#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <stb_image.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "Shader.h"
#include "Camera.h"
#include "Model.h"

#define TEXTURES_DIR "../../../../textures/"
#define MODELS_DIR	 "../../../../models/"
#define SHADERS_DIR	"../src/shaders/"

using namespace std;
typedef unsigned int uint;

// Global Constants
// ...
// Global Variables
GLFWwindow* window;
int WINDOW_WIDTH = 800;
int WINDOW_HEIGHT = 600;
Camera myCamera(glm::vec3(0.0f, 0.0f, 3.0f));
float deltaTime = 0.0f;
float lastFrame = 0.0f;
float lastX = 400;
float lastY = 300;
bool firstmouse = true;
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);
glm::vec3 lightColor(1.0f, 1.0f, 1.0f);

uint8_t init(void);
void framebuffersize_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void proccessInput(GLFWwindow* window);
unsigned int load_texture(const char* path, bool flip = true);

int main(int argc, char** argv)
{
	if (init() != 0)
		return -1;		

	Shader lightingShader(SHADERS_DIR "glmlShader.vert", SHADERS_DIR "glmlShader.frag");

	stbi_set_flip_vertically_on_load(1);
	glml::Model backpack(MODELS_DIR "backpack/backpack.obj");

	glEnable(GL_DEPTH_TEST);
	/* ------------------ MAIN loop ------------------ */
	while (!glfwWindowShouldClose(window)) {
		float currentFrame = glfwGetTime();
		deltaTime = currentFrame - lastFrame;	// cas jak dlouho trval posledni frame
		lastFrame = currentFrame;				// cas kdy zacal tento frame
		// input ...
		proccessInput(window);

		// rendering commands here ...
		glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		
				
		lightingShader.Use();
//		lightingShader.setVec3("light.position", lightPos);
		
		glm::mat4 view = myCamera.getViewMatrix();
		glm::mat4 projection(1.0f);
		projection = glm::perspective(glm::radians(myCamera.FOV), (float)WINDOW_WIDTH / WINDOW_HEIGHT, 0.1f, 100.0f);		
		glm::mat4 model(1.0f);
		glm::mat3 normalMatrix = glm::transpose(glm::inverse(model));
				
		lightingShader.setMat4("view", view);
		lightingShader.setMat4("projection", projection);
		lightingShader.setMat4("model", model);
		lightingShader.setMat3("normalMatrix", normalMatrix);

		glm::vec3 lightColor = glm::vec3(1.0f);
		glm::vec3 lightPos = glm::vec3(-1.13f, 2.0f, 2.0f);

		lightingShader.setVec3("pointLights[0].position", lightPos);
//		lightingShader.setVec3("spotLight.direction", myCamera.Front);
		lightingShader.setVec3("pointLights[0].ambient_intensity", glm::vec3(0.1f));
		lightingShader.setVec3("pointLights[0].diffuse_intensity", lightColor * glm::vec3(0.5f));
		lightingShader.setVec3("pointLights[0].specular_intensity", lightColor * glm::vec3(1.0f));
		lightingShader.setFloat("pointLights[0].constant", 1.0f);
		lightingShader.setFloat("pointLights[0].linear", 0.07f);
		lightingShader.setFloat("pointLights[0].quadratic", 0.032f);
//		lightingShader.setFloat("spotLight.cutOff", glm::cos(glm::radians(12.5f)));
//		lightingShader.setFloat("spotLight.outerCutOff", glm::cos(glm::radians(17.5f)));

		lightingShader.setVec3("viewPos", myCamera.Position);
		lightingShader.setFloat("material.shininess", 32.0f);

		backpack.Draw(lightingShader);				

		// check and calls events and swap the buffers
		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	glfwTerminate();

	return 0;
}

uint8_t init(void) {
	// init of glfw window
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);	
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	window = glfwCreateWindow(WINDOW_WIDTH, WINDOW_HEIGHT, "6. Multiple Lights", NULL, NULL);
	if (window == NULL) {
		cerr << "Failed to create glfw window" << endl;
		glfwTerminate();
		return 1;
	}
	glfwMakeContextCurrent(window);
	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	// init of GLAD
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
		cerr << "Failed to initialize GLAD" << endl;
	}

	glfwSetFramebufferSizeCallback(window, framebuffersize_callback);
	glfwSetCursorPosCallback(window, mouse_callback);
	glfwSetScrollCallback(window, scroll_callback);
	return 0;
}
void framebuffersize_callback(GLFWwindow* window, int width, int height)
{
	glViewport(0, 0, width, height);
	WINDOW_HEIGHT = height;
	WINDOW_WIDTH = width;
}
void proccessInput(GLFWwindow* window)
{	
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(window, true);
	if (glfwGetKey(window, GLFW_KEY_F1) == GLFW_PRESS)
		glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
	if (glfwGetKey(window, GLFW_KEY_F2) == GLFW_PRESS)
		glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
	/* -------------------- Movement -------------------- */
	if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
		myCamera.ProccessKeyboard(CAM_FORWARD, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
		myCamera.ProccessKeyboard(CAM_BACKWARD, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
		myCamera.ProccessKeyboard(CAM_RIGHT, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
		myCamera.ProccessKeyboard(CAM_LEFT, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_LEFT_SHIFT) == GLFW_PRESS)
		myCamera.ProccessKeyboard(CAM_DOWN, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS)
		myCamera.ProccessKeyboard(CAM_UP, deltaTime);

}
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
	if (firstmouse) {
		lastX = xpos;
		lastY = ypos;
		firstmouse = false;
	}

	float xoffset = xpos - lastX;
	float yoffset = lastY - ypos;
	lastX = xpos;
	lastY = ypos;

	myCamera.ProccessMouse(xoffset, yoffset);
}
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
	myCamera.ProccessScroll(yoffset);
}
unsigned int load_texture(const char* path, bool flip)
{
	unsigned int texture = 0;
	int width, height, nrChannels, format;
	stbi_set_flip_vertically_on_load(flip);
	unsigned char* data = stbi_load(path, &width, &height, &nrChannels, 0);		// load image to the array of bytes (char = 1 byte)	
	
	switch (nrChannels)
	{
	case 4: format = GL_RGBA; break;
	case 3: format = GL_RGB; break;
	case 2: format = GL_RED; break;
	default: format = GL_RGB; break;
	}

	if (data) // data != NULL
	{
		glGenTextures(1, &texture);
		glBindTexture(GL_TEXTURE_2D, texture);

		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, format, GL_UNSIGNED_BYTE, data);	// generates texture
		glGenerateMipmap(GL_TEXTURE_2D);
	}
	else {
		cerr << "Could not load texture '" << path << "'\n";
	}
	stbi_image_free(data);

	return texture;
}