#include "BsGLTimerQuery.h"
#include "BsMath.h"
#include "BsRenderStats.h"

namespace BansheeEngine
{
	GLTimerQuery::GLTimerQuery()
		:mQueryStartObj(0), mQueryEndObj(0), 
		mTimeDelta(0.0f), mFinalized(false), mEndIssued(false)
	{
		GLuint queries[2];
		glGenQueries(2, queries);

		mQueryStartObj = queries[0];
		mQueryEndObj = queries[1];

		BS_INC_RENDER_STAT_CAT(ResCreated, RenderStatObject_Query);
	}

	GLTimerQuery::~GLTimerQuery()
	{
		GLuint queries[2];
		queries[0] = mQueryStartObj;
		queries[1] = mQueryEndObj;

		glDeleteQueries(2, queries);

		BS_INC_RENDER_STAT_CAT(ResDestroyed, RenderStatObject_Query);
	}

	void GLTimerQuery::begin()
	{
		glQueryCounter(mQueryStartObj, GL_TIMESTAMP);

		setActive(true);
		mEndIssued = false;
	}

	void GLTimerQuery::end()
	{
		glQueryCounter(mQueryEndObj, GL_TIMESTAMP);

		mEndIssued = true;
		mFinalized = false;
	}

	bool GLTimerQuery::isReady() const
	{
		if (!mEndIssued)
			return false;

		GLint done = 0;
		glGetQueryObjectiv(mQueryEndObj, GL_QUERY_RESULT_AVAILABLE, &done);

		return done == GL_TRUE;
	}

	float GLTimerQuery::getTimeMs() 
	{
		if(!mFinalized && isReady())
		{
			finalize();
		}

		return mTimeDelta;
	}

	void GLTimerQuery::finalize()
	{
		mFinalized = true;

		GLuint64 timeStart;
		GLuint64 timeEnd;

		glGetQueryObjectui64v(mQueryStartObj, GL_QUERY_RESULT, &timeStart);
		glGetQueryObjectui64v(mQueryEndObj, GL_QUERY_RESULT, &timeEnd);

		mTimeDelta = (timeEnd - timeStart) / 1000000.0f;
	}
}