#include "rch.h"

#include <glad.h>  
#include <glfw3.h>  

#include <string.h>  
#include <stdio.h>  

const char* vert_src = "#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"void main() {\n"
"    gl_Position = vec4(aPos, 1.0);\n"
"}\n";

const char* frag_src = "#version 330 core\n"
"out vec4 FragColor;\n"
"void main() {\n"
"    FragColor = vec4(1.0, 0.5, 0.2, 1.0);\n"
"}\n";

int main() {
    if (!glfwInit()) {
        fprintf(stderr, "failed to initialize GLFW\n");
        return -1;
    }

    // OpenGL version 3.3 core 
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    // create window  
    GLFWwindow* window = glfwCreateWindow(800, 600, "window", NULL, NULL);
    if (!window) {
        fprintf(stderr, "failed to create GLFW window\n");
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

    // load OpenGL functions with GLAD  
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
        fprintf(stderr, "failed to initialize GLAD\n");
        return -1;
    }

    // vertex data for hello triangle 
    float vertices[] = {
         0.0f,  0.5f, 0.0f,
        -0.5f, -0.5f, 0.0f,
         0.5f, -0.5f, 0.0f
    };

    unsigned int vao, vbo;
    glGenVertexArrays(1, &vao);
    glGenBuffers(1, &vbo);

    glBindVertexArray(vao);

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

    // define vertexes  
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);

    // compile shaders  
    unsigned int vert_shader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vert_shader, 1, &vert_src, NULL);
    glCompileShader(vert_shader);
    unsigned int frag_shader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(frag_shader, 1, &frag_src, NULL);
    glCompileShader(frag_shader);

    // link shaders  
    unsigned int shader_program = glCreateProgram();
    glAttachShader(shader_program, vert_shader);
    glAttachShader(shader_program, frag_shader);
    glLinkProgram(shader_program);

    // delete local shader data  
    glDeleteShader(vert_shader);
    glDeleteShader(frag_shader);

    // main loop
    while (!glfwWindowShouldClose(window)) {
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

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

        glfwSwapBuffers(window);
        glfwPollEvents();
    }


    // free and clear
    glDeleteVertexArrays(1, &vao);
    glDeleteBuffers(1, &vbo);
    glDeleteProgram(shader_program);

    glfwDestroyWindow(window);
    glfwTerminate();
    return 0;
}