using Microsoft.Net.Http.Headers;
using Sarand.Net.Standard.Base.App;
using Sarand.Net.Standard.Base.Core;
using Sarand.Net.Standard.Base.Net;
using Sarand.Net.Standard.Base.Tasks;
using Sarand.Net.Standard.Base.Utils;
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Sarand.Net.Standard.Base.Helpers
{
	//=======================================================================
	public static class SacsHttpClientHelper
	{
		//-------------------------------------------------------------------
		/// <summary>Request configuration</summary>
		public class RequestData : SacsTaskData
		{
			// Construction.
			public RequestData(CancellationToken? cancellationToken) : base(cancellationToken) { }
			/// <summary>URL to send request to.</summary>
			public UriBuilder UriBuilder { get; } = new UriBuilder();
			/// <summary>
			/// Request timeout. Default: 5 secs.
			/// <para>NB Not currently supported as can only be changed when static HTTP Client not in use.</para>
			/// </summary>
			public int TimeoutSecs { get; set; } = SacsHttpClient.RequestTimeoutSecs_Default;
			/// <summary>
			/// Headers to send with request.
			/// <para>Accept, Accept-Charset, Accept-Encoding, Accept-Language, User-Agent, Transfer-Encoding, Pragma, Expect etc.</para>
			/// </summary>
			public Dictionary<String, List<String>> RequestHeaders { get; } = new Dictionary<String, List<String>>();
			/// <summary>
			/// Content Headers to send with request.
			/// <para>Content-Length (bytes), Content-Type (media type), Content-Encoding (compression algorithm), Content-Language etc.</para>
			/// <para>Content-Type header is defaulted for POST request if not specified.</para>
			/// </summary>
			public Dictionary<String, List<String>> ContentHeaders { get; } = new Dictionary<String, List<String>>();
			/// <summary>
			/// Form values to post as 'URL Encoded'.
			/// <para>Content-Type defaults to 'application/x-www-form-urlencoded; charset=utf-8'.</para>
			/// </summary>
			public List<KeyValuePair<string, string>> FormData { get; } = new List<KeyValuePair<string, string>>();
			/// <summary>
			/// Data to POST. Ignored if FormData populated.
			/// <para>Content-Type defaults to 'text/plain; charset=utf-8'.</para>
			/// </summary>
			public String PostData { get; set; }
			/// <summary>Use POST request rather than GET even if no data to post.</summary>
			public bool ForcePost { get; set; }
		}

		//-------------------------------------------------------------------
		/// <summary>Response data</summary>
		public class ResponseData : SacsHttpResponseData
		{
		}

		//-------------------------------------------------------------------
		// Data members.

		//-------------------------------------------------------------------
		// Static initialisation.
		static SacsHttpClientHelper()
		{
		}

		//-------------------------------------------------------------------
		// Properties.
		public static HttpClient HttpClient { get { return SacsHttpClient.HttpClient; } }
		public static int RequestTimeoutSecs_Default { get { return SacsHttpClient.RequestTimeoutSecs_Default; } }
		public static String HeaderName_ContentType { get {; return SacsHttpClient.HeaderName_ContentType; } }

		//-------------------------------------------------------------------
		public static async Task<ResponseData> DoRequest(RequestData requestData)
		{
			requestData.ThrowIfCancellationRequested();
			ResponseData responseData = new ResponseData();

			// Construct content to post.
			HttpContent postContent = null;
			if (requestData.FormData.Count > 0)
			{
				postContent = new FormUrlEncodedContent(requestData.FormData);
				if (!requestData.ContentHeaders.ContainsKey(SacsHttpClient.HeaderName_ContentType))
					requestData.ContentHeaders.Add(SacsHttpClient.HeaderName_ContentType, "application/x-www-form-urlencoded; charset=utf-8");
			}
			else if (!StringUtil.IsEmpty(requestData.PostData) || requestData.ForcePost)
			{
				postContent = new StringContent(StringUtil.EmptyOnNull(requestData.PostData), Encoding.UTF8);
				if (!requestData.ContentHeaders.ContainsKey(SacsHttpClient.HeaderName_ContentType))
					requestData.ContentHeaders.Add(SacsHttpClient.HeaderName_ContentType, "text/plain; charset=utf-8");
			}
			requestData.ThrowIfCancellationRequested();

			// Make request.
			DateTime startedAt = DateTime.Now;
			try
			{
				// Request.
				using (HttpRequestMessage request = new HttpRequestMessage())
				{
					request.RequestUri = requestData.UriBuilder.Uri;

					// Request headers.
					foreach (String headerName in requestData.RequestHeaders.Keys)
					{
						if (request.Headers.Contains(headerName))
							request.Headers.Remove(headerName);
						request.Headers.Add(headerName, requestData.RequestHeaders[headerName]);
					}

					// Default request headers.
					if (SacsHttpClient.HttpClient.DefaultRequestHeaders.Accept.Count == 0 && request.Headers.Accept.Count == 0)
						request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("text/*"));

					// Configure request.
					HttpResponseMessage response = null;
					// Send request.
					if (postContent != null)
					{
						// POST.
						request.Method = HttpMethod.Post;
						request.Content = postContent;
						// Content headers.
						foreach (String headerName in requestData.ContentHeaders.Keys)
						{
							if (request.Content.Headers.Contains(headerName))
								request.Content.Headers.Remove(headerName);
							request.Content.Headers.Add(headerName, requestData.ContentHeaders[headerName]);
						}
						// Send request.
						responseData.RequestStarted = DateTime.Now;
						response = await SacsHttpClient.HttpClient.SendAsync(request, requestData.CancellationToken);
						responseData.RequestCompleted = DateTime.Now;
					}
					else
					{
						// GET.
						request.Method = HttpMethod.Get;
						responseData.RequestStarted = DateTime.Now;
						response = await SacsHttpClient.HttpClient.SendAsync(request, requestData.CancellationToken);
						responseData.RequestCompleted = DateTime.Now;
					}

					// Extract response data.
					responseData.Version = response.Version;
					responseData.Success = response.IsSuccessStatusCode;
					responseData.StatusCode = response.StatusCode;
					responseData.ReasonPhrase = response.ReasonPhrase;
					if (response.Headers != null)
					{
						foreach (var header in response.Headers)
							responseData.ResponseHeaders[header.Key] = new List<String>(header.Value);
					}
					if (response.Content != null && response.Content.Headers != null)
					{
						foreach (var header in response.Content.Headers)
							responseData.ContentHeaders[header.Key] = new List<String>(header.Value);
					}
					responseData.Data = await response.Content.ReadAsStringAsync();
					if (response != null) response.Dispose();
				}
			}
			catch (Exception exc)
			{
				// Ignore if task has been cancelled.
				if (requestData.IsCancellationRequested) throw exc;
				// Record exception.
				responseData.Exception = exc;
				if (exc.InnerException != null)
				{
					exc = exc.InnerException;
				}
				String msg = exc.GetType().Name + ": " + exc.Message;
				SaLogger.Warn(SysUtil.Fn + " " + msg + ExceptionUtil.GetStackEntries(exc, 6).Concat("", "\n\t"));
				responseData.ErrorStateMessage = msg;
			}
			requestData.ThrowIfCancellationRequested();

			// Complete response data.
			responseData.Elapsed = DateTime.Now - startedAt;
			return responseData;
		}

		//-------------------------------------------------------------------
		//       R e s p o n s e   S t a t u s   D e s c r i p t i o n
		//-------------------------------------------------------------------
		public static String GetResponseStatusDescription(HttpStatusCode httpStatus)
		{
			return SacsHttpClient.GetResponseStatusDescription(httpStatus);
		}

		//-------------------------------------------------------------------
	}
	//=======================================================================
}