#include <glad/glad.h>
#include <GLFW/glfw3.h>
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include "shader_m.h"
#include "camera.h"

#include <iostream>
#include <pthread.h>

#ifdef __linux__
#include <unistd.h>
#endif
#ifdef _WIN32
#include <Windows.h>
#endif

void framebuffer_size_callback(GLFWwindow *window, int width, int height);
void mouse_callback(GLFWwindow *window, double xpos, double ypos);
void scroll_callback(GLFWwindow *window, double xoffset, double yoffset);
void focus_callback(GLFWwindow *window, int focused);
void processInput(GLFWwindow *window);
void delay_fps(int fps, int render_time_us);
void *getting_fps(void *window);

bool running = true;
bool pausing = false;
bool just_dispaused = false;

// settings
const unsigned int SCR_WIDTH = 854;
const unsigned int SCR_HEIGHT = 480;

// camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX = SCR_WIDTH / 2.0f;
float lastY = SCR_HEIGHT / 2.0f;
bool firstMouse = true;

// timing
float deltaTime = 0.0f; // time between current frame and last frame
float lastFrame = 0.0f;

// focuse controlling
bool window_focused = false;

// window managing
int curr_width;
int curr_height;
int curr_x;
int curr_y;

// monitors controlling
int monitor_count;
GLFWmonitor **monitors;

// fps control
int fps;

int main()
{
    // std::cout << "debug";
    //  glfw: initialize and configure
    //  ------------------------------
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_SCALE_TO_MONITOR, GLFW_FALSE);
    glfwWindowHint(GLFW_SCALE_FRAMEBUFFER, GLFW_FALSE);

#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif

    // glfw window creation
    // --------------------
    GLFWwindow *window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "Jungle", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }

    monitors = glfwGetMonitors(&monitor_count);

    pthread_t thr_getting_fps;
    pthread_create(&thr_getting_fps, nullptr, getting_fps, window);

    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
    glfwSetCursorPosCallback(window, mouse_callback);
    glfwSetScrollCallback(window, scroll_callback);
    glfwSetWindowFocusCallback(window, focus_callback);

    // tell GLFW to capture our mouse
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

    // glad: load all OpenGL function pointers
    // ---------------------------------------
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

    // configure global opengl state
    // -----------------------------
    // glEnable(GL_DEPTH_TEST);

    // build and compile our shader zprogram
    // ------------------------------------
    Shader ourShader("demo.vs", "demo.fs");

    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------
    float vertices[] = {
        // back
        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
        0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
        0.5f, 0.5f, -0.5f, 1.0f, 1.0f,

        0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f,

        // front
        -0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
        0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
        0.5f, 0.5f, 0.5f, 1.0f, 1.0f,

        0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
        -0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
        -0.5f, -0.5f, 0.5f, 0.0f, 0.0f,

        // left
        -0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f,

        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
        -0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
        -0.5f, 0.5f, 0.5f, 1.0f, 1.0f,

        // right
        0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
        0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
        0.5f, -0.5f, -0.5f, 0.0f, 0.0f,

        0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
        0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
        0.5f, 0.5f, 0.5f, 1.0f, 1.0f,

        // down
        -0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
        0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
        0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
        0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
        -0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
        -0.5f, -0.5f, -0.5f, 0.0f, 1.0f,

        // up
        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
        0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
        0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
        0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
        -0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f};
    // world space positions of our cubes
    glm::ivec3 cubePositions[] = {
        glm::ivec3(0, 0, 0),
        glm::ivec3(2, 5, -15),
        glm::ivec3(-1, -2, -2),
        glm::ivec3(-3, -2, -12),
        glm::ivec3(2, -0, -3),
        glm::ivec3(-1, 3, -7),
        glm::ivec3(1, -2, -2),
        glm::ivec3(1, 2, -2),
        glm::ivec3(1, 0, -1),
        glm::ivec3(-1, 1, -1)};

    glm::ivec2 cubeTextures[] = {
        glm::ivec2(1, 14),
        glm::ivec2(8, 3),
        glm::ivec2(0, 4),
        glm::ivec2(1, 12),
        glm::ivec2(1, 6),

        glm::ivec2(0, 6),
        glm::ivec2(1, 2),
        glm::ivec2(0, 14),
        glm::ivec2(3, 12),
        glm::ivec2(1, 12)};

    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);

    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void *)0);
    glEnableVertexAttribArray(0);
    // texture coord attribute
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void *)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    ////////////////////////////////////////////////////////////////////////////////////
    // load and create a texture
    // -------------------------
    unsigned int texture1; //, texture2;
    // texture 1
    // ---------
    glGenTextures(1, &texture1);
    glBindTexture(GL_TEXTURE_2D, texture1);
    // set the texture wrapping parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // set texture filtering parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load image, create texture and generate mipmaps
    int width, height, nrChannels;
    stbi_set_flip_vertically_on_load(true); // tell stb_image.h to flip loaded texture's on the y-axis.
    unsigned char *data = stbi_load("./terrain.png", &width, &height, &nrChannels, STBI_rgb_alpha);
    if (data)
    {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        // glGenerateMipmap(GL_TEXTURE_2D);
    }
    else
    {
        std::cout << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);

    // texture 2
    // ---------
    // glGenTextures(1, &texture2);
    // glBindTexture(GL_TEXTURE_2D, texture2);
    // set the texture wrapping parameters
    // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // set texture filtering parameters
    // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    // load image, create texture and generate mipmaps
    // data = stbi_load("./resources/textures/awesomeface.png", &width, &height, &nrChannels, 0);
    // if (data)
    //{
    //    // note that the awesomeface.png has transparency and thus an alpha channel, so make sure to tell OpenGL the data type is of GL_RGBA
    //    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
    //    glGenerateMipmap(GL_TEXTURE_2D);
    //}
    // else
    //{
    //    std::cout << "Failed to load texture" << std::endl;
    //}
    // stbi_image_free(data);

    // tell opengl for each sampler to which texture unit it belongs to (only has to be done once)
    // -------------------------------------------------------------------------------------------
    ourShader.use();
    ourShader.setInt("texture1", 0);
    // ourShader.setInt("texture2", 1);

    // bind textures on corresponding texture units
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture1);
    // glActiveTexture(GL_TEXTURE1);
    // glBindTexture(GL_TEXTURE_2D, texture2);

    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);

    // glfwSetCursorPos(window, curr_x + curr_width / 2, curr_y + curr_height / 2);
    //  render loop
    //  -----------
    while (!glfwWindowShouldClose(window))
    {
        // per-frame time logic
        // --------------------
        float currentFrame = static_cast<float>(glfwGetTime());
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;

        // input
        // -----
        processInput(window);

        // render
        // ------
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        // activate shader
        ourShader.use();

        // pass projection matrix to shader (note that in this case it could change every frame)
        glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
        ourShader.setMat4("projection", projection);

        // camera/view transformation
        glm::mat4 view = camera.GetViewMatrix();
        ourShader.setMat4("view", view);

        // glEnable(GL_DEPTH_TEST);

        // glDepthMask(GL_TRUE);
        //  render opaque objects first
        glBindVertexArray(VAO);

        for (unsigned int i = 0; i < 10; i++)
        {
            ourShader.setIVec2("index", cubeTextures[i]);

            // calculate the model matrix for each object and pass it to shader before drawing
            glm::mat4 model = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first
            model = glm::translate(model, glm::vec3(cubePositions[i]));
            ourShader.setMat4("model", model);
            glDrawArrays(GL_TRIANGLES, 0, 36);
        }
        // glDepthMask(GL_FALSE);

        // render transparent objects with blending enabled

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

        float renderTime = static_cast<float>(glfwGetTime()) - lastFrame;
        delay_fps(fps, (int)(renderTime * 1000 * 1000));
    }

    running = false;

    glDisable(GL_DEPTH_TEST);

    // 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
// ---------------------------------------------------------------------------------------------------------
bool ESC_KEY_PRESSED = false;
void processInput(GLFWwindow *window)
{
    int esc_key_evetype = glfwGetKey(window, GLFW_KEY_ESCAPE);
    if (!ESC_KEY_PRESSED && esc_key_evetype == GLFW_PRESS)
    {
        ESC_KEY_PRESSED = true;
        pausing = !pausing;
        if (!pausing)
            just_dispaused = true;
        if (!pausing)
            glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
        else
            glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
    }
    else if (esc_key_evetype == GLFW_RELEASE)
    {
        ESC_KEY_PRESSED = false;
    }

    if (pausing)
        return;

    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
        camera.ProcessKeyboard(FORWARD, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
        camera.ProcessKeyboard(BACKWARD, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
        camera.ProcessKeyboard(LEFT, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
        camera.ProcessKeyboard(RIGHT, deltaTime);

    if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS)
        camera.ProcessKeyboard(UP, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_LEFT_SHIFT) == GLFW_PRESS)
        camera.ProcessKeyboard(DOWN, deltaTime);
}

// 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.
    curr_width = width;
    curr_height = height;
    if ((double)width / height > (double)SCR_WIDTH / SCR_HEIGHT)
    { // When profiled screen size rate less than new size
        int vpwidth = width;
        int vpheight = width * SCR_HEIGHT / SCR_WIDTH;
        glViewport(0, -(vpheight - height) / 2, vpwidth, vpheight);
    }
    else
    { // or more than
        int vpheight = height;
        int vpwidth = height * SCR_WIDTH / SCR_HEIGHT;
        glViewport(-(vpwidth - width) / 2, 0, vpwidth, vpheight);
    }
}

// glfw: whenever the mouse moves, this callback is called
// -------------------------------------------------------
void mouse_callback(GLFWwindow *window, double xposIn, double yposIn)
{
    if (pausing)
        return;

    float xpos = static_cast<float>(xposIn);
    float ypos = static_cast<float>(yposIn);

    if (just_dispaused)
    {
        lastX = xpos;
        lastY = ypos;
        just_dispaused = false;
    }

    if (firstMouse)
    {
        lastX = xpos;
        lastY = ypos;
        firstMouse = false;
    }

    float xoffset = xpos - lastX;
    float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top

    lastX = xpos;
    lastY = ypos;

    camera.ProcessMouseMovement(xoffset, yoffset);
}

// glfw: whenever the mouse scroll wheel scrolls, this callback is called
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow *window, double xoffset, double yoffset)
{
    camera.ProcessMouseScroll(static_cast<float>(yoffset));
}

void focus_callback(GLFWwindow *window, int focused)
{
    if (focused)
    {
        window_focused = true;
    }
    else
    {
        window_focused = false;
        pausing = true;
        glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
    }
}

void *getting_fps(void *_window)
{
    GLFWwindow *window = static_cast<GLFWwindow *>(_window);
    while (running)
    {
        glfwGetWindowPos(window, &curr_x, &curr_y);
        glfwGetWindowSize(window, &curr_width, &curr_height);
        // get current monitor's scale
        int on_which = -1;
        GLFWvidmode *vmode;
        for (int i = 0; i < monitor_count; i++)
        {
            int monx, mony;
            glfwGetMonitorPos(monitors[i], &monx, &mony);
            GLFWvidmode *mode = const_cast<GLFWvidmode *>(glfwGetVideoMode(monitors[i]));
            if (curr_x >= monx && curr_x < mode->width && curr_y >= mony && curr_y < mode->height)
            {
                on_which = i;
                vmode = mode;
                break;
            }
        }
        if (on_which != -1)
        {
            fps = vmode->refreshRate;
        }
#ifdef __linux__
        usleep(1000);
#endif
#ifdef _WIN32
        Sleep(1);
#endif
    }
    std::cout << std::endl;
    return nullptr;
}

void delay_fps(int fps, int render_time_us)
{
#ifdef __linux__
    int del = 1000 * 1000 / fps;
    usleep(del - render_time_us);
#endif
#ifdef _WIN32
    int del = 1000 / fps;
    Sleep(del - render_time_us / 1000);
#endif
}