#define STATE_OFF    0
#define STATE_DIM    1
#define STATE_NORMAL 2
#define STATE_ALERT  3

int LED = 9;
int BUTTON = 2;
int PHOTO = A0;

int currentState = STATE_OFF;
long lastPress = 0;
bool buttonPressed = false;

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(BUTTON, INPUT_PULLUP);
  pinMode(PHOTO, INPUT);
}

void loop() {
  checkTransitions();
  executeState();
  delay(50);
}

void changeState(int newState) {
  currentState = newState;
}

void executeState() {
  switch (currentState) {
    case STATE_OFF:
      analogWrite(LED, 0);
      break;
    case STATE_DIM:
      analogWrite(LED, 64); 
      break;
    case STATE_NORMAL:
      analogWrite(LED, 255); 
      break;
    case STATE_ALERT:
      if (millis() % 400 < 200) {
        analogWrite(LED, 255);
      }
      else {
        analogWrite(LED, 0);
      }
      break;
  }
}

void checkTransitions() {
  if (!digitalRead(BUTTON)) {
    if (!buttonPressed && millis() - lastPress > 300) {
      changeState((currentState + 1) % 4);
      buttonPressed = true;
      lastPress = millis();
    }
  } 
  else {
    buttonPressed = false;
  }

  int light = analogRead(PHOTO);
  if (light > 500 && currentState != STATE_DIM) {
    changeState(STATE_DIM);
  }
}