//
// Created by olivier on 5/3/22.
//

#include <iostream>

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include "src/Shader.h"


void framebuffer_size_callback(GLFWwindow* window, int width, int height);

int main() {
    // Initialize GLFW
    glfwInit();
    // Set window hints
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

    //Create the window
    GLFWwindow *window = glfwCreateWindow(800, 600, "OpenGL", nullptr, nullptr);
    if(window == nullptr) {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

    // Setup GLAD
    if(!gladLoadGLLoader((GLADloadproc) glfwGetProcAddress)) {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    // Setup viewport
    glViewport(0, 0, 800, 600);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);

    //// Setup geometry
    float vertices[] = {
            0.5f,  0.5f, 0.0f, 1.0f, 1.0f, 0.0f,  // top right
            0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f,  // bottom right
            -0.5f, -0.5f, 0.0f,0.0f, 0.0f, 1.0f, // bottom left
            -0.5f,  0.5f, 0.0f,1.0f, 0.0f, 0.0f // top left
    };
    unsigned int indices[] = {
            0, 1, 3, // first triangle
            1, 2, 3  // second triangle
    };

    unsigned int VBO, VAO, EBO;


    //generate buffers
    glGenBuffers(1, &VBO);
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &EBO);

    //Bind buffers
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBindVertexArray(VAO);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);

    //copy data to buffers
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    //SetVertexAttribPointer
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), nullptr);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3*sizeof(float)));
    glEnableVertexAttribArray(1);


    //Create shaders
    Shader ourShader("src/shaders/shader.vert", "src/shaders/shader.frag");
    ourShader.use();




    // Render loop
    while(!glfwWindowShouldClose(window)) {
        // Render
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        ourShader.use();
        glBindVertexArray(VAO);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);

        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);


        // Swap buffers
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
    glfwTerminate();
    return 0;
}

void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
    glViewport(0, 0, width, height);
}