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

void display() {
    glClear(GL_COLOR_BUFFER_BIT);
    glBegin(GL_TRIANGLES);
    glColor3f(1.0, 0.0, 0.0);
    glVertex2f(-0.5, -0.5);
    glColor3f(0.0, 1.0, 0.0);
    glVertex2f(0.5, -0.5);
    glColor3f(0.0, 0.0, 1.0);
    glVertex2f(0.0, 0.5);
    glEnd();
    glFlush();
}

/*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);
}

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

    GLFWwindow* window;

    if (!glfwInit())
        return -1;

    window = glfwCreateWindow(640, 480, "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);

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


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


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

        glfwSwapBuffers(window);
    }

    glfwTerminate();
}