计算从哪天起应该购买预售火车票.cs

using System;
using System.Diagnostics;
using System.IO;
using System.Threading;
using System.Threading.Tasks;

class Program
{
	static ConsoleColor DefaultForegroundColor = Console.ForegroundColor;
	
	static int Main(params string[] args)
	{
		int days = 0;
		if (args.Length>0)
		{
			if(!int.TryParse(args[0], out days))
			{
				ShowHelp();
				Console.Write("按任意键退出...");
				Console.ReadKey(true);
				Environment.Exit(1); //第一个参数错误
			}
			else if(args.Length>1)
			{
				DateTime argsDate;
				if(args[1].Trim().Equals("now",StringComparison.OrdinalIgnoreCase))
				{
					argsDate = DateTime.Now.AddDays(days - 1);
				}
				else if(!DateTime.TryParse(args[1], out argsDate))
				{
					ShowHelp();
					Console.Write("按任意键退出...");
					Console.ReadKey(true);
					Environment.Exit(2); //第二个参数错误
				}				
				Console.WriteLine("\r\n * 火车票预售期为：{0}天\r\n\r\n出行日期：{1}",days, FormatDate(argsDate));
				OutputDays(days, argsDate);
				var paused = true;
				if(args.Length>2)
				{
					if(args[2].Trim().Equals("nopause",StringComparison.OrdinalIgnoreCase))
					{
						paused = false;
					}
				}
				if(paused)
				{
					Console.Write("\r\n按任意键退出...");
					Console.ReadKey(true);
				}
				Environment.Exit(0);
			}
		}
		else
		{
			Console.WriteLine("计算从哪天起应该购买预售火车票");
			Console.WriteLine();
		}
		if(days <= 0)
		{
			Console.Write("火车票预售期（缺省为60天）：");
			var input=Console.ReadLine().Trim();
			inputToExit(input);
			if (!int.TryParse(input, out days)||days<=0)
			{
				days = 60;
				ConsoleCursorRelativeLine(-1);
				var point = ConsoleCursorGetCurrentPosition();
				if(point!=null)
				{
					ConsoleCursorFillLines(point.Value.Top,point.Value.Top);
					Console.Write("火车票预售期（缺省为60天）：{0}\r\n", days);
				}
			}
		}
		Console.WriteLine("\r\n * 火车票预售期为：{0}天",days);
		Console.WriteLine(" * 今天可以预定 {0} 的火车票", FormatDate(DateTime.Now.AddDays(days - 1)));
		Console.WriteLine(" * 输入\"exit\"可退出程序，输入\"g\"打开12306订票网站。\r\n");
		while(true)
		{
			Console.Write("出行日期：");
		    var input = Console.ReadLine().Trim();
			inputToExit(input);
			if(input.Equals("g",StringComparison.OrdinalIgnoreCase))
			{
				const string web = "http://www.12306.cn";
				Process.Start(web);
				Console.WriteLine("正在打开 {0} ", web);
			}
			else
			{
				DateTime dest;
				if(DateTime.TryParse(input, out dest))
				{
					ConsoleCursorRelativeLine(-1);
					var point = ConsoleCursorGetCurrentPosition();
					if(point!=null)
					{
						ConsoleCursorFillLines(point.Value.Top,point.Value.Top);
						Console.WriteLine("出行日期：{0}",FormatDate(dest));
					}
					OutputDays(days, dest);
				}
				else
				{
					Console.ForegroundColor = ConsoleColor.Red;
					Console.WriteLine("输入错误");
					Console.ForegroundColor = DefaultForegroundColor;
					ConsoleCursorRelativeLine(-3);
					var point = ConsoleCursorGetCurrentPosition();
					if(point!=null)
					{
						ConsoleCursorFillLines(point.Value.Top,point.Value.Top+1);
					}
				}
			}
			Console.WriteLine();
		}
	}
	
	static void inputToExit(string input)
	{
		if(input.Equals("exit", StringComparison.OrdinalIgnoreCase))
		{
			 Environment.Exit(0);
		}
	}
	
	static void ShowHelp()
	{
		var appname = Path.GetFileName(Environment.GetCommandLineArgs()[0]);
		Console.WriteLine(" * 参数格式：");
		Console.WriteLine("   {0} <火车票预售期>", appname);
		Console.WriteLine("   {0} <火车票预售期> <出行日期> [nopause]", appname);
		Console.WriteLine("   {0} <火车票预售期> now [nopause]", appname);
		Console.WriteLine("\r\n * 例子：预售期60天，查看今天可以预定哪天火车票");
		Console.WriteLine("   {0} 60 now", appname);
		Console.WriteLine("\r\n * 批处理：");
		Console.WriteLine("   {0} 60 now nopause|Find \"出行日期：\"", appname);
		Console.WriteLine();
	}
	
	static string FormatDate(DateTime date)
	{
		ConsoleColor? cc;
		return FormatDate(date, out cc);
	}
	
	static string FormatDate(DateTime date, out ConsoleColor? consoleColor)
	{
		var dayOfWeek = new []{ "周日", "周一", "周二", "周三", "周四", "周五", "周六" };
		var d = (date.Date - DateTime.Now.Date).Days;
		string tip;
		switch (d)
		{
			case -2:
				tip = "（前天）";
				break;
			case -1:
				tip = "（昨天）";
				break;
			case 0:
				tip = "（今天）";
				break;
			case 1:
				tip = "（明天）";
				break;
			case 2:
				tip = "（后天）";
				break;
			default:
				tip = string.Format("（{0}）",dayOfWeek[(int)date.DayOfWeek]);
				break;
		}
		
		if (d>=0)
		{
			consoleColor = ConsoleColor.Green;
		}
		else if(d<0)
		{
			consoleColor = ConsoleColor.Yellow;
		}
		else
		{
			consoleColor = null;
		}
		
		return string.Format("{0:yyyy-M-d}{1}", date, tip);
	}
	
	static void OutputDays(int days, DateTime destDate)
	{
		var date = destDate.AddDays(-days + 1);
		ConsoleColor? cc;
		var formattedDest = FormatDate(date, out cc);
		Console.ForegroundColor = DefaultForegroundColor;
		Console.Write("预售日期：");
		if(cc.HasValue)
		{
			Console.ForegroundColor = cc.Value;
		}
		Console.WriteLine(formattedDest);
		Console.ForegroundColor = DefaultForegroundColor;
	}
	
	static bool ConsoleCursorRelativeLine(int rows)
	{
		try
		{
			var t = Console.CursorTop + rows;
			Console.SetCursorPosition(0, t);
			return true;
		}
		catch
		{
		}
		return false;
	}
	
	static bool ConsoleCursorFillLines(int startLine, int endLine, char @char = ‘ ‘)
	{
		var d = endLine - startLine + 1;
		if (d>0)
		{
			try 
			{
				var point = ConsoleCursorGetCurrentPosition().Value;			
				Console.SetCursorPosition(0, startLine);
				Console.Write(new string(@char,Console.BufferWidth * d));
				Console.SetCursorPosition(point.Left, point.Top);
			}
			catch
			{
			}
		}
		return false;
	}
	
	static Point? ConsoleCursorGetCurrentPosition()
	{
		try
		{
			return new Point(Console.CursorLeft, Console.CursorTop);
		}
		catch
		{
		}
		return null;
	}
	
	struct Point
	{
		public int Left;
		public int Top;
		
		public Point(int left, int top)
		{
			Left = left;
			Top = top;
		}
	}
}