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

LiquidCrystal_I2C lcd(0x27, 16, 2);

const int buttonPins[4] = {2, 3, 4, 5};
const int ledPins[4]    = {6, 7, 8, 9};
const int potPins[4]    = {A0, A1, A2, A3};

void setup() {
  for (int i = 0; i < 4; i++) {
    pinMode(buttonPins[i], INPUT_PULLUP);
    pinMode(ledPins[i], OUTPUT);
    digitalWrite(ledPins[i], LOW);
  }

  lcd.init();
  lcd.backlight();
  Serial.begin(9600);
}

void loop() {
  bool anyButtonPressed = false;

  for (int i = 0; i < 4; i++) {
    if (digitalRead(buttonPins[i]) == LOW) {  // Button is pressed
      anyButtonPressed = true;

      // Turn ON corresponding LED
      digitalWrite(ledPins[i], HIGH);

      // Read corresponding potentiometer
      int rawValue = analogRead(potPins[i]);
      float voltage = rawValue * (5.0 / 1023.0);

      // Update LCD
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("LED ");
      lcd.print(i + 1);
      lcd.print(": ON");

      lcd.setCursor(0, 1);
      lcd.print("POT ");
      lcd.print(i + 1);
      lcd.print(": ");
      lcd.print(voltage, 2);
      lcd.print(" V");

      delay(500);  // Debounce delay
    } else {
      // Button is not pressed → Turn OFF LED
      digitalWrite(ledPins[i], LOW);
    }
  }

  if (!anyButtonPressed) {
    lcd.clear();  // No button pressed → blank screen
  }
}