/*
 * Oak Video Editor - Non-Linear Video Editor
 * Copyright (C) 2025 Olive CE Team
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "renderer.h"

#include <QDateTime>
#include <QThread>
#include <QTimer>
#include <QVector2D>

namespace olive
{

Renderer::Renderer(QObject *parent)
	: QObject(parent)
{
}

TexturePtr Renderer::CreateTexture(const VideoParams &params, const void *data,
								   int linesize)
{
	QVariant v;

	if (USE_TEXTURE_CACHE) {
		QMutexLocker locker(&texture_cache_lock_);
		for (auto it = texture_cache_.begin(); it != texture_cache_.end();
			 it++) {
			if (it->width == params.effective_width() &&
				it->height == params.effective_height() &&
				it->depth == params.effective_depth() &&
				it->format == params.format() &&
				it->channel_count == params.channel_count()) {
				v = it->handle;
				texture_cache_.erase(it);
				break;
			}
		}
	}

	if (v.isNull()) {
		v = CreateNativeTexture(params.effective_width(),
								params.effective_height(),
								params.effective_depth(), params.format(),
								params.channel_count(), data, linesize);
	} else if (data) {
		UploadToTexture(v, params, data, linesize);
	} else {
		this->Flush();
	}

	return CreateTextureFromNativeHandle(v, params);
}

void Renderer::DestroyTexture(Texture *texture)
{
	if (USE_TEXTURE_CACHE) {
		// HACK: Dirty, dirty hack. OpenGL uses "contexts" to store all of its data, and each context
		//       can only be used by the thread that created it. However there are also "shared contexts"
		//       where assets from one context can be used in another. We use shared contexts so that
		//       textures rendered in the background can be displayed on the screen, travelling from
		//       a background thread to the main UI thread. However, when that texture is destroyed, it
		//       comes back here to be placed in the texture cache. But that leads to a race condition
		//       because it will call the background thread's renderer in the main thread. Since all
		//       assets are shared, we could technically just get the texture to call "destroy" in the
		//       viewer's renderer instance, but that would mean all textures would end up stranded
		//       there unusable by the background renderer, negating the very advantage of the texture
		//       cache in the first place. Therefore, we simply allow the thread calling to happen, and
		//       use mutexes to prevent race conditions.
		//
		//       Presumably Vulkan would not have this issue because it allows for application-wide
		//       instances and multithreading.
		texture_cache_lock_.lock();
		texture_cache_.push_back(
			{ texture->params().effective_width(),
			  texture->params().effective_height(),
			  texture->params().effective_depth(), texture->params().format(),
			  texture->params().channel_count(), texture->id(),
			  QDateTime::currentMSecsSinceEpoch() });
		texture_cache_lock_.unlock();

		if (QThread::currentThread() == this->thread()) {
			ClearOldTextures();
		}
	} else {
		DestroyNativeTexture(texture->id());
	}
}

TexturePtr Renderer::InterlaceTexture(TexturePtr top, TexturePtr bottom,
									  const VideoParams &params)
{
	color_cache_mutex_.lock();
	if (interlace_texture_.isNull()) {
		interlace_texture_ =
			CreateNativeShader(ShaderCode(FileFunctions::ReadFileAsString(
				QStringLiteral(":/shaders/interlace.frag"))));
	}
	color_cache_mutex_.unlock();

	ShaderJob job;
	job.Insert(QStringLiteral("top_tex_in"),
			   NodeValue(NodeValue::kTexture, QVariant::fromValue(top)));
	job.Insert(QStringLiteral("bottom_tex_in"),
			   NodeValue(NodeValue::kTexture, QVariant::fromValue(bottom)));
	job.Insert(QStringLiteral("resolution_in"),
			   NodeValue(NodeValue::kVec2,
						 QVector2D(params.effective_width(),
								   params.effective_height())));

	TexturePtr output = CreateTexture(params);

	BlitToTexture(interlace_texture_, job, output.get());

	return output;
}

QVariant Renderer::GetDefaultShader()
{
	QMutexLocker locker(&color_cache_mutex_);

	if (default_shader_.isNull()) {
		default_shader_ = CreateNativeShader(ShaderCode(QString(), QString()));
	}

	return default_shader_;
}

void Renderer::Destroy()
{
	if (!default_shader_.isNull()) {
		DestroyNativeShader(default_shader_);
		default_shader_.clear();
	}

	color_cache_.clear();

	if (!interlace_texture_.isNull()) {
		DestroyNativeShader(interlace_texture_);
		interlace_texture_.clear();
	}

	for (auto it = texture_cache_.begin(); it != texture_cache_.end(); it++) {
		DestroyNativeTexture(it->handle);
	}
	texture_cache_.clear();

	DestroyInternal();
}

TexturePtr Renderer::CreateTextureFromNativeHandle(const QVariant &v,
												   const VideoParams &params)
{
	if (v.isNull()) {
		return nullptr;
	}

	return std::make_shared<Texture>(this, v, params);
}

bool Renderer::GetColorContext(const ColorTransformJob &color_job,
							   Renderer::ColorContext *ctx)
{
	QMutexLocker locker(&color_cache_mutex_);

	ColorContext &color_ctx = *ctx;

	QString proc_id = color_job.id();

	if (color_cache_.contains(proc_id)) {
		color_ctx = color_cache_.value(proc_id);
		return true;
	} else {
		// Create shader description
		QString ocio_func_name;
		if (color_job.GetFunctionName().isEmpty()) {
			ocio_func_name = "OCIODisplay";
		} else {
			ocio_func_name = color_job.GetFunctionName();
		}
		auto shader_desc = OCIO::GpuShaderDesc::CreateShaderDesc();
		shader_desc->setLanguage(OCIO::GPU_LANGUAGE_GLSL_ES_3_0);
		shader_desc->setFunctionName(ocio_func_name.toUtf8());
		shader_desc->setResourcePrefix("ocio_");

		// Generate shader
		color_job.GetColorProcessor()
			->GetProcessor()
			->getDefaultGPUProcessor()
			->extractGpuShaderInfo(shader_desc);

		ShaderCode code;
		if (const Node *shader_src = color_job.CustomShaderSource()) {
			// Use shader code from associated node
			code = shader_src->GetShaderCode(
				{ color_job.CustomShaderID(), shader_desc->getShaderText() });
		} else {
			// Generate shader code using OCIO stub and our auto-generated name
			code = FileFunctions::ReadFileAsString(
				QStringLiteral(":shaders/colormanage.frag"));
			code.set_frag_code(
				code.frag_code().arg(shader_desc->getShaderText()));
		}

		// Try to compile shader
		color_ctx.compiled_shader = CreateNativeShader(code);

		if (color_ctx.compiled_shader.isNull()) {
			return false;
		}

		color_ctx.lut3d_textures.resize(shader_desc->getNum3DTextures());
		for (unsigned int i = 0; i < shader_desc->getNum3DTextures(); i++) {
			const char *tex_name = nullptr;
			const char *sampler_name = nullptr;
			unsigned int edge_len = 0;
			OCIO::Interpolation interpolation = OCIO::INTERP_LINEAR;

			shader_desc->get3DTexture(i, tex_name, sampler_name, edge_len,
									  interpolation);

			if (!tex_name || !*tex_name || !sampler_name || !*sampler_name ||
				!edge_len) {
				qCritical() << "3D LUT texture data is corrupted";
				return false;
			}

			const float *values = nullptr;
			shader_desc->get3DTextureValues(i, values);
			if (!values) {
				qCritical() << "3D LUT texture values are missing";
				return false;
			}

			// Allocate 3D LUT
			color_ctx.lut3d_textures[i].texture = CreateTexture(
				VideoParams(edge_len, edge_len, edge_len, PixelFormat::F32,
							VideoParams::kRGBChannelCount),
				values);
			color_ctx.lut3d_textures[i].name = sampler_name;
			color_ctx.lut3d_textures[i].interpolation =
				(interpolation == OCIO::INTERP_NEAREST) ? Texture::kNearest :
														  Texture::kLinear;
		}

		color_ctx.lut1d_textures.resize(shader_desc->getNumTextures());
		for (unsigned int i = 0; i < shader_desc->getNumTextures(); i++) {
			const char *tex_name = nullptr;
			const char *sampler_name = nullptr;
			unsigned int width = 0, height = 0;
			OCIO::GpuShaderDesc::TextureType channel =
				OCIO::GpuShaderDesc::TEXTURE_RGB_CHANNEL;
			OCIO::Interpolation interpolation = OCIO::INTERP_LINEAR;
			OCIO::GpuShaderDesc::TextureDimensions dimensions =
				OCIO::GpuShaderDesc::TEXTURE_2D;
			shader_desc->getTexture(i, tex_name, sampler_name, width, height,
									channel, dimensions, interpolation);

			if (!tex_name || !*tex_name || !sampler_name || !*sampler_name ||
				!width) {
				qCritical() << "1D LUT texture data is corrupted";
				return false;
			}

			const float *values = nullptr;
			shader_desc->getTextureValues(i, values);
			if (!values) {
				qCritical() << "1D LUT texture values are missing";
				return false;
			}

			// Allocate 1D LUT
			color_ctx.lut1d_textures[i].texture = CreateTexture(
				VideoParams(width, height, PixelFormat::F32,
							(channel ==
							 OCIO::GpuShaderDesc::TEXTURE_RED_CHANNEL) ?
								1 :
								VideoParams::kRGBChannelCount),
				values);
			color_ctx.lut1d_textures[i].name = sampler_name;
			color_ctx.lut1d_textures[i].interpolation =
				(interpolation == OCIO::INTERP_NEAREST) ? Texture::kNearest :
														  Texture::kLinear;
		}

		color_cache_.insert(proc_id, color_ctx);

		return true;
	}
}

void Renderer::ClearOldTextures()
{
	QMutexLocker locker(&texture_cache_lock_);

	for (auto it = texture_cache_.begin(); it != texture_cache_.end();) {
		if (it->accessed <
			QDateTime::currentMSecsSinceEpoch() - MAX_TEXTURE_LIFE) {
			DestroyNativeTexture(it->handle);
			it = texture_cache_.erase(it);
		} else {
			it++;
		}
	}
}

void Renderer::BlitColorManaged(const ColorTransformJob &color_job,
								Texture *destination, const VideoParams &params)
{
	ColorContext color_ctx;
	if (!GetColorContext(color_job, &color_ctx)) {
		return;
	}

	ShaderJob job;
	job.Insert(QStringLiteral("ove_maintex"), color_job.GetInputTexture());
	job.Insert(QStringLiteral("ove_mvpmat"),
			   NodeValue(NodeValue::kMatrix, color_job.GetTransformMatrix()));
	job.Insert(QStringLiteral("ove_cropmatrix"),
			   NodeValue(NodeValue::kMatrix,
						 color_job.GetCropMatrix().inverted()));
	job.Insert(QStringLiteral("ove_maintex_alpha"),
			   NodeValue(NodeValue::kInt,
						 int(color_job.GetInputAlphaAssociation())));
	job.Insert(QStringLiteral("ove_force_opaque"),
			   NodeValue(NodeValue::kBoolean, color_job.GetForceOpaque()));
	job.Insert(color_job.GetValues());

	foreach (const ColorContext::LUT &l, color_ctx.lut3d_textures) {
		job.Insert(l.name, NodeValue(NodeValue::kTexture,
									 QVariant::fromValue(l.texture)));
		job.SetInterpolation(l.name, l.interpolation);
	}
	foreach (const ColorContext::LUT &l, color_ctx.lut1d_textures) {
		job.Insert(l.name, NodeValue(NodeValue::kTexture,
									 QVariant::fromValue(l.texture)));
		job.SetInterpolation(l.name, l.interpolation);
	}

	if (destination) {
		BlitToTexture(color_ctx.compiled_shader, job, destination,
					  color_job.IsClearDestinationEnabled());
	} else {
		Blit(color_ctx.compiled_shader, job, params,
			 color_job.IsClearDestinationEnabled());
	}
}

}
