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

#include <zencore/thread.h>

#include <fmt/format.h>
#include <zencore/except.h>
#include <zencore/string.h>
#include <zencore/windows.h>
#include <thread>

namespace zen {

void
RwLock::AcquireShared()
{
	AcquireSRWLockShared((PSRWLOCK)&m_Srw);
}

void
RwLock::ReleaseShared()
{
	ReleaseSRWLockShared((PSRWLOCK)&m_Srw);
}

void
RwLock::AcquireExclusive()
{
	AcquireSRWLockExclusive((PSRWLOCK)&m_Srw);
}

void
RwLock::ReleaseExclusive()
{
	ReleaseSRWLockExclusive((PSRWLOCK)&m_Srw);
}

Event::Event()
{
	m_EventHandle = CreateEvent(nullptr, true, false, nullptr);
}

Event::~Event()
{
	CloseHandle(m_EventHandle);
}

void
Event::Set()
{
	SetEvent(m_EventHandle);
}

void
Event::Reset()
{
	ResetEvent(m_EventHandle);
}

bool
Event::Wait(int TimeoutMs)
{
	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);
}

NamedEvent::NamedEvent(std::u8string_view EventName) : Event(nullptr)
{
	using namespace std::literals;

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

	m_EventHandle = CreateEventA(nullptr, true, false, Name.c_str());
}

NamedEvent::NamedEvent(std::string_view EventName) : Event(nullptr)
{
	using namespace std::literals;

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

	m_EventHandle = CreateEventA(nullptr, true, false, Name.c_str());
}

NamedMutex::~NamedMutex()
{
	if (m_MutexHandle)
	{
		CloseHandle(m_MutexHandle);
	}
}

bool
NamedMutex::Create(std::string_view MutexName)
{
	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;
}

bool
NamedMutex::Exists(std::string_view MutexName)
{
	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;
}

ProcessHandle::ProcessHandle() = default;

void
ProcessHandle::Initialize(void* ProcessHandle)
{
	ZEN_ASSERT(m_ProcessHandle == nullptr);
	// TODO: perform some debug verification here to verify it's a valid handle?
	m_ProcessHandle = ProcessHandle;
}

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

void
ProcessHandle::Initialize(int Pid)
{
	ZEN_ASSERT(m_ProcessHandle == nullptr);
	m_ProcessHandle = OpenProcess(PROCESS_QUERY_INFORMATION | SYNCHRONIZE, FALSE, Pid);

	using namespace fmt::literals;

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

	m_Pid = Pid;
}

bool
ProcessHandle::IsRunning() const
{
	DWORD ExitCode = 0;
	GetExitCodeProcess(m_ProcessHandle, &ExitCode);

	return ExitCode == STILL_ACTIVE;
}

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

void
ProcessHandle::Terminate(int ExitCode)
{
	if (IsRunning())
	{
		TerminateProcess(m_ProcessHandle, ExitCode);
	}

	DWORD WaitResult = WaitForSingleObject(m_ProcessHandle, INFINITE);

	if (WaitResult != WAIT_OBJECT_0)
	{
		// What might go wrong here, and what is meaningful to act on?
	}
}

void
ProcessHandle::Reset()
{
	if (IsValid())
	{
		CloseHandle(m_ProcessHandle);
		m_ProcessHandle = nullptr;
	}
}

bool
ProcessHandle::Wait(int TimeoutMs)
{
	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:
			// What might go wrong here, and what is meaningful to act on?
			throw WindowsException("Process::Wait failed");
	}

	return false;
}

bool
IsProcessRunning(int pid)
{
	HANDLE hProc = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, FALSE, pid);

	if (hProc == NULL)
	{
		return false;
	}

	CloseHandle(hProc);

	return true;
}

int
GetCurrentProcessId()
{
	return ::GetCurrentProcessId();
}

void
Sleep(int ms)
{
	::Sleep(ms);
}

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

void
thread_forcelink()
{
}

}  // namespace zen