/*
    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/>.
*/

#include "gltypes.h"
#include "qglview.h"
#include "glshaders.h"
#include "glshaders_headers.h"

using namespace QGLEngineShaders;


bool addShader(QOpenGLShaderProgram * prog, QOpenGLShader::ShaderType type, QString & content, const QString & file, const QString & defs) {
	if (type == 0 || content.isEmpty()) {
		content.clear();
		return true;
	}
	//qDebug() << "[QGLView] Shader" << file << "found" << (QOpenGLShader::ShaderTypeBit)(int)type << "section ...";
	switch (type) {
	case QOpenGLShader::Fragment:
		content.prepend(qgl_fragment_head);
		content.prepend(qgl_uniform);
		content.prepend(qgl_structs);
		break;
	case QOpenGLShader::Vertex  :
		content.prepend(qgl_vertex_head  );
		break;
	case QOpenGLShader::Geometry:
		content.prepend(qgl_geometry_head);
		break;
	}
	content.prepend(defs);
	content.prepend(qgl_common_head);
	bool ret = prog->addShaderFromSourceCode(type, content.toLatin1());
	if (!ret) qDebug() << "[QGLView] Shader" << file << "Compile error:\n" << prog->log();
	content.clear();
	return ret;
}


QString prepareDefines(const QStringList & defines) {
	if (defines.isEmpty()) return QString();
	QString ret;
	foreach (QString s, defines)
		ret.append("#define " + s + "\n");
	return ret;
}


bool QGLEngineShaders::loadShadersMulti(QOpenGLShaderProgram *& prog, const QString & file, const QStringList & defines) {
	if (!prog)
		prog = new QOpenGLShaderProgram();
	prog->removeAllShaders();
	QFile f(file);
	if (!f.open(QIODevice::ReadOnly)) {
		qDebug() << "[QGLView] Shader" << file << "Error: can`t open file!";
		return false;
	}
	QTextStream ts(&f);
	QString cur_shader, line, pl, defs = prepareDefines(defines);
	QOpenGLShader::ShaderType type = 0;
	while (!ts.atEnd()) {
		line = ts.readLine();
		pl = line.trimmed().remove(' ').remove('\t').mid(2).toLower();
		pl.chop(2);
		if (pl == "vertex" || pl == "vert") {
			if (!addShader(prog, type, cur_shader, file, defs)) return false;
			type = QOpenGLShader::Vertex;
			continue;
		}
		if (pl == "fragment" || pl == "frag") {
			if (!addShader(prog, type, cur_shader, file, defs)) return false;
			type = QOpenGLShader::Fragment;
			continue;
		}
		if (pl == "geometry" || pl == "geom") {
			if (!addShader(prog, type, cur_shader, file, defs)) return false;
			type = QOpenGLShader::Geometry;
			continue;
		}
		if (pl == "tessellation_control") {
			if (!addShader(prog, type, cur_shader, file, defs)) return false;
			type = QOpenGLShader::TessellationControl;
			continue;
		}
		if (pl == "tessellation_evaluation") {
			if (!addShader(prog, type, cur_shader, file, defs)) return false;
			type = QOpenGLShader::TessellationEvaluation;
			continue;
		}
		cur_shader.append("\n");
		cur_shader.append(line);
	}
	if (!addShader(prog, type, cur_shader, file, defs)) return false;
	if (!prog->link()) {
		qDebug() << "[QGLView] Shader" << file << "Link error:\n" << prog->log();
		return false;
	}
	qDebug() << "[QGLView] Shader" << file << "ok";
	return true;
}


void QGLEngineShaders::setUniformMatrices(QOpenGLShaderProgram * prog, QMatrix4x4 proj, QMatrix4x4 view, QMatrix4x4 prevproj, QMatrix4x4 prevview) {
	if (!prog) return;
	if (!prog->isLinked()) return;
	QMatrix4x4 mvpm = proj * view;
	QMatrix4x4 pmvpm = prevproj * prevview;
	QMatrix3x3 nm = view.normalMatrix();
	//nm.in;
	prog->setUniformValue("qgl_ModelViewMatrix", view);
	prog->setUniformValue("qgl_ProjectionMatrix", proj);
	prog->setUniformValue("prev_ModelViewProjectioMatrix", pmvpm);
	prog->setUniformValue("prev_ModelViewMatrix", prevview);
	prog->setUniformValue("qgl_ModelViewProjectionMatrix", mvpm);
	prog->setUniformValue("qgl_NormalMatrix", nm);
	//prog->setUniformValue("qgl_BumpMatrix", nm.);
	prog->setUniformValue("qgl_ModelViewMatrixTranspose", view.transposed());
	prog->setUniformValue("qgl_ProjectionMatrixTranspose", proj.transposed());
	prog->setUniformValue("qgl_ModelViewProjectionMatrixTranspose", mvpm.transposed());
}


void QGLEngineShaders::setUniformLights(QOpenGLShaderProgram * prog, const QVector<Light*> & lights, const QMatrix4x4 & mat, int shadow_start) {
	for (int i = 0; i < lights.size(); ++i)
		;//setUniformLight(prog, lights[i], QString("qgl_Light[%1]").arg(i), mat, shadow_start + i);
}
/*
"	vec3 position;\n"
"	vec3 direction;\n"
"	vec4 color;\n"
"	float intensity;\n"
"	float startAngle;\n"
"	float endAngle;\n"
"	float constantAttenuation;\n"
"	float linearAttenuation;\n"
"	float quadraticAttenuation;\n"
"	sampler2DShadow shadow;\n"
"	mat4 shadowMatrix;\n"
*/
void QGLEngineShaders::setUniformLight(QOpenGLShaderProgram * prog, Light * light, QString ulightn, const QMatrix4x4 & mat, int shadow) {
	if (!prog) return;
	if (!prog->isLinked()) return;
	QMatrix4x4 m = mat * light->worldTransform();
	QVector4D pos(0, 0, 0, 1.), dir(light->direction(), 1);//, dir0(light->dir0), dir1(light->dir1);
	pos = m * pos;
	dir = ((m * dir) - pos).normalized();
	float ang_start = light->angle_start / 2.f, ang_end = light->angle_end / 2.f;
	if (light->light_type == Light::Omni)
		ang_start = ang_end = 180.;
	//qDebug() << "light" << light->name() << ulightn << pos;
	prog->setUniformValue((ulightn + ".position").toLatin1().constData(), pos);
	prog->setUniformValue((ulightn + ".direction").toLatin1().constData(), dir);
	prog->setUniformValue((ulightn + ".intensity").toLatin1().constData(), GLfloat(light->intensity));
	prog->setUniformValue((ulightn + ".startAngle").toLatin1().constData(), GLfloat(ang_start));
	prog->setUniformValue((ulightn + ".startAngleCos").toLatin1().constData(), GLfloat(cosf(ang_start * deg2rad)));
	prog->setUniformValue((ulightn + ".endAngle").toLatin1().constData(), GLfloat(ang_end));
	prog->setUniformValue((ulightn + ".endAngleCos").toLatin1().constData(), GLfloat(cosf(ang_end * deg2rad)));
	//prog->setUniformValue((ulightn + ".color").toLatin1().constData(), light->color());
	prog->setUniformValue((ulightn + ".constantAttenuation").toLatin1().constData(), GLfloat(light->decay_const));
	prog->setUniformValue((ulightn + ".linearAttenuation").toLatin1().constData(), GLfloat(light->decay_linear));
	prog->setUniformValue((ulightn + ".quadraticAttenuation").toLatin1().constData(), GLfloat(light->decay_quadratic));
	prog->setUniformValue((ulightn + ".shadow").toLatin1().constData(), shadow);
	prog->setUniformValue((ulightn + ".shadowColor").toLatin1().constData(), shadow);
	prog->setUniformValue((ulightn + ".shadowMatrix").toLatin1().constData(), light->shadow_matrix);
	//qDebug() << light->shadow_matrix;
	//prog->setUniformValue((ulightn + ".shadowDir0").toLatin1().constData(), (mat * dir0));
	//prog->setUniformValue((ulightn + ".shadowDir1").toLatin1().constData(), (mat * dir1));
	//qDebug() << light->direction << light->dir0 << light->dir1;
}