#include "OpenGlViewer.h"
#include "defines.h"
#include "Vertex.h"

#include <iostream>

static const Vertex sg_vertexes[] = {
	Vertex(QVector3D(0.00f,  0.75f, 1.0f), QVector3D(1.0f, 0.0f, 0.0f)),
	Vertex(QVector3D(0.75f, -0.75f, 1.0f), QVector3D(0.0f, 1.0f, 0.0f)),
	Vertex(QVector3D(-0.75f, -0.75f, 1.0f), QVector3D(0.0f, 0.0f, 1.0f))
};

OpenGlViewer::OpenGlViewer(QWidget *parent)
	: QOpenGLWidget(parent)
{
	QSurfaceFormat format;
	format.setRenderableType(QSurfaceFormat::OpenGL);
	format.setProfile(QSurfaceFormat::CompatibilityProfile);
	format.setVersion(DEFAULT_MAJOR_VERSION, DEFAULT_MINOR_VERSION);

	setFormat(format);
}

OpenGlViewer::~OpenGlViewer()
{
	mVertexArray.destroy();
	mVertexBuffer.destroy();
	delete mProgram;
}

void OpenGlViewer::printContextInformation()
{
	QString glType;
	QString glVersion;
	QString glProfile;

	glType = (context()->isOpenGLES()) ? "OpenGL ES" : "OpenGL";
	glVersion = reinterpret_cast<const char*>(glGetString(GL_VERSION));

#define CASE(c) case QSurfaceFormat::c: glProfile = #c; break
	switch (format().profile())
	{
		CASE(NoProfile);
		CASE(CoreProfile);
		CASE(CompatibilityProfile);
	}
#undef CASE

	std::cout << glType.toStdString() << " - " << glVersion.toStdString() << " (" << glProfile.toStdString() << ")";
}

void OpenGlViewer::initializeGL()
{
	initializeOpenGLFunctions();
	printContextInformation();

	//glEnable(GL_DEPTH_TEST);
	glClearColor(DEAFAULT_BACKGROUND);

	mProgram = new QOpenGLShaderProgram();
	mProgram->addShaderFromSourceFile(QOpenGLShader::Vertex, ":/shaders/simple.vert");
	mProgram->addShaderFromSourceFile(QOpenGLShader::Fragment, ":/shaders/simple.frag");
	mProgram->link();
	mProgram->bind();

	mVertexBuffer.create();
	mVertexBuffer.bind();
	mVertexBuffer.setUsagePattern(QOpenGLBuffer::StaticDraw);
	mVertexBuffer.allocate(sg_vertexes, sizeof(sg_vertexes));

	mVertexArray.create();
	mVertexArray.bind();
	mProgram->enableAttributeArray(0);
	mProgram->enableAttributeArray(1);
	mProgram->setAttributeBuffer(0, GL_FLOAT, Vertex::positionOffset(), Vertex::PositionTupleSize, Vertex::stride());
	mProgram->setAttributeBuffer(1, GL_FLOAT, Vertex::colorOffset(), Vertex::ColorTupleSize, Vertex::stride());

	mVertexArray.release();
	mVertexBuffer.release();
	mProgram->release();

}

void OpenGlViewer::resizeGL(int w, int h)
{
	//TODO: change perspective
}

void OpenGlViewer::paintGL()
{
	//TODO: paint here
	glClear(GL_COLOR_BUFFER_BIT);

	mProgram->bind();
	mVertexArray.bind();
	glDrawArrays(GL_TRIANGLES, 0, sizeof(sg_vertexes) / sizeof(sg_vertexes[0]));
	mVertexArray.release();
	mProgram->release();
}