// 1602 MultiMenu v2.0
// by Myth! 

// Intuitive multi-level menu navigation with customizable interface and button controls.
// Seamlessly integrate user-defined functions for efficient task execution.

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define pins for button controls
const int pinUp = 2;
const int pinDown = 3;
const int pinOK = 4;
const int pinCancel = 5;

// Define menu options for level 1 and level 2
const char* menuLevel1[] = {"Option 1", "Option 2", "Option 3", "Exit"};
const char* menuLevel2[][4] = {
  {"Option 1.1", "Option 1.2", "Option 1.3", "Back"},
  {"Option 2.1", "Option 2.2", "Option 2.3", "Back"},
  {"Option 3.1", "Option 3.2", "Option 3.3", "Back"}
};

// Define custom characters for menu arrows
byte arrowUp[8] = {
  B00000,
  B00100,
  B01110,
  B11111,
  B00000,
  B00000,
  B00000,
  B00000
};

byte arrowDown[8] = {
  B00000,
  B00000,
  B00000,
  B11111,
  B01110,
  B00100,
  B00000,
  B00000
};

// Variables to track current selection and menu level
int selectionLevel1 = 0;
int selectionLevel2 = 0;
int currentLevel = 1;

// Setup function to initialize pins and LCD
void setup() {
  pinMode(pinUp, INPUT_PULLUP);
  pinMode(pinDown, INPUT_PULLUP);
  pinMode(pinOK, INPUT_PULLUP);
  pinMode(pinCancel, INPUT_PULLUP);

  lcd.init();
  lcd.backlight();
  lcd.createChar(0, arrowUp);
  lcd.createChar(1, arrowDown);

  lcd.setCursor(0, 0);
  lcd.print(" 1602 MultiMenu ");
  lcd.setCursor(0, 1);
  lcd.print("    by Myth!    ");
  delay(3000);
  lcd.clear();

  showMenuLevel1();
}

// Main loop for menu navigation and button handling
void loop() {
  // Check if "Up" button is pressed
  if (digitalRead(pinUp) == LOW) {
    if (currentLevel == 1) {
      // Move selection up in level 1 menu
      selectionLevel1 = (selectionLevel1 - 1 + sizeof(menuLevel1) / sizeof(menuLevel1[0])) % (sizeof(menuLevel1) / sizeof(menuLevel1[0]));
      showMenuLevel1();
    } else {
      // Move selection up in level 2 menu
      selectionLevel2 = (selectionLevel2 - 1 + sizeof(menuLevel2[selectionLevel1]) / sizeof(menuLevel2[selectionLevel1][0])) % (sizeof(menuLevel2[selectionLevel1]) / sizeof(menuLevel2[selectionLevel1][0]));
      showMenuLevel2();
    }
    delay(200);
  }

  // Check if "Down" button is pressed
  if (digitalRead(pinDown) == LOW) {
    if (currentLevel == 1) {
      // Move selection down in level 1 menu
      selectionLevel1 = (selectionLevel1 + 1) % (sizeof(menuLevel1) / sizeof(menuLevel1[0]));
      showMenuLevel1();
    } else {
      // Move selection down in level 2 menu
      selectionLevel2 = (selectionLevel2 + 1) % (sizeof(menuLevel2[selectionLevel1]) / sizeof(menuLevel2[selectionLevel1][0]));
      showMenuLevel2();
    }
    delay(200);
  }

  // Check if "OK" button is pressed
  if (digitalRead(pinOK) == LOW) {
    if (currentLevel == 1) {
      if (selectionLevel1 == sizeof(menuLevel1) / sizeof(menuLevel1[0]) - 1) {
        // Exit program if "Exit" option is selected in level 1
        lcd.clear();
        lcd.print("Prog. terminated");
        while (true);
      } else {
        // Enter level 2 menu
        currentLevel = 2;
        showMenuLevel2();
      }
    } else {
      if (selectionLevel2 == sizeof(menuLevel2[selectionLevel1]) / sizeof(menuLevel2[selectionLevel1][0]) - 1) {
        // Return to level 1 menu if "Back" option is selected in level 2
        currentLevel = 1;
        showMenuLevel1();
      } else {
        // Execute selected function
        executeFunction(selectionLevel1, selectionLevel2);
      }
    }
    delay(200);
  }

  // Check if "Cancel" button is pressed
  if (digitalRead(pinCancel) == LOW) {
    if (currentLevel == 2) {
      // Return to level 1 menu if in level 2 menu
      currentLevel = 1;
      showMenuLevel1();
    }
    delay(200);
  }
}

// Function to display level 1 menu on LCD
void showMenuLevel1() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(menuLevel1[selectionLevel1]);
  lcd.setCursor(15, 0);
  lcd.write(byte(0)); // Display up arrow
  lcd.setCursor(15, 1);
  lcd.write(byte(1)); // Display down arrow
}

// Function to display level 2 menu on LCD
void showMenuLevel2() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(menuLevel1[selectionLevel1]);
  lcd.setCursor(15, 0);
  lcd.write(byte(0)); // Display up arrow
  lcd.setCursor(0, 1);
  lcd.print(menuLevel2[selectionLevel1][selectionLevel2]);
  lcd.setCursor(15, 1);
  lcd.write(byte(1)); // Display down arrow
}

// Function to execute selected function
void executeFunction(int indexLevel1, int indexLevel2) {
  lcd.clear();
  lcd.print("Executing: ");
  lcd.setCursor(0, 1);
  lcd.print(menuLevel2[indexLevel1][indexLevel2]);

  delay(3000);
  lcd.clear();
  lcd.print("Function done");
  delay(2000);
  showMenuLevel2();
}