#include "..\Header\GeometryEngine.h"
#include "..\Header\MshFile.h"


/////////////////////////////////////////////////////////////////////////
// public constructor/destructor

GeometryEngine::GeometryEngine()
	: m_indexBuf(QOpenGLBuffer::IndexBuffer)
{
	initializeOpenGLFunctions();

	// Generate 2 VBOs
	m_arrayBuf.create();
	m_indexBuf.create();

	// Initializes cube geometry and transfers it to VBOs
	initCubeGeometry();
}

GeometryEngine::~GeometryEngine()
{
	m_arrayBuf.destroy();
	m_indexBuf.destroy();

	for (auto it : m_textures)
		delete it;
	m_textures.clear();
	m_drawList.clear();
}


/////////////////////////////////////////////////////////////////////////
// private functions

void GeometryEngine::initCubeGeometry()
{
	QVector<Model*>* models;
	QVector<VertexData> vertexData;
	QVector<GLuint> indexData;

	try
	{
		MshFile file("..\\Release\\Msh\\triClothMan.msh");
		 models = file.getModels();
		//TODO normalize
		//TODO: handle the textures

		// collect data
		unsigned int offsetCount(0);
		for (auto& modelIterator : *models)
		{
			for (auto& segmentIterator : modelIterator->segmList)
			{
				// get draw information
				DrawInformation new_info;
				new_info.offset = offsetCount;
				new_info.size = segmentIterator->indices.size();
				new_info.textureIndex = segmentIterator->textureIndex;
				new_info.modelMatrix = modelIterator->m4x4Translation;

				// add offset to indices
				for (auto& it : segmentIterator->indices)
					it += new_info.offset;

				// save data
				vertexData += segmentIterator->vertices;
				indexData += segmentIterator->indices;
				m_drawList.push_back(new_info);

				// update offset
				offsetCount += new_info.size;
			}
		}

		// Transfer vertex data to VBO 0
		m_arrayBuf.bind();
		m_arrayBuf.allocate(vertexData.data(), vertexData.size() * sizeof(VertexData));

		// Transfer index data to VBO 1
		m_indexBuf.bind();
		m_indexBuf.allocate(indexData.data(), indexData.size() * sizeof(GLuint));

		// load the texture
		initTexture();

	}
	catch (std::invalid_argument e)
	{
		//TODO: make a cool message box
		auto msg = e.what();
	}

	
}

void GeometryEngine::initTexture()
{
	// Load cube.png image
	QOpenGLTexture* new_texture = new QOpenGLTexture(QImage(":images/cube.png").mirrored());

	// Set nearest filtering mode for texture minification
	new_texture->setMinificationFilter(QOpenGLTexture::Nearest);

	// Set bilinear filtering mode for texture magnification
	new_texture->setMagnificationFilter(QOpenGLTexture::Linear);

	// Wrap texture coordinates by repeating
	// f.ex. texture coordinate (1.1, 1.2) is same as (0.1, 0.2)
	new_texture->setWrapMode(QOpenGLTexture::Repeat);

	m_textures.push_back(new_texture);
}


/////////////////////////////////////////////////////////////////////////
// public functions

void GeometryEngine::drawGeometry(QOpenGLShaderProgram *program)
{
// Setup
	// Tell OpenGL which VBOs to use
	m_arrayBuf.bind();
	m_indexBuf.bind();

	// Allways use texture unit 0
	program->setUniformValue("texture", 0);

	// Offset for position
	quintptr offset = 0;

	// Tell OpenGL programmable pipeline how to locate vertex position data
	int vertexLocation = program->attributeLocation("a_position");
	program->enableAttributeArray(vertexLocation);
	program->setAttributeBuffer(vertexLocation, GL_FLOAT, offset, 3, sizeof(VertexData));

	// Offset for texture coordinate
	offset += sizeof(QVector3D);

	// Tell OpenGL programmable pipeline how to locate vertex texture coordinate data
	int texcoordLocation = program->attributeLocation("a_texcoord");
	program->enableAttributeArray(texcoordLocation);
	program->setAttributeBuffer(texcoordLocation, GL_FLOAT, offset, 2, sizeof(VertexData));

// Paint

	for (auto& it : m_drawList)
	{
		// bind the correct texture
		if (it.textureIndex < m_textures.size())
			m_textures.at(it.textureIndex)->bind();
		else
			m_textures.last()->bind();

		// Set model matrix
		program->setUniformValue("m_matrix", it.modelMatrix);

		// Draw cube geometry using indices from VBO 1
		glDrawElements(GL_TRIANGLES, it.size, GL_UNSIGNED_INT, (void*)(it.offset * sizeof(GLuint)));
	}
}