// Copyright 1998-2018 Epic Games, Inc. All Rights Reserved.
// This software is provided "as-is," without any express or implied warranty. 
// In no event shall the author, nor Epic Games, Inc. be held liable for any damages arising from the use of this software.
// This software will not be supported.
// Use at your own risk.
using System;
using System.Threading;
using System.Diagnostics;
using UnrealBuildTool;
using System.Reflection;
using Tools.DotNETCommon;
using System.IO;
using System.Collections.Generic;
using System.Text;

namespace AutomationTool
{
	public class Program
	{
		/// <summary>
		/// Keep a persistent reference to the delegate for handling Ctrl-C events. Since it's passed to non-managed code, we have to prevent it from being garbage collected.
		/// </summary>
		static ProcessManager.CtrlHandlerDelegate CtrlHandlerDelegateInstance = CtrlHandler;

		[STAThread]
		public static int Main()
		{
			// Parse the command line
			string[] Arguments = SharedUtils.ParseCommandLineAndRemoveExe(Environment.CommandLine);

            // Ensure UTF8Output flag is respected, since we are initializing logging early in the program.
            if (CommandUtils.ParseParam(Arguments, "-Utf8output"))
            {
                Console.OutputEncoding = new System.Text.UTF8Encoding(false, false);
            }

			// Parse the log level argument
			LogEventType LogLevel = LogEventType.Log;
			if(CommandUtils.ParseParam(Arguments, "-Verbose"))
			{
				LogLevel = LogEventType.Verbose;
			}
			if(CommandUtils.ParseParam(Arguments, "-VeryVerbose"))
			{
				LogLevel = LogEventType.VeryVerbose;
			}

			// Initialize the log system, buffering the output until we can create the log file
			StartupTraceListener StartupListener = new StartupTraceListener();
			Log.InitLogging(
                bLogTimestamps: CommandUtils.ParseParam(Arguments, "-Timestamps"),
				InLogLevel: LogLevel,
                bLogSeverity: true,
				bLogProgramNameWithSeverity: false,
                bLogSources: true,
				bLogSourcesToConsole: false,
                bColorConsoleOutput: true,
                TraceListeners: new TraceListener[]
                {
					StartupListener
				}
			);

			// Enter the main program section
            ExitCode ReturnCode = ExitCode.Success;
			try
			{
				// Set the working directory to the UE4 root
				Environment.CurrentDirectory = Path.GetFullPath(Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().GetOriginalLocation()), "..", "..", ".."));

				// Ensure we can resolve any external assemblies as necessary.
				AssemblyUtils.InstallAssemblyResolver(Path.GetDirectoryName(Assembly.GetEntryAssembly().GetOriginalLocation()));

				// Initialize the host platform layer
				HostPlatform.Initialize();

				// Log the operating environment. Since we usually compile to AnyCPU, we may be executed using different system paths under WOW64.
				Log.TraceVerbose("{2}: Running on {0} as a {1}-bit process.", HostPlatform.Current.GetType().Name, Environment.Is64BitProcess ? 64 : 32, DateTime.UtcNow.ToString("o"));

				// Log if we're running from the launcher
				string ExecutingAssemblyLocation = Assembly.GetExecutingAssembly().Location;
				if (string.Compare(ExecutingAssemblyLocation, Assembly.GetEntryAssembly().GetOriginalLocation(), StringComparison.OrdinalIgnoreCase) != 0)
				{
					Log.TraceVerbose("Executed from AutomationToolLauncher ({0})", ExecutingAssemblyLocation);
				}
				Log.TraceVerbose("CWD={0}", Environment.CurrentDirectory);

				// Hook up exit callbacks
				AppDomain Domain = AppDomain.CurrentDomain;
				Domain.ProcessExit += Domain_ProcessExit;
				Domain.DomainUnload += Domain_ProcessExit;
				HostPlatform.Current.SetConsoleCtrlHandler(CtrlHandlerDelegateInstance);

				// Log the application version
				FileVersionInfo Version = AssemblyUtils.ExecutableVersion;
				Log.TraceVerbose("{0} ver. {1}", Version.ProductName, Version.ProductVersion);

				// Don't allow simultaneous execution of AT (in the same branch)
				ReturnCode = InternalUtils.RunSingleInstance(() => MainProc(Arguments, StartupListener));
			}
			catch (AutomationException Ex)
			{
				// Take the exit code from the exception
				Log.WriteException(Ex, LogUtils.FinalLogFileName);
				ReturnCode = Ex.ErrorCode;
			}
			catch (Exception Ex)
			{
				// Use a default exit code
				Log.WriteException(Ex, LogUtils.FinalLogFileName);
				ReturnCode = ExitCode.Error_Unknown;
			}
            finally
            {
                // In all cases, do necessary shut down stuff, but don't let any additional exceptions leak out while trying to shut down.

                // Make sure there's no directories on the stack.
                NoThrow(() => CommandUtils.ClearDirStack(), "Clear Dir Stack");

                // Try to kill process before app domain exits to leave the other KillAll call to extreme edge cases
                NoThrow(() => { if (ShouldKillProcesses && !Utils.IsRunningOnMono) ProcessManager.KillAll(); }, "Kill All Processes");

				// Write the exit code
                Log.TraceInformation("AutomationTool exiting with ExitCode={0} ({1})", (int)ReturnCode, ReturnCode);

                // Can't use NoThrow here because the code logs exceptions. We're shutting down logging!
                Trace.Close();
            }
            return (int)ReturnCode;
        }

		/// <summary>
		/// Wraps an action in an exception block.
		/// Ensures individual actions can be performed and exceptions won't prevent further actions from being executed.
		/// Useful for shutdown code where shutdown may be in several stages and it's important that all stages get a chance to run.
		/// </summary>
		/// <param name="Action"></param>
		private static void NoThrow(System.Action Action, string ActionDesc)
        {
            try
            {
                Action();
            }
            catch (Exception Ex)
            {
                Log.TraceError("Exception performing nothrow action \"{0}\": {1}", ActionDesc, LogUtils.FormatException(Ex));
            }
        }

        static bool CtrlHandler(CtrlTypes EventType)
		{
			Domain_ProcessExit(null, null);
			if (EventType == CtrlTypes.CTRL_C_EVENT)
			{
				// Force exit
				Environment.Exit(3);
			}			
			return true;
		}

		static void Domain_ProcessExit(object sender, EventArgs e)
		{
			// Kill all spawned processes (Console instead of Log because logging is closed at this time anyway)
			if (ShouldKillProcesses && !Utils.IsRunningOnMono)
			{			
				ProcessManager.KillAll();
			}
			Trace.Close();
		}

		static ExitCode MainProc(string[] Arguments, StartupTraceListener StartupListener)
		{
			ExitCode Result = Automation.Process(Arguments, StartupListener);
			ShouldKillProcesses = Automation.ShouldKillProcesses;
			return Result;
		}

		static bool ShouldKillProcesses = true;
	}
}