/*
    QGLView
    Copyright (C) 2019  Ivan Pelipenko peri4ko@yandex.ru

    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/>.
*/

#define GL_GLEXT_PROTOTYPES
#include <QOpenGLExtraFunctions>
#include "renderer.h"
#include "qglview.h"
#include "glmesh.h"
#include "gltexture_manager.h"
#include <qad_types.h>

using namespace QGLEngineShaders;


Renderer::Renderer(QGLView * view_): RendererBase(view_),
		fbo_selection(view_, 4),
		fbo_ds       (view_, 5, true , GL_RGBA16F),
		fbo_out      (view_, 3, false, GL_RGBA16F),
		fbo_hsmall   (view_, 1, false, GL_RGB16F ),
		rend_mat(this), rend_service(this) {
	quad = Primitive::plane(2., 2.);
	sel_frame = quad->clone();
	cam_light = new Light();
	cam_light->intensity = 0.75;
	cam_light->setName("Camera_Light");
	line_thick_ = 2.;
	id_hover = 0;

	shader_files[srSelectionFill ] = "selection.glsl";
	shader_files[srSelectionHalo ] = "selection_halo.glsl";
	shader_files[srSelectionApply] = "selection_apply.glsl";
	shader_files[srSelectionFrame] = "selection_frame.glsl";

	shader_files[srService] = "service.glsl";

	shader_files[srGeometryPass] = "ds_geom.glsl";
	shader_files[srLightingPass] = "ds_light.glsl";
	shader_files[srFinalPass   ] = "ds_final.glsl";

	/*shaders << ShaderPair("FXAA", &shader_fxaa)
			<< ShaderPair("dsl_pass_0", &shader_ds_0)
			<< ShaderPair("dsl_pass_1", &shader_ds_1)
			<< ShaderPair("hdr", &shader_hdr)
			<< ShaderPair("downscale", &shader_small)
			<< ShaderPair("bloom_pass_0", &shader_bloom_0)
			<< ShaderPair("bloom_pass_1", &shader_bloom_1)
			<< ShaderPair("fbo_add", &shader_fbo_add)
			<< ShaderPair("motion_blur", &shader_motion_blur)
			<< ShaderPair("shadow", &shader_shadow)
			<< ShaderPair("ssr", &shader_ssr)
			<< ShaderPair("ssr_blur", &shader_ssr_blur)
			<< ShaderPair("ssr_merge", &shader_ssr_merge)
			<< ShaderPair("ssao_blur", &shader_ssao_blur)
			<< ShaderPair("ssao_merge", &shader_ssao_merge)
			<< ShaderPair("dof", &shader_dof);*/
	exposure_ = 1.;
	edit_mode = need_init_shaders = is_camera_light = true;
	proc_sel_pbo = false;
}


Renderer::~Renderer() {
	delete quad;
	delete sel_frame;
	delete cam_light;
	qDeleteAll(shaders.values());
}


void Renderer::init(int width, int height) {
	resize(width, height);
	rend_mat.init(width, height);
	rend_service.init(width, height);
	initQuad(quad);
	initTextureArrays();
	need_init_shaders = true;
}


void Renderer::resize(int width, int height) {
	rend_mat.resize(width, height);
	rend_service.resize(width, height);
	fbo_selection.enablePixelBuffer();
	fbo_selection.resize(width, height);
	fbo_ds       .resize(width, height);
	fbo_out      .resize(width, height);
	fbo_hsmall   .resize(width / 16, height / 16);
	line_thick_ = lineThickness() + 1.;
}


void Renderer::reloadShaders() {
	QMapIterator<ShaderRole, QString> it(shader_files);
	while (it.hasNext()) {
		it.next();
		loadShadersMulti(shaders[it.key()], "shaders/" + it.value());
	}
	need_init_shaders = true;
}


bool Renderer::bindShader(Renderer::ShaderRole role, QOpenGLShaderProgram ** ret) {
	QOpenGLShaderProgram * prog = shaders.value(role);
	if (ret) *ret = prog;
	if (!prog) return false;
	if (!prog->isLinked()) return false;
	prog->bind();
	return true;
}


void Renderer::initShaders() {
	if (!need_init_shaders) return;
	need_init_shaders = false;
	initUniformBuffer(shaders.value(srGeometryPass), &buffer_materials , bpMaterials      , "QGLMaterialData"      );
	initUniformBuffer(shaders.value(srLightingPass), &buffer_materials , bpMaterials      , "QGLMaterialData"      );
	initUniformBuffer(shaders.value(srLightingPass), &buffer_lights    , bpLightParameters, "QGLLightParameterData");
	initUniformBuffer(shaders.value(srLightingPass), &buffer_lights_pos, bpLightPositions , "QGLLightPositionData" );
}


void Renderer::releaseShader() {
	view->glUseProgram(0);
}


void Renderer::generateObjectsID(Scene & scene) {
	ids.clear();
	QMapIterator<Mesh*, QList<ObjectBase*> > it(scene.geometries_used);
	while (it.hasNext()) {
		it.next();
		foreach (ObjectBase * o, it.value()) {
			uint id = qHash(o);
			ids[id] = o;
			o->id_ = id;
		}
	}
}


void Renderer::fillSelectionsBuffer(const QList<ObjectBase *> & ol) {
	cur_selections_.resize(ol.size());
	for (int i = 0; i < ol.size(); ++i) {
		cur_selections_[i] = (ol[i]->isSelected(true) ? 1 : 0);
	}
}


void Renderer::fillObjectsBuffer(const QList<ObjectBase *> & ol, RenderPass pass) {
	cur_objects_.resize(ol.size());
	for (int i = 0; i < ol.size(); ++i) {
		Object & so(cur_objects_[i]);
		ObjectBase * o = ol[i];
		if (o->material()) {
			so.material = o->material()->_index;
			so.color = QVector4D(1,1,1,1);
		} else {
			so.material = 0;
			so.color = QColor2QVector(o->color_);
		}
		so.object_id = o->id_;
		o->worldTransform().transposed().copyDataTo(so.modelmatrix);
		//qDebug() << "load obj" << o->name() << o->worldTransform();
	}
	//qDebug() << "fillObjectsBuffer" << ol.size();

}


void Renderer::renderObjects(Scene & scene, RenderPass pass) {
	QOpenGLExtraFunctions * f = view;
	QMapIterator<Mesh*, QList<ObjectBase*> > it(scene.geometries_used);
	while (it.hasNext()) {
		it.next();
		Mesh * mesh = it.key();
		if (mesh->objects_changed) {
			mesh->objects_changed = false;
			fillObjectsBuffer(it.value(), pass);
			mesh->loadObjects(f, cur_objects_);
		}
		if (mesh->selected_changed && edit_mode) {
			mesh->selected_changed = false;
			fillSelectionsBuffer(it.value());
			mesh->loadSelections(f, cur_selections_);
		}
		mesh->draw(f, it.value().size());
	}
}


void Renderer::renderSelection(Scene & scene) {
	QOpenGLShaderProgram * prog = 0;
	if (bindShader(srSelectionFill, &prog)) {
		view->hov_objects.clear();
		id_hover = 0;
		if (fbo_selection.queriedPoints() > 0) {
			if (fbo_selection.queriedPoints() == 1) {
				id_hover = fbo_selection.getPoint();
				view->hov_objects.resize(1);
				view->hov_objects[0] = ids.value(id_hover);
				//qDebug() << id_hover;
			} else {
				QVector<uint> points = fbo_selection.getPoints();
				QSet<uint> ids_hover;
				foreach (uint i, points)
					ids_hover << i;
				view->hov_objects.clear();
				foreach (uint i, ids_hover)
					view->hov_objects << ids.value(i);
				//qDebug() << ids_hover;
			}
		}

		fbo_selection.bind();

		fbo_selection.setWriteBuffers();
		glEnableDepth();
		glClearFramebuffer(QColor(0,0,0,0));
		setUniformCamera(prog, view->camera());
		renderObjects(scene, rpSelection);
		//mouse_rect = fbo_selection.rect();
		if (mouse_rect.isNull())
			fbo_selection.queryPoint(0, mouse_pos);
		else
			fbo_selection.queryPoints(0, mouse_rect);

		//qDebug() << id_hover;
		fbo_selection.bindColorTextures();
		fbo_selection.setWriteBuffers();
		if (!view->hoverHalo_ && !view->selectionHalo_)
			glClearFramebuffer(QColor(0,0,0,0), false);
		else {
			bindShader(srSelectionHalo, &prog);
			setUniformHalo(prog, "hover"    , view->hoverHaloColor()    , view->hoverHaloFillAlpha());
			setUniformHalo(prog, "selection", view->selectionHaloColor(), view->selectionHaloFillAlpha());
			prog->setUniformValue("has_hover"    , view->hoverHalo_ && (id_hover > 0) ? 1.f : 0.f);
			prog->setUniformValue("has_selection", view->selectionHalo_ ? 1.f : 0.f);
			prog->setUniformValue("fb_hover"    , (int)sbrSrcHover);
			prog->setUniformValue("fb_selection", (int)sbrSrcSelect);
			prog->setUniformValue("hover_id", QVector4D(float( id_hover        & 0xFF) / 255.f,
														float((id_hover >> 8 ) & 0xFF) / 255.f,
														float((id_hover >> 16) & 0xFF) / 255.f,
														float((id_hover >> 24) & 0xFF) / 255.f));
			renderQuad(prog, quad, view->camera());
		}

		fbo_selection.release();
	}
}


void Renderer::renderSelectionFrame() {
	QOpenGLShaderProgram * prog = 0;
	if (bindShader(srSelectionFrame, &prog)) {
		QMatrix4x4 mat;
		double mrx = mouse_rect.x(), mrw = mouse_rect.width() , vw = view->width();
		double mry = mouse_rect.y(), mrh = mouse_rect.height(), vh = view->height();
		mat.translate(-1. + (mrw + mrx*2) / vw, 1. - (mrh + mry*2) / vh, 0.);
		mat.scale(mrw / vw, mrh / vh, 0.);
		initQuad(sel_frame, mat);
		prog->setUniformValue("size", QVector2D(mrw / vw, mrh / vh));
		prog->setUniformValue("thickness", line_thick_);
		glEnable(GL_BLEND);
		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
		renderQuad(prog, sel_frame);
		glDisable(GL_BLEND);
	}
}


void Renderer::renderScene() {
	initShaders();
	QOpenGLExtraFunctions * f = view;
	Scene & scene(*(view->scene_));
	Camera * cam = view->camera();
	QOpenGLShaderProgram * prog = 0;
	bool scene_changed = scene.prepare();

	/// reload materials on change
	if (scene_changed || scene.need_reload_materials) {
		if (scene.need_reload_materials)
			maps_hash = 0;
		generateObjectsID(scene);
		reloadMaterials(scene);
		if (edit_mode)
			recreateMaterialThumbnails();
		emit view->materialsChanged();
	}

	/// material thumbnails
	if (edit_mode && !scene_changed) {
		rend_mat.procQueue();
	}

	/// lights
	QList<Light*> ll = scene.lights_used;
	if (is_camera_light) {
		ll << cam_light;
		cam_light->setPos(cam->pos());
	}
	if (scene.lights_changed) {
		scene.lights_changed = false;
		reloadLightsParameters(ll);
	}
	reloadLightsPositions(ll, cam);

	/// selection
	if (edit_mode) {
		renderSelection(scene);
	}

	/// geometry pass
	fbo_ds.bind();
	glEnableDepth();
	glClearFramebuffer();
	if (bindShader(srGeometryPass, &prog)) {
		setUniformMaps(prog);
		setUniformCamera(prog, cam);
		textures_empty.bind(f, tarEmpty);
		textures_maps .bind(f, tarMaps );
		renderObjects(scene, rpSolid);
	}
	fbo_ds.release();

	/// lighting pass
	fbo_ds.bindColorTextures();
	fbo_ds.bindDepthTexture(5);
	fbo_out.bind();
	if (bindShader(srLightingPass, &prog)) {
		setUniformCamera(prog, cam);
		setUniformViewCorners(prog, cam);
		for (int i = 0; i < 5; ++i)
			prog->setUniformValue(QString("tex_%1").arg(i).toLatin1().constData(), i);
		prog->setUniformValue("tex_d", 5);
		prog->setUniformValue("lights_count", ll.size());
		glClearFramebuffer(view->backColor(), false);
		renderQuad(prog, quad, cam);
		/*QVector<float> _fb = fbo_out.grabF(0);
		if (!_fb.isEmpty()) {
			double sum = 0.;
			foreach (float f, _fb) sum += f;
			sum /= _fb.size();
			qDebug() << "sum =" << sum;
		}*/
	}
	fbo_out.release();

	/// apply hovers and selection frame
	if (edit_mode) {
		if (bindShader(srSelectionApply, &prog)) {
			fbo_selection.bindColorTextures();
			fbo_out.bindColorTexture(0);
			prog->setUniformValue("fb_out"   , 0);
			prog->setUniformValue("fb_hover" , (int)sbrHovered );
			prog->setUniformValue("fb_select", (int)sbrSelected);
			renderQuad(prog, quad, cam);

			if (!mouse_rect.isNull()) {
				renderSelectionFrame();
			}

			rend_service.renderService();
		}
	} else {
		fbo_out.blit(0, 0, 0, fbo_out.rect(), QRect(QPoint(), view->size()));
	}

}


void Renderer::setCameraLightOn(bool on) {
	is_camera_light = on;
	view->scene()->setLightsChanged();
}