// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace UnrealBuildTool
{
	/// <summary>
	/// Host platform abstraction
	/// </summary>
	public abstract class BuildHostPlatform
	{
		private static BuildHostPlatform CurrentPlatform;
		private static bool bIsMac = File.Exists("/System/Library/CoreServices/SystemVersion.plist");

		/// <summary>
		/// Returns the name of platform UBT is running on. Internal use only. If you need access this this enum, use BuildHostPlatform.Current.Platform */
		/// </summary>
		private static UnrealTargetPlatform GetRuntimePlatform()
		{
			PlatformID Platform = Environment.OSVersion.Platform;
			switch (Platform)
			{
				case PlatformID.Win32NT:
					return UnrealTargetPlatform.Win64;
				case PlatformID.Unix:
					return bIsMac ? UnrealTargetPlatform.Mac : UnrealTargetPlatform.Linux;
				case PlatformID.MacOSX:
					return UnrealTargetPlatform.Mac;
				default:
					throw new BuildException("Unhandled runtime platform " + Platform);
			}
		}

		/// <summary>
		/// Host platform singleton.
		/// </summary>
		static public BuildHostPlatform Current
		{
			get 
			{
				if (CurrentPlatform == null)
				{
					switch (GetRuntimePlatform())
					{
						case UnrealTargetPlatform.Win64:
							CurrentPlatform = new WindowsBuildHostPlatform();
							break;
						case UnrealTargetPlatform.Mac:
							CurrentPlatform = new MacBuildHostPlatform();
							break;
						case UnrealTargetPlatform.Linux:
							CurrentPlatform = new LinuxBuildHostPlatform();
							break;
					}
				}
				return CurrentPlatform;
			}
		}

		/// <summary>
		/// Gets the current host platform type.
		/// </summary>
		abstract public UnrealTargetPlatform Platform { get; }

		/// <summary>
		/// Checks the API version of a dynamic library
		/// </summary>
		/// <param name="Filename">Filename of the library</param>
		/// <returns>API version of -1 if not found.</returns>
		abstract public int GetDllApiVersion(string Filename);

		/// <summary>
		/// Class that holds information about a running process
		/// </summary>
		public class ProcessInfo
		{
			/// <summary>
			/// Process ID
			/// </summary>
			public int PID;
			/// <summary>
			/// Name of the process
			/// </summary>
			public string Name;
			/// <summary>
			/// Filename of the process binary
			/// </summary>
			public string Filename;

			public ProcessInfo(int InPID, string InName, string InFilename, string[] InModules)
			{
				PID = InPID;
				Name = InName;
				Filename = InFilename;
			}
			public ProcessInfo(Process Proc)
			{
				PID = Proc.Id;
				Name = Proc.ProcessName;
				Filename = Path.GetFullPath(Proc.MainModule.FileName);
			}
			public override string ToString()
			{
				return String.Format("{0}, {1}", Name, Filename);
			}
		}
			
		/// <summary>
		/// Gets all currently running processes.
		/// </summary>
		/// <returns></returns>
		public virtual ProcessInfo[] GetProcesses()
		{
			var AllProcesses = Process.GetProcesses();
			var Result = new List<ProcessInfo>(AllProcesses.Length);
			foreach (var Proc in AllProcesses) 
			{
				try 
				{
					if (!Proc.HasExited) 
					{
						Result.Add(new ProcessInfo(Proc));
					}
				} catch {}
			}
			return Result.ToArray();
		}

		/// <summary>
		/// Gets a process by name.
		/// </summary>
		/// <param name="Name">Name of the process to get information for.</param>
		/// <returns></returns>
		public virtual ProcessInfo GetProcessByName(string Name)
		{
			var AllProcess = GetProcesses();
			foreach (var Info in AllProcess) 
			{
				if (Info.Name == Name) 
				{
					return Info;
				}
			}
			return null;
		}

		/// <summary>
		/// Gets processes by name.
		/// </summary>
		/// <param name="Name">Name of the process to get information for.</param>
		/// <returns></returns>
		public virtual ProcessInfo[] GetProcessesByName(string Name)
		{
			var AllProcess = GetProcesses();
			var Result = new List<ProcessInfo>();
			foreach (var Info in AllProcess) 
			{
				if (Info.Name == Name) 
				{
					Result.Add(Info);
				}
			}
			return Result.ToArray();
		}

		/// <summary>
		/// Gets the filenames of all modules associated with a process
		/// </summary>
		/// <param name="PID">Process ID</param>
		/// <param name="Filename">Filename of the binary associated with the process.</param>
		/// <returns>An array of all module filenames associated with the process. Can be empty of the process is no longer running.</returns>
		public virtual string[] GetProcessModules(int PID, string Filename)
		{
			List<string> Modules = new List<string>();
			try
			{
				var Proc = Process.GetProcessById(PID);
				if (Proc != null)
				{
					foreach (var Module in Proc.Modules.Cast<System.Diagnostics.ProcessModule>())
					{
						Modules.Add(Path.GetFullPath(Module.FileName));
					}
				}
			}
			catch { }
			return Modules.ToArray();
		}
	}

	class WindowsBuildHostPlatform : BuildHostPlatform
	{
		public override UnrealTargetPlatform Platform
		{
			get { return UnrealTargetPlatform.Win64; }
		}

		[DllImport("kernel32.dll", SetLastError = true)]
		static extern IntPtr LoadLibraryEx(string lpFileName, IntPtr hFile, uint dwFlags);
		[DllImport("kernel32.dll", SetLastError = true)]
		static extern IntPtr FindResource(IntPtr hModule, string lpName, string lpType);
		[DllImport("kernel32.dll")]
		static extern IntPtr FindResource(IntPtr hModule, IntPtr lpID, IntPtr lpType);
		[DllImport("kernel32.dll", SetLastError = true)]
		static extern IntPtr LoadResource(IntPtr hModule, IntPtr hResInfo);
		[DllImport("kernel32.dll", SetLastError = true)]
		static extern uint SizeofResource(IntPtr hModule, IntPtr hResInfo);
		[DllImport("kernel32.dll", SetLastError = true)]
		static extern IntPtr LockResource(IntPtr hResData);
		[DllImport("kernel32.dll", SetLastError = true)]
		static extern void UnlockResource(IntPtr hResInfo);
		[DllImport("kernel32.dll", SetLastError = true)]
		static extern void FreeLibrary(IntPtr hModule);

		[Flags]
		enum LoadLibraryFlags : uint
		{
			DONT_RESOLVE_DLL_REFERENCES = 0x00000001,
			LOAD_LIBRARY_AS_DATAFILE = 0x00000002,
			LOAD_WITH_ALTERED_SEARCH_PATH = 0x00000008,
			LOAD_IGNORE_CODE_AUTHZ_LEVEL = 0x00000010,
			LOAD_LIBRARY_AS_IMAGE_RESOURCE = 0x00000020,
			LOAD_LIBRARY_AS_DATAFILE_EXCLUSIVE = 0x00000040,
			LOAD_LIBRARY_REQUIRE_SIGNED_TARGET = 0x00000080
		}

		enum ResourceType
		{
			RT_CURSOR = 1,
			RT_BITMAP = 2,
			RT_ICON = 3,
			RT_MENU = 4,
			RT_DIALOG = 5,
			RT_STRING = 6,
			RT_FONTDIR = 7,
			RT_FONT = 8,
			RT_ACCELERATOR = 9,
			RT_RCDATA = 10,
			RT_MESSAGETABLE = 11
		}

		public override int GetDllApiVersion(string Filename)
		{
			int Result = -1;

			try
			{
				const int ID_MODULE_API_VERSION_RESOURCE = 191;

				// Retrieves the embedded API version from a DLL
				IntPtr hModule = LoadLibraryEx(Filename, IntPtr.Zero, (uint)LoadLibraryFlags.LOAD_LIBRARY_AS_DATAFILE);
				if (hModule != IntPtr.Zero)
				{
					IntPtr hResInfo = FindResource(hModule, new IntPtr(ID_MODULE_API_VERSION_RESOURCE), new IntPtr((int)ResourceType.RT_RCDATA));
					if (hResInfo != IntPtr.Zero)
					{
						IntPtr hResGlobal = LoadResource(hModule, hResInfo);
						if (hResGlobal != IntPtr.Zero)
						{
							IntPtr pResData = LockResource(hResGlobal);
							if (pResData != IntPtr.Zero)
							{
								uint Length = SizeofResource(hModule, hResInfo);
								if (Length > 0)
								{
									var Str = Marshal.PtrToStringAnsi(pResData);
									Result = Int32.Parse(Str);
								}
							}
						}
					}
					FreeLibrary(hModule);
				}
			}
			catch (Exception Ex)
			{
				Log.TraceWarning("Failed to get DLL API version for {0}. Exception: {1}", Filename, Ex.Message);
			}

			return Result;
		}

	}

	class MacBuildHostPlatform : BuildHostPlatform
	{
		public override UnrealTargetPlatform Platform
		{
			get { return UnrealTargetPlatform.Mac; }
		}

		public override int GetDllApiVersion(string Filename)
		{
			// @TODO: Implement GetDllApiVersion for Mac
			return -1;
		}

		/// <summary>
		/// Currently Mono returns incomplete process names in Process.GetProcesses() so we need to parse 'ps' output.
		/// </summary>
		/// <returns></returns>
		public override ProcessInfo[] GetProcesses()
		{
			var Result = new List<ProcessInfo>();

			var StartInfo = new ProcessStartInfo ();
			StartInfo.FileName = "ps";
			StartInfo.Arguments = "-eaw -o pid,comm";
			StartInfo.CreateNoWindow = true;
			StartInfo.UseShellExecute = false;
			StartInfo.RedirectStandardOutput = true;

			var Proc = new Process ();
			Proc.StartInfo = StartInfo;
			try
			{
				Proc.Start();
				Proc.WaitForExit();
				for (string Line = Proc.StandardOutput.ReadLine(); Line != null; Line = Proc.StandardOutput.ReadLine())
				{
					Line = Line.Trim();
					int PIDEnd = Line.IndexOf(' ');
					var PIDString = Line.Substring(0, PIDEnd);
					if (PIDString != "PID")
					{
						var Filename = Line.Substring(PIDEnd + 1);
						var Pid = Int32.Parse(PIDString);
						try
						{
							var ExistingProc = Process.GetProcessById(Pid);
							if (ExistingProc != null && Pid != Process.GetCurrentProcess().Id && ExistingProc.HasExited == false)
							{
								var ProcInfo = new ProcessInfo(ExistingProc);
								ProcInfo.Name = Path.GetFileName(Filename);
								ProcInfo.Filename = Filename;
								Result.Add(ProcInfo);
							}
						} catch {}
					}
				}

			}
			catch {}
			return Result.ToArray();
		}

		/// <summary>
		/// Currently Mono returns incomplete list of modules for Process.Modules so we need to parse vmmap output.
		/// </summary>
		/// <param name="PID"></param>
		/// <param name="Filename"></param>
		/// <returns></returns>
		public override string[] GetProcessModules(int PID, string Filename)
		{
			HashSet<string> Modules = new HashSet<string>();
			// Add the process file name to the module list. This is to make it compatible with the results of Process.Modules on Windows.
			Modules.Add(Filename);

			var StartInfo = new ProcessStartInfo();
			StartInfo.FileName = "vmmap";
			StartInfo.Arguments = String.Format("{0} -w", PID);
			StartInfo.CreateNoWindow = true;
			StartInfo.UseShellExecute = false;
			StartInfo.RedirectStandardOutput = true;

			var Proc = new Process();
			Proc.StartInfo = StartInfo;
			try
			{
				Proc.Start();
				// Start processing output before vmmap exits otherwise it's going to hang
				while (!Proc.WaitForExit(1))
				{
					ProcessVMMapOutput(Proc, Modules);
				}
				ProcessVMMapOutput(Proc, Modules);
			}
			catch { }
			return Modules.ToArray();
		}
		private void ProcessVMMapOutput(Process Proc, HashSet<string> Modules)
		{
			for (string Line = Proc.StandardOutput.ReadLine(); Line != null; Line = Proc.StandardOutput.ReadLine())
			{
				Line = Line.Trim();
				if (Line.EndsWith(".dylib"))
				{
					const int SharingModeLength = 6;
					int SMStart = Line.IndexOf("SM=");
					int PathStart = SMStart + SharingModeLength;
					string Module = Line.Substring(PathStart).Trim();
					if (!Modules.Contains(Module))
					{
						Modules.Add(Module);
					}
				}
			}
		}
	}

	class LinuxBuildHostPlatform : BuildHostPlatform
	{
		public override UnrealTargetPlatform Platform
		{
			get { return UnrealTargetPlatform.Linux; }
		}

		public override int GetDllApiVersion(string Filename)
		{
			// @TODO: Implement GetDllApiVersion for Linux
			return -1;
		}

		/// <summary>
		/// Currently Mono returns incomplete process names in Process.GetProcesses() so we need to use /proc
		/// (also, Mono locks up during process traversal sometimes, trying to open /dev/snd/pcm*)
		/// </summary>
		/// <returns></returns>
		public override ProcessInfo[] GetProcesses()
		{
			// @TODO: Implement for Linux
			return new List<ProcessInfo>().ToArray();
		}
		
		/// <summary>
		/// Currently Mono returns incomplete list of modules for Process.Modules so we need to parse /proc/PID/maps.
		/// (also, Mono locks up during process traversal sometimes, trying to open /dev/snd/pcm*)
		/// </summary>
		/// <param name="PID"></param>
		/// <param name="Filename"></param>
		/// <returns></returns>
		public override string[] GetProcessModules(int PID, string Filename)
		{
			// @TODO: Implement for Linux
			return new List<string>().ToArray();
		}
	}
}