#include <algorithm>
#include "MyGlWindow.h"
//Getting the projection matrix
glm::mat4x4 perspective(float fovy, float aspect, float near, float far)
{
	float fovy2 = glm::tan(fovy / 2);

	glm::mat4x4 pmat{ { 1 / (aspect * fovy2), 0, 0, 0},
					  { 0, 1 / fovy2, 0, 0},
					  { 0, 0, -((far + near) / (far - near)), -1},
					  { 0, 0, -((2 * far * near) / (far - near)), 0} };


	return pmat;
}

// Getting the view matrix
glm::mat4x4 lookAt(glm::vec3 campos, glm::vec3 look, glm::vec3 up)
{
	glm::vec3 ZCam(glm::normalize(campos - look));
	glm::vec3 XCam(glm::normalize(glm::cross(up, ZCam)));
	glm::vec3 YCam(glm::normalize(glm::cross(ZCam, XCam)));

	glm::mat4x4 cam_mat{ {XCam.x, YCam.x, ZCam.x, 0},
						 {XCam.y, YCam.y, ZCam.y, 0},
						 {XCam.z, YCam.z, ZCam.z, 0},
						 {0, 0, 0 ,1} };

	glm::mat4x4 norm_mat{ {1, 0, 0, 0},
						  {0, 1, 0, 0},
						  {0, 0, 1, 0},
						  {-campos.x, -campos.y, -campos.z, 1} };

	return cam_mat * norm_mat;
}


MyGlWindow::MyGlWindow(int w, int h) : 
	viewer(glm::vec3(5, 5, 5), glm::vec3(0, 0, 0), glm::vec3(0, 1, 0), 45.0f, (w / (float)h))
{
	m_width = w;
	m_height = h;

	setup();
}

MyGlWindow::~MyGlWindow()
{
}

void MyGlWindow::setBgColor(float bgColor[3])
{
	_bgColor[0] = bgColor[0];
	_bgColor[1] = bgColor[1];
	_bgColor[2] = bgColor[2];
}

void MyGlWindow::setup()
{
	_staticShader = new ShaderProgram();
	_staticShader->initFromFiles("simple.vert", "simple.frag");
	_lightShader = new ShaderProgram();
	_lightShader->initFromFiles("light.vert", "simple.frag");

	_static_drawables.emplace_back(new CheckeredFloor(50, 16));	
	_light_drawables.push_back(new ColorCube(false));
	_light_drawables.back()->addTranslation(glm::vec4(2, 1.1f, 0, 0));	
	_light_drawables.push_back(new Sphere(1, 100, 100));
	_light_drawables.back()->addTranslation(glm::vec4(-2, 1.1f, 0, 0));
	_light_drawables.push_back(new VBOTeapot(64, glm::identity<glm::mat4x4>()));
	_light_drawables.back()->addTranslation(glm::vec4(2, 3, -7, 0));
	_light_drawables.back()->addRotation(glm::vec4(1, 0, 0, -90));	
}

void MyGlWindow::draw()
{	
	glClearColor(_bgColor[0], _bgColor[1], _bgColor[2], 1);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glViewport(0, 0, m_width, m_height);
	glEnable(GL_DEPTH_TEST);
	
	glm::vec3 eye(viewer.getViewPoint().x, viewer.getViewPoint().y, viewer.getViewPoint().z);
	glm::vec3 look(viewer.getViewCenter().x, viewer.getViewCenter().y, viewer.getViewCenter().z);
	glm::vec3 up(viewer.getUpVector().x, viewer.getUpVector().y, viewer.getUpVector().z);
	glm::mat4 view = lookAt(eye, look, up);   //Calculate view matrix from paramters of m_viewer
	glm::mat4 projection = perspective(45.0f, m_width / m_height, 0.1f, 500.0f);

	_staticShader->use();		

	_staticShader->addUniform("mvp");
	
	for (ADrawable *drawable : _static_drawables)		
		drawable->draw(_staticShader, projection, view);				
	
	_staticShader->disable();

	_lightShader->use();

	_lightShader->addUniform("mvp");	
	_lightShader->addUniform("LightLocation"); //Light Position to camera coordinates : vec4

	_lightShader->addUniform("Kd"); //Diffuse Object Color :vec3
	glUniform3fv(_lightShader->uniform("Kd"), 1, glm::value_ptr(glm::vec3(1, 1, 0)));
	_lightShader->addUniform("Ld"); //Diffuse Light Color : vec3
	glUniform3fv(_lightShader->uniform("Ld"), 1, glm::value_ptr(glm::vec3(1, 1, 1)));

	_lightShader->addUniform("Ka"); //Diffuse Object Color :vec3
	glUniform3fv(_lightShader->uniform("Ka"), 1, glm::value_ptr(glm::vec3(0.2, 0.2, 0)));
	_lightShader->addUniform("La"); //Diffuse Light Color : vec3
	glUniform3fv(_lightShader->uniform("La"), 1, glm::value_ptr(glm::vec3(1, 1, 1)));

	_lightShader->addUniform("Ks"); //Diffuse Object Color :vec3
	glUniform3fv(_lightShader->uniform("Ks"), 1, glm::value_ptr(glm::vec3(0.3, 0.3, 0)));
	_lightShader->addUniform("Ls"); //Diffuse Light Color : vec3
	glUniform3fv(_lightShader->uniform("Ls"), 1, glm::value_ptr(glm::vec3(1, 1, 1)));

	_lightShader->addUniform("NormalMatrix"); //Refer next slide : mat3	
	_lightShader->addUniform("ModelViewMatrix"); //View*Model : mat4	

	for (ADrawable *drawable : _light_drawables)
		drawable->draw(_lightShader, projection, view);

	_lightShader->disable();
}

void MyGlWindow::AddDrawable(ADrawable *d)
{
	_static_drawables.push_back(d);
}

void MyGlWindow::resize(int w, int h)
{
	m_width = w;
	m_height = h;
	viewer.setAspectRatio(w / float(h));
}