#include "OpenGLRenderPass.h"

#include "GlRenderConstants.h"
#include "VideoFrameTransfer.h"

OpenGLRenderPass::OpenGLRenderPass(OpenGLRenderer& renderer) :
	mRenderer(renderer)
{
}

void OpenGLRenderPass::Render(
	bool hasInputSource,
	const std::vector<RuntimeRenderState>& layerStates,
	unsigned inputFrameWidth,
	unsigned inputFrameHeight,
	unsigned historyCap,
	const TextBindingUpdater& updateTextBinding,
	const GlobalParamsUpdater& updateGlobalParams)
{
	if (hasInputSource && mRenderer.mFastTransferExtensionAvailable)
	{
		// Signal that we're about to draw using mCaptureTexture onto mFBOTexture.
		VideoFrameTransfer::beginTextureInUse(VideoFrameTransfer::CPUtoGPU);
	}

	glDisable(GL_BLEND);
	glDisable(GL_DEPTH_TEST);
	if (hasInputSource)
	{
		RenderDecodePass(inputFrameWidth, inputFrameHeight);
	}
	else
	{
		glBindFramebuffer(GL_FRAMEBUFFER, mRenderer.mDecodeFrameBuf);
		glViewport(0, 0, inputFrameWidth, inputFrameHeight);
		glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);
	}

	if (layerStates.empty() || mRenderer.mLayerPrograms.empty())
	{
		glBindFramebuffer(GL_READ_FRAMEBUFFER, mRenderer.mDecodeFrameBuf);
		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, mRenderer.mIdFrameBuf);
		glBlitFramebuffer(0, 0, inputFrameWidth, inputFrameHeight, 0, 0, inputFrameWidth, inputFrameHeight, GL_COLOR_BUFFER_BIT, GL_LINEAR);
		glBindFramebuffer(GL_FRAMEBUFFER, mRenderer.mIdFrameBuf);
	}
	else
	{
		GLuint sourceTexture = mRenderer.mDecodedTexture;
		GLuint sourceFrameBuffer = mRenderer.mDecodeFrameBuf;
		for (std::size_t index = 0; index < layerStates.size() && index < mRenderer.mLayerPrograms.size(); ++index)
		{
			const std::size_t remaining = layerStates.size() - index;
			const bool writeToMain = (remaining % 2) == 1;
			RenderShaderProgram(
				sourceTexture,
				writeToMain ? mRenderer.mIdFrameBuf : mRenderer.mLayerTempFrameBuf,
				mRenderer.mLayerPrograms[index],
				layerStates[index],
				inputFrameWidth,
				inputFrameHeight,
				historyCap,
				updateTextBinding,
				updateGlobalParams);
			if (layerStates[index].temporalHistorySource == TemporalHistorySource::PreLayerInput)
				mRenderer.mTemporalHistory.PushPreLayerFramebuffer(layerStates[index].layerId, sourceFrameBuffer, inputFrameWidth, inputFrameHeight);
			sourceTexture = writeToMain ? mRenderer.mFBOTexture : mRenderer.mLayerTempTexture;
			sourceFrameBuffer = writeToMain ? mRenderer.mIdFrameBuf : mRenderer.mLayerTempFrameBuf;
		}
	}

	mRenderer.mTemporalHistory.PushSourceFramebuffer(mRenderer.mDecodeFrameBuf, inputFrameWidth, inputFrameHeight);

	if (hasInputSource && mRenderer.mFastTransferExtensionAvailable)
		VideoFrameTransfer::endTextureInUse(VideoFrameTransfer::CPUtoGPU);
}

void OpenGLRenderPass::RenderDecodePass(unsigned inputFrameWidth, unsigned inputFrameHeight)
{
	glBindFramebuffer(GL_FRAMEBUFFER, mRenderer.mDecodeFrameBuf);
	glViewport(0, 0, inputFrameWidth, inputFrameHeight);
	glClear(GL_COLOR_BUFFER_BIT);
	glActiveTexture(GL_TEXTURE0 + kPackedVideoTextureUnit);
	glBindTexture(GL_TEXTURE_2D, mRenderer.mCaptureTexture);
	glBindVertexArray(mRenderer.mFullscreenVAO);
	glUseProgram(mRenderer.mDecodeProgram);

	const GLint packedResolutionLocation = glGetUniformLocation(mRenderer.mDecodeProgram, "uPackedVideoResolution");
	const GLint decodedResolutionLocation = glGetUniformLocation(mRenderer.mDecodeProgram, "uDecodedVideoResolution");
	if (packedResolutionLocation >= 0)
		glUniform2f(packedResolutionLocation, static_cast<float>(inputFrameWidth / 2), static_cast<float>(inputFrameHeight));
	if (decodedResolutionLocation >= 0)
		glUniform2f(decodedResolutionLocation, static_cast<float>(inputFrameWidth), static_cast<float>(inputFrameHeight));

	glDrawArrays(GL_TRIANGLES, 0, 3);

	glUseProgram(0);
	glBindVertexArray(0);
	glBindTexture(GL_TEXTURE_2D, 0);
	glActiveTexture(GL_TEXTURE0);
}

void OpenGLRenderPass::RenderShaderProgram(
	GLuint sourceTexture,
	GLuint destinationFrameBuffer,
	LayerProgram& layerProgram,
	const RuntimeRenderState& state,
	unsigned inputFrameWidth,
	unsigned inputFrameHeight,
	unsigned historyCap,
	const TextBindingUpdater& updateTextBinding,
	const GlobalParamsUpdater& updateGlobalParams)
{
	for (LayerProgram::TextBinding& textBinding : layerProgram.textBindings)
	{
		std::string textError;
		if (!updateTextBinding(state, textBinding, textError))
			OutputDebugStringA((textError + "\n").c_str());
	}

	glBindFramebuffer(GL_FRAMEBUFFER, destinationFrameBuffer);
	glViewport(0, 0, inputFrameWidth, inputFrameHeight);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glActiveTexture(GL_TEXTURE0 + kDecodedVideoTextureUnit);
	glBindTexture(GL_TEXTURE_2D, sourceTexture);
	mRenderer.mTemporalHistory.BindSamplers(state, sourceTexture, historyCap);
	BindLayerTextureAssets(layerProgram);
	glBindVertexArray(mRenderer.mFullscreenVAO);
	glUseProgram(layerProgram.program);
	updateGlobalParams(state, mRenderer.mTemporalHistory.SourceAvailableCount(), mRenderer.mTemporalHistory.AvailableCountForLayer(state.layerId));
	glDrawArrays(GL_TRIANGLES, 0, 3);
	glUseProgram(0);
	glBindVertexArray(0);
	UnbindLayerTextureAssets(layerProgram, historyCap);
}

void OpenGLRenderPass::BindLayerTextureAssets(const LayerProgram& layerProgram)
{
	const GLuint shaderTextureBase = layerProgram.shaderTextureBase != 0 ? layerProgram.shaderTextureBase : kSourceHistoryTextureUnitBase;
	for (std::size_t index = 0; index < layerProgram.textureBindings.size(); ++index)
	{
		glActiveTexture(GL_TEXTURE0 + shaderTextureBase + static_cast<GLuint>(index));
		glBindTexture(GL_TEXTURE_2D, layerProgram.textureBindings[index].texture);
	}
	const GLuint textTextureBase = shaderTextureBase + static_cast<GLuint>(layerProgram.textureBindings.size());
	for (std::size_t index = 0; index < layerProgram.textBindings.size(); ++index)
	{
		glActiveTexture(GL_TEXTURE0 + textTextureBase + static_cast<GLuint>(index));
		glBindTexture(GL_TEXTURE_2D, layerProgram.textBindings[index].texture);
	}
	glActiveTexture(GL_TEXTURE0);
}

void OpenGLRenderPass::UnbindLayerTextureAssets(const LayerProgram& layerProgram, unsigned historyCap)
{
	for (unsigned index = 0; index < historyCap; ++index)
	{
		glActiveTexture(GL_TEXTURE0 + kSourceHistoryTextureUnitBase + index);
		glBindTexture(GL_TEXTURE_2D, 0);
		glActiveTexture(GL_TEXTURE0 + kSourceHistoryTextureUnitBase + historyCap + index);
		glBindTexture(GL_TEXTURE_2D, 0);
	}
	const GLuint shaderTextureBase = layerProgram.shaderTextureBase != 0 ? layerProgram.shaderTextureBase : kSourceHistoryTextureUnitBase;
	for (std::size_t index = 0; index < layerProgram.textureBindings.size() + layerProgram.textBindings.size(); ++index)
	{
		glActiveTexture(GL_TEXTURE0 + shaderTextureBase + static_cast<GLuint>(index));
		glBindTexture(GL_TEXTURE_2D, 0);
	}
	glActiveTexture(GL_TEXTURE0 + kDecodedVideoTextureUnit);
	glBindTexture(GL_TEXTURE_2D, 0);
	glActiveTexture(GL_TEXTURE0);
}