#ifndef WIN32
#include <errno.h>
#include <time.h>
#endif

#include "GLTB/exception.h"
#include "GLTB/semaphore.h"


namespace gltb {

	Semaphore::Semaphore(int maxCount, int initialCount)
	{
#ifdef WIN32
		semaphoreHandle=CreateSemaphore(NULL,initialCount,maxCount,NULL);
		if(semaphoreHandle==NULL) {
			int error=GetLastError();
			throw Exception("CreateSemaphore failed","Semaphore::Semaphore()");
		}
#else
		if(sem_init(&semaphore, 0, initialCount) != 0) {
			throw Exception("sem_init() failed", "Semaphore::Semaphore()");
		}
#endif
	}

	Semaphore::~Semaphore()
	{
#ifdef WIN32
		CloseHandle(semaphoreHandle);
#else
		sem_destroy(&semaphore);
#endif
	}

	void Semaphore::signal()
	{
#ifdef WIN32
		ReleaseSemaphore(semaphoreHandle, 1, NULL);
#else
		if(sem_post(&semaphore) != 0) {
			throw Exception("sem_post() failed", "Semaphore::signal()");
		}
#endif
	}

	void Semaphore::wait()
	{
#ifdef WIN32
		int result=WaitForSingleObject(semaphoreHandle, INFINITE);

		if(result==WAIT_FAILED) {
			int error=GetLastError();
			throw Exception("WaitForSingleObject failed","Semaphore::wait()");
		}
#else
		if(sem_wait(&semaphore) != 0) {
			throw Exception("sem_wait() failed", "Semaphore::wait()");
		}
#endif
	}

	bool Semaphore::wait(int timeout)
	{
#ifdef WIN32
		int result=WaitForSingleObject(semaphoreHandle,timeout);

		switch(result) {
		case WAIT_OBJECT_0:
			return true;
		case WAIT_ABANDONED:
			return true;
		case WAIT_TIMEOUT:
			return false;
		case WAIT_FAILED:
			int error=GetLastError();
			throw Exception("WaitForSingleObject failed","Semaphore::wait()");
		}

		return false;
#else
		timespec time;
		clock_gettime(CLOCK_REALTIME,&time);

		time.tv_nsec+=timeout*1000000;
		while(time.tv_nsec>1000000000) { // correct nanoseconds overflow
			time.tv_sec++;
			time.tv_nsec-=1000000000;
		}

		int result;
		while((result = sem_timedwait(&semaphore, &time)) != 0) {
			if(errno == ETIMEDOUT) {
				return false;
			} else {
				throw Exception("sem_timedwait() failed", "Semaphore::wait()");
			}
		}

		return true;
#endif
	}

	RefPtr<Semaphore> Semaphore::createSemaphore(int maxCount, int initialCount)
	{
		return new Semaphore(maxCount,initialCount);
	}
}