#include <iostream>

#include "glad/gl.h"
#include "GLFW/glfw3.h"

#include "spdlog/spdlog.h"

GLFWwindow* gWindow;
int gWindowWidth = 800;
int gWindowHeight = 600;

int glVersionMajor;
int glVersionMinor;

void glfw_error_callback(int error, const char* description);
void glfw_key_callback(GLFWwindow* window, int key, int scancode, int action, int mods);
void glfw_framebuffer_size_callback(GLFWwindow* window, int width, int height);

int main() {
    spdlog::info("b_engine start");

    if (!glfwInit()) {
        spdlog::error("could not initialize glfw");
        std::exit(1);
    }

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    glfwSetErrorCallback(glfw_error_callback);

    gWindow = glfwCreateWindow(gWindowWidth, gWindowHeight, "b_engine v0.0.1", nullptr, nullptr);
    if (!gWindow) {
        spdlog::error("failed to create glfw window");
        std::exit(1);
    }

    glfwMakeContextCurrent(gWindow);

    glfwSetKeyCallback(gWindow, glfw_key_callback);
    glfwSetFramebufferSizeCallback(gWindow, glfw_framebuffer_size_callback);

    int version = gladLoadGL(glfwGetProcAddress);
    glVersionMajor = GLAD_VERSION_MAJOR(version);
    glVersionMinor = GLAD_VERSION_MINOR(version);
    spdlog::info("gl version {}.{}", glVersionMajor, glVersionMinor);

    int fbWidth, fbHeight;
    glfwGetFramebufferSize(gWindow, &fbWidth, &fbHeight);
    glViewport(0, 0, fbWidth, fbHeight);

    while (!glfwWindowShouldClose(gWindow)) {
        glfwPollEvents();

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

        glfwSwapBuffers(gWindow);
    }

    glfwDestroyWindow(gWindow);
    glfwTerminate();

    return 0;
}

void glfw_error_callback(int error, const char* description) {
    spdlog::error("glfw error: {}", description);
}

void glfw_key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS) {
        glfwSetWindowShouldClose(window, GL_TRUE);
    }
}

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