#define GL_GLEXT_PROTOTYPES

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

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

const char *fragment_shader_source =
"#version 330 core\n"
"out vec4 FragColor;\n"
"in vec2 uv;\n"
"\n"
"void main()\n"
"{\n"
"    FragColor = vec4(gl_FragCoord.xy / 800, 0.0, 1.0);\n"
"}\n";

GLuint compile_shader(GLuint type, const char *src) {
    GLuint id = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(id, 1, &src, 0);
    glCompileShader(id);

    int result;
    glGetShaderiv(id, GL_COMPILE_STATUS, &result);
    if (result == GL_FALSE) {
        int length;
        glGetShaderiv(id, GL_INFO_LOG_LENGTH, &result);
        char *message = alloca(length * sizeof(char));
        glGetShaderInfoLog(id, length, &length, message);
        printf("failed to compile %s shader\n", type == GL_VERTEX_SHADER ? "vertex" : "fragment");
        printf("%s\n", message);
        glDeleteShader(id);
        return 0;
    }

    return id;
}

GLuint create_shader(const char *fragment_src) {
    GLuint program = glCreateProgram();
    GLuint fragment_shader = compile_shader(GL_FRAGMENT_SHADER, fragment_src);

    glAttachShader(program, fragment_shader);
    glLinkProgram(program);
    glValidateProgram(program);
    glDeleteShader(fragment_shader);

    return program;
}

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;

    GLuint shader = create_shader(fragment_shader_source);
    glUseProgram(shader);

    while (running) {
        while (SDL_PollEvent(&e)) {
            if (e.type == SDL_EVENT_QUIT) running = false;
        }
        checkGlError();

        // Rendorrrr
        glViewport(0, 0, 800, 800);
        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);
        glVertex2f(-1, 1);
        glVertex2f(-1,-1);
        glVertex2f( 1,-1);
        glVertex2f( 1, 1);

        glEnd();

        SDL_GL_SwapWindow(window);
        angle += 0.5;
    }

    checkGlError();
}