// main.c
#include <stdio.h>
#include <stdlib.h>

#include "gl_utils.h"

int main(void) {
    int winW = 800;
    int winH = 600;

    GLFWwindow* window = init_glfw_glad("Falling Sand - Fullscreen Quad", winW, winH);
    if (!window) {
        return EXIT_FAILURE;
    }

    printf("Renderer: %s\n",  (const char*)glGetString(GL_RENDERER));
    printf("OpenGL:   %s\n",  (const char*)glGetString(GL_VERSION));
    printf("GLSL:     %s\n",  (const char*)glGetString(GL_SHADING_LANGUAGE_VERSION));

    // --- Create fullscreen triangle geometry (VAO + VBO) ---
    float vertices[] = {
        // x, y
        -1.0f, -1.0f,
         3.0f, -1.0f,
        -1.0f,  3.0f
    };

    GLuint vao = 0, vbo = 0;
    glGenVertexArrays(1, &vao);
    glGenBuffers(1, &vbo);

    glBindVertexArray(vao);

    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    // layout(location = 0) in vec2 aPos;
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(
        0,
        2,
        GL_FLOAT,
        GL_FALSE,
        2 * sizeof(float),
        (void*)0
    );

    glBindVertexArray(0);

    // --- Create shader program ---
    GLuint program = create_program_from_files(
        "shaders/fullscreen.vert",
        "shaders/gradient.frag"
    );

    glUseProgram(program);

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

    // --- Main loop ---
    while (!glfwWindowShouldClose(window)) {
        glfwPollEvents();

        glClear(GL_COLOR_BUFFER_BIT);

        glUseProgram(program);
        glBindVertexArray(vao);
        glDrawArrays(GL_TRIANGLES, 0, 3);

        glfwSwapBuffers(window);
    }

    // --- Cleanup ---
    glDeleteProgram(program);
    glDeleteBuffers(1, &vbo);
    glDeleteVertexArrays(1, &vao);

    glfwDestroyWindow(window);
    glfwTerminate();
    return EXIT_SUCCESS;
}