Light12306/Web12306/Servers/TrainSuggestion/TrainSuggestionHandler.cs

namespace Web12306.Servers.TrainSuggestion
{
	using System;
	using System.Collections.Generic;
	using System.IO;
	using System.Linq;
	using System.Text;
	using System.Text.RegularExpressions;
	using System.Web;
	using System.Web.Hosting;
	using Newtonsoft.Json;
	using Newtonsoft.Json.Serialization;

	public class TrainSuggestionHandler : IHttpHandler
	{
		#region Implementation of IHttpHandler

		/// <summary>
		/// 通过实现 <see cref="T:System.Web.IHttpHandler"/> 接口的自定义 HttpHandler 启用 HTTP Web 请求的处理。
		/// </summary>
		/// <param name="context"><see cref="T:System.Web.HttpContext"/> 对象，它提供对用于为 HTTP 请求提供服务的内部服务器对象（如 Request、Response、Session 和 Server）的引用。</param>
		public void ProcessRequest(HttpContext context)
		{
			var request = context.Request;
			context.Response.StatusCode = 404;
			if (request.UrlReferrer == null || !Regex.IsMatch(request.UrlReferrer.Host, @"^.*?\.(fishlee\.net|liebao\.cn)$"))
				return;

			//check code
			var r = request.QueryString["r"];
			if (string.IsNullOrEmpty(r))
				return;

			var data = request.Form["data"];
			if (string.IsNullOrEmpty(data))
				return;

			var crc = GetTextCrc(data);
			if (!r.EndsWith(crc + ""))
			{
				return;
			}

			var origin = request.Headers["Origin"];
			var callback = request.QueryString["calllback"];
			if (!string.IsNullOrEmpty(origin))
			{
				if (Regex.IsMatch(origin, @"^(https?://.*?\.(fishlee\.net|liebao\.cn)|chrome-extension://.*)$"))
					context.Response.AddHeader("Access-Control-Allow-Origin", origin);
				else
				{
					//非法提交
					return;
				}
			}
			else
			{
				return;
			}
			context.Response.ContentType = string.IsNullOrEmpty(callback) ? "application/json" : "application/javascript";
			context.Response.BufferOutput = true;
			context.Response.StatusCode = 200;

			try
			{
				var ri = JsonConvert.DeserializeObject<RequestInfo>(data);
				var suggestion = GetSuggestionResponseContent(ri);

				if (!string.IsNullOrEmpty(callback))
				{
					context.Response.Write(callback + "(");
				}
				context.Response.Write(suggestion);
				if (!string.IsNullOrEmpty(callback))
				{
					context.Response.Write(callback + ");");
				}
			}
			catch (Exception ex)
			{
				//log error
				var sb = new StringBuilder();
				sb.AppendLine(string.Format("请求URL： {0}", context.Request.Url));
				sb.AppendLine("数据:");
				sb.AppendLine(data);
				sb.AppendLine();

				sb.AppendLine("错误信息:");
				sb.AppendLine(ex.ToString());

				var log = DateTime.Now.Ticks + ".log";
				var path = HostingEnvironment.MapPath("~/errors/tr/");
				path = PathUtility.Combine(path, log);
				Directory.CreateDirectory(Path.GetDirectoryName(path));
				File.WriteAllText(path, sb.ToString());
			}
		}

		int GetTextCrc(string txt)
		{
			var crc = 0;
			for (var i = 0; i < txt.Length - 1; i += 2)
			{
				crc += txt[i] ^ txt[i + 1];
				if (crc > 48360)
					crc -= 36048;
			}
			if (txt.Length % 2 == 1)
				crc += txt[txt.Length - 1];
			if (crc > 48360)
				crc -= 36048;
			crc = crc ^ 5299;

			return crc;
		}

		/// <summary>
		/// 获取一个值，该值指示其他请求是否可以使用 <see cref="T:System.Web.IHttpHandler"/> 实例。
		/// </summary>
		/// <returns>
		/// 如果 <see cref="T:System.Web.IHttpHandler"/> 实例可再次使用，则为 true；否则为 false。
		/// </returns>
		public bool IsReusable { get { return true; } }

		#endregion

		#region 生成建议

		static JsonSerializerSettings _camelJsonSetting = new JsonSerializerSettings
														{
															ContractResolver = new CamelCasePropertyNamesContractResolver()
														};

		string GetSuggestionResponseContent(RequestInfo ri)
		{
			if (ri.CheckIllegal())
				return string.Empty;

			return JsonConvert.SerializeObject(GetSuggestionResponseContentCore(ri), Formatting.None, _camelJsonSetting);
		}

		SuggestionResponse GetSuggestionResponseContentCore(RequestInfo ri)
		{
			//预处理
			PreProcessRequestData(ri);

			//获得所有的可替换站点
			var alllines = ri.Stops.Values.SelectMany(s => GetAlternativeLines(s, ri.Date) ?? new List<AlternativeLine>()).Where(s => s != null).ToArray();

			//对线路进行分组排序
			var lineGrouped = alllines.GroupBy(s => s.LineName).Select(s =>
			{
				var list = s.ToList();
				var f = list[0];
				return new AlternativeLineGroup(f.From.Name, f.To.Name, f.Date, list, f.IsCrossDate);
			}).ToList();

			//过滤
			FilteAlternativeLine(ri, lineGrouped);

			//填充数据
			FillExtraInfo(ri, lineGrouped);

			//排序
			SortLineRecommand(ri, lineGrouped);

			return new SuggestionResponse()
					{
						Key = "盗用可耻，鄙视无耻的各个国产IT同行！",
						Accepted = true,
						Groups = lineGrouped
					};
		}

		void PreProcessRequestData(RequestInfo ri)
		{
			ri.PreprocessData();
		}

		void FilteAlternativeLine(RequestInfo ri, List<AlternativeLineGroup> line)
		{
			for (var i = line.Count - 1; i >= 0; i--)
			{
				var train = ri.Stops[line[i].Lines[0].TrainCode];

				var maxAllowElapsedTime = train.TrainInfo.elapsedTime.Value.Add(train.TrainInfo.elapsedTime.MaxAddTime);
				for (var j = line[i].Lines.Count - 1; j >= 0; j--)
				{
					var current = line[i].Lines[j];
					//如果同时是发站和到站，则删除不推荐
					if (current.From.IsOriginal && current.To.IsOriginal)
						line[i].Lines.RemoveAt(j);
					//如果时间会超过原来最大的允许值，则排除
					else if (current.ElapsedTime > maxAllowElapsedTime)
						line[i].Lines.RemoveAt(j);
				}
				if (line[i].Lines.Count == 0)
				{
					line.RemoveAt(i);
				}
			}
		}

		/// <summary>
		/// 根据停靠站获得权重
		/// </summary>
		/// <param name="lineList"></param>
		/// <returns></returns>
		int GetLineStationEndpointWeight(List<AlternativeLine> lineList)
		{
			var point = 0;
			foreach (var line in lineList)
			{
				if (line.From.IsEndPoint && line.To.IsEndPoint)
					point += 2;
				else if (line.From.IsEndPoint || line.To.IsEndPoint)
					point += 1;
			}
			return point;
		}

		void SortLineRecommand(RequestInfo ri, List<AlternativeLineGroup> line)
		{
			line.Sort((x, y) =>
			{
				var ceo1 = GetLineStationEndpointWeight(x.Lines);
				var ceo2 = GetLineStationEndpointWeight(y.Lines);
				if (ceo1 != ceo2)
					return ceo2 - ceo1;

				if (x.Lines.Count != y.Lines.Count)
					return y.Lines.Count - x.Lines.Count;

				//再看停靠时间
				var ep1 = (int)x.Lines.Min(s => s.From.StopTime + s.To.StopTime).TotalSeconds;
				var ep2 = (int)y.Lines.Min(s => s.From.StopTime + s.To.StopTime).TotalSeconds;
				if (ep1 != ep2)
					return ep2 - ep1;


				//再看价格
				var ap1 = x.Lines.Min(s => s.Radio);
				var ap2 = y.Lines.Min(s => s.Radio);
				if (ap1 != ap2)
					return ap1 - ap2;

				return 0;
			});
			//最多推荐5条线路
			if (line.Count > 5)
				line.RemoveRange(5, line.Count - 5);

			//再对组内排序
			foreach (var current in line)
			{
				current.Lines.Sort((x, y) =>
				{
					//再看停靠时间
					var ep1 = (int)(x.From.StopTime + x.To.StopTime).TotalSeconds;
					var ep2 = (int)(y.From.StopTime + y.To.StopTime).TotalSeconds;
					if (ep1 != ep2)
						return ep2 - ep1;

					//再看价格
					var ap1 = (int)x.ExtraPrice;
					var ap2 = (int)y.ExtraPrice;
					if (ap1 != ap2)
						return ap1 - ap2;

					return 0;
				});
			}
		}

		void FillExtraInfo(RequestInfo ri, List<AlternativeLineGroup> line)
		{
			for (var i = line.Count - 1; i >= 0; i--)
			{
				for (var j = line[i].Lines.Count - 1; j >= 0; j--)
				{
					var train = ri.Stops[line[i].Lines[j].TrainCode];
					var current = line[i].Lines[j];
					var originalTime = train.TrainInfo.elapsedTime.Value;
					//如果时间会超过原来最大的允许值，则排除
					var priceExtraRadio = ((current.ElapsedTime - originalTime).TotalSeconds / (1.0 * originalTime.TotalSeconds));
					current.BasePriceSeat = Cn12306SuggestionUtility.BaseSeatCodes.First(s => train.TrainInfo.ticketMap.ContainsKey(s));
					current.BasePrice = train.TrainInfo.ticketMap[current.BasePriceSeat].price / 10.0;
					current.ExtraPrice = Math.Round(priceExtraRadio * current.BasePrice, 2);
					current.Radio = (int)(priceExtraRadio * 100);
				}
			}
		}

		List<AlternativeLine> GetAlternativeLines(TrainInfoItem train, DateTime requestDate)
		{
			var info = train.TrainInfo;
			var stops = train.StopInfos;

			var indexFrom = Array.FindIndex(stops, s => s.station_name == info.from.name);
			var indexTo = Array.FindIndex(stops, indexFrom + 1, s => s.station_name == info.to.name);

			if (indexFrom == -1 || indexTo == -1)
				return null;

			var altFrom = new List<AlternativeStation>();
			var altTo = new List<AlternativeStation>();
			var maxAddTime = train.TrainInfo.elapsedTime.MaxAddTime;

			if (indexFrom != 0)
			{
				var stopTimeFrom = stops[indexFrom].StopTime;
				var arriveTime = stops[indexFrom].ArriveTime;
				for (var i = 0; i < indexFrom; i++)
				{
					//如果isEnabled为true，则说明会停靠这个站点。不能推荐更短的。
					//如果时间过久，则不做推荐
					if (stops[i].isEnabled || stops[i].StartTime - arriveTime > maxAddTime)
						continue;

					var stopTime = i == 0 ? TimeSpan.Zero : stops[i].StopTime;
					if (i != 0)
					{
						//对于非始发站，停靠时间相同或更短，则不做推荐。
						if (stopTime < stopTimeFrom && i < indexFrom - 3)
							continue;
					}

					//添加到推荐列表中
					altFrom.Add(new AlternativeStation()
								{
									ArriveTime = stops[i].StartTime,
									IsEndPoint = i == 0,
									IsFromStation = true,
									Name = stops[i].station_name,
									StopTime = stopTime,
									TrainID = info.id,
									TrainCode = info.code,
									Date = stops[i].StartTime,
									IsCrossDate = requestDate != stops[i].StartTime.Date
								});
				}

				//排序
				altFrom.Sort(new AlternativeStationComparer());
				if (altFrom.Count > 5)
					altFrom.RemoveRange(5, altFrom.Count - 5);
			}
			if (indexTo != stops.Length - 1)
			{
				var stopTimeTo = stops[indexTo].StopTime;
				var startTime = stops[indexTo].StartTime;

				for (var i = stops.Length - 1; i >= indexTo; i--)
				{
					//如果isEnabled为true，则说明会停靠这个站点。不能推荐更短的。
					//如果时间过久，则不做推荐
					if (stops[i].isEnabled || stops[i].ArriveTime - startTime > maxAddTime)
						continue;

					var stopTime = i == 0 ? TimeSpan.Zero : stops[i].StopTime;
					if (i != stops.Length - 1)
					{
						//对于非终到站，停靠时间相同或更短，则不做推荐。
						if (stopTime < stopTimeTo && i > indexTo + 3)
							continue;
					}

					//添加到推荐列表中
					altTo.Add(new AlternativeStation()
							{
								ArriveTime = stops[i].ArriveTime,
								IsEndPoint = i == stops.Length - 1,
								IsFromStation = false,
								Name = stops[i].station_name,
								TrainID = info.id,
								StopTime = stopTime,
								TrainCode = info.code
							});
				}
				altTo.Sort(new AlternativeStationComparer());
				if (altTo.Count > 5)
					altTo.RemoveRange(5, altTo.Count - 5);
			}
			//plus 原始线路
			altFrom.Add(new AlternativeStation
						{
							ArriveTime = stops[indexFrom].StartTime,
							IsEndPoint = indexFrom == 0,
							IsFromStation = true,
							Name = stops[indexFrom].station_name,
							StopTime = indexFrom == 0 ? TimeSpan.Zero : stops[indexFrom].StopTime,
							TrainCode = info.code,
							IsOriginal = true,
							TrainID = info.id,
							IsCrossDate = false,
							Date = stops[indexFrom].StartTime
						});

			altTo.Add(new AlternativeStation
					{
						ArriveTime = stops[indexTo].ArriveTime,
						IsEndPoint = indexTo == stops.Length - 1,
						IsFromStation = false,
						TrainID = info.id,
						Name = stops[indexTo].station_name,
						StopTime = indexTo == stops.Length - 1 ? TimeSpan.Zero : stops[indexFrom].StopTime,
						TrainCode = info.code,
						IsOriginal = true
					});

			var lines = altFrom.CrossJoin(altTo).Where(s => !s.Key.IsOriginal || !s.Value.IsOriginal).Select(s => new AlternativeLine(s.Key, s.Value, s.Key.Date, s.Key.IsCrossDate) { TrainCode = s.Key.TrainCode, TrainId = s.Key.TrainID }).ToList();
			return lines;
		}

		#endregion

	}
}