#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <qrcode.h>

// OLED width and height
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

// OLED reset pin (usualy do not use)
#define OLED_RESET    -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

void generateQRCode(const char* text) {
  // Create a QR code object
  QRCode qrcode;
  
  // Define the size of the QR code (1-40, higher means bigger size)
  uint8_t qrcodeData[qrcode_getBufferSize(2)];
  qrcode_initText(&qrcode, qrcodeData, 2, ECC_LOW, text);

  // Clear the display
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(63, 20);
  display.print("Selected:");
  display.setCursor(63, 30);
  display.print(text);
  // Calculate the scale factor
  //int scale = min(SCREEN_WIDTH / qrcode.size, SCREEN_HEIGHT / qrcode.size);
  int scale = 2;
  
  // Calculate horizontal shift
  int shiftX = (SCREEN_WIDTH - qrcode.size*scale)/8;
  
  // Calculate horizontal shift
  int shiftY = ((SCREEN_HEIGHT)  - qrcode.size*scale)/1;

  // Draw the QR code on the display
  for (uint8_t y = 0; y < qrcode.size; y++) {
    for (uint8_t x = 0; x < qrcode.size; x++) {
      if (qrcode_getModule(&qrcode, x, y)) {
        display.fillRect(shiftX + x*scale, shiftY + y*scale, scale, scale, WHITE);
      }
    }
  }

  // Update the display
  display.display();
}

// Rotary Encoder pins
const int encoderPinA = 2;
const int encoderPinB = 4;
const int encoderButtonPin = 3;

class Menu {
  private:
    char** items;
    //har** itemsValue;
    int numItems;
    int currentIndex;
    char* title;
    Menu* parentMenu;

  public:
  //Menu(char** menuItems, char** itemsVal, int itemCount, String menuTitle, Menu* parent = nullptr) {
  Menu(char** menuItems, int itemCount, char* menuTitle, Menu* parent = nullptr) {
      items = menuItems;
      //itemsValue = itemsVal;
      numItems = itemCount;
      currentIndex = 0;
      title = menuTitle;
      parentMenu = parent;
    }

    void nextItem() {
      currentIndex = (currentIndex + 1) % numItems;
    }

    void previousItem() {
      currentIndex = (currentIndex - 1 + numItems) % numItems;
    }

    void setCurrentIndex(int index) {
      currentIndex = index;
    }

    char* selectItem() {
      return items[currentIndex];
    }

    void displayMenu() {
      display.clearDisplay();
      display.setTextSize(1);
      display.setTextColor(WHITE);
      display.setCursor(0, 0);
      display.print(title);
      display.setTextSize(1);

      int start = max(0, currentIndex - 2);
      int end = min(numItems, start + 5);

      for (int i = start; i < end; i++) {
        if (i == currentIndex) {
          display.fillRect(0, 14 + (i - start) * 12, SCREEN_WIDTH, 14, WHITE);
          display.setTextColor(BLACK);
        } else {
          display.setTextColor(WHITE);
        }
        display.setCursor(0, 17 + (i - start) * 12);
        display.print(items[i]);
        /*if (String(items[i]).startsWith("Back")) {
          display.print(items[i]);
        } else {
          display.print(String(items[i]) + "      XX");
        }*/
      }

      display.display();
    }

    Menu* getParentMenu() {
      return parentMenu;
    }

    int getCurrentIndex() {
      return currentIndex;
    }
};

// Menu Items
const char *mainMenuItems[] = {"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"};
const char *subMenu1Items[] = {"SubItem 1", "SubItem 2", "SubItem 3", "Back"};
const char *subMenu2Items[] = {"Sub2Item 1", "Sub2Item 2", "Back"};

/*const char *mainMenuItemsVal[] = {"00", "00", "AA", "BB", "CC"};
const char *subMenu1ItemsVal[] = {"00", "AA", "BB", "CC"};
const char *subMenu2ItemsVal[] = {"00", "AA", "BB", "CC"};*/

const int numMainMenuItems = sizeof(mainMenuItems) / sizeof(mainMenuItems[0]);
const int numSubMenu1Items = sizeof(subMenu1Items) / sizeof(subMenu1Items[0]);
const int numSubMenu2Items = sizeof(subMenu2Items) / sizeof(subMenu2Items[0]);

// Menu objects
Menu mainMenu(mainMenuItems, numMainMenuItems, "Main Menu");
Menu subMenu1(subMenu1Items, numSubMenu1Items, "SubMenu1", &mainMenu);
Menu subMenu2(subMenu2Items, numSubMenu2Items, "SubMenu2", &subMenu1);
/*Menu mainMenu(mainMenuItems, mainMenuItemsVal, numMainMenuItems, "Main Menu");
Menu subMenu(subMenu1Items, subMenu1ItemsVal, numSubMenu1Items, "SubMenu1", &mainMenu);
Menu sub2Menu(subMenu2Items, subMenu2ItemsVal, numSubMenu2Items, "SubMenu2", &subMenu);*/

// Variable that holds the current menu
Menu* currentMenu = &mainMenu;

// Rotary Encoder Variables
//volatile int lastEncoded = 0;
volatile long encoderValue = 0;
long lastencoderValue = 0;

bool buttonPressed = false;

void buttonPress() {
  buttonPressed = true;
}

// Encoder read function
void updateEncoder() {
  int ENCB = digitalRead(encoderPinB);
  if (ENCB > 0) {
    encoderValue++;
  } else {
    encoderValue--;
  }
  /*int MSB = digitalRead(encoderPinA); // MSB = most significant bit
  int LSB = digitalRead(encoderPinB); // LSB = least significant bit

  int encoded = (MSB << 1) | LSB; // Modified 2-bit value
  int sum = (lastEncoded << 2) | encoded; // Combine old and new values

  if (sum == 0b1101 || sum == 0b0100 || sum == 0b0010 || sum == 0b1011) encoderValue++;
  if (sum == 0b1110 || sum == 0b0111 || sum == 0b0001 || sum == 0b1000) encoderValue--;

  lastEncoded = encoded;*/
}

void selectedItemFunc(const char* item) {
  char buffer[40];
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(0, 0);
  display.print("Selected:");
  display.setCursor(0, 30);
  display.print(item);
  display.display();
  delay(1000);
  //sprintf(buffer, "Selected: %s", item);
  //generateQRCode(buffer);
  generateQRCode(item);
  delay(5000);
}

void setup() {
  Serial.begin(115200);
  while ( !Serial ) yield();
  Serial.println("Initializing...");
  // OLED starting
  if(!display.begin(SSD1306_EXTERNALVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.display();
  delay(2000);
  display.clearDisplay();

  // Set Rotary Encoder pins as input
  pinMode(encoderPinA, INPUT);
  pinMode(encoderPinB, INPUT);
  pinMode(encoderButtonPin, INPUT_PULLUP);

  // Set interrupt operation for encoder inputs
  attachInterrupt(digitalPinToInterrupt(encoderPinA), updateEncoder, RISING);
  //attachInterrupt(digitalPinToInterrupt(encoderPinB), updateEncoder, CHANGE);
  attachInterrupt(digitalPinToInterrupt(encoderButtonPin), buttonPress, FALLING);

  // Show menu item at startup
  currentMenu->displayMenu();
}

void loop() {
  // Check encoder value and update menu
  if (encoderValue != lastencoderValue) {
    if (encoderValue > lastencoderValue) {
      currentMenu->nextItem();
    } else {
      currentMenu->previousItem();
    }
    lastencoderValue = encoderValue;
    currentMenu->displayMenu();
    //delay(200); // Encoder Debouncing
  }

  // Select item when Encoder button is pressed
  if (buttonPressed) {
    buttonPressed = false;
    if (currentMenu == &mainMenu) {
      switch(currentMenu->getCurrentIndex()) {
        case 2: currentMenu = &subMenu1; currentMenu->setCurrentIndex(0);
          break;
        default: selectedItemFunc(currentMenu->selectItem());
          break;
      }
    } else if (currentMenu == &subMenu1) {
      switch(currentMenu->getCurrentIndex()) {
        case 2: currentMenu = &subMenu2; currentMenu->setCurrentIndex(0);
          break;
        case 3: currentMenu = currentMenu->getParentMenu();
          break;
        default: selectedItemFunc(currentMenu->selectItem());
          break;
      }
    } else if (currentMenu == &subMenu2) {
      switch(currentMenu->getCurrentIndex()) {
        case 2: currentMenu = currentMenu->getParentMenu();
          break;
        default: selectedItemFunc(currentMenu->selectItem());
          break;
      }
    }
    currentMenu->displayMenu();
    //delay(500); // Buton debouncing
  }
/*
  if (digitalRead(encoderButtonPin) == LOW) {
    char* selectedItem = currentMenu->selectItem();

    if (selectedItem == "Back") {
      if (currentMenu->getParentMenu() != nullptr) {
        currentMenu = currentMenu->getParentMenu();
      }
    } else if (selectedItem == "Item 3") {
      currentMenu = &subMenu1;
    } else if (selectedItem == "SubItem 3") {
      currentMenu = &subMenu2;
    } else {
      display.clearDisplay();
      display.setTextSize(2);
      display.setTextColor(WHITE);
      display.setCursor(0, 0);
      display.print("Selected:");
      display.setCursor(0, 30);
      display.print(selectedItem);
      display.display();
      delay(1000);
      currentMenu->displayMenu();
    }

    currentMenu->displayMenu();
    delay(500); // Buton debouncing
  }*/
}