#include <cstring>
#include "anki/gl/BufferObject.h"
#include "anki/gl/GlException.h"
#include "anki/util/Exception.h"

namespace anki {

//==============================================================================

const thread_local BufferObject* BufferObject::lastBindedBo = nullptr;

//==============================================================================
BufferObject::~BufferObject()
{
	if(isCreated())
	{
		destroy();
	}
}

//==============================================================================
void BufferObject::create(GLenum target_, uint sizeInBytes_,
	const void* dataPtr, GLenum usage_)
{
	ANKI_ASSERT(!isCreated());

	ANKI_ASSERT(usage_ == GL_STREAM_DRAW
		|| usage_ == GL_STATIC_DRAW
		|| usage_ == GL_DYNAMIC_DRAW);

	ANKI_ASSERT(sizeInBytes_ > 0 && "Unacceptable sizeInBytes");

	usage = usage_;
	target = target_;
	sizeInBytes = sizeInBytes_;

	glGenBuffers(1, &glId);
	bind();
	glBufferData(target, sizeInBytes, dataPtr, usage);

	// make a check
	int bufferSize = 0;
	glGetBufferParameteriv(target, GL_BUFFER_SIZE, &bufferSize);
	if(sizeInBytes != (uint)bufferSize)
	{
		destroy();
		throw ANKI_EXCEPTION("Data size mismatch");
	}

	unbind();
	ANKI_CHECK_GL_ERROR();
}

//==============================================================================
void BufferObject::write(void* buff)
{
	ANKI_ASSERT(isCreated());
	ANKI_ASSERT(usage != GL_STATIC_DRAW);
	bind();
	void* mapped = glMapBuffer(target, GL_WRITE_ONLY);
	memcpy(mapped, buff, sizeInBytes);
	glUnmapBuffer(target);
	unbind();
}

//==============================================================================
void BufferObject::write(void* buff, size_t offset, size_t size)
{
	ANKI_ASSERT(isCreated());
	ANKI_ASSERT(usage != GL_STATIC_DRAW);
	ANKI_ASSERT(offset + size <= sizeInBytes);
	bind();
	void* mapped = glMapBufferRange(target, offset, size, GL_MAP_WRITE_BIT);
	memcpy(mapped, buff, size);
	glUnmapBuffer(target);
	unbind();
}

} // end namespace