#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <cstdio>
#include "FullScreenQuad.hpp"

float vertices[] = {
    -0.5f, -0.5f, 0.0f,
     0.5f, -0.5f, 0.0f,
     0.0f,  0.5f, 0.0f
}; 


const char *vertexShaderSource = "#version 330 core\n"
    "layout (location = 0) in vec3 aPos;\n"
    "void main()\n"
    "{\n"
    "   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
    "}\0";

const char *fragmentShaderSource = "#version 330 core\n"
    "out vec4 FragColor;\n"
    "void main()\n"
    "{\n"
    "   FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
    "}\n\0";

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

void processInput(GLFWwindow *window)
{
    if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}

unsigned int initVBO() {
    unsigned int VBO;
    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    return VBO;
}

unsigned int initVAO() {
    unsigned int VAO;
    glGenVertexArrays(1, &VAO);
    glBindVertexArray(VAO);
    // 2. copy our vertices array in a buffer for OpenGL to use
    glBindBuffer(GL_ARRAY_BUFFER, initVBO());
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
    // 3. then set our vertex attributes pointers
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    return VAO;
}


unsigned int compVertexShader() {
    unsigned int vertexShader;
    vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    return vertexShader;
}

unsigned int compFragmentShader() {
    unsigned int fragmentShader;
    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    return fragmentShader;
}

unsigned int compShader() {
    unsigned int shaderProgram;
    shaderProgram = glCreateProgram();
    unsigned int vert = compVertexShader();
    unsigned int frag = compFragmentShader();
    glAttachShader(shaderProgram, vert);
    glAttachShader(shaderProgram, frag);
    glLinkProgram(shaderProgram);
    
    glDeleteShader(vert);
    glDeleteShader(frag);  

    return shaderProgram;
}

void linkVBO() { 
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0); 
}

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

int main(int argc, char** argv) {

    GLFWwindow* window;

    if (!glfwInit())
        return -1;

    window = glfwCreateWindow(800, 600, "Hello World", NULL, NULL);

    if (!window)
    {
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);

    GLenum err = glewInit();
    if (GLEW_OK != err) {
        fprintf(stderr, "GLEW error: %s\n", glewGetErrorString(err));
        return 1;
    }


    glViewport(0, 0, 800, 600);


    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);  

    unsigned int shaderProgramm = compShader();
    unsigned int VAO = initVAO();

    FullScreenQuad fsq{};

    while (!glfwWindowShouldClose(window))
    {
        processInput(window);
        /* Render here */


        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

	
	glUseProgram(shaderProgramm);

        glBindVertexArray(VAO);
	glDrawArrays(GL_TRIANGLES, 0, 3);
	glBindVertexArray(fsq.getVAO());	
	glDrawArrays(GL_TRIANGLES, 0, 6);

        /* Poll for and process events */
        glfwPollEvents();

        glfwSwapBuffers(window);
    }

    glfwTerminate();
}