using System;
using System.Diagnostics;
using System.Configuration;

namespace ChangeAppConfigProperty
{
	class ChangeAppConfigProperty
	{
		private static string pathToExeFile;
		private static string keyName;
		private static string newValue;
		static void Main(string[] args)
		{
			if (args.Length < 3)
			{
				Console.WriteLine("Updates an application configuration setting file property.");
				Console.WriteLine("Usage: ChangeAppConfigProperty.exe /exeFile:{PathToExe.exe} /key:{AppSettingsKeyName} /value:{newValue} [/debug]");
			}
			foreach (string arg in args)
			{
				if (arg.ToUpperInvariant().Contains("/exeFile:".ToUpperInvariant()))
				{
					pathToExeFile = arg.Split(':')[1];
				}
				if (arg.ToUpperInvariant().Contains("/key:".ToUpperInvariant()))
				{
					keyName = arg.Split(':')[1];
				}
				if (arg.ToUpperInvariant().Contains("/value:".ToUpperInvariant()))
				{
					newValue = arg.Split(':')[1];
				}
				if (arg.ToUpperInvariant().Contains("/debug".ToUpperInvariant()))
				{
					Debugger.Break();
				}
			}

			//save a backup copy first.
			var cfg = ConfigurationManager.OpenExeConfiguration(pathToExeFile);
			cfg.SaveAs(cfg.FilePath + "." + DateTime.Now.ToFileTime() + ".bak");

			//reopen the original config again and update it.
			cfg = ConfigurationManager.OpenExeConfiguration(pathToExeFile);
			var setting = cfg.AppSettings.Settings[keyName];
			setting.Value = newValue;

			//save the changed configuration.
			cfg.Save(ConfigurationSaveMode.Full);

		}
	}
}