///////////////////////////////////////////////////////////////////////////////
//
// This program Generates a plain red pyramid
//
///////////////////////////////////////////////////////////////////////////////
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <string>
#include <iostream>
#include <fstream>
#include <cmath>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp> // glm::value_ptr
#include <glm/gtc/matrix_transform.hpp> // glm::translate, glm::rotate, glm::scale, glm::perspective
#include "Utils.h"
using namespace std;

#define numVAOs 1
#define numVBOs 2

Utils util = Utils();
float cameraX, cameraY, cameraZ;
float cubeLocX, cubeLocY, cubeLocZ;
GLuint renderingProgram;
GLuint vao[numVAOs];
GLuint vbo[numVBOs];

// variable allocation for display
GLuint mvLoc, projLoc;
int width, height;
float aspect;
glm::mat4 pMat, vMat, mMat, mvMat;

void setupVertices(void) {
	float vertexPositions[54] = {
		// Base tris
		1.0f, -1.0f, 1.0f,
		1.0f, -1.0f, -1.0f,
		-1.0f, -1.0f, 1.0f,

		-1.0f, -1.0f, -1.0f,
		-1.0f, -1.0f, 1.0f,
		1.0f, -1.0f, -1.0f,

		// Upright tris
		-1.0f, -1.0f, -1.0f,
		1.0f, -1.0f, -1.0f,
		0.0f, 1.0f, 0.0f,
		
		-1.0f, -1.0f, -1.0f,
		-1.0f, -1.0f, 1.0f,
		0.0f, 1.0f, 0.0f,
		
		1.0f, -1.0f, -1.0f,
		1.0f, -1.0f, 1.0f,
		0.0f, 1.0f, 0.0f,
		
		-1.0f, -1.0f, 1.0f,
		1.0f, -1.0f, 1.0f,
		0.0f, 1.0f, 0.0f
	};

	glGenVertexArrays(1, vao);
	glBindVertexArray(vao[0]);
	glGenBuffers(numVBOs, vbo);

	glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertexPositions), vertexPositions, GL_STATIC_DRAW);
}

void init(GLFWwindow* window) {
	renderingProgram = Utils::createShaderProgram("vertShader.glsl", "fragShader.glsl");
	cameraX = 0.0f; cameraY = 0.0f; cameraZ = 8.0f;
	cubeLocX = 0.0f; cubeLocY = -2.0f; cubeLocZ = 0.0f;
	setupVertices();
}

void display(GLFWwindow* window, double currentTime) {
	glClear(GL_DEPTH_BUFFER_BIT);

	glUseProgram(renderingProgram);

	mvLoc = glGetUniformLocation(renderingProgram, "mv_matrix");
	projLoc = glGetUniformLocation(renderingProgram, "proj_matrix");

	glfwGetFramebufferSize(window, &width, &height);
	aspect = (float)width / (float)height;
	pMat = glm::perspective(1.0472f, aspect, 0.1f, 1000.0f);

	vMat = glm::translate(glm::mat4(1.0f), glm::vec3(-cameraX, -cameraY, -cameraZ));
	mMat = glm::translate(glm::mat4(1.0f), glm::vec3(cubeLocX, cubeLocY, cubeLocZ));
	mvMat = vMat * mMat;

	glUniformMatrix4fv(mvLoc, 1, GL_FALSE, glm::value_ptr(mvMat));
	glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(pMat));

	glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
	glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
	glEnableVertexAttribArray(0);

	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LEQUAL);

	glDrawArrays(GL_TRIANGLES, 0, 18);
}

int main(void) {
	if (!glfwInit()) { exit(EXIT_FAILURE); }
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	GLFWwindow* window = glfwCreateWindow(600, 600, "Homework 4-1 - Nicholas Reel", NULL, NULL);
	glfwMakeContextCurrent(window);
	if (glewInit() != GLEW_OK) { exit(EXIT_FAILURE); }
	glfwSwapInterval(1);

	init(window);

	while (!glfwWindowShouldClose(window)) {
		display(window, glfwGetTime());
		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	glfwDestroyWindow(window);
	glfwTerminate();
	exit(EXIT_SUCCESS);
}