// CC-BY Edouard.Thiel@univ-amu.fr - 22/01/2019

#include "glarea.h"
#include <QDebug>
#include <QSurfaceFormat>
#include <QMatrix4x4>
#include <stdio.h>

static const QString vertexShaderFile   = ":/basic.vsh";
static const QString fragmentShaderFile = ":/basic.fsh";


GLArea::GLArea(QWidget *parent) :
    QOpenGLWidget(parent)
{
    qDebug() << "init GLArea" ;
    QSurfaceFormat sf;
    sf.setDepthBufferSize(24);
    sf.setSamples(16);
    setFormat(sf);
    qDebug() << "Depth is"<< format().depthBufferSize();
    setEnabled(true); // Événements clavier et souris.
    setFocusPolicy(Qt::StrongFocus); // Accepte focus.
    setFocus(); // Donne le focus.
    timer = new QTimer(this);
    timer->setInterval(16); // ms
    connect(timer, SIGNAL(timeout()), this, SLOT(onTimeout()));
}


GLArea::~GLArea()
{
    qDebug() << "destroy GLArea";
    delete timer;
    // Contrairement aux méthodes virtuelles initializeGL, resizeGL et repaintGL,
    // dans le destructeur le contexte GL n'est pas automatiquement rendu courant.
    makeCurrent();
    // ici destructions de ressources GL
    doneCurrent();
}


void GLArea::initializeGL()
{
    qDebug() << __FUNCTION__ ;
    initializeOpenGLFunctions();
    glEnable(GL_DEPTH_TEST);

    // Shaders.
    program = new QOpenGLShaderProgram(this);
    program->addShaderFromSourceFile
		(QOpenGLShader::Vertex, vertexShaderFile);
    program->addShaderFromSourceFile
		(QOpenGLShader::Fragment, fragmentShaderFile);
    if (!program->link()) {
        qWarning("Failed to compile and link shader program:");
        qWarning() << program->log();
    }
    // Récupère identifiants de "variables" dans les shaders.
    posAttr = program->attributeLocation("posAttr");
    colAttr = program->attributeLocation("colAttr");
    matrix_uniform = program->uniformLocation("matrix");
}


void GLArea::resizeGL(int w, int h)
{
    qDebug() << __FUNCTION__ << w << h;
    // C'est fait par défaut
    glViewport(0, 0, w, h);
    ratio = (double) w / h;
    // doProjection();
}


void GLArea::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    program->bind();

    QMatrix4x4 matrix;
    GLfloat hr = focal_length;
	GLfloat wr = hr * ratio;
    matrix.frustum(-wr, wr, -hr, hr, near_clip, far_clip);
    matrix.translate(0, 0, -distance);
    matrix.rotate(angle, 0, 1, 0);
    matrix.rotate(horiz_angle, 0,
				  cos(vert_angle * 2*M_PI /360),
				  sin(vert_angle * 2*M_PI /360));
    matrix.rotate(vert_angle, 1, 0, 0);
    program->setUniformValue(matrix_uniform, matrix);
	scene.draw((QOpenGLFunctions&) (*this), program, matrix_uniform,
				 anim * 360, matrix, posAttr, colAttr);
    program->release();
}


void GLArea::keyPressEvent(QKeyEvent *ev)
{
	QString text = ev->text();
    switch(ev->key()) {
	case Qt::Key_A:
		timer->isActive() ? timer->stop() : timer->start();
		break;
	case Qt::Key_Z:
		setDistance(distance + (text == "z" ? -distance_step : distance_step));
		break;
	case Qt::Key_R:
		setFocalLength(focal_length + (text == "r" ? -focal_length_step : focal_length_step));
		break;
	case Qt::Key_N:
		setNearClip(near_clip + (text == "n" ? -near_clip_step : near_clip_step));
		break;
	case Qt::Key_F:
		setFarClip(far_clip + (text == "f" ? -far_clip_step : far_clip_step));
		break;
	case Qt::Key_Space:
		setAngle(angle + angle_step);
		update();
		break;
    }
}


void GLArea::mousePressEvent(QMouseEvent *ev)
{
	mouse_last[0] = ev->x() / (float) width();
	mouse_last[1] = ev->y() / (float) height();
}


void GLArea::mouseMoveEvent(QMouseEvent *ev)
{
	float x = ev->x() / (float) width();
	float y = ev->y() / (float) height();
	float dx = x - mouse_last[0];
	float dy = y - mouse_last[1];
	horiz_angle += dx * 200;
	vert_angle += dy * 200;
	if (vert_angle > 90) vert_angle = 90;
	if (vert_angle < -90) vert_angle = -90;
	mouse_last[0] = x;
	mouse_last[1] = y;
	update();
}


void GLArea::wheelEvent(QWheelEvent *ev)
{
	setDistance(distance - ev->angleDelta().y() / 1000.);
	update();
}


void GLArea::onTimeout()
{
    anim += 0.0001;
	if (anim > 1) anim--;
    update();
}


#define SET_VALUE(orig, signal) \
	qDebug() << "GLArea, setting " #orig " from" << orig << "to" << value; \
	if (value > orig##_max) value = orig##_max;\
	if (value < orig##_min) value = orig##_min;\
	if (value != orig) {\
		orig = value;\
		emit signal(orig);\
		update();\
	}
void GLArea::setDistance(double value) { SET_VALUE(distance, distanceChanged); }
void GLArea::setFocalLength(double value) { SET_VALUE(focal_length, focalLengthChanged); }
void GLArea::setNearClip(double value) { SET_VALUE(near_clip, nearClipChanged); }
void GLArea::setFarClip(double value) { SET_VALUE(far_clip, farClipChanged); }
void GLArea::setAngle(double value)
{
	while (value > angle_max) value -= angle_max;
	while (value < angle_min) value += angle_min;
	SET_VALUE(angle, angleChanged);
}
#undef SET_VALUE