#include <avr/sleep.h>

const byte btnPin = 2;
const byte ledPin = 4;
bool ledStatus = false;
unsigned long ledTimeShot = 0;
unsigned long sleepTimeShot = 0;
unsigned long ledInterval = 1000;
unsigned long sleepInterval = 4000;

void setup() {
  pinMode(btnPin, INPUT_PULLUP);
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  unsigned long currentTime = millis();
  int btnStatus = digitalRead(btnPin);

  if (btnStatus == 0) {
    Serial.println(btnStatus);
  }

  if (currentTime - ledTimeShot >= ledInterval) {
    ledTimeShot = currentTime;
    ledStatus = !ledStatus;
    digitalWrite(ledPin, ledStatus);
    Serial.println("Bla " + String(ledStatus));
  }

  if (currentTime - sleepTimeShot >= sleepInterval) {
    sleepTimeShot = currentTime;
    
    toSleep();
  }
}

void toSleep() {
  sleep_enable();
  attachInterrupt(digitalPinToInterrupt(btnPin), wakeUp, CHANGE);
  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
  digitalWrite(ledPin, LOW);
  delay(1000);

  sleep_cpu();
  Serial.println("just woke up!");
  digitalWrite(ledPin, HIGH);
}

void wakeUp(){
  Serial.println("Interrrupt Fired");

  sleep_disable();
  // detachInterrupt(0);
}