/********************************************************************************
* ReactPhysics3D physics library, http://www.ephysics.com				 *
* Copyright (c) 2010-2016 Daniel Chappuis									   *
*********************************************************************************
*																			   *
* This software is provided 'as-is', without any express or implied warranty.   *
* In no event will the authors be held liable for any damages arising from the  *
* use of this software.														 *
*																			   *
* Permission is granted to anyone to use this software for any purpose,		 *
* including commercial applications, and to alter it and redistribute it		*
* freely, subject to the following restrictions:								*
*																			   *
* 1. The origin of this software must not be misrepresented; you must not claim *
*	that you wrote the original software. If you use this software in a		*
*	product, an acknowledgment in the product documentation would be		   *
*	appreciated but is not required.										   *
*																			   *
* 2. Altered source versions must be plainly marked as such, and must not be	*
*	misrepresented as being the original software.							 *
*																			   *
* 3. This notice may not be removed or altered from any source distribution.	*
*																			   *
********************************************************************************/

// Libraries
#include <ephysics/HeightField.hpp>
#include <ephysics/PerlinNoise.hpp>

// Constructor
HeightField::HeightField(const openglframework::vec3 &position,
					   ephysics::CollisionWorld* world)
		   : openglframework::Mesh(), mVBOVertices(GL_ARRAY_BUFFER),
			 mVBONormals(GL_ARRAY_BUFFER), mVBOTextureCoords(GL_ARRAY_BUFFER),
			 mVBOIndices(GL_ELEMENT_ARRAY_BUFFER) {

	// Initialize the position where the sphere will be rendered
	translateWorld(position);

	// Compute the scaling matrix
	m_scalingMatrix = openglframework::Matrix4::identity();

	// Generate the height field
	generateHeightField();

	// Generate the graphics mesh
	generateGraphicsMesh();

	// Create the collision shape for the rigid body (convex mesh shape) and
	// do not forget to delete it at the end
	mHeightFieldShape = new ephysics::HeightFieldShape(NB_POINTS_WIDTH, NB_POINTS_LENGTH, m_minHeight, m_maxHeight,
											   mHeightData, ephysics::HeightFieldShape::HEIGHT_FLOAT_TYPE);

	// Initial position and orientation of the rigid body
	ephysics::vec3 initPosition(position.x(), position.y(), position.z());
	ephysics::etk::Quaternion initOrientation = ephysics::Quaternion::identity();
	ephysics::etk::Transform3D transform(initPosition, initOrientation);

	mPreviousetk::Transform3D = transform;

	// Create a rigid body corresponding to the sphere in the dynamics world
	m_body = world->createCollisionBody(transform);

	// Add a collision shape to the body and specify the mass of the collision shape
	m_proxyShape = m_body->addCollisionShape(mHeightFieldShape, ephysics::etk::Transform3D::identity());

	// Create the VBOs and VAO
	createVBOAndVAO();

	m_transformMatrix = m_transformMatrix * m_scalingMatrix;
}

// Constructor
HeightField::HeightField(const openglframework::vec3 &position, float mass,
					   ephysics::DynamicsWorld* dynamicsWorld)
		   : openglframework::Mesh(), mVBOVertices(GL_ARRAY_BUFFER),
			 mVBONormals(GL_ARRAY_BUFFER), mVBOTextureCoords(GL_ARRAY_BUFFER),
			 mVBOIndices(GL_ELEMENT_ARRAY_BUFFER) {

	// Initialize the position where the sphere will be rendered
	translateWorld(position);

	// Compute the scaling matrix
	m_scalingMatrix = openglframework::Matrix4::identity();

	// Generate the height field
	generateHeightField();

	// Generate the graphics mesh
	generateGraphicsMesh();

	// Create the collision shape for the rigid body (convex mesh shape) and
	// do not forget to delete it at the end
	mHeightFieldShape = new ephysics::HeightFieldShape(NB_POINTS_WIDTH, NB_POINTS_LENGTH, m_minHeight, m_maxHeight,
												   mHeightData, ephysics::HeightFieldShape::HEIGHT_FLOAT_TYPE);

	// Initial position and orientation of the rigid body
	ephysics::vec3 initPosition(position.x(), position.y(), position.z());
	ephysics::etk::Quaternion initOrientation = ephysics::Quaternion::identity();
	ephysics::etk::Transform3D transform(initPosition, initOrientation);

	// Create a rigid body corresponding to the sphere in the dynamics world
	ephysics::RigidBody* body = dynamicsWorld->createRigidBody(transform);

	// Add a collision shape to the body and specify the mass of the collision shape
	m_proxyShape = body->addCollisionShape(mHeightFieldShape, ephysics::etk::Transform3D::identity(), mass);

	m_body = body;

	// Create the VBOs and VAO
	createVBOAndVAO();

	m_transformMatrix = m_transformMatrix * m_scalingMatrix;
}

// Destructor
HeightField::~HeightField() {

	// Destroy the mesh
	destroy();

	// Destroy the VBOs and VAO
	mVBOIndices.destroy();
	mVBOVertices.destroy();
	mVBONormals.destroy();
	mVBOTextureCoords.destroy();
	mVAO.destroy();

	delete mHeightFieldShape;
}

// Render the sphere at the correct position and with the correct orientation
void HeightField::render(openglframework::Shader& shader,
					const openglframework::Matrix4& worldToCameraMatrix) {

	// Bind the shader
	shader.bind();

	// Set the model to camera matrix
	shader.setMatrix4x4Uniform("localToWorldMatrix", m_transformMatrix);
	shader.setMatrix4x4Uniform("worldToCameraMatrix", worldToCameraMatrix);

	// Set the normal matrix (inverse transpose of the 3x3 upper-left sub matrix of the
	// model-view matrix)
	const openglframework::Matrix4 localToCameraMatrix = worldToCameraMatrix * m_transformMatrix;
	const openglframework::Matrix3 normalMatrix =
					   localToCameraMatrix.getUpperLeft3x3Matrix().getInverse().getTranspose();
	shader.setetk::Matrix3x3Uniform("normalMatrix", normalMatrix, false);

	// Set the vertex color
	openglframework::Color currentColor = m_body->isSleeping() ? mSleepingColor : mColor;
	openglframework::Vector4 color(currentColor.r, currentColor.g, currentColor.b, currentColor.a);
	shader.setVector4Uniform("vertexColor", color, false);

	// Bind the VAO
	mVAO.bind();

	mVBOVertices.bind();

	// Get the location of shader attribute variables
	GLint32_t vertexPositionLoc = shader.getAttribLocation("vertexPosition");
	GLint32_t vertexNormalLoc = shader.getAttribLocation("vertexNormal", false);

	glEnableVertexAttribArray(vertexPositionLoc);
	glVertexAttribPointer(vertexPositionLoc, 3, GL_FLOAT, GL_FALSE, 0, (char*)NULL);

	mVBONormals.bind();

	if (vertexNormalLoc != -1) glVertexAttribPointer(vertexNormalLoc, 3, GL_FLOAT, GL_FALSE, 0, (char*)NULL);
	if (vertexNormalLoc != -1) glEnableVertexAttribArray(vertexNormalLoc);

	// For each part of the mesh
	for (uint32_t i=0; i<getNbParts(); i++) {
		glDrawElements(GL_TRIANGLES, getNbFaces(i) * 3, GL_UNSIGNED_INT, (char*)NULL);
	}

	glDisableVertexAttribArray(vertexPositionLoc);
	if (vertexNormalLoc != -1) glDisableVertexAttribArray(vertexNormalLoc);

	mVBONormals.unbind();
	mVBOVertices.unbind();

	// Unbind the VAO
	mVAO.unbind();

	// Unbind the shader
	shader.unbind();
}

// Compute the heights of the height field
void HeightField::generateHeightField() {

	double persistence = 9;
	double frequency = 0.28;
	double amplitude = 12;
	int32_t octaves = 1;
	int32_t randomseed = 23;
	PerlinNoise perlinNoise(persistence, frequency, amplitude, octaves, randomseed);

	m_minHeight = 0;
	m_maxHeight = 0;

	float width = (NB_POINTS_WIDTH - 1);
	float length = (NB_POINTS_LENGTH - 1);

	for (int32_t i=0; i<NB_POINTS_WIDTH; i++) {
		for (int32_t j=0; j<NB_POINTS_LENGTH; j++) {

			int32_t arrayIndex = j * NB_POINTS_WIDTH + i;

			mHeightData[arrayIndex] = (float)(perlinNoise.GetHeight(-width * 0.5 + i, -length * 0.5 + j));

			if (i==0 && j==0) {
				m_minHeight = mHeightData[arrayIndex] ;
				m_maxHeight = mHeightData[arrayIndex] ;
			}

			if (mHeightData[arrayIndex] > m_maxHeight) m_maxHeight = mHeightData[arrayIndex] ;
			if (mHeightData[arrayIndex] < m_minHeight) m_minHeight = mHeightData[arrayIndex] ;
		}
	}
}

// Generate the graphics mesh to render the height field
void HeightField::generateGraphicsMesh() {

	etk::Vector<uint32_t> indices;
	int32_t vertexId = 0;

	for (int32_t i=0; i<NB_POINTS_WIDTH; i++) {
		for (int32_t j=0; j<NB_POINTS_LENGTH; j++) {

			float originHeight = -(m_maxHeight - m_minHeight) * 0.5f - m_minHeight;
			float height = originHeight + mHeightData[j * NB_POINTS_WIDTH + i];
			openglframework::vec3 vertex(-(NB_POINTS_WIDTH - 1) * 0.5f + i, height, -(NB_POINTS_LENGTH - 1) * 0.5f + j);

			m_vertices.pushBack(vertex);

			// Triangle indices
			if ((i < NB_POINTS_WIDTH - 1) && (j < NB_POINTS_LENGTH - 1)) {

				uint32_t v1 = vertexId;
				uint32_t v2 = vertexId + 1;
				uint32_t v3 = vertexId + NB_POINTS_LENGTH;
				uint32_t v4 = vertexId + NB_POINTS_LENGTH + 1;

				// First triangle
				indices.pushBack(v1);
				indices.pushBack(v2);
				indices.pushBack(v3);

				// Second triangle
				indices.pushBack(v2);
				indices.pushBack(v4);
				indices.pushBack(v3);
			}

			vertexId++;
		}
	}

	mIndices.pushBack(indices);

	calculateNormals();
}

// Create the Vertex Buffer Objects used to render with OpenGL.
/// We create two VBOs (one for vertices and one for indices)
void HeightField::createVBOAndVAO() {

	// Create the VBO for the vertices data
	mVBOVertices.create();
	mVBOVertices.bind();
	size_t sizeVertices = m_vertices.size() * sizeof(openglframework::vec3);
	mVBOVertices.copyDataIntoVBO(sizeVertices, getVerticesPointer(), GL_STATIC_DRAW);
	mVBOVertices.unbind();

	// Create the VBO for the normals data
	mVBONormals.create();
	mVBONormals.bind();
	size_t sizeNormals = mNormals.size() * sizeof(openglframework::vec3);
	mVBONormals.copyDataIntoVBO(sizeNormals, getNormalsPointer(), GL_STATIC_DRAW);
	mVBONormals.unbind();

	if (hasTexture()) {
		// Create the VBO for the texture co data
		mVBOTextureCoords.create();
		mVBOTextureCoords.bind();
		size_t sizeTextureCoords = mUVs.size() * sizeof(openglframework::vec2);
		mVBOTextureCoords.copyDataIntoVBO(sizeTextureCoords, getUVTextureCoordinatesPointer(), GL_STATIC_DRAW);
		mVBOTextureCoords.unbind();
	}

	// Create th VBO for the indices data
	mVBOIndices.create();
	mVBOIndices.bind();
	size_t sizeIndices = mIndices[0].size() * sizeof(uint32_t);
	mVBOIndices.copyDataIntoVBO(sizeIndices, getIndicesPointer(), GL_STATIC_DRAW);
	mVBOIndices.unbind();

	// Create the VAO for both VBOs
	mVAO.create();
	mVAO.bind();

	// Bind the VBO of vertices
	mVBOVertices.bind();

	// Bind the VBO of normals
	mVBONormals.bind();

	if (hasTexture()) {
		// Bind the VBO of texture coords
		mVBOTextureCoords.bind();
	}

	// Bind the VBO of indices
	mVBOIndices.bind();

	// Unbind the VAO
	mVAO.unbind();
}

// Reset the transform
void HeightField::resetTransform(const ephysics::Transform& transform) {

	// Reset the transform
	m_body->setTransform(transform);

	m_body->setIsSleeping(false);

	// Reset the velocity of the rigid body
	ephysics::RigidBody* rigidBody = dynamic_cast<ephysics::RigidBody*>(m_body);
	if (rigidBody != NULL) {
		rigidBody->setLinearVelocity(ephysics::vec3(0, 0, 0));
		rigidBody->setAngularVelocity(ephysics::vec3(0, 0, 0));
	}

	updateetk::Transform3D(1.0f);
}

// Set the scaling of the object
void HeightField::setScaling(const openglframework::vec3& scaling) {

	// Scale the collision shape
	m_proxyShape->setLocalScaling(ephysics::vec3(scaling.x(), scaling.y(), scaling.z()));

	// Scale the graphics object
	m_scalingMatrix = openglframework::Matrix4(scaling.x(), 0, 0, 0,
											  0, scaling.y(), 0,0,
											  0, 0, scaling.z(), 0,
											  0, 0, 0, 1.0f);
}