#define LED 3
#define BTN 2

#define BLINK_DLAY 1000

enum possibleStates {on, blink, off};

possibleStates state = on;
unsigned long lastPressed = 0;

void setup() {
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT);
  pinMode(BTN, INPUT_PULLUP);

  attachInterrupt(digitalPinToInterrupt(BTN), btnPressed, FALLING);
  

}

void loop() {

  static unsigned long lastBlink = millis();
  
  // put your main code here, to run repeatedly:
  switch (state) {
    case on:
      digitalWrite(LED, HIGH);
      break;
    case blink:
      if (lastBlink + BLINK_DLAY < millis()) {
        digitalWrite(LED, !digitalRead(LED));
        lastBlink = millis();
      }
      break;
    case off:
      digitalWrite(LED, LOW);
      break;
  }
}

void btnPressed() {
  int now = millis();
  if (now < lastPressed + 200) {return;}
  state = (state + 1) % 3;
  lastPressed = now;
}