#define GL_GLEXT_PROTOTYPES

#include <stdio.h>
#include <GL/gl.h>
#include <GL/glext.h>
#include <SDL3/SDL.h>

float tanf(float in) {
    return in;
}

void perspective(float fovY, float aspect, float zNear, float zFar, float* matrix) {
    float f = 1.0f / tanf(fovY * 0.5f * (3.14159265358979323846f / 180.0f));
    matrix[0]  = f / aspect;
    matrix[1]  = 0;
    matrix[2]  = 0;
    matrix[3]  = 0;

    matrix[4]  = 0;
    matrix[5]  = f;
    matrix[6]  = 0;
    matrix[7]  = 0;

    matrix[8]  = 0;
    matrix[9]  = 0;
    matrix[10] = (zFar + zNear) / (zNear - zFar);
    matrix[11] = -1;

    matrix[12] = 0;
    matrix[13] = 0;
    matrix[14] = (2 * zFar * zNear) / (zNear - zFar);
    matrix[15] = 0;
}

void drawCube() {
    glBegin(GL_QUADS);

    // Back
    glColor3f(0, 1, 0);
    glVertex3f(-1, -1, -1);
    glVertex3f(-1,  1, -1);
    glVertex3f( 1,  1, -1);
    glVertex3f( 1, -1, -1);

    // Top
    glColor3f(0, 0, 1);
    glVertex3f(-1, 1, -1);
    glVertex3f(-1, 1,  1);
    glVertex3f( 1, 1,  1);
    glVertex3f( 1, 1, -1);

    // Bottom
    glColor3f(1, 1, 0);
    glVertex3f(-1, -1, -1);
    glVertex3f( 1, -1, -1);
    glVertex3f( 1, -1,  1);
    glVertex3f(-1, -1,  1);

    // Right
    glColor3f(1, 0, 1);
    glVertex3f(1, -1, -1);
    glVertex3f(1,  1, -1);
    glVertex3f(1,  1,  1);
    glVertex3f(1, -1,  1);

    // Left
    glColor3f(0, 1, 1);
    glVertex3f(-1, -1, -1);
    glVertex3f(-1, -1,  1);
    glVertex3f(-1,  1,  1);
    glVertex3f(-1,  1, -1);

    glEnd();
}

void checkGlError() {
    const char *err = SDL_GetError();
    if (*err != 0) {
        printf("OpenGL error: %s", err);
    }
}

const char *vertex_shader_source = "";

GLuint create_shader() {
    GLuint vshader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vshader, 1, &vertex_shader_source, NULL); // vertex_shader_source is a GLchar* containing glsl shader source code
    glCompileShader(vshader);
    return vshader;
}

int main() {
    printf("Good Morning 🍵\n");
    SDL_Init(SDL_INIT_VIDEO);
    SDL_Window* window = SDL_CreateWindow("SDL3 OpenGL Cube",
    800, 600, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
    if (!window) {
        printf("CreateWindow Error: %s\n", SDL_GetError());
        SDL_Quit();
        return 1;
    }
    
    SDL_GLContext glContext = SDL_GL_CreateContext(window);
    if (!glContext) {
        printf("GL Context Error: %s\n", SDL_GetError());
        SDL_DestroyWindow(window);
        SDL_Quit();
        return 1;
    }
    glEnable(GL_DEPTH_TEST);

    SDL_Event e;
    int running = 1;
    float angle = 0.0;
    while (running) {
        while (SDL_PollEvent(&e)) {
            if (e.type == SDL_EVENT_QUIT) running = false;
        }
        checkGlError();

        // Rendorrrr
        glViewport(0, 0, 800, 600);
        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);  // Dark gray background
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        
        //drawCube();
        // Front
        glBegin(GL_QUADS);
        glColor3f(1, 0, 0);
        glVertex2f(-1, -1);
        glVertex2f(-1,  1);
        glVertex2f( 1,  1);
        glVertex2f( 1, -1);
        glEnd();

        SDL_GL_SwapWindow(window);
        angle += 0.5;
    }

    checkGlError();
}