      _httpClient.Timeout = timeout;
    }

    private static HttpMessageHandler CreateMessageHandler(IProxyConfig proxyConfig)
    {
      var proxy = new WebProxy
      {
        Address = new UriBuilder(proxyConfig.Host) { Port = proxyConfig.Port }.Uri,
        UseDefaultCredentials = true,
        BypassProxyOnLocal = proxyConfig.BypassProxyOnLocal
      };

      if (!string.IsNullOrEmpty(proxyConfig.User) || !string.IsNullOrEmpty(proxyConfig.Password))
      {
        proxy.UseDefaultCredentials = false;
        proxy.Credentials = new NetworkCredential(proxyConfig.User, proxyConfig.Password);
      }

      var httpClientHandler = new HttpClientHandler
      {
        PreAuthenticate = proxy.UseDefaultCredentials,
        UseDefaultCredentials = proxy.UseDefaultCredentials,
        UseProxy = true,
        Proxy = proxy,
      };
      if (proxyConfig.SkipSSLCheck)
      {
        httpClientHandler.ServerCertificateCustomValidationCallback = (sender, cert, chain, sslPolicyErrors) => true;
      }

      return httpClientHandler;
    }
  }
}