/*     _______________   ,----------------------------------------------------------------.
      //`````````````\\  \                                                                 \
     //~~~~~~~~~~~~~~~\\  \   by @ohsqueezy           &  @sleepin                           \ 
    //=================\\  \     [ohsqueezy.itch.io]     [sleepin.itch.io]                   \ 
   //                   \\  \                                                                 \ 
  //                     \\  \  code released under the zlib license [git.nugget.fun/pudding]  \ 
 //      ☆ GUNKISS ☆      \\  \                                                                 \
//_________________________\\  `---------------------------------------------------------------*/

#ifndef PUDDING_H_
#define PUDDING_H_

/* Needed for functions in glm/gtx/ */
#define GLM_ENABLE_EXPERIMENTAL

/* cURL and cv::VideoCapture are not available for Emscripten, so use alternatives for Emscripten builds */
#if defined(__EMSCRIPTEN__)
#include <emscripten/fetch.h>
#include <emscripten/bind.h>
using namespace emscripten;
#else
#include <curl/curl.h>
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp"
#endif

#include <stdlib.h>
#include <string>
#include <iostream>
#include <algorithm>
#include <thread>
#include <mutex>
#include <memory>
#include <stdexcept>
#include <functional>
#include <chrono>
#include "SDL.h"
#include "SDL_image.h"
#include "sdl2-gfx/SDL2_gfxPrimitives.h"
#include "json/json.hpp"
#include "glm/glm.hpp"
#include "glm/gtx/matrix_decompose.hpp"
#include "opencv2/core.hpp"
#include "opencv2/imgproc.hpp"
#include "zbar.h"
#include "Game.hpp"
#include "Color.hpp"
#include "extension.hpp"
#include "filesystem.hpp"
#include "Animation.hpp"
#include "Texture.hpp"
#include "GLObject.hpp"
#include "Log.hpp"
#include "Attributes.hpp"
#include "VBO.hpp"
#include "Item.hpp"
#include "Model.hpp"
#include "utility.hpp"
#include "Box.hpp"

/*!
 * This class is used for printing the running time of a function or lambda. It can be
 * inserted inline into existing code by wrapping the block to time in a lambda. It can also be
 * given a function and optionally the function's arguments and will return a value of the type specified.
 * 
 * The following code
 * 
 * ~~~{.cpp}
 *     std::string fake(std::string x, std::string y)
 *     {
 *         return x + y;
 *     }
 *
 *     // Needs SPACEBOX initialization for log call
 *     int ii = 0;
 *     time_it()([&] { while (ii++ < 1000); });
 *     ii = 0;
 *     int revolving = time_it<int, int>("for revolving")([&](int x) -> int { while (ii++ < 10000); return x; }, 1);
 *     ii = 0;
 *     std::cout << "Revolving is " << revolving << std::endl;
 *     std::string addition = time_it<std::string, std::string, std::string>("for combination")(fake, "Hello, ", "World!");
 *     std::cout << "Combination is " << addition << std::endl;
 *     time_it("for many combinations")([&] { while (ii++ < 100000) { fake("a", "b"); } });
 * ~~~
 *
 * gives the expected output
 * 
 *     Elapsed time: 2.588e-06s
 *     Elapsed time for revolving: 2.1547e-05s
 *     Revolving is 1
 *     Elapsed time for combination: 7.27e-07s
 *     Combination is Hello, World!
 *     Elapsed time for many combinations: 0.0107351s
 */
template<typename return_type = void, typename... arguments>
class time_it
{

private:

    std::string info = "";

public:

    time_it(std::string info = "") : info(info) {};

    return_type operator()(const std::function<return_type(arguments...)>&& block, arguments... args)
    {
        std::cout << "{Elapsed time";
        if (!info.empty())
        {
            std::cout << " " << info;
        }
        std::cout << ": ";
        auto start = std::chrono::steady_clock::now();
        std::chrono::duration<float> elapsed;
        if constexpr (std::is_same_v<return_type, void>)
        {
            block(args...);
            elapsed = std::chrono::steady_clock::now() - start;
            std::cout << elapsed.count() << "s}" << std::endl;
        }
        else
        {
            return_type result = block(args...);
            elapsed = std::chrono::steady_clock::now() - start;
            std::cout << elapsed.count() << "s}" << std::endl;
            return result;
        }
    }

};

/* A connection is an object containing a binary state of either on (connected) or off (not connected)
 * and user supplied functions that run automatically on each state change. The functions each have the
 * same return type, number of arguments, and argument types determined by the template arguments.
 *
 * Original test code:
 *
 * Connection<> connection_d(std::bind(&Game::print_frame_length_history, this));
 * connection_d.toggle();
 * Connection<int, int, int> connection_f {
 *     std::function<int(int, int)>(&sb::mod), std::function<int(int, int)>(&sb::mod) };
 * Connection<> connection_g = connection_d;
 * connection_g.toggle();
 * connection_g.disconnect();
 * int result;
 * result = connection_f.connect(3, 5);
 * std::cout << result << " ";
 * std::cout << connection_f.disconnect(20, 6) << " ";
 * result = connection_f.toggle(800, 120);
 * std::cout << result << std::endl;
 * result = connection_f.connect(111, 44);
 * std::cout << result << std::endl;
*/
template<typename return_type = void, typename... arguments>
class Connection
{
    
private:
    
    enum State : bool
    {
        STATE_OFF,
        STATE_ON
    };

    using callback = std::function<return_type(arguments...)>;

    State connection_state = STATE_OFF;
    callback on_connect_callback, on_disconnect_callback;

public:

    /* Without any arguments, the connection object will be in the disconnected state with empty functions. Otherwise,
     * the supplied functions will be added to the connection object. The first function argument will be run on a
     * connection, and the second function argument will be run on a disconnection. */
    Connection(callback on_connect_callback = callback(), callback on_disconnect_callback = callback())
    {
        if (on_connect_callback)
        {
            on_connect(on_connect_callback);
            if (on_disconnect_callback)
            {
                on_disconnect(on_disconnect_callback);
            }
        }
    }

    /* Set the function that will run when a connection is made. */
    void on_connect(callback on_connect)
    {
        on_connect_callback = on_connect;
    }

    /* Set the function that will run when a disconnection happens. */
    void on_disconnect(callback on_disconnect)
    {
        on_disconnect_callback = on_disconnect;
    }

    /* Set state to Connection::STATE_ON and run response function. If return_type is non-void and the
     * connection is already connected, the function will not run and the return value will be a default
     * constructed value of the type return_type. Therefore, return_type must be default constructible. */
    return_type connect(arguments... args)
    {
        if (!*this)
        {
            connection_state = STATE_ON;
            if (on_connect_callback)
            {
                return on_connect_callback(args...);
            }
        }
        return return_type();
    }

    /* Set state to Connection::STATE_OFF and run response function. If return_type is non-void and the
     * connection is already disconnected, the function will not run and the return value will be a default
     * constructed value of the type return_type. Therefore, return_type must be default constructible. */
    return_type disconnect(arguments... args)
    {
        if (*this)
        {
            connection_state = STATE_OFF;
            if (on_disconnect_callback)
            {
                return on_disconnect_callback(args...);
            }
        }
        return return_type();
    }

    /* Set state to the opposite of current state, causing the appropriate response function to run. */
    return_type toggle(arguments... args)
    {
        if (*this)
        {
            return disconnect(args...);
        }
        else
        {
            return connect(args...);
        }
    }

    /* Return true if state is Connection::STATE_ON, false otherwise. */
    bool connected()
    {
        return connection_state;
    }

    /* When called as a boolean, return the connection state. */
    operator bool()
    {
        return connected();
    }

};

/* Drawable class that is a plane containing a connection. Each instance:
 *  
 * - Shares vertices and UV in VBO
 * - Has its own Texture representing the button on-screen
 * - Has its own response to click
 * - Shares mouse collision code
 * - Has its own translate + scale transformation
 *
 * Example:
 *
 * glm::vec3 w = glm::mat3({{1, 0, 0}, {0, 1, 0}, {-0.6739, -0.74, 1}}) * glm::mat3({{.1, 0, 0}, {0, .1 * (460.0 / 768.0), 0}, {0, 0, 1}}) *
 *     glm::vec3({-1, -1, 1});
 * std::cout << w << std::endl << glm::translate(glm::vec3{-0.6739, -0.74, 0}) *
 *     glm::scale(glm::vec3{.1, .1 * (460.0 / 768.0), 1})  * glm::vec4{-1, -1, 0, 1} << std::endl;
 * Pad p {background.current(), {-0.6739f, -0.74f}, 0.1f, get_display().window_box().aspect(), std::function<void()>()};
 * const std::vector<glm::vec2>& p_position = *p.attributes("position");
 * glm::vec4 final_position = p.transformation() * glm::vec4{p_position[2].x, p_position[2].y, 0, 1};
 * std::cout << p.transformation() << std::endl << final_position << std::endl;
 * assert(final_position == glm::vec4({w.x, w.y, 0, 1}));
*/
class Pad : public Plane
{

private:

    inline static const glm::vec3 ROTATION_AXIS {0.0f, 0.0f, 1.0f};
    using callback = std::function<void()>;
    Connection<> connection;
    Box collision_box;
    float rotation_angle = 0.0f, scale_factor = 0.0f, scale_ratio = 1.0f;
    glm::vec2 translation_vector {0.0f, 0.0f};

    void transform();

public:

    Pad() {};
    Pad(sb::Texture, glm::vec2, float, float, callback, float = 0.0f);
    void rotation(float);
    void scale(float, float = 1.0f);
    void translation(const glm::vec2&);
    void on_connect(callback);
    bool collide(const glm::vec2&) const;
    void draw(GLuint);

};

/* These variables will be bound to JS. They are placed in the global scope, so they can be read and written by both
 * C++ and JS. The associated functions are bound to JS so they can be used to write values to the variables. The
 * first flag is used by both C++ and JS builds, so it is always included. */
bool new_frame_available = false;
#ifdef __EMSCRIPTEN__
unsigned int emscripten_heap_offset = 0;
void flag_frame();
void set_heap_offset(int offset);
#endif

class Pudding : public Game
{

private:

    /* Defines for effect IDs that will be passed to the shader program. Since EFFECT_COUNT is last and every value
     * is the default integer, it will be set to the number of effects available. */
    enum Effect
    {
        EFFECT_NONE,
        EFFECT_SNAKE,
        EFFECT_WOBBLE,
        EFFECT_COUNT
    };

    /* Defines for UV transformations available in the fragment shader program */
    enum UVTransformation
    {
        UV_NONE,
        UV_SQUIRCLE
    };

    /* Convention for calling parent class in a consistent way across classes */
    typedef Game super;

    /* Constants */
    inline static const std::string OPEN_FOOD_API_URL = "https://world.openfoodfacts.org/api/v0/product/";
    inline static const std::string OPEN_PRODUCTS_API_URL = "https://world.openproductsfacts.org/api/v0/product/";
    inline static const std::string NUTRONIX_API_URL = "https://trackapi.nutritionix.com/v2/search/item?upc=";
    inline static const std::string BARCODE_MONSTER_API_URL = "https://barcode.monster/api/";
    inline static const std::string BEST_BUY_API_URL_1 = "https://api.bestbuy.com/v1/products(upc=";
    inline static const std::string BEST_BUY_API_URL_2 = ")?format=json&apiKey=";
    inline static const std::string NUTRONIX_NOT_FOUND = "resource not found";
    inline static const std::string GOOGLE_BOOKS_API_URL = "https://www.googleapis.com/books/v1/volumes?q=isbn:";
    inline static const std::string GIANTBOMB_API_URL = "https://www.giantbomb.com/api/release/?api_key=";
    inline static const glm::vec3 ZERO_VECTOR_3D {0, 0, 0};
    inline static const glm::vec3 Y_UNIT_NORMAL_3D {0, 1, 0};
    inline static const glm::mat4 VIEW_MATRIX = glm::lookAt({4.0f, 2.0f, 1.0f}, {0.0f, -0.325f, 0.0f}, Y_UNIT_NORMAL_3D);
    inline static const glm::vec3 PUDDING_BROWN {0.713f, 0.359f, 0.224f};
    inline static const glm::vec3 PUDDING_YELLOW {0.878f, 0.859f, 0.122f};

    /* Member variables */
    std::shared_ptr<SDL_Cursor> poke;
    std::string current_barcode, previous_barcode, current_config_barcode, current_camera_barcode;
    std::vector<Item> items;
    Carousel item_carousel;
    int effect_id = EFFECT_NONE, pudding_triangle_vertex_count = 0, pudding_fan_vertex_count = 0;
#ifndef __EMSCRIPTEN__
    cv::VideoCapture capture;
#endif
    cv::Mat camera_frame;
    zbar::ImageScanner image_scanner;
    std::map<std::string, std::map<std::string, GLuint>> uniform;
    GLuint flat_program, mvp_program;
    glm::mat4 projection, model {1.0f}, mvp;
    Model pudding_model;
    Plane plane, camera_view;
    Background background;
    bool show_item = false;
    sb::VAO vao;
    sb::VBO vbo;
    std::map<std::string, sb::Texture> labels;
    Pad camera_button, previous_button, next_button, inventory_button;
    Box viewport, main_viewport, pop_up_viewport;
    std::mutex camera_mutex;

    void load_pudding_model(float, float, int, int = 1, float = -1.0f, float = 1.0f, float = 0.3f);
    void load_gl_context();
    void load_tiles();
    void load_pads();
    void open_camera();

    /*!
    * Release camera resources.
    */
    void close_camera();

    void incorporate_open_api(Item&, const std::string&);
    void incorporate_nutronix_api(Item&);
    void incorporate_edamam_api(Item&);
    void incorporate_best_buy_api(Item&);
    void incorporate_google_books_api(Item&);
    void save_item_json(const nlohmann::json&, const Item&, const std::string&) const;
    nlohmann::json json_from_url(const std::string& url, const std::vector<std::string>& = {});
    void web_get_bytes(const std::string& url, std::vector<std::uint8_t>& storage, const std::vector<std::string>& = {}) const;
    sb::Texture texture_from_image_url(const std::string&) const;
    static void destroy_texture(GLuint*);
    bool item_display_active() const;
    void capture_frame();

    /* Define the appropriate callbacks for URL data loaders. Either cURL by default, or Fetch if compiling for Emscripten. */
#if defined(__EMSCRIPTEN__)
    static void fetch_success(emscripten_fetch_t* fetch);
    static void fetch_error(emscripten_fetch_t* fetch);
#else
    static size_t curl_write_response(std::uint8_t*, size_t, size_t, std::vector<std::uint8_t>*);
#endif

    /* Open camera on connection and close on disconnection. */
    Connection<> camera_switch {
        std::bind(&Pudding::open_camera, this),
        std::bind(&Pudding::close_camera, this)
        // [&] { capture.release(); }
    };

public:

    Pudding();
    void respond(SDL_Event&);
    void add_item(const std::string&);
    Item& current_item();
    void update();
    virtual std::string class_name() const { return "Pudding"; }

};

/* Apply force until reaching a threshold. Use a connection object to run user functions
 * when force reaches threshold and when force goes below threshold. */
template<typename return_type, typename ...arguments>
class Button
{

private:

    Connection<return_type, arguments...> connection;

    /* float threshold = 1.0f */
    /* float force = 0.0f */
    /* apply() */
    /* remove() */
    /* float weighted depression rate */
};

/* Allow a box object to be passed to glViewport instead of four vertices. */
void glViewport(Box);

#endif