/*
    QGLView
    Copyright (C) 2020  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 "glvbo.h"


GLVBO::GLVBO(GLenum usage_) {
	buffer_ = 0;
	va_ = 0;
	usage = usage_;
	changed = true;
}


GLVBO::~GLVBO() {
	//destroy();
}


void GLVBO::init() {
	initializeOpenGLFunctions();
	if (!isInit()) {
		//glGenVertexArrays(1, &va_);
		glGenBuffers(1, &buffer_);
	}
	changed = true;
}


void GLVBO::destroy() {
	if (buffer_ != 0) glDeleteFramebuffers(1, &buffer_);
	buffer_ = 0;
//	if (va_ != 0) glDeleteVertexArrays(1, &va_);
//	va_ = 0;
}


void GLVBO::calculateBinormals() {
	tangents_.clear();
	bitangents_.clear();
	if (vertices_.isEmpty() || texcoords_.isEmpty()) return;
	int vcnt = vertices_.size() / 3;
	if (texcoords_.size() != vcnt * 2) return;
	int tcnt = vcnt / 3;
	//qDebug() << "calculateBinormals" << vcnt << tcnt << vertices_.size() << texcoords_.size() << "...";
	for (int t = 0; t < tcnt; ++t) {
		int vi = t*9, ti = t*6;
		Vector3d v0(vertices_[vi + 0], vertices_[vi + 1], vertices_[vi + 2]);
		Vector3d v1(vertices_[vi + 3], vertices_[vi + 4], vertices_[vi + 5]);
		Vector3d v2(vertices_[vi + 6], vertices_[vi + 7], vertices_[vi + 8]);
		Vector2d t0(texcoords_[ti + 0], texcoords_[ti + 1]);
		Vector2d t1(texcoords_[ti + 2], texcoords_[ti + 3]);
		Vector2d t2(texcoords_[ti + 4], texcoords_[ti + 5]);
		Vector3d dv1 = v1 - v0, dv2 = v2 - v0;
		Vector2d dt1 = t1 - t0, dt2 = t2 - t0;
		Vector3d tan;
		Vector3d bitan;
		tan = (dv1 * dt2.y - dv2 * dt1.y).normalize();
		bitan = (dv2 * dt1.x - dv1 * dt2.x).normalize();
		for (int i = 0; i < 3; ++i) {
			tangents_ << tan.x << tan.y << tan.z;
			bitangents_ << bitan.x << bitan.y << bitan.z;
		}
		//qDebug() << "  t" << t << vi << ti << dv1.toQVector3D() << "...";
	}
	//qDebug() << "calculateBinormals" << vcnt << tcnt << tangents_.size();
}


bool GLVBO::rebuffer(bool clear_) {
	initializeOpenGLFunctions();
	QVector<GLfloat> data;
	//data.clear();
	calculateBinormals();
	data << vertices_;
	if (!normals_.isEmpty()) {
		data << normals_;
		has_normals = true;
	} else has_normals = false;
	if (!texcoords_.isEmpty()) {
		data << texcoords_;
		has_texcoords = true;
	} else has_texcoords = false;
	if (!colors_.isEmpty()) {
		data << colors_;
		has_colors = true;
	} else has_colors = false;
	if (!tangents_.isEmpty()) {
		data << tangents_ << bitangents_;
		has_binormals = true;
	} else has_binormals = false;
	//glBindVertexArray(va_);
	//qDebug() << "load buffer" << data.size() << buffer_;
	glBindBuffer(GL_ARRAY_BUFFER, buffer_);
	glBufferData(GL_ARRAY_BUFFER, data.size() * sizeof(GLfloat), data.constData(), usage);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	//glBindVertexArray(0);
	vert_count = vertices_.size() / 3;
	changed = false;
	//qDebug() << "rebuff" << buffer_ << vert_count;
	if (clear_) clear();
	return !isEmpty();
}


void GLVBO::draw(GLenum type, QOpenGLShaderProgram * prog, bool simplest) {
	if (buffer_ == 0 || vert_count == 0) return;
	if (changed) rebuffer();
	//qDebug() << "draw" << vert_count;
	void * offset = (void*)(vert_count * 3 * sizeof(GLfloat));
	//glBindVertexArray(va_);
	void * offsets[5] = {0, 0, 0, 0, 0};
	if (!simplest) {
		if (has_normals) {
			offsets[0] = offset;
			offset = (void*)(llong(offset) + vert_count * 3 * sizeof(GLfloat));
		}
		if (has_texcoords) {
			offsets[1] = offset;
			offset = (void*)(llong(offset) + vert_count * 2 * sizeof(GLfloat));
		}
		if (has_colors) {
			offsets[2] = offset;
			offset = (void*)(llong(offset) + vert_count * 4 * sizeof(GLfloat));
		}
		if (has_binormals) {
			offsets[3] = offset;
			offset = (void*)(llong(offset) + vert_count * 3 * sizeof(GLfloat));
			offsets[4] = offset;
		}
	}

	glBindBuffer(GL_ARRAY_BUFFER, buffer_);
	if (prog) {
		locs.clear();
		glDisableClientState(GL_VERTEX_ARRAY);
		glDisableClientState(GL_NORMAL_ARRAY);
		glDisableClientState(GL_TEXTURE_COORD_ARRAY);
		glDisableClientState(GL_COLOR_ARRAY);
		int loc = prog->attributeLocation("qgl_Vertex");
		glEnableVertexAttribArray(loc);
		glVertexAttribPointer(loc, 3, GL_FLOAT, 0, 0, 0);
		locs << loc;
		if (!simplest) {
			loc = prog->attributeLocation("qgl_Normal");
			if (has_normals) {
				glEnableVertexAttribArray(loc);
				glVertexAttribPointer(loc, 3, GL_FLOAT, 0, 0, offsets[0]);
				locs << loc;
			} else
				glDisableVertexAttribArray(loc);
			loc = prog->attributeLocation("qgl_Texture");
			if (has_texcoords) {
				glEnableVertexAttribArray(loc);
				glVertexAttribPointer(loc, 2, GL_FLOAT, 0, 0, offsets[1]);
				locs << loc;
			} else
				glDisableVertexAttribArray(loc);
			loc = prog->attributeLocation("qgl_Color");
			if (has_colors) {
				glEnableVertexAttribArray(loc);
				glVertexAttribPointer(loc, 4, GL_FLOAT, 0, 0, offsets[2]);
				locs << loc;
			} else
				glDisableVertexAttribArray(loc);
			loc = prog->attributeLocation("qgl_Tangent");
			int loc2 = prog->attributeLocation("qgl_Bitangent");
			if (has_binormals) {
				glEnableVertexAttribArray(loc);
				glEnableVertexAttribArray(loc2);
				glVertexAttribPointer(loc, 3, GL_FLOAT, 0, 0, offsets[3]);
				glVertexAttribPointer(loc2, 3, GL_FLOAT, 0, 0, offsets[4]);
				locs << loc << loc2;
			} else {
				glDisableVertexAttribArray(loc);
				glDisableVertexAttribArray(loc2);
			}
		}
	} else {
		glEnableClientState(GL_VERTEX_ARRAY);
		glVertexPointer(3, GL_FLOAT, 0, 0);
		if (!simplest) {
			if (has_normals) {
				glEnableClientState(GL_NORMAL_ARRAY);
				glNormalPointer(GL_FLOAT, 0, offsets[0]);
			} else glDisableClientState(GL_NORMAL_ARRAY);
			if (has_texcoords) {
				glEnableClientState(GL_TEXTURE_COORD_ARRAY);
				glTexCoordPointer(2, GL_FLOAT, 0, offsets[1]);
			} else glDisableClientState(GL_TEXTURE_COORD_ARRAY);
			if (has_colors) {
				glEnableClientState(GL_COLOR_ARRAY);
				glColorPointer(4, GL_FLOAT, 0, offsets[2]);
			} else glDisableClientState(GL_COLOR_ARRAY);
		}
	}
	//qDebug() << "draw" << vert_count << buffer_ << offsets[0] << offsets[1] << offsets[3];
	glDrawArrays(type, 0, vert_count);
	//qDebug() << "draw" << vert_count << buffer_ << "done";
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	foreach (int l, locs)
		glDisableVertexAttribArray(l);
}


void GLVBO::clear() {
	vertices_.clear();
	normals_.clear();
	texcoords_.clear();
	colors_.clear();
}


void GLVBO::translatePoints(const QVector3D & dp) {
	if (vertices_.isEmpty()) return;
	int vcnt = vertices_.size() / 3;
	for (int i = 0; i < vcnt; ++i) {
		int vi = i * 3;
		vertices_[vi + 0] += dp.x();
		vertices_[vi + 1] += dp.y();
		vertices_[vi + 2] += dp.z();
	}
	changed = true;
}


void GLVBO::scalePoints(const QVector3D & dp) {
	if (vertices_.isEmpty()) return;
	int vcnt = vertices_.size() / 3;
	for (int i = 0; i < vcnt; ++i) {
		int vi = i * 3;
		vertices_[vi + 0] *= dp.x();
		vertices_[vi + 1] *= dp.y();
		vertices_[vi + 2] *= dp.z();
	}
	changed = true;
}


bool GLVBO::saveToFile(const QString & filename) {
	if (filename.isEmpty()) return false;
	QFile f(filename);
	QByteArray ba;
	if (f.open(QFile::WriteOnly)) {
		QDataStream out(&ba, QFile::WriteOnly);
		out << vertices_ << normals_ << texcoords_ << colors_;
		ba = qCompress(ba);
		f.resize(0);
		f.write(ba);
		f.close();
		return true;
	}
	return false;
}


bool GLVBO::loadFromFile(const QString & filename) {
	if (filename.isEmpty()) return false;
	QFile f(filename);
	QByteArray ba;
	if (f.open(QFile::ReadOnly)) {
		ba = f.readAll();
		if (ba.isEmpty()) return false;
		ba = qUncompress(ba);
		QDataStream in(ba);
		in >> vertices_ >> normals_ >> texcoords_ >> colors_;
		changed = true;
		f.close();
		return !isEmpty();
	}
	return false;
}


Box3D GLVBO::boundingBox() const {
	if (vertices_.size() < 3) return Box3D();
	int vcnt = vertices_.size() / 3;
	//qDebug() << "calculateBinormals" << vcnt << tcnt << vertices_.size() << texcoords_.size() << "...";
	GLfloat mix, miy, miz, max, may, maz;
	Vector3d v0(vertices_[0], vertices_[1], vertices_[2]);
	mix = max = v0.x;
	miy = may = v0.y;
	miz = maz = v0.z;
	Box3D bound;
	for (int t = 1; t < vcnt; ++t) {
		int vi = t*3;
		Vector3d v(vertices_[vi + 0], vertices_[vi + 1], vertices_[vi + 2]);
		if (mix > v.x) mix = v.x;
		if (max < v.x) max = v.x;
		if (miy > v.y) miy = v.y;
		if (may < v.y) may = v.y;
		if (miz > v.z) miz = v.z;
		if (maz < v.z) maz = v.z;
	}
	bound.x = mix;
	bound.y = miy;
	bound.z = miz;
	bound.length = max - mix;
	bound.width  = may - miy;
	bound.height = maz - miz;
	return bound;
}