// Copyright Epic Games, Inc. All Rights Reserved.

#include <zenutil/service.h>

#include <zencore/except.h>
#include <zencore/process.h>
#include <zencore/scopeguard.h>
#include <zencore/zencore.h>
#include <string_view>

#if ZEN_PLATFORM_WINDOWS
#	include <zencore/windows.h>
#	include <zenutil/windows/service.h>
#endif
#if ZEN_PLATFORM_MAC
#	include <zencore/filesystem.h>
#	include <zencore/fmtutils.h>

#	include <unistd.h>
#	include <sys/stat.h>
#endif
#if ZEN_PLATFORM_LINUX
#	include <zencore/filesystem.h>
#	include <zencore/fmtutils.h>

#	include <unistd.h>
#	include <sys/stat.h>
#	include <regex>

ZEN_THIRD_PARTY_INCLUDES_START
#	include <systemd/sd-daemon.h>
ZEN_THIRD_PARTY_INCLUDES_END

#endif

namespace zen {
using namespace std::literals;

void
ReportServiceStatus(ServiceStatus Status)
{
#if ZEN_PLATFORM_WINDOWS
	switch (Status)
	{
		case ServiceStatus::Starting:
			ReportSvcStatus(SERVICE_START_PENDING, NO_ERROR, 3000);
			break;
		case ServiceStatus::Running:
			ReportSvcStatus(SERVICE_RUNNING, NO_ERROR, 0);
			break;
		case ServiceStatus::Stopping:
			ReportSvcStatus(SERVICE_STOP_PENDING, NO_ERROR, 0);
			break;
		case ServiceStatus::Stopped:
			ReportSvcStatus(SERVICE_STOPPED, (DWORD)ApplicationExitCode(), 0);
			break;
		default:
			break;
	}
#elif ZEN_PLATFORM_LINUX
	switch (Status)
	{
		case ServiceStatus::Running:
			sd_notify(0, "READY=1");
			break;
		case ServiceStatus::Stopping:
			sd_notify(0, "STOPPING=1");
			break;
		case ServiceStatus::Stopped:
			sd_notifyf(0, "EXIT_STATUS=%d", ApplicationExitCode());
			break;
	}
#endif
	(void)Status;
}

namespace {
#if ZEN_PLATFORM_WINDOWS

	bool SplitExecutableAndArgs(const std::wstring& ExeAndArgs, std::filesystem::path& OutExecutablePath, std::string& OutArguments)
	{
		if (ExeAndArgs.size())
		{
			if (ExeAndArgs[0] == '"')
			{
				std::wstring::size_type ExecutableEnd = ExeAndArgs.find('"', 1);
				if (ExecutableEnd == std::wstring::npos)
				{
					OutExecutablePath = ExeAndArgs;
					return true;
				}
				else
				{
					OutExecutablePath = ExeAndArgs.substr(0, ExecutableEnd + 1);
					OutArguments	  = WideToUtf8(ExeAndArgs.substr(ExecutableEnd + 1 + ExeAndArgs[ExecutableEnd + 1] == ' ' ? 1 : 0));
					return true;
				}
			}
			else
			{
				std::wstring::size_type ExecutableEnd = ExeAndArgs.find(' ', 1);
				if (ExecutableEnd == std::wstring::npos)
				{
					OutExecutablePath = ExeAndArgs;
					return true;
				}
				else
				{
					OutExecutablePath = ExeAndArgs.substr(0, ExecutableEnd);
					OutArguments	  = WideToUtf8(ExeAndArgs.substr(ExecutableEnd + 1));
					return true;
				}
			}
		}
		return false;
	}

#endif	// ZEN_PLATFORM_WINDOWS

#if ZEN_PLATFORM_MAC
	std::vector<std::string_view> SplitArguments(std::string_view Arguments)
	{
		bool						  IsQuote = false;
		size_t						  Start	  = 0;
		size_t						  Offset  = 0;
		std::vector<std::string_view> Result;
		for (; Offset < Arguments.length(); Offset++)
		{
			switch (Arguments[Offset])
			{
				case ' ':
					if (IsQuote)
					{
						continue;
					}
					else if (Offset > Start)
					{
						Result.push_back(Arguments.substr(Start, Offset - Start));
						Start = Offset + 1;
					}
					break;
				case '"':
					if (IsQuote)
					{
						IsQuote = false;
						if (Offset - Start > 1)
						{
							Result.push_back(Arguments.substr(Start + 1, Offset - (Start + 1)));
						}
						Start = Offset + 1;
					}
					else
					{
						IsQuote = true;
					}
					break;
				case '=':
					if (IsQuote)
					{
						continue;
					}
					else if (Offset > Start)
					{
						Result.push_back(Arguments.substr(Start, Offset - Start));
						Start = Offset + 1;
					}
					break;
				default:
					break;
			}
		}
		ZEN_ASSERT(!IsQuote);
		if (Offset > Start)
		{
			Result.push_back(Arguments.substr(Start, Offset - Start));
		}
		return Result;
	}

	// Needs special character escaping
	void AppendEscaped(std::string_view String, StringBuilderBase& SB)
	{
		size_t Offset = 0;
		while (Offset < String.length())
		{
			size_t NextEscapeCharacter = String.find_first_of("\"'<>&", Offset);
			if (NextEscapeCharacter == std::string_view::npos)
			{
				break;
			}
			if (NextEscapeCharacter > Offset)
			{
				SB.Append(String.substr(Offset, NextEscapeCharacter - Offset));
			}
			switch (String[NextEscapeCharacter])
			{
				case '"':
					SB.Append("&quot");
					break;
				case '\'':
					SB.Append("&apos");
					break;
				case '<':
					SB.Append("&lt");
					break;
				case '>':
					SB.Append("&gt");
					break;
				case '&':
					SB.Append("&amp");
					break;
				default:
					ZEN_ASSERT(false);
					break;
			}
			Offset = NextEscapeCharacter + 1;
		}
		if (Offset == 0)
		{
			SB.Append(String);
		}
		else if (String.length() > Offset)
		{
			SB.Append(String.substr(Offset));
		}
	}

	std::string GetDaemonName(std::string_view ServiceName) { return fmt::format("com.epicgames.unreal.{}", ServiceName); }

	std::filesystem::path GetPListPath(const std::string& DaemonName)
	{
		const std::filesystem::path PListFolder = "/Library/LaunchDaemons";
		return PListFolder / (DaemonName + ".plist");
	}

	std::string BuildPlist(std::string_view				ServiceName,
						   const std::filesystem::path& ExecutablePath,
						   std::string_view				CommandLineOptions,
						   std::string_view				DaemonName,
						   bool							Debug)
	{
		std::vector<std::string_view> Arguments = SplitArguments(CommandLineOptions);
		ExtendableStringBuilder<256>  ProgramArguments;
		for (const std::string_view Argument : Arguments)
		{
			ProgramArguments.Append("    <string>");
			AppendEscaped(Argument, ProgramArguments);
			ProgramArguments.Append("</string>\n");
		}

		return fmt::format(
			"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
			"<!DOCTYPE plist PUBLIC \"-//Apple//DTD PLIST 1.0//EN\" \"http://www.apple.com/DTDs/PropertyList-1.0.dtd\">\n"
			"<plist version=\"1.0\">\n"
			"<dict>\n"
			"  <key>Label</key>\n"
			"  <string>{}</string>\n"  // DaemonName
			"  \n"
			"  <key>ProgramArguments</key>\n"
			"  <array>\n"
			"    <string>{}</string>\n"	 // Program name
			"{}"						 // "<string>arg</string>\n" * number of arguments
			"  </array>\n"
			"  \n"
			"  <key>RunAtLoad</key>\n"
			"  <true/>\n"
			"  \n"
			//			"  <key>KeepAlive</key>\n"
			//			"  <true/>\n"
			//			"  \n"
			"  <key>StandardOutPath</key>\n"
			"  <string>/var/log/{}.log</string>\n"
			"  \n"
			"  <key>StandardErrorPath</key>\n"
			"  <string>/var/log/{}.err.log</string>\n"
			"  \n"
			"  <key>Debug</key>\n"
			"  <{}/>\n"
			"  \n"
			"</dict>\n"
			"</plist>\n",
			DaemonName,
			ExecutablePath,
			ProgramArguments.ToView(),
			ServiceName,
			ServiceName,
			Debug ? "true"sv : "false"sv);

		//            "<key>Sockets</key>"
		//            "<dict>"
		//                "<key>Listeners</key>"
		//                "<dict>"
		//                    "<key>SockServiceName</key>"
		//                    "<string>{}</string>"       // Listen socket
		//                    "<key>SockType</key>"
		//                    "<string>tcp</string>"
		//                    "<key>SockFamily</key>"
		//                    "<string>IPv4</string>"
		//                "</dict>"
		//            "</dict>"
	}

#endif	// ZEN_PLATFORM_MAC

#if ZEN_PLATFORM_MAC || ZEN_PLATFORM_LINUX

	std::pair<int, std::string> ExecuteProgram(std::string_view Cmd)
	{
		std::string Data;
		const int	BufferSize = 256;
		char		Buffer[BufferSize];
		std::string Command(Cmd);
		Command.append(" 2>&1");

		ZEN_DEBUG("Running: '{}'", Command);

		FILE* Stream = popen(Command.c_str(), "r");
		if (Stream)
		{
			while (!feof(Stream))
			{
				if (fgets(Buffer, BufferSize, Stream) != NULL)
				{
					Data.append(Buffer);
				}
			}

			while (!Data.empty() && isspace(Data[Data.length() - 1]))
			{
				Data.pop_back();
			}

			int Res	   = -1;
			int Status = pclose(Stream);
			if (Status < 0)
			{
				ZEN_DEBUG("Command {} returned {}, errno {}", Command, Status, errno);
				return {Status, Data};
			}
			uint64_t WaitMS = 100;
			if (WIFEXITED(Status))
			{
				Res = WEXITSTATUS(Status);
			}
			if (Res != 0 && Res != (128 + 13))
			{
				return {Res, Data};
			}
			return {0, Data};
		}
		return {errno, ""};
	}

#endif	// ZEN_PLATFORM_MAC || ZEN_PLATFORM_LINUX

#if ZEN_PLATFORM_LINUX
	std::string GetUnitName(std::string_view ServiceName) { return fmt::format("com.epicgames.unreal.{}", ServiceName); }

	std::filesystem::path GetServiceUnitPath(const std::string& UnitName)
	{
		const std::filesystem::path SystemUnitFolder = "/etc/systemd/system/";
		return SystemUnitFolder / (UnitName + ".service");
	}

	std::string BuildUnitFile(std::string_view			   ServiceName,
							  const std::filesystem::path& ExecutablePath,
							  std::string_view			   CommandLineOptions,
							  std::string_view			   UserName)
	{
		return fmt::format(
			"[Unit]\n"
			"Description={}\n"
			"Documentation=https://github.com/epicgames/zen\n"
			"\n"
			"DefaultDependencies=no\n"
			"After=network.target\n"
			"StartLimitIntervalSec=0\n"
			"\n"
			"[Service]\n"
			"Type=notify\n"
			"Restart=always\n"
			"RestartSec=1\n"
			"User={}\n"
			"ExecStart={} {}\n"
			"RuntimeDirectory={}\n"
			"[Install]\n"
			"WantedBy=multi-user.target",
			ServiceName,
			UserName,
			ExecutablePath,
			CommandLineOptions,
			ExecutablePath.parent_path());
	}

#endif	// ZEN_PLATFORM_LINUX
}  // namespace

std::string_view
ToString(ServiceStatus Status)
{
	switch (Status)
	{
		case ServiceStatus::NotInstalled:
			return "Not installed"sv;
		case ServiceStatus::Starting:
			return "Starting"sv;
		case ServiceStatus::Running:
			return "Running"sv;
		case ServiceStatus::Stopping:
			return "Stopping"sv;
		case ServiceStatus::Stopped:
			return "Stopped"sv;
		case ServiceStatus::Pausing:
			return "Pausing"sv;
		case ServiceStatus::Paused:
			return "Paused"sv;
		case ServiceStatus::Resuming:
			return "Resuming"sv;
		default:
			ZEN_ASSERT(false);
			return ""sv;
	}
}

#if ZEN_PLATFORM_WINDOWS

std::error_code
InstallService(std::string_view ServiceName, const ServiceSpec& Spec)
{
	// TODO: Is "LocalService account" the correct account?
	// TODO: Is ther eother parameters/security settings that we need to set up properly?

	// Get a handle to the SCM database.
	SC_HANDLE schSCManager = OpenSCManager(NULL,					// local computer
										   NULL,					// ServicesActive database
										   SC_MANAGER_ALL_ACCESS);	// full access rights

	if (NULL == schSCManager)
	{
		return MakeErrorCodeFromLastError();
	}

	auto _ = MakeGuard([schSCManager]() { CloseServiceHandle(schSCManager); });

	// Create the service

	ExtendableWideStringBuilder<128> Name;
	Utf8ToWide(ServiceName, Name);

	ExtendableWideStringBuilder<128> DisplayName;
	Utf8ToWide(Spec.DisplayName, DisplayName);

	ExtendableWideStringBuilder<128> Path;
	Path.Append(Spec.ExecutablePath.c_str());
	if (!Spec.CommandLineOptions.empty())
	{
		Path.AppendAscii(" ");
		Utf8ToWide(Spec.CommandLineOptions, Path);
	}

	SC_HANDLE schService = CreateService(schSCManager,						  // SCM database
										 Name.c_str(),						  // name of service
										 DisplayName.c_str(),				  // service name to display
										 SERVICE_ALL_ACCESS,				  // desired access
										 SERVICE_WIN32_OWN_PROCESS,			  // service type
										 SERVICE_AUTO_START,				  // start type
										 SERVICE_ERROR_NORMAL,				  // error control type
										 Path.c_str(),						  // path to service's binary
										 NULL,								  // no load ordering group
										 NULL,								  // no tag identifier
										 NULL,								  // no dependencies
										 TEXT("NT AUTHORITY\\LocalService"),  // LocalService account
										 NULL);								  // no password

	if (schService == NULL)
	{
		return MakeErrorCodeFromLastError();
	}

	auto __ = MakeGuard([schService]() { CloseServiceHandle(schService); });

	if (!Spec.Description.empty())
	{
		ExtendableWideStringBuilder<128> DescriptionBuilder;
		Utf8ToWide(Spec.Description, DescriptionBuilder);

		SERVICE_DESCRIPTION Description;
		Description.lpDescription = const_cast<wchar_t*>(DescriptionBuilder.c_str());
		if (!ChangeServiceConfig2(schService, SERVICE_CONFIG_DESCRIPTION, &Description))
		{
			return MakeErrorCodeFromLastError();
		}
	}

	// Actions defining what the service manager should do in the event of a zenserver crash.
	// Attempt an immediate restart twice. If both restarts fail, stop trying.
	// The attempt count will be reset based on the timeout specified in SERVICE_FAILURE_ACTIONS.
	// If the service manages to survive for the length of that timeout, the reset attempt count
	// will be reset and we will try restarting if we fail again.
	SC_ACTION Actions[] = {{SC_ACTION_RESTART, 0}, {SC_ACTION_RESTART, 0}, {SC_ACTION_NONE, 0}};

	SERVICE_FAILURE_ACTIONS FailureAction = {
		60,	   // if we haven't failed for one minute, assume the service is healthy and reset the failure count
		NULL,  // no reboot message - we don't want to reboot the whole system if zen dies
		NULL,  // no command to run on failure - just attempt restarting the service
		ZEN_ARRAY_COUNT(Actions),
		Actions};

	if (!ChangeServiceConfig2(schService, SERVICE_CONFIG_FAILURE_ACTIONS, &FailureAction))
	{
		return MakeErrorCodeFromLastError();
	}

	return {};
}

std::error_code
UninstallService(std::string_view ServiceName)
{
	// Get a handle to the SCM database.
	SC_HANDLE schSCManager = OpenSCManager(NULL,					// local computer
										   NULL,					// ServicesActive database
										   SC_MANAGER_ALL_ACCESS);	// full access rights

	if (NULL == schSCManager)
	{
		return MakeErrorCodeFromLastError();
	}

	auto _ = MakeGuard([schSCManager]() { CloseServiceHandle(schSCManager); });

	// Get a handle to the service.

	ExtendableWideStringBuilder<128> Name;
	Utf8ToWide(ServiceName, Name);

	SC_HANDLE schService = OpenService(schSCManager,  // SCM database
									   Name.c_str(),  // name of service
									   DELETE);		  // need delete access

	if (schService == NULL)
	{
		DWORD Error = ::GetLastError();
		if (Error == ERROR_SERVICE_DOES_NOT_EXIST)
		{
			return {};
		}
		return MakeErrorCode(Error);
	}
	auto __ = MakeGuard([schService]() { CloseServiceHandle(schService); });

	// Delete the service.

	if (!DeleteService(schService))
	{
		return MakeErrorCodeFromLastError();
	}

	return {};
}

std::error_code
QueryInstalledService(std::string_view ServiceName, ServiceInfo& OutInfo)
{
	// Get a handle to the SCM database.
	SC_HANDLE schSCManager = OpenSCManager(NULL,				 // local computer
										   NULL,				 // ServicesActive database
										   SC_MANAGER_CONNECT);	 // standard access rights

	if (NULL == schSCManager)
	{
		return MakeErrorCodeFromLastError();
	}

	auto _ = MakeGuard([schSCManager]() { CloseServiceHandle(schSCManager); });

	// Get a handle to the service.

	ExtendableWideStringBuilder<128> Name;
	Utf8ToWide(ServiceName, Name);

	SC_HANDLE schService = OpenService(schSCManager,								  // SCM database
									   Name.c_str(),								  // name of service
									   SERVICE_QUERY_STATUS | SERVICE_QUERY_CONFIG);  // need delete access

	if (schService == NULL)
	{
		DWORD Error = ::GetLastError();
		if (Error == ERROR_SERVICE_DOES_NOT_EXIST)
		{
			OutInfo.Status = ServiceStatus::NotInstalled;
			return {};
		}
		return MakeErrorCode(Error);
	}
	auto __ = MakeGuard([schService]() { CloseServiceHandle(schService); });

	std::vector<std::uint8_t> Buffer(8192);
	QUERY_SERVICE_CONFIG*	  ServiceConfig = reinterpret_cast<QUERY_SERVICE_CONFIG*>(Buffer.data());
	DWORD					  BytesNeeded	= 0;
	if (!QueryServiceConfig(schService, ServiceConfig, (DWORD)Buffer.size(), &BytesNeeded))
	{
		return MakeErrorCodeFromLastError();
	}

	std::wstring BinaryWithArguments(ServiceConfig->lpBinaryPathName);
	(void)SplitExecutableAndArgs(BinaryWithArguments, OutInfo.Spec.ExecutablePath, OutInfo.Spec.CommandLineOptions);
	OutInfo.Spec.DisplayName = WideToUtf8(ServiceConfig->lpDisplayName);

	SERVICE_STATUS ServiceStatus;
	if (!::QueryServiceStatus(schService, &ServiceStatus))
	{
		return MakeErrorCodeFromLastError();
	}

	switch (ServiceStatus.dwCurrentState)
	{
		case SERVICE_STOPPED:
			OutInfo.Status = ServiceStatus::Stopped;
			break;
		case SERVICE_START_PENDING:
			OutInfo.Status = ServiceStatus::Starting;
			break;
		case SERVICE_STOP_PENDING:
			OutInfo.Status = ServiceStatus::Stopping;
			break;
		case SERVICE_RUNNING:
			OutInfo.Status = ServiceStatus::Running;
			break;
		case SERVICE_CONTINUE_PENDING:
			OutInfo.Status = ServiceStatus::Resuming;
			break;
		case SERVICE_PAUSE_PENDING:
			OutInfo.Status = ServiceStatus::Pausing;
			break;
		case SERVICE_PAUSED:
			OutInfo.Status = ServiceStatus::Paused;
			break;
		default:
			throw std::runtime_error(fmt::format("Unknown service status for '{}': {}", ServiceName, ServiceStatus.dwCurrentState));
	}

	if (!QueryServiceConfig2(schService, SERVICE_CONFIG_DESCRIPTION, Buffer.data(), (DWORD)Buffer.size(), &BytesNeeded))
	{
		DWORD Error = ::GetLastError();
		if (Error == ERROR_INSUFFICIENT_BUFFER)
		{
			Buffer.resize((size_t)BytesNeeded);
			if (!QueryServiceConfig2(schService, SERVICE_CONFIG_DESCRIPTION, Buffer.data(), (DWORD)Buffer.size(), &BytesNeeded))
			{
				return MakeErrorCodeFromLastError();
			}
		}
		else
		{
			return MakeErrorCode(Error);
		}
	}
	SERVICE_DESCRIPTION* Description = (SERVICE_DESCRIPTION*)Buffer.data();
	if (Description->lpDescription != NULL)
	{
		OutInfo.Spec.Description = WideToUtf8(std::wstring(Description->lpDescription));
	}

	return {};
}

std::error_code
StartService(std::string_view ServiceName)
{
	// Get a handle to the SCM database.
	SC_HANDLE schSCManager = OpenSCManager(NULL,				 // local computer
										   NULL,				 // ServicesActive database
										   SC_MANAGER_CONNECT);	 // default access rights

	if (NULL == schSCManager)
	{
		return MakeErrorCodeFromLastError();
	}

	auto _ = MakeGuard([schSCManager]() { CloseServiceHandle(schSCManager); });

	// Get a handle to the service.

	ExtendableWideStringBuilder<128> Name;
	Utf8ToWide(ServiceName, Name);

	SC_HANDLE schService = OpenService(schSCManager,	// SCM database
									   Name.c_str(),	// name of service
									   SERVICE_START);	// need start access

	if (schService == NULL)
	{
		return MakeErrorCodeFromLastError();
	}
	auto __ = MakeGuard([schService]() { CloseServiceHandle(schService); });

	// Start the service.

	if (!::StartService(schService, 0, NULL))
	{
		return MakeErrorCodeFromLastError();
	}

	return {};
}

std::error_code
StopService(std::string_view ServiceName)
{
	// Get a handle to the SCM database.
	SC_HANDLE schSCManager = OpenSCManager(NULL,				 // local computer
										   NULL,				 // ServicesActive database
										   SC_MANAGER_CONNECT);	 // default access rights

	if (NULL == schSCManager)
	{
		return MakeErrorCodeFromLastError();
	}

	auto _ = MakeGuard([schSCManager]() { CloseServiceHandle(schSCManager); });

	// Get a handle to the service.

	ExtendableWideStringBuilder<128> Name;
	Utf8ToWide(ServiceName, Name);

	SC_HANDLE schService = OpenService(schSCManager,   // SCM database
									   Name.c_str(),   // name of service
									   SERVICE_STOP);  // need start access

	if (schService == NULL)
	{
		return MakeErrorCodeFromLastError();
	}
	auto __ = MakeGuard([schService]() { CloseServiceHandle(schService); });

	// Stop the service.
	SERVICE_STATUS ServiceStatus;
	if (!::ControlService(schService, SERVICE_CONTROL_STOP, &ServiceStatus))
	{
		return MakeErrorCodeFromLastError();
	}

	return {};
}

#endif

#if ZEN_PLATFORM_MAC

std::error_code
InstallService(std::string_view ServiceName, const ServiceSpec& Spec)
{
	// TODO: Do we need to create a separate user for the service or is running as the default service user OK?
	const std::string DaemonName = GetDaemonName(ServiceName);
	std::string		  PList		 = BuildPlist(ServiceName, Spec.ExecutablePath, Spec.CommandLineOptions, DaemonName, true);

	const std::filesystem::path PListPath = GetPListPath(DaemonName);
	ZEN_INFO("Writing launchd plist to {}", PListPath.string());
	try
	{
		zen::WriteFile(PListPath, IoBuffer(IoBuffer::Wrap, PList.data(), PList.size()));
	}
	catch (const std::system_error& Ex)
	{
		return MakeErrorCode(Ex.code().value());
	}

	ZEN_INFO("Changing permissions to 644 for {}", PListPath.string());
	if (chmod(PListPath.string().c_str(), 0644) == -1)
	{
		return MakeErrorCodeFromLastError();
	}
	return {};
}

std::error_code
UninstallService(std::string_view ServiceName)
{
	const std::string			DaemonName = GetDaemonName(ServiceName);
	const std::filesystem::path PListPath  = GetPListPath(DaemonName);
	ZEN_INFO("Attempting to remove launchd plist from {}", PListPath.string());
	std::error_code Ec;
	std::filesystem::remove(PListPath, Ec);
	return Ec;
}

std::error_code
QueryInstalledService(std::string_view ServiceName, ServiceInfo& OutInfo)
{
	OutInfo.Status				 = ServiceStatus::NotInstalled;
	const std::string DaemonName = GetDaemonName(ServiceName);

	const std::filesystem::path PListPath = GetPListPath(DaemonName);
	if (std::filesystem::is_regular_file(PListPath))
	{
		OutInfo.Status = ServiceStatus::Stopped;

		{
			// Parse plist :(
			IoBuffer	Buffer = ReadFile(PListPath).Flatten();
			MemoryView	Data   = Buffer.GetView();
			std::string PList((const char*)Data.GetData(), Data.GetSize());

			enum class ParseMode
			{
				None,
				ExpectingProgramArgumentsArray,
				ExpectingProgramExecutablePath,
				ExpectingCommandLineOption
			};

			ParseMode Mode = ParseMode::None;

			ForEachStrTok(PList, '\n', [&](std::string_view Line) {
				switch (Mode)
				{
					case ParseMode::None:
						{
							if (Line.find("<key>ProgramArguments</key>") != std::string_view::npos)
							{
								Mode = ParseMode::ExpectingProgramArgumentsArray;
								return true;
							}
						}
						break;
					case ParseMode::ExpectingProgramArgumentsArray:
						{
							if (Line.find("<array>") != std::string_view::npos)
							{
								Mode = ParseMode::ExpectingProgramExecutablePath;
								return true;
							}
							Mode = ParseMode::None;
						}
						break;
					case ParseMode::ExpectingProgramExecutablePath:
						{
							if (std::string_view::size_type ArgStart = Line.find("<string>"); ArgStart != std::string_view::npos)
							{
								ArgStart += 8;
								if (std::string_view::size_type ArgEnd = Line.find("</string>", ArgStart); ArgEnd != std::string_view::npos)
								{
									std::string_view ProgramString = Line.substr(ArgStart, ArgEnd - ArgStart);
									OutInfo.Spec.ExecutablePath	   = ProgramString;
									Mode						   = ParseMode::ExpectingCommandLineOption;
									return true;
								}
							}
							Mode = ParseMode::None;
						}
						break;
					case ParseMode::ExpectingCommandLineOption:
						{
							if (std::string_view::size_type ArgStart = Line.find("</array>"); ArgStart != std::string_view::npos)
							{
								Mode = ParseMode::None;
								return true;
							}
							else if (std::string_view::size_type ArgStart = Line.find("<string>"); ArgStart != std::string_view::npos)
							{
								ArgStart += 8;
								if (std::string_view::size_type ArgEnd = Line.find("</string>", ArgStart); ArgEnd != std::string_view::npos)
								{
									std::string_view ArgumentString = Line.substr(ArgStart, ArgEnd - ArgStart);
									if (!OutInfo.Spec.CommandLineOptions.empty())
									{
										OutInfo.Spec.CommandLineOptions += " ";
									}
									OutInfo.Spec.CommandLineOptions += ArgumentString;
									return true;
								}
							}
							Mode = ParseMode::None;
						}
						break;
				}
				return true;
			});
		}
		{
			std::pair<int, std::string> Res = ExecuteProgram(fmt::format("launchctl list {}", DaemonName));
			if (Res.first == 0 && !Res.second.empty())
			{
				ForEachStrTok(Res.second, '\n', [&](std::string_view Line) {
					if (Line.find("\"PID\"") != std::string_view::npos)
					{
						std::string_view::size_type PidStart  = Line.find('=');
						std::string_view::size_type PidEnd	  = Line.find(';');
						std::string_view			PidString = Line.substr(PidStart + 2, PidEnd - (PidStart + 2));
						if (ParseInt<int>(PidString).has_value())
						{
							OutInfo.Status = ServiceStatus::Running;
						}
						return false;
					}
					return true;
				});
				// Parse installed info
			}
		}
	}

	return {};
}

std::error_code
StartService(std::string_view ServiceName)
{
	const std::string			DaemonName = GetDaemonName(ServiceName);
	const std::filesystem::path PListPath  = GetPListPath(DaemonName);

	std::pair<int, std::string> Res = ExecuteProgram(fmt::format("launchctl bootstrap system {}", PListPath));
	if (Res.first != 0)
	{
		return MakeErrorCode(Res.first);
	}

	return {};
}

std::error_code
StopService(std::string_view ServiceName)
{
	const std::string			DaemonName = GetDaemonName(ServiceName);
	const std::filesystem::path PListPath  = GetPListPath(DaemonName);

	/*
	std::pair<int, std::string> Res = ExecuteProgram(fmt::format("launchctl bootout system ", PListPath.));
	if (Res.first != 0)
	{
		return MakeErrorCode(Res.first);
	}
	*/

	return {};
}

#endif	// ZEN_PLATFORM_MAC

#if ZEN_PLATFORM_LINUX

std::error_code
InstallService(std::string_view ServiceName, const ServiceSpec& Spec)
{
	const std::string			UnitName		= GetUnitName(ServiceName);
	const std::filesystem::path ServiceUnitPath = GetServiceUnitPath(UnitName);
	std::string					UserName		= Spec.UserName;

	if (UserName == "")
	{
		std::pair<int, std::string> UserResult = ExecuteProgram("echo $SUDO_USER");
		if (UserResult.first != 0 || UserResult.second.empty())
		{
			ZEN_ERROR("Unable to determine current user");
			return MakeErrorCode(UserResult.first);
		}

		UserName = UserResult.second;
	}

	std::string UnitFile = BuildUnitFile(ServiceName, Spec.ExecutablePath, Spec.CommandLineOptions, UserName);
	ZEN_DEBUG("Writing systemd unit file to {}", ServiceUnitPath.string());
	try
	{
		zen::WriteFile(ServiceUnitPath, IoBuffer(IoBuffer::Wrap, UnitFile.data(), UnitFile.size()));
	}
	catch (const std::system_error& Ex)
	{
		return MakeErrorCode(Ex.code().value());
	}

	ZEN_DEBUG("Changing permissions to 644 for {}", ServiceUnitPath.string());
	if (chmod(ServiceUnitPath.string().c_str(), 0644) == -1)
	{
		return MakeErrorCodeFromLastError();
	}

	std::pair<int, std::string> Res = ExecuteProgram("systemctl daemon-reload");
	if (Res.first != 0 && Res.first != -1)
	{
		ZEN_ERROR("systemctl daemon-reload failed with {}: '{}'", Res.first, Res.second);
		return MakeErrorCode(Res.first);
	}

	Res = ExecuteProgram(fmt::format("systemctl enable {}", UnitName));
	if (Res.first != 0 && Res.first != -1)
	{
		ZEN_ERROR("systemctl enable failed with {}: '{}'", Res.first, Res.second);
		return MakeErrorCode(Res.first);
	}

	return {};
}

std::error_code
UninstallService(std::string_view ServiceName)
{
	const std::string			UnitName		= GetUnitName(ServiceName);
	const std::filesystem::path ServiceUnitPath = GetServiceUnitPath(UnitName);

	std::pair<int, std::string> Res = ExecuteProgram(fmt::format("systemctl disable {}", UnitName));
	if (Res.first != 0 && Res.first != -1)
	{
		ZEN_ERROR("systemctl disable failed with {}: '{}'", Res.first, Res.second);
		return MakeErrorCode(Res.first);
	}

	ZEN_DEBUG("Attempting to remove systemd unit file from {}", ServiceUnitPath.string());
	std::error_code Ec;
	std::filesystem::remove(ServiceUnitPath, Ec);
	if (Ec)
	{
		ZEN_ERROR("failed to remove {}: '{}'", ServiceUnitPath, Ec.message());
		return Ec;
	}

	Res = ExecuteProgram("systemctl daemon-reload");
	if (Res.first != 0 && Res.first != -1)
	{
		ZEN_ERROR("systemctl daemon-reload failed with {}: '{}'", Res.first, Res.second);
		return MakeErrorCode(Res.first);
	}

	return {};
}

std::error_code
QueryInstalledService(std::string_view ServiceName, ServiceInfo& OutInfo)
{
	const std::string			UnitName		= GetUnitName(ServiceName);
	const std::filesystem::path ServiceUnitPath = GetServiceUnitPath(UnitName);

	OutInfo.Status = ServiceStatus::NotInstalled;

	if (std::filesystem::is_regular_file(ServiceUnitPath))
	{
		OutInfo.Status = ServiceStatus::Stopped;

		std::pair<int, std::string> Res = ExecuteProgram(fmt::format("systemctl is-active --quiet {}", UnitName));
		if (Res.first == 0)
		{
			OutInfo.Status = ServiceStatus::Running;

			std::pair<int, std::string> ShowResult = ExecuteProgram(fmt::format("systemctl show -p ExecStart {}", UnitName));
			if (ShowResult.first == 0)
			{
				std::regex	Regex(R"~(ExecStart=\{ path=(.*?) ; argv\[\]=(.*?) ;)~");
				std::smatch Match;

				if (std::regex_search(ShowResult.second, Match, Regex))
				{
					std::string Executable			= Match[1].str();
					std::string CommandLine			= Match[2].str();
					OutInfo.Spec.ExecutablePath		= Executable;
					OutInfo.Spec.CommandLineOptions = CommandLine.substr(Executable.size(), CommandLine.size());
				}
				else
				{
					ZEN_WARN("Failed to parse output of systemctl show: {}", ShowResult.second);
				}
			}
			else
			{
				ZEN_WARN("Failed to read start info from systemctl: error code {}", ShowResult.first);
			}
		}
		else
		{
			ZEN_DEBUG("systemctl status failed with '{}'({})", Res.second, Res.first);
		}
	}

	return {};
}

std::error_code
StartService(std::string_view ServiceName)
{
	// TODO: Starting the service returns -1 from ExecuteProgram, so the service won't start
	// TODO: Running start from command line gives no output but the service does not start - not sure what is wrong.
	// Starting the same command line for the service using `sudo` *will* start the service sucessfully so I
	// assume that the Unit file or some config is wrong/missing.

	const std::string			UnitName		= GetUnitName(ServiceName);
	const std::filesystem::path ServiceUnitPath = GetServiceUnitPath(UnitName);

	std::pair<int, std::string> Res = ExecuteProgram(fmt::format("systemctl start {}", UnitName));
	if (Res.first != 0)
	{
		ZEN_ERROR("service start failed with {}: '{}'", Res.first, Res.second);
		return MakeErrorCode(Res.first);
	}

	return {};
}

std::error_code
StopService(std::string_view ServiceName)
{
	// TODO: Stopping the service returns -1 from ExecuteProgram, maybe this ie expected as I have yet to successfully start the service
	// using systemctl start

	const std::string			UnitName		= GetUnitName(ServiceName);
	const std::filesystem::path ServiceUnitPath = GetServiceUnitPath(UnitName);

	std::pair<int, std::string> Res = ExecuteProgram(fmt::format("systemctl stop {}", UnitName));
	if (Res.first != 0)
	{
		ZEN_ERROR("service stop failed with {}: '{}'", Res.first, Res.second);
		return MakeErrorCode(Res.first);
	}

	return {};
}

#endif	// ZEN_PLATFORM_LINUX

}  // namespace zen