// Problem 1: Make a 2-state FSM with one button and one LED:
// STATE_IDLE: LED is OFF, waiting for button press.
// STATE_ACTION: LED blinks (toggle every 500ms).
// If button is pressed again → go back to STATE_IDLE (LED OFF).

void led_toggle();

enum States {
  IDLE,
  ACTION
};

States cur_st = IDLE;

void enterState(States new_st)
{
  cur_st = new_st;
  switch(new_st)
  {
    case IDLE:
    Serial.println("Waiting for button press!!");
    digitalWrite(LED, LOW);
    break;
    
    case ACTION:
    Serial.println("Button pressed");
    break;
  }
  
}

void fsmUpdate()
{
  switch(cur_st)
  {
    case IDLE:
      // if button pressed -> enterState ACTION
      if(digitalRead(BUT) == 0) enterState(ACTION);

      break;
    case ACTION:
      // Toggle led 0.5s
      led_toggle();
      // if button pressed -> enterstate IDLE
      if(digitalRead(BUT) == 0) enterState(IDLE);
      break;
  }
}

#define LED 13
#define BUT 12

void setup() {
  Serial.begin(9600);
  pinMode(LED, OUTPUT);
  pinMode(BUT, INPUT_PULLUP);
  Serial.println("-- Starting --");
  enterState(IDLE);
}

void loop() {
  fsmUpdate();
}

int led_st = LOW;
unsigned long lastBlinkTime = 0;

void led_toggle()
{
  // digitalWrite(LED,1);
  // delay(500);
  // digitalWrite(LED,0);
  // delay(500);

  unsigned long now = millis();
  if(now - lastBlinkTime >= 500)
  {
    led_st = !led_st;
    digitalWrite(LED,led_st);
    lastBlinkTime = now;
  }
}