//-----------------------------------------------------------------------
// <copyright file="FileSource.cs" company="Mapbox">
//     Copyright (c) 2016 Mapbox. All rights reserved.
// </copyright>
//-----------------------------------------------------------------------

using Mapbox.Unity;

namespace Mapbox.Platform
{
	using Mapbox.Map;
	using Mapbox.Unity.Utilities;
	using System;
	using System.Collections;
	using System.Collections.Generic;
	using System.Linq;
	using System.Net;
	using System.Net.Security;
#if !NETFX_CORE
	using System.Security.Cryptography.X509Certificates;
#endif
#if !UNITY_5_3_OR_NEWER
	using System.Threading;
#endif
#if UNITY_EDITOR
	using UnityEditor;
#endif
#if UNITY_5_3_OR_NEWER
	using UnityEngine;
#endif

	/// <summary>
	///     Mono implementation of the FileSource class. It will use Mono's
	///     <see href="http://www.mono-project.com/docs/advanced/runtime/">runtime</see> to
	///     asynchronously fetch data from the network via HTTP or HTTPS requests.
	/// </summary>
	/// <remarks>
	///     This implementation requires .NET 4.5 and later. The access token is expected to
	///     be exported to the environment as MAPBOX_ACCESS_TOKEN.
	/// </remarks>
	public sealed class FileSource : IFileSource
	{

		private Func<string> _getMapsSkuToken;
		private readonly Dictionary<IAsyncRequest, int> _requests = new Dictionary<IAsyncRequest, int>();
		private readonly string _accessToken;
		private readonly object _lock = new object();

		/// <summary>Length of rate-limiting interval in seconds. https://www.mapbox.com/api-documentation/#rate-limit-headers </summary>
#pragma warning disable 0414
		private int? XRateLimitInterval;
		/// <summary>Maximum number of requests you may make in the current interval before reaching the limit. https://www.mapbox.com/api-documentation/#rate-limit-headers </summary>
		private long? XRateLimitLimit;
		/// <summary>Timestamp of when the current interval will end and the ratelimit counter is reset. https://www.mapbox.com/api-documentation/#rate-limit-headers </summary>
		private DateTime? XRateLimitReset;
#pragma warning restore 0414


		public FileSource(Func<string> getMapsSkuToken, string acessToken = null)
		{
			_getMapsSkuToken = getMapsSkuToken;
			if (string.IsNullOrEmpty(acessToken))
			{
				_accessToken = Environment.GetEnvironmentVariable("MAPBOX_ACCESS_TOKEN");
			}
			else
			{
				_accessToken = acessToken;
			}
		}

		/// <summary> Performs a request asynchronously. </summary>
		/// <param name="url"> The HTTP/HTTPS url. </param>
		/// <param name="callback"> Callback to be called after the request is completed. </param>
		/// <returns>
		///     Returns a <see cref="IAsyncRequest" /> that can be used for canceling a pending
		///     request. This handle can be completely ignored if there is no intention of ever
		///     canceling the request.
		/// </returns>
		public IAsyncRequest Request(
			string url
			, Action<Response> callback
			, int timeout = 10
			, CanonicalTileId tileId = new CanonicalTileId()
			, string tilesetId = null
		)
		{
			if (!string.IsNullOrEmpty(_accessToken))
			{
				var uriBuilder = new UriBuilder(url);
				string accessTokenQuery = "access_token=" + _accessToken;
				string skuToken = "sku=" + _getMapsSkuToken();
				if (uriBuilder.Query != null && uriBuilder.Query.Length > 1)
				{
					uriBuilder.Query = uriBuilder.Query.Substring(1) + "&" + accessTokenQuery + "&" + skuToken;;
				}
				else
				{
					uriBuilder.Query = accessTokenQuery + "&" + skuToken;
				}

				url = uriBuilder.ToString();
			}

			// TODO:
			// * add queue for requests
			// * evaluate rate limits (headers and status code)
			// * throttle requests accordingly
			//var request = new HTTPRequest(url, callback);
			//IEnumerator<IAsyncRequest> proxy = proxyResponse(url, callback);
			//proxy.MoveNext();
			//IAsyncRequest request = proxy.Current;

			//return request;

			return proxyResponse(url, callback, timeout, tileId, tilesetId);
		}


		// TODO: look at requests and implement throttling if needed
		//private IEnumerator<IAsyncRequest> proxyResponse(string url, Action<Response> callback) {
		private IAsyncRequest proxyResponse(
			string url
			, Action<Response> callback
			, int timeout
			, CanonicalTileId tileId
			, string tilesetId
		)
		{

			// TODO: plugin caching somewhere around here

			var request = IAsyncRequestFactory.CreateRequest(
				url
				, (Response response) =>
				{
					if (response.XRateLimitInterval.HasValue) { XRateLimitInterval = response.XRateLimitInterval; }
					if (response.XRateLimitLimit.HasValue) { XRateLimitLimit = response.XRateLimitLimit; }
					if (response.XRateLimitReset.HasValue) { XRateLimitReset = response.XRateLimitReset; }
					callback(response);
					lock (_lock)
					{
						//another place to catch if request has been cancelled
						try
						{
							_requests.Remove(response.Request);
						}
						catch (Exception ex)
						{
							System.Diagnostics.Debug.WriteLine(ex);
						}
					}
				}
				, timeout
			);
			lock (_lock)
			{
				//sometimes we get here after the request has already finished
				if (!request.IsCompleted)
				{
					_requests.Add(request, 0);
				}
			}
			//yield return request;
			return request;
		}


#if UNITY_5_3_OR_NEWER
		/// <summary>
		///     Block until all the requests are processed.
		/// </summary>
		public IEnumerator WaitForAllRequests()
		{
			while (_requests.Count > 0)
			{
				lock (_lock)
				{
					List<IAsyncRequest> reqs = _requests.Keys.ToList();
					for (int i = reqs.Count - 1; i > -1; i--)
					{
						if (reqs[i].IsCompleted)
						{
							// another place to watch out if request has been cancelled
							try
							{
								_requests.Remove(reqs[i]);
							}
							catch (Exception ex)
							{
								System.Diagnostics.Debug.WriteLine(ex);
							}
						}
					}
				}
				yield return new WaitForSeconds(0.2f);
			}
		}
#endif



#if !UNITY_5_3_OR_NEWER
		/// <summary>
		///     Block until all the requests are processed.
		/// </summary>
		public void WaitForAllRequests()
		{
			int waitTimeMs = 200;
			while (_requests.Count > 0)
			{
				lock (_lock)
				{
					List<IAsyncRequest> reqs = _requests.Keys.ToList();
					for (int i = reqs.Count - 1; i > -1; i--)
					{
						if (reqs[i].IsCompleted)
						{
							// another place to watch out if request has been cancelled
							try
							{
								_requests.Remove(reqs[i]);
							}
							catch (Exception ex)
							{
								System.Diagnostics.Debug.WriteLine(ex);
							}
						}
					}
				}

#if WINDOWS_UWP
				System.Threading.Tasks.Task.Delay(waitTimeMs).Wait();
#else
				//Thread.Sleep(50);
				// TODO: get rid of DoEvents!!! and find non-blocking wait that works for Net3.5
				//System.Windows.Forms.Application.DoEvents();

				var resetEvent = new ManualResetEvent(false);
				ThreadPool.QueueUserWorkItem(new WaitCallback(delegate
				{
					Thread.Sleep(waitTimeMs);
					resetEvent.Set();
				}), null);
				UnityEngine.Debug.Log("before waitOne " + DateTime.Now.Ticks);
				resetEvent.WaitOne();
				UnityEngine.Debug.Log("after waitOne " + DateTime.Now.Ticks);
				resetEvent.Close();
				resetEvent = null;
#endif
			}
		}
#endif
	}
}
