const int BUTTON_PIN = 7;             // Arduino pin connected to button's pin
const int RELAY_PIN  = 3;             // Arduino pin connected to relay's pin
volatile bool buttonPressed = false;  // Flag to indicate if button is pressed
volatile unsigned long ledOnTime = 0; // Time when LED was turned on

void setup() {
  Serial.begin(9600);                // initialize serial
  pinMode(BUTTON_PIN, INPUT_PULLUP); // set arduino pin to input pull-up mode
  pinMode(RELAY_PIN, OUTPUT);        // set arduino pin to output mode

  cli();                                              // zaustavimo prekide
  TCCR1A = 0;                                         // Set timer to normal mode
  TCCR1B = (1 << WGM12) | (1 << CS11) | (1 << CS10);  // Timer mode: CTC, Prescaler: 64
  OCR1A = 249;                                        // Compare match value for 1 ms
  TIMSK1 = (1 << OCIE1A);                             // Enable timer compare interrupt
  sei();                                              // konačno dozvolimo prekide
}

void loop() {
}

ISR(TIMER1_COMPA_vect) {
  static unsigned long lastDebounceTime = 0; // Time when button was last debounced
  static bool lastButtonState = HIGH;        // Previous state of the button
  bool buttonState = digitalRead(BUTTON_PIN);

  // Debounce the button
  if (buttonState != lastButtonState) {
    lastDebounceTime = millis();
  }
  if ((millis() - lastDebounceTime) > 50) {
    if (buttonState == LOW) {
      buttonPressed = true;
      ledOnTime = millis();
    }
  }
  lastButtonState = buttonState;

  // Check if LED should be on
  if (buttonPressed && (millis() - ledOnTime < 5000)) {
    digitalWrite(RELAY_PIN, HIGH);
  } else {
    digitalWrite(RELAY_PIN, LOW);
    buttonPressed = false;
  }
}