window.h

#ifndef window_h
#define window_h

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>

void resizeWindow(GLFWwindow *window, int width, int height);
void processInput(GLFWwindow *window);

const int WINDOW_WIDTH = 800, WINDOW_HEIGHT = 600;

// Vertex shader
const char *vertexShaderSource = "#version 330 core\n"
    "layout (location = 0) in vec3 aPos;\n"
    "void main()\n"
    "{\n"
    "   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
    "}\0";

// Fragment shader
const char *fragmentShaderSource = "#version 330 core\n"
    "out vec4 FragColor;\n"
    "void main()\n"
    "{\n"
    "   FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
    "}\n\0";



// openWindow() opens the game window and begins the game loop
int openWindow(){
    // Initialize GLFW
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    #ifdef __APPLE__
        // If OSX, specify forward compatibility
        glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    #endif

    // Create our GLFW window
    GLFWwindow* window = glfwCreateWindow(WINDOW_WIDTH, WINDOW_HEIGHT, "Minecraft 2", NULL, NULL);
    if (window == NULL) {
        // If window was not created successfully, terminate
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, resizeWindow);

    // Ensure GLAD function pointers can be read
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }


    // Build and compile vertex shaders
    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);

    int success;
    char infoLog[512];
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);

    // If building failed, output an error
    if (!success){
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }

    // Build and compile fragment shaders
    unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);

    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);

    // If building failed, output an error
    if (!success) {
        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
    }

    // Link the shaders
    unsigned int shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);

    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);

    // If linking failed, output an error
    if (!success) {
        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
    }
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    // Initialize vertex data
    float vertices[] = {
        -0.5f, -0.5f, 0.0f, // left  
         0.5f, -0.5f, 0.0f, // right 
         0.0f,  0.5f, 0.0f  // top   
    }; 

    // Bind our BAO and VBO
    unsigned int VBO, VAO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);

    glBindVertexArray(VAO);

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

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

    glBindBuffer(GL_ARRAY_BUFFER, 0); 

    glBindVertexArray(0); 


    // Render loop
    while (!glfwWindowShouldClose(window)) {
        // Process user inputs
        processInput(window);

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

        // Draw the triangle
        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 3);

        // No need to unbind right now
        // glBindVertexArray(0); 
 
        // Swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // De-allocate resources
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteProgram(shaderProgram);

    // Clear all allocated GLFW resources
    glfwTerminate();
    return 0;
}

// processInput() processes user inputs
void processInput(GLFWwindow *window)
{
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}

// resizeWindow() resizes the game window
void resizeWindow(GLFWwindow* window, int width, int height)
{
    // make sure the viewport matches the new window dimensions; note that width and 
    // height will be significantly larger than specified on retina displays.
    glViewport(0, 0, width, height);
}

#endif