#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()
{	
	_scnctx.lights.emplace("Light1", Light(glm::vec3(0.0f, 0.5f, 0.5f), glm::vec4(10, 10, 0, 1)));
	_scnctx.lights.emplace("Light2", Light(glm::vec3(0.0f, 0.0f, 0.5f), glm::vec4(3.09, 10, 9.51, 1)));
	_scnctx.lights.emplace("Light3", Light(glm::vec3(0.5f, 0.0f, 0.0f), glm::vec4(-8.09, 10, 5.87, 1)));
	_scnctx.lights.emplace("Light4", Light(glm::vec3(0.0f, 0.5f, 0.0f), glm::vec4(-8.09, 10, -5.87, 1)));
	_scnctx.lights.emplace("Light5", Light(glm::vec3(0.5f, 0.5f, 0.5f), glm::vec4(3.09, 10, -9.51, 1)));

	shaders["StandardLight"] = new Shader("light.vert", "light.frag");
	shaders["FogShader"] = new Shader("fog.vert", "fog.frag");

	shaders["SilhouetteShader"] = new Shader("silhouette.vert", "silhouette.frag");
	shaders["SilhouetteShader"]->uniformFlags = ShaderFlags::MVP_FLAG;
	shaders["SilhouetteShader"]->addUniform("fColor", glm::vec3(237/255, 229/255, 194/255));
	shaders["SilhouetteShader"]->addUniform("sil_offset", 0.1f);	

	shaders["ToonShader"] = new Shader("light.vert", "toon.frag");
	//Removing useless specular component
	shaders["ToonShader"]->uniformFlags &= ~ShaderFlags::KS_FLAG;
	shaders["ToonShader"]->uniformFlags &= ~ShaderFlags::SHINE_FLAG;
	
	Dataset cube;
	cube.simpleCube();
	
	meshes.push_back(new Mesh("teapot.obj", shaders["SilhouetteShader"]));
	meshes.back()->cullMode = FRONT;
	meshes.back()->addTranslation(glm::vec4(-2, 0, -5, 0));
	meshes.push_back(new Mesh("teapot.obj", shaders["ToonShader"]));
	meshes.back()->cullMode = BACK;
	meshes.back()->addTranslation(glm::vec4(-2, 0, -5, 0));
	meshes.push_back(new Mesh(cube, shaders["StandardLight"]));
}

void MyGlWindow::draw()
{	
	glClearColor(_bgColor[0], _bgColor[1], _bgColor[2], 1);	
	glViewport(0, 0, m_width, m_height);
	glEnable(GL_DEPTH_TEST);
	glEnable(GL_DEPTH_BUFFER);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	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 parameters of m_viewer
	glm::mat4 projection = perspective(45.0f, (float)m_width / (float)m_height, 0.1f, 500.0f);
	
	_scnctx.viewMatrix = view;
	_scnctx.projectionMatrix = projection;
	for (auto it = meshes.begin(); it != meshes.end(); it++)
		(*it)->draw(_scnctx);
}

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