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

#include <iostream>
#include <vector>

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



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";
const char *fragmentShaderSource = "#version 330 core\n"
                                   "out vec4 FragColor;\n"
                                   "void main()\n"
                                   "{\n"
                                   "   FragColor = vec4(1.0f, 1.f, 1.f, 1.0f);\n"
                                   "}\n\0";
const char *blackFragmentShaderSource = "#version 330 core\n"
                                   "out vec4 FragColor;\n"
                                   "void main()\n"
                                   "{\n"
                                   "   FragColor = vec4(1.0f, 1.f, 1.f, 1.0f);\n"
                                   "}\n\0";

void createSquare(float x0, float y0, float side_length, std::vector<float> &vertices, std::vector<int> &indices)
{
    int first = vertices.size()/3;
    vertices.insert(vertices.end(), { x0 + side_length, y0 + side_length, 0.f,
                                      x0 + side_length, y0, 0.f,
                                      x0, y0, 0.f,
                                      x0, y0 + side_length, 0.f});
    indices.insert(indices.end(), { first, first + 1 , first + 3,
                                    first + 1, first + 2, first + 3 });
}

void createSierpinskiCarpet(float x0, float y0, float side_length, int iterationsCount, std::vector<float> &vertices, std::vector<int> &indices)
{
    if(iterationsCount == 0)
        return;

    createSquare(x0 + (side_length/3.f), y0 + (side_length/3.f), side_length/3.f, vertices, indices);

    for(int i = 0 ; i < 3; i++)
    {
        for(int j = 0 ; j < 3; j++)
        {
            if((i == 1 && j == 1))
                continue;
            //createSquare(x0 + (j * (side_length/3.f)), y0 + (i * (side_length/3.f)), side_length/3.f, vertices, indices);
            createSierpinskiCarpet(x0 + (j * (side_length/3.f)), y0 + (i * (side_length/3.f)), side_length/3.f, iterationsCount-1, vertices, indices);
        }
    }
}

int main()
{
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    GLFWwindow* window = glfwCreateWindow(700, 600, "Ćwiczenie 1", nullptr, nullptr);
    if (window == nullptr)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

    // inicjalizacja funkcji OpenGL dzięki bibliotece GLAD
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }
    glViewport(0, 0, 600, 600);
    //Callback dla zmiany okna przez użytkownika
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);


    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    // check for shader compile errors
    int success;
    char infoLog[512];
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    // fragment shader
    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    GLuint blackFragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glShaderSource(blackFragmentShader, 1, &blackFragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    glCompileShader(blackFragmentShader);
    // check for shader compile errors
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    glGetShaderiv(blackFragmentShader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(blackFragmentShader, 512, NULL, infoLog);
        std::cout << "ERROR::BLACK::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    // link shaders
    GLuint shaderProgram = glCreateProgram();
    GLuint shaderProgramBLACK = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);

    glAttachShader(shaderProgramBLACK, vertexShader);
    glAttachShader(shaderProgramBLACK, blackFragmentShader);
    glLinkProgram(shaderProgramBLACK);
    // check for linking errors
    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
    if (!success) {
        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
    }
    // check for linking errors
    glGetProgramiv(shaderProgramBLACK, GL_LINK_STATUS, &success);
    if (!success) {
        glGetProgramInfoLog(shaderProgramBLACK, 512, NULL, infoLog);
        std::cout << "ERROR::BLACK::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
    }
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);
    glDeleteShader(blackFragmentShader);

    GLuint VBO, VAO, EBO;

    std::vector<float> verticesVector;
    std::vector<int> indicesVector;
    createSierpinskiCarpet(-0.9f, -0.9f, 1.8f, 6, verticesVector, indicesVector);

    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);
    // bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s).
    glBindVertexArray(VAO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(verticesVector[0]) * verticesVector.size(), &verticesVector[0], GL_STATIC_DRAW);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indicesVector[0]) * indicesVector.size(), &indicesVector[0], GL_STATIC_DRAW);

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

    // note that this is allowed, the call to glVertexAttribPointer registered VBO as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);

    while (!glfwWindowShouldClose(window))
    {
        processInput(window);

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

        // 2. Włącz program cieniujący, którego chcemy użyć do renderowania
        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
        glDrawElements(GL_TRIANGLES, indicesVector.size(), GL_UNSIGNED_INT, 0);


        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
        // -------------------------------------------------------------------------------
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // optional: de-allocate all resources once they've outlived their purpose:
    // ------------------------------------------------------------------------
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);

    // glfw: terminate, clearing all previously allocated GLFW resources.
    // ------------------------------------------------------------------
    glfwTerminate();
    return 0;
}

// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);
}

// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(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.
    int lowerValue = (width - (width / 6) < height? width - (width / 6) : height);

    glViewport(0, 0, lowerValue, lowerValue);
}