//
// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) Contributors to the OpenEXR Project.
//

//-----------------------------------------------------------------------------
//
//	class Semaphore -- implementation for Windows
//
//-----------------------------------------------------------------------------

#include "IlmThreadSemaphore.h"

#if ILMTHREAD_SEMAPHORE_WINDOWS

#include "Iex.h"
#include <assert.h>
#include <iostream>
#include <string>

ILMTHREAD_INTERNAL_NAMESPACE_SOURCE_ENTER

using namespace IEX_NAMESPACE;

namespace
{

std::string
errorString ()
{
    LPSTR       messageBuffer;
    DWORD       bufferLength;
    std::string message;

    //
    // Call FormatMessage() to allow for message
    // text to be acquired from the system.
    //

    if (bufferLength = FormatMessageA (
            FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_IGNORE_INSERTS |
                FORMAT_MESSAGE_FROM_SYSTEM,
            0,
            GetLastError (),
            MAKELANGID (LANG_NEUTRAL, SUBLANG_DEFAULT),
            (LPSTR) &messageBuffer,
            0,
            NULL))
    {
        message = messageBuffer;
        LocalFree (messageBuffer);
    }

    return message;
}

} // namespace

Semaphore::Semaphore (unsigned int value)
{
    if ((_semaphore = ::CreateSemaphore (0, value, 0x7fffffff, 0)) == 0)
    {
        THROW (
            LogicExc,
            "Could not create semaphore "
            "(" << errorString ()
                << ").");
    }
}

Semaphore::~Semaphore ()
{
    bool ok = ::CloseHandle (_semaphore) != FALSE;
    assert (ok);
}

void
Semaphore::wait ()
{
    if (::WaitForSingleObject (_semaphore, INFINITE) != WAIT_OBJECT_0)
    {
        THROW (
            LogicExc,
            "Could not wait on semaphore "
            "(" << errorString ()
                << ").");
    }
}

bool
Semaphore::tryWait ()
{
    return ::WaitForSingleObject (_semaphore, 0) == WAIT_OBJECT_0;
}

void
Semaphore::post ()
{
    if (!::ReleaseSemaphore (_semaphore, 1, 0))
    {
        THROW (
            LogicExc,
            "Could not post on semaphore "
            "(" << errorString ()
                << ").");
    }
}

int
Semaphore::value () const
{
    LONG v = -1;

    if (!::ReleaseSemaphore (_semaphore, 0, &v) || v < 0)
    {
        THROW (
            LogicExc,
            "Could not get value of semaphore "
            "(" << errorString ()
                << ").");
    }

    return v;
}

ILMTHREAD_INTERNAL_NAMESPACE_SOURCE_EXIT

#endif // ILMTHREAD_SEMAPHORE_WINDOWS

