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

#include <zencore/thread.h>

#include <zencore/except.h>
#include <zencore/filesystem.h>
#include <zencore/scopeguard.h>
#include <zencore/string.h>
#include <zencore/testing.h>

#if ZEN_PLATFORM_WINDOWS
#	include <shellapi.h>
#	include <Shlobj.h>
#	include <zencore/windows.h>
#elif ZEN_PLATFORM_LINUX
#	include <chrono>
#	include <condition_variable>
#	include <mutex>

#	include <fcntl.h>
#	include <mqueue.h>
#	include <pthread.h>
#	include <signal.h>
#	include <sys/file.h>
#	include <time.h>
#	include <unistd.h>
#endif

#include <thread>

ZEN_THIRD_PARTY_INCLUDES_START
#include <fmt/format.h>
ZEN_THIRD_PARTY_INCLUDES_END

namespace zen {

#if ZEN_PLATFORM_WINDOWS
// The information on how to set the thread name comes from
// a MSDN article: http://msdn2.microsoft.com/en-us/library/xcb2z8hs.aspx
const DWORD kVCThreadNameException = 0x406D1388;
typedef struct tagTHREADNAME_INFO
{
	DWORD  dwType;		// Must be 0x1000.
	LPCSTR szName;		// Pointer to name (in user addr space).
	DWORD  dwThreadID;	// Thread ID (-1=caller thread).
	DWORD  dwFlags;		// Reserved for future use, must be zero.
} THREADNAME_INFO;
// The SetThreadDescription API was brought in version 1607 of Windows 10.
typedef HRESULT(WINAPI* SetThreadDescription)(HANDLE hThread, PCWSTR lpThreadDescription);
// This function has try handling, so it is separated out of its caller.
void
SetNameInternal(DWORD thread_id, const char* name)
{
	THREADNAME_INFO info;
	info.dwType		= 0x1000;
	info.szName		= name;
	info.dwThreadID = thread_id;
	info.dwFlags	= 0;
	__try
	{
		RaiseException(kVCThreadNameException, 0, sizeof(info) / sizeof(DWORD), reinterpret_cast<DWORD_PTR*>(&info));
	}
	__except (EXCEPTION_CONTINUE_EXECUTION)
	{
	}
}
#endif

void
SetCurrentThreadName([[maybe_unused]] std::string_view ThreadName)
{
#if ZEN_PLATFORM_WINDOWS
	// The SetThreadDescription API works even if no debugger is attached.
	static auto SetThreadDescriptionFunc =
		reinterpret_cast<SetThreadDescription>(::GetProcAddress(::GetModuleHandle(L"Kernel32.dll"), "SetThreadDescription"));

	if (SetThreadDescriptionFunc)
	{
		SetThreadDescriptionFunc(::GetCurrentThread(), Utf8ToWide(ThreadName).c_str());
	}
	// The debugger needs to be around to catch the name in the exception.  If
	// there isn't a debugger, we are just needlessly throwing an exception.
	if (!::IsDebuggerPresent())
		return;

	std::string ThreadNameZ{ThreadName};
	SetNameInternal(GetCurrentThreadId(), ThreadNameZ.c_str());
#else
	std::string ThreadNameZ{ThreadName};
	pthread_setname_np(pthread_self(), ThreadNameZ.c_str());
#endif
}  // namespace zen

void
RwLock::AcquireShared()
{
	m_Mutex.lock_shared();
}

void
RwLock::ReleaseShared()
{
	m_Mutex.unlock_shared();
}

void
RwLock::AcquireExclusive()
{
	m_Mutex.lock();
}

void
RwLock::ReleaseExclusive()
{
	m_Mutex.unlock();
}

//////////////////////////////////////////////////////////////////////////

#if !ZEN_PLATFORM_WINDOWS
struct EventInner
{
	std::mutex				Mutex;
	std::condition_variable	CondVar;
	bool volatile			bSet		= false;
};
#endif // !ZEN_PLATFORM_WINDOWS

Event::Event()
{
	bool bManualReset = true;
	bool bInitialState = false;

#if ZEN_PLATFORM_WINDOWS
	m_EventHandle = CreateEvent(nullptr, bManualReset, bInitialState, nullptr);
#else
	ZEN_UNUSED(bManualReset);
	auto* Inner = new EventInner();
	Inner->bSet = bInitialState;
	m_EventHandle = Inner;
#endif
}

Event::~Event()
{
	Close();
}

void
Event::Set()
{
#if ZEN_PLATFORM_WINDOWS
	SetEvent(m_EventHandle);
#else
	auto* Inner = (EventInner*)m_EventHandle;
	{
		std::unique_lock Lock(Inner->Mutex);
		Inner->bSet = true;
	}
	Inner->CondVar.notify_all();
#endif
}

void
Event::Reset()
{
#if ZEN_PLATFORM_WINDOWS
	ResetEvent(m_EventHandle);
#else
	auto* Inner = (EventInner*)m_EventHandle;
	{
		std::unique_lock Lock(Inner->Mutex);
		Inner->bSet = false;
	}
#endif
}

void
Event::Close()
{
#if ZEN_PLATFORM_WINDOWS
	CloseHandle(m_EventHandle);
#else
	auto* Inner = (EventInner*)m_EventHandle;
	delete Inner;
#endif
	m_EventHandle = nullptr;
}

bool
Event::Wait(int TimeoutMs)
{
#if ZEN_PLATFORM_WINDOWS
	using namespace std::literals;

	const DWORD Timeout = (TimeoutMs < 0) ? INFINITE : TimeoutMs;

	DWORD Result = WaitForSingleObject(m_EventHandle, Timeout);

	if (Result == WAIT_FAILED)
	{
		zen::ThrowLastError("Event wait failed"sv);
	}

	return (Result == WAIT_OBJECT_0);
#else
	auto* Inner = (EventInner*)m_EventHandle;

	if (TimeoutMs >= 0)
	{
		std::unique_lock Lock(Inner->Mutex);

		if (Inner->bSet)
		{
			return true;
		}

		return Inner->CondVar.wait_for(
			Lock,
			std::chrono::milliseconds(TimeoutMs),
			[&] { return Inner->bSet; }
		);
	}

	std::unique_lock Lock(Inner->Mutex);

	if (!Inner->bSet)
	{
		Inner->CondVar.wait(Lock, [&] { return Inner->bSet; });
	}

	return true;
#endif
}

//////////////////////////////////////////////////////////////////////////

#if ZEN_PLATFORM_LINUX
static bool IsThereAMessageInQueue(int Fd)
{
	// Check if there is already a message in the queue.
	mq_attr Attributes = { O_NONBLOCK, 1, 1, 0 };
	mq_getattr(Fd, &Attributes);
	return (Attributes.mq_curmsgs > 0);
}
#endif // ZEN_PLATFORM_LINUX



NamedEvent::NamedEvent(std::string_view EventName)
{
#if ZEN_PLATFORM_WINDOWS
	using namespace std::literals;

	ExtendableStringBuilder<64> Name;
	Name << "Local\\"sv;
	Name << EventName;

	m_EventHandle = CreateEventA(nullptr, true, false, Name.c_str());
#elif ZEN_PLATFORM_LINUX
	ExtendableStringBuilder<64> Name;
	Name << "/";
	Name << EventName;

	mq_attr Attributes = {
		0, // flags
		1, // max message count
		1, // max message size
		0, // current messages
	};

	int Inner = mq_open(Name.c_str(), O_RDWR|O_CREAT|O_CLOEXEC, 0644, &Attributes);
	if (Inner < 0)
	{
		ThrowLastError("Failed to get message queue from mq_open()");
	}

	int LockResult = flock(Inner, LOCK_EX|LOCK_NB);
	if (LockResult == 0)
	{
		ZEN_ASSERT( IsThereAMessageInQueue(Inner) == false,
					"Ownership of a non-empty '{}' message queue occurred", Name.c_str());
	}

	m_EventHandle = (void*)intptr_t(Inner);
#else
#	error Implement NamedEvent for this platform
#endif
}

NamedEvent::~NamedEvent()
{
	Close();
}

void NamedEvent::Close()
{
	if (m_EventHandle == nullptr)
	{
		return;
	}

#if ZEN_PLATFORM_WINDOWS
	CloseHandle(m_EventHandle);
#elif ZEN_PLATFORM_LINUX
	int Inner = int(intptr_t(m_EventHandle));

	if (flock(Inner, LOCK_EX|LOCK_NB) == 0)
	{
		flock(Inner, LOCK_UN|LOCK_NB);
		std::filesystem::path Name = PathFromHandle((void*)(intptr_t(Inner)));
		mq_unlink(Name.c_str());
	}

	close(Inner);
#endif

	m_EventHandle = nullptr;
}

void NamedEvent::Set()
{
#if ZEN_PLATFORM_WINDOWS
	SetEvent(m_EventHandle);
#elif ZEN_PLATFORM_LINUX
	int Inner = int(intptr_t(m_EventHandle));

	if (IsThereAMessageInQueue(Inner))
	{
		return;
	}

	char Message = 0x49;
	if (mq_send(Inner, &Message, sizeof(Message), 0) != 0)
	{
		ThrowLastError("Unable to send set message to queue");
	}

	IsThereAMessageInQueue(Inner);
#endif
}

bool NamedEvent::Wait(int TimeoutMs)
{
#if ZEN_PLATFORM_WINDOWS
	const DWORD Timeout = (TimeoutMs < 0) ? INFINITE : TimeoutMs;

	DWORD Result = WaitForSingleObject(m_EventHandle, Timeout);

	if (Result == WAIT_FAILED)
	{
		using namespace std::literals;
		zen::ThrowLastError("Event wait failed"sv);
	}

	return (Result == WAIT_OBJECT_0);
#elif ZEN_PLATFORM_LINUX
	int Inner = int(intptr_t(m_EventHandle));

	if (IsThereAMessageInQueue(Inner))
	{
		return true;
	}

	struct timeval TimeoutValue = {
		.tv_sec  = 0,
		.tv_usec = TimeoutMs << 10,
	};
	struct timeval* TimeoutPtr = (TimeoutMs < 0) ? nullptr : &TimeoutValue;

	fd_set FdSet;
	FD_ZERO(&FdSet);
	FD_SET(Inner, &FdSet);
	return select(Inner + 1, &FdSet, nullptr, nullptr, TimeoutPtr) > 0;
#endif
}

//////////////////////////////////////////////////////////////////////////

NamedMutex::~NamedMutex()
{
#if ZEN_PLATFORM_WINDOWS
	if (m_MutexHandle)
	{
		CloseHandle(m_MutexHandle);
	}
#else
	/* ZEN_TODO_MR: NamedMutex */
#endif
}

bool
NamedMutex::Create(std::string_view MutexName)
{
#if ZEN_PLATFORM_WINDOWS
	ZEN_ASSERT(m_MutexHandle == nullptr);

	using namespace std::literals;

	ExtendableStringBuilder<64> Name;
	Name << "Global\\"sv;
	Name << MutexName;

	m_MutexHandle = CreateMutexA(nullptr, /* InitialOwner */ TRUE, Name.c_str());

	return !!m_MutexHandle;
#else
	ZEN_UNUSED(MutexName);
	/* ZEN_TODO_MR: NamedMutex */
	return true;
#endif // ZEN_PLATFORM_WINDOWS
}

bool
NamedMutex::Exists(std::string_view MutexName)
{
#if ZEN_PLATFORM_WINDOWS
	using namespace std::literals;

	ExtendableStringBuilder<64> Name;
	Name << "Global\\"sv;
	Name << MutexName;

	void* MutexHandle = OpenMutexA(SYNCHRONIZE, /* InheritHandle */ FALSE, Name.c_str());

	if (MutexHandle == nullptr)
	{
		return false;
	}

	CloseHandle(MutexHandle);

	return true;
#else
	ZEN_UNUSED(MutexName);
	/* ZEN_TODO_MR: NamedMutex */
	return false;
#endif // ZEN_PLATFORM_WINDOWS
}

//////////////////////////////////////////////////////////////////////////

ProcessHandle::ProcessHandle() = default;

#if ZEN_PLATFORM_WINDOWS
void
ProcessHandle::Initialize(void* ProcessHandle)
{
	ZEN_ASSERT(m_ProcessHandle == nullptr);

	if (ProcessHandle == INVALID_HANDLE_VALUE)
	{
		ProcessHandle = nullptr;
	}

	// TODO: perform some debug verification here to verify it's a valid handle?
	m_ProcessHandle = ProcessHandle;
	m_Pid			= GetProcessId(m_ProcessHandle);
}
#endif // ZEN_PLATFORM_WINDOWS

ProcessHandle::~ProcessHandle()
{
	Reset();
}

void
ProcessHandle::Initialize(int Pid)
{
	ZEN_ASSERT(m_ProcessHandle == nullptr);

#if ZEN_PLATFORM_WINDOWS
	m_ProcessHandle = OpenProcess(PROCESS_QUERY_INFORMATION | SYNCHRONIZE, FALSE, Pid);
#elif ZEN_PLATFORM_LINUX
	if (Pid > 0)
	{
		m_ProcessHandle = (void*)(intptr_t(Pid));
	}
#else
#	error Check process control on this platform
#endif

	if (!m_ProcessHandle)
	{
		using namespace fmt::literals;
		ThrowLastError("ProcessHandle::Initialize(pid: {}) failed"_format(Pid));
	}

	m_Pid = Pid;
}

bool
ProcessHandle::IsRunning() const
{
	bool bActive = false;

#if ZEN_PLATFORM_WINDOWS
	DWORD ExitCode = 0;
	GetExitCodeProcess(m_ProcessHandle, &ExitCode);
	bActive = (ExitCode == STILL_ACTIVE);
#elif ZEN_PLATFORM_LINUX
	StringBuilder<64> ProcPath;
	ProcPath << "/proc/" << m_Pid;
	bActive = (access(ProcPath.c_str(), F_OK) != 0);
#else
#	error Check process control on this platform
#endif

	return bActive;
}

bool
ProcessHandle::IsValid() const
{
	return (m_ProcessHandle != nullptr);
}

void
ProcessHandle::Terminate(int ExitCode)
{
	if (!IsRunning())
	{
		return;
	}

	bool bSuccess = false;

#if ZEN_PLATFORM_WINDOWS
	TerminateProcess(m_ProcessHandle, ExitCode);
	DWORD WaitResult = WaitForSingleObject(m_ProcessHandle, INFINITE);
	bSuccess = (WaitResult != WAIT_OBJECT_0);
#elif ZEN_PLATFORM_LINUX
	ZEN_UNUSED(ExitCode);
	bSuccess = (kill(m_Pid, SIGKILL) == 0);
#else
#	error Check kill() on this platform
#endif

	if (!bSuccess)
	{
		// What might go wrong here, and what is meaningful to act on?
	}
}

void
ProcessHandle::Reset()
{
	if (IsValid())
	{
#if ZEN_PLATFORM_WINDOWS
		CloseHandle(m_ProcessHandle);
#endif
		m_ProcessHandle = nullptr;
		m_Pid = 0;
	}
}

bool
ProcessHandle::Wait(int TimeoutMs)
{
	using namespace std::literals;

#if ZEN_PLATFORM_WINDOWS
	const DWORD Timeout = (TimeoutMs < 0) ? INFINITE : TimeoutMs;

	const DWORD WaitResult = WaitForSingleObject(m_ProcessHandle, Timeout);

	switch (WaitResult)
	{
		case WAIT_OBJECT_0:
			return true;

		case WAIT_TIMEOUT:
			return false;

		case WAIT_FAILED:
			break;
	}
#elif ZEN_PLATFORM_LINUX
	const int SleepMs = 20;
	timespec SleepTime = { 0, SleepMs * 1000 * 1000 };
	for (int i = 0; ; i += SleepMs)
	{
		if (i >= TimeoutMs)
		{
			return false;
		}

		if (kill(m_Pid, 0) < 0)
		{
			if (zen::GetLastError() == ESRCH)
			{
				return true;
			}
			break;
		}

		nanosleep(&SleepTime, nullptr);
	}
#else
#	error Check kill() on this platform
#endif

	// What might go wrong here, and what is meaningful to act on?
	ThrowLastError("Process::Wait failed"sv);
}

//////////////////////////////////////////////////////////////////////////

static void BuildArgV(std::vector<char*>& Out, char* CommandLine)
{
	char* Cursor = CommandLine;
	while (true)
	{
		// Skip leading whitespace
		for (; *Cursor == ' '; ++Cursor);

		// Check for nullp terminator
		if (*Cursor == '\0')
		{
			break;
		}

		Out.push_back(Cursor);

		// Extract word
		int QuoteCount = 0;
		do
		{
			QuoteCount += (*Cursor == '\"');
			if (*Cursor == ' ' && !(QuoteCount & 1))
			{
				break;
			}
			++Cursor;
		}
		while (*Cursor != '\0');

		if (*Cursor == '\0')
		{
			break;
		}

		*Cursor = '\0';
		++Cursor;
	}
}

#if ZEN_PLATFORM_WINDOWS
static CreateProcResult CreateProcNormal(
	const std::filesystem::path& Executable,
	std::string_view			 CommandLine,
	const CreateProcOptions&	 Options)
{
	PROCESS_INFORMATION ProcessInfo{};
	STARTUPINFO			StartupInfo{.cb = sizeof(STARTUPINFO)};

	const bool			  InheritHandles	= false;
	void*				  Environment		= nullptr;
	LPSECURITY_ATTRIBUTES ProcessAttributes = nullptr;
	LPSECURITY_ATTRIBUTES ThreadAttributes	= nullptr;

	DWORD CreationFlags = 0;
	if (Options.Flags & CreateProcOptions::Flag_NewConsole)
	{
		CreationFlags |= CREATE_NEW_CONSOLE;
	}

	const wchar_t* WorkingDir = nullptr;
	if (Options.WorkingDirectory != nullptr)
	{
		WorkingDir = Options.WorkingDirectory->c_str();
	}

	ExtendableWideStringBuilder<256> CommandLineZ;
	CommandLineZ << CommandLine;

	BOOL Success = CreateProcessW(Executable.c_str(),
								  CommandLineZ.Data(),
								  ProcessAttributes,
								  ThreadAttributes,
								  InheritHandles,
								  CreationFlags,
								  Environment,
								  WorkingDir,
								  &StartupInfo,
								  &ProcessInfo);

	if (!Success)
	{
		return nullptr;
	}

	CloseHandle(ProcessInfo.hThread);
	return ProcessInfo.hProcess;
}

static CreateProcResult CreateProcUnelevated(
	const std::filesystem::path& Executable,
	std::string_view			 CommandLine,
	const CreateProcOptions&	 Options)
{
	/* Launches a binary with the shell as its parent. The shell (such as
	   Explorer) should be an unelevated process. */

	// No sense in using this route if we are not elevated in the first place
	if (IsUserAnAdmin() == FALSE)
	{
		return CreateProcNormal(Executable, CommandLine, Options);
	}

	// Get the users' shell process and open it for process creation
	HWND ShellWnd = GetShellWindow();
	if (ShellWnd == nullptr)
	{
		return nullptr;
	}

	DWORD ShellPid;
	GetWindowThreadProcessId(ShellWnd, &ShellPid);

	HANDLE Process = OpenProcess(PROCESS_CREATE_PROCESS, FALSE, ShellPid);
	if (Process == nullptr)
	{
		return nullptr;
	}
	auto $0 = MakeGuard([&] { CloseHandle(Process); });

	// Creating a process as a child of another process is done by setting a
	// thread-attribute list on the startup info passed to CreateProcess()
	SIZE_T AttrListSize;
	InitializeProcThreadAttributeList(nullptr, 1, 0, &AttrListSize);

	auto AttrList = (PPROC_THREAD_ATTRIBUTE_LIST)malloc(AttrListSize);
	auto $1 = MakeGuard([&] { free(AttrList); });

	if (!InitializeProcThreadAttributeList(AttrList, 1, 0, &AttrListSize))
	{
		return nullptr;
	}

	BOOL bOk = UpdateProcThreadAttribute(AttrList, 0, PROC_THREAD_ATTRIBUTE_PARENT_PROCESS,
		(HANDLE*)&Process, sizeof(Process), nullptr, nullptr);
	if (!bOk)
	{
		return nullptr;
	}

	// By this point we know we are an elevated process. It is not allowed to
	// create a process as a child of another unelevated process that share our
	// elevated console window if we have one. So we'll need to create a new one.
	uint32_t CreateProcFlags = EXTENDED_STARTUPINFO_PRESENT;
	if (GetConsoleWindow() != nullptr)
	{
		CreateProcFlags |= CREATE_NEW_CONSOLE;
	}
	else
	{
		CreateProcFlags |= DETACHED_PROCESS;
	}

	// Everything is set up now so we can proceed and launch the process
	STARTUPINFOEXW StartupInfo = {
		.StartupInfo	 = { .cb = sizeof(STARTUPINFOEXW) },
		.lpAttributeList = AttrList,
	};
	PROCESS_INFORMATION ProcessInfo = {};

	if (Options.Flags & CreateProcOptions::Flag_NewConsole)
	{
		CreateProcFlags |= CREATE_NEW_CONSOLE;
	}

	ExtendableWideStringBuilder<256> CommandLineZ;
	CommandLineZ << CommandLine;

	bOk = CreateProcessW(Executable.c_str(), CommandLineZ.Data(), nullptr, nullptr,
		FALSE, CreateProcFlags, nullptr, nullptr, &StartupInfo.StartupInfo,
		&ProcessInfo);
	if (bOk == FALSE)
	{
		return nullptr;
	}

	CloseHandle(ProcessInfo.hThread);
	return ProcessInfo.hProcess;
}

static CreateProcResult CreateProcElevated(
	const std::filesystem::path& Executable,
	std::string_view			 CommandLine,
	const CreateProcOptions&	 Options)
{
	ExtendableWideStringBuilder<256> CommandLineZ;
	CommandLineZ << CommandLine;

	SHELLEXECUTEINFO ShellExecuteInfo;
	ZeroMemory(&ShellExecuteInfo, sizeof(ShellExecuteInfo));
	ShellExecuteInfo.cbSize		  = sizeof(ShellExecuteInfo);
	ShellExecuteInfo.fMask		  = SEE_MASK_UNICODE | SEE_MASK_NOCLOSEPROCESS;
	ShellExecuteInfo.lpFile		  = Executable.c_str();
	ShellExecuteInfo.lpVerb		  = TEXT("runas");
	ShellExecuteInfo.nShow		  = SW_SHOW;
	ShellExecuteInfo.lpParameters = CommandLineZ.c_str();

	if (Options.WorkingDirectory != nullptr)
	{
		ShellExecuteInfo.lpDirectory = Options.WorkingDirectory->c_str();
	}

	if (::ShellExecuteEx(&ShellExecuteInfo))
	{
		return ShellExecuteInfo.hProcess;
	}

	return nullptr;
}
#endif // ZEN_PLATFORM_WINDOWS

CreateProcResult CreateProc(
	const std::filesystem::path& Executable,
	std::string_view			 CommandLine,
	const CreateProcOptions&	 Options)
{
#if ZEN_PLATFORM_WINDOWS
	if (Options.Flags & CreateProcOptions::Flag_Unelevated)
	{
		return CreateProcUnelevated(Executable, CommandLine, Options);
	}

	if (Options.Flags & CreateProcOptions::Flag_Elevated)
	{
		return CreateProcElevated(Executable, CommandLine, Options);
	}

	return CreateProcNormal(Executable, CommandLine, Options);
#else
	std::vector<char*> ArgV;
	std::string CommandLineZ(CommandLine);
	BuildArgV(ArgV, CommandLineZ.data());
	ArgV.push_back(nullptr);

	int ChildPid = fork();
	if (ChildPid < 0)
	{
		ThrowLastError("Failed to fork a new child process");
	}
	else if (ChildPid == 0)
	{
		if (Options.WorkingDirectory != nullptr)
		{
			chdir(Options.WorkingDirectory->c_str());
		}

		if (execv(Executable.c_str(), ArgV.data()) < 0)
		{
			ThrowLastError("Failed to exec() a new process image");
		}
	}

	return ChildPid;
#endif
}

//////////////////////////////////////////////////////////////////////////

ProcessMonitor::ProcessMonitor()
{
}

ProcessMonitor::~ProcessMonitor()
{
	RwLock::ExclusiveLockScope _(m_Lock);

	for (HandleType& Proc : m_ProcessHandles)
	{
#if ZEN_PLATFORM_WINDOWS
		CloseHandle(Proc);
#endif
		Proc = 0;
	}
}

bool
ProcessMonitor::IsRunning()
{
	RwLock::ExclusiveLockScope _(m_Lock);

	bool FoundOne = false;

	for (HandleType& Proc : m_ProcessHandles)
	{
		bool ProcIsActive;

#if ZEN_PLATFORM_WINDOWS
		DWORD ExitCode = 0;
		GetExitCodeProcess(Proc, &ExitCode);

		ProcIsActive = (ExitCode != STILL_ACTIVE);
		if (!ProcIsActive)
		{
			CloseHandle(Proc);
		}
#else
		int Pid = int(intptr_t(Proc));
		ProcIsActive = IsProcessRunning(Pid);
#endif

		if (!ProcIsActive)
		{
			Proc = 0;
		}

		// Still alive
		FoundOne |= ProcIsActive;
	}

	std::erase_if(m_ProcessHandles, [](HandleType Handle) { return Handle == 0; });

	return FoundOne;
}

void
ProcessMonitor::AddPid(int Pid)
{
	HandleType ProcessHandle;

#if ZEN_PLATFORM_WINDOWS
	ProcessHandle = OpenProcess(PROCESS_QUERY_INFORMATION | SYNCHRONIZE, FALSE, Pid);
#else
	ProcessHandle = HandleType(intptr_t(Pid));
#endif

	if (ProcessHandle)
	{
		RwLock::ExclusiveLockScope _(m_Lock);
		m_ProcessHandles.push_back(ProcessHandle);
	}
}

bool
ProcessMonitor::IsActive() const
{
	RwLock::SharedLockScope _(m_Lock);
	return m_ProcessHandles.empty() == false;
}

//////////////////////////////////////////////////////////////////////////

bool
IsProcessRunning(int pid)
{
	// This function is arguably not super useful, a pid can be re-used
	// by the OS so holding on to a pid and polling it over some time
	// period will not necessarily tell you what you probably want to know.

#if ZEN_PLATFORM_WINDOWS
	HANDLE hProc = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, FALSE, pid);

	if (!hProc)
	{
		DWORD Error = zen::GetLastError();

		if (Error == ERROR_INVALID_PARAMETER)
		{
			return false;
		}

		using namespace fmt::literals;
		ThrowSystemError(Error, "failed to open process with pid {}"_format(pid));
	}

	CloseHandle(hProc);

	return true;
#else
	char Buffer[64];
	sprintf(Buffer, "/proc/%d", pid);
	return access(Buffer, F_OK) == 0;
#endif
}

int
GetCurrentProcessId()
{
#if ZEN_PLATFORM_WINDOWS
	return ::GetCurrentProcessId();
#else
	return int(getpid());
#endif
}

int
GetCurrentThreadId()
{
#if ZEN_PLATFORM_WINDOWS
	return ::GetCurrentThreadId();
#else
	return int(gettid());
#endif
}

void
Sleep(int ms)
{
#if ZEN_PLATFORM_WINDOWS
	::Sleep(ms);
#else
	usleep(ms * 1000U);
#endif
}

//////////////////////////////////////////////////////////////////////////
//
// Testing related code follows...
//

#if ZEN_WITH_TESTS

void
thread_forcelink()
{
}

TEST_CASE("Thread")
{
	int Pid = GetCurrentProcessId();
	CHECK(Pid > 0);
	CHECK(IsProcessRunning(Pid));
}

TEST_CASE("BuildArgV")
{
	const char* Words[] = { "one", "two", "three", "four", "five" };
	struct {
		int			WordCount;
		const char* Input;
	} Cases[] = {
		{ 0, "" },
		{ 0, "  " },
		{ 1, "one" },
		{ 1, " one" },
		{ 1, "one  " },
		{ 2, "one two" },
		{ 2, " one two" },
		{ 2, "one two " },
		{ 2, " one two" },
		{ 2, "one two " },
		{ 2, "one two " },
		{ 3, "one two three" },
		{ 3, "\"one\" two \"three\"" },
		{ 5, "one two three four five" },
	};

	for (const auto& Case : Cases)
	{
		std::vector<char*> OutArgs;
		StringBuilder<64> Mutable;
		Mutable << Case.Input;
		BuildArgV(OutArgs, Mutable.Data());

		CHECK_EQ(OutArgs.size(), Case.WordCount);

		for (int i = 0, n = int(OutArgs.size()); i < n; ++i)
		{
			const char* Truth = Words[i];
			size_t TruthLen = strlen(Truth);

			const char* Candidate = OutArgs[i];
			bool bQuoted = (Candidate[0] == '\"');
			Candidate += bQuoted;

			CHECK(strncmp(Truth, Candidate, TruthLen) == 0);

			if (bQuoted)
			{
				CHECK_EQ(Candidate[TruthLen], '\"');
			}
		}
	}
}

TEST_CASE("ipc")
{
	using namespace fmt::literals;

	std::string Name = "zencore_test_event_{}"_format(GetCurrentProcessId());
	NamedEvent TestEvent(Name);

	// Timeout test
	for (uint32_t i = 0; i < 8; ++i)
	{
		bool bEventSet = TestEvent.Wait(100);
		CHECK(!bEventSet);
	}
	
	// Thread check
	std::thread Waiter = std::thread([Name] () {
		NamedEvent ReadyEvent(Name + "_ready");
		ReadyEvent.Set();

		NamedEvent TestEvent(Name);
		TestEvent.Wait(1000);
	});

	NamedEvent ReadyEvent(Name + "_ready");
	ReadyEvent.Wait();

	zen::Sleep(500);
	TestEvent.Set();

	Waiter.join();

	// Manual reset property
	for (uint32_t i = 0; i < 8; ++i)
	{
		bool bEventSet = TestEvent.Wait(100);
		CHECK(bEventSet);
	}
}

#endif // ZEN_WITH_TESTS

}  // namespace zen