#include "InputFrameTexture.h"

#include <chrono>

InputFrameTexture::~InputFrameTexture()
{
	ShutdownGl();
}

GLuint InputFrameTexture::PollAndUpload(InputFrameMailbox* mailbox)
{
	if (mailbox == nullptr)
		return mTexture;

	InputFrame frame;
	if (!mailbox->TryAcquireLatest(frame))
	{
		++mUploadMisses;
		mLastUploadMilliseconds = 0.0;
		return mTexture;
	}

	if (frame.bytes != nullptr && frame.pixelFormat == VideoIOPixelFormat::Bgra8 && EnsureTexture(frame))
	{
		mLastFrameFormatSupported = true;
		const auto uploadStart = std::chrono::steady_clock::now();
		UploadBgra8FrameFlippedVertically(frame);
		const auto uploadEnd = std::chrono::steady_clock::now();
		mLastUploadMilliseconds = std::chrono::duration_cast<std::chrono::duration<double, std::milli>>(uploadEnd - uploadStart).count();
		++mUploadedFrames;
	}
	else
	{
		mLastFrameFormatSupported = frame.pixelFormat == VideoIOPixelFormat::Bgra8;
		mLastUploadMilliseconds = 0.0;
	}

	mailbox->Release(frame);
	return mTexture;
}

void InputFrameTexture::ShutdownGl()
{
	if (mTexture != 0)
		glDeleteTextures(1, &mTexture);
	mTexture = 0;
	mWidth = 0;
	mHeight = 0;
}

bool InputFrameTexture::EnsureTexture(const InputFrame& frame)
{
	if (frame.width == 0 || frame.height == 0)
		return false;

	if (mTexture != 0 && mWidth == frame.width && mHeight == frame.height)
		return true;

	ShutdownGl();
	glGenTextures(1, &mTexture);
	glBindTexture(GL_TEXTURE_2D, mTexture);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexImage2D(
		GL_TEXTURE_2D,
		0,
		GL_RGBA8,
		static_cast<GLsizei>(frame.width),
		static_cast<GLsizei>(frame.height),
		0,
		GL_BGRA,
		GL_UNSIGNED_INT_8_8_8_8_REV,
		nullptr);
	glBindTexture(GL_TEXTURE_2D, 0);

	mWidth = frame.width;
	mHeight = frame.height;
	return mTexture != 0;
}

void InputFrameTexture::UploadBgra8FrameFlippedVertically(const InputFrame& frame)
{
	glBindTexture(GL_TEXTURE_2D, mTexture);
	glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
	glPixelStorei(GL_UNPACK_ROW_LENGTH, frame.rowBytes > 0 ? static_cast<GLint>(frame.rowBytes / 4) : 0);

	const unsigned char* sourceBytes = static_cast<const unsigned char*>(frame.bytes);
	for (unsigned destinationY = 0; destinationY < frame.height; ++destinationY)
	{
		const unsigned sourceY = frame.height - 1u - destinationY;
		const unsigned char* sourceRow = sourceBytes + static_cast<std::size_t>(sourceY) * static_cast<std::size_t>(frame.rowBytes);
		glTexSubImage2D(
			GL_TEXTURE_2D,
			0,
			0,
			static_cast<GLint>(destinationY),
			static_cast<GLsizei>(frame.width),
			1,
			GL_BGRA,
			GL_UNSIGNED_INT_8_8_8_8_REV,
			sourceRow);
	}

	glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
	glBindTexture(GL_TEXTURE_2D, 0);
}