// https://wokwi.com/projects/419523916199154689

const byte switchPin   = 2;
const byte redLedPin   = 3;
const byte buzzerPin   = 4;
const byte greenLedPin = 5;

const byte powerPin = 6;

const byte photoresistorPin = A0;
const int photoresistorThreshold = 777;

enum : byte {NORMAL, ACTIVATED, MUTED} state = NORMAL;

bool powerIsOff()
{
  bool power = analogRead(photoresistorPin) < photoresistorThreshold;
  digitalWrite(powerPin, !power);

  return power;
}

bool powerIsOn()
{
  bool power = powerIsOff(); 
  digitalWrite(powerPin, !power);

  return !power;
}

bool buttonIsPressed() {
  return digitalRead(switchPin) == LOW;
}

void alarmOn() {
  digitalWrite(greenLedPin, LOW);
  digitalWrite(redLedPin, HIGH);
  tone(buzzerPin, 777);  // 4000 = upset cat!
  state = ACTIVATED;
}

void alarmOff() {
  digitalWrite(greenLedPin, HIGH);
  digitalWrite(redLedPin, LOW);
  noTone(buzzerPin);
  state = NORMAL;
}

void buzzerOff() {
  noTone(buzzerPin);
  state = MUTED;
}

void setup() {
  pinMode(greenLedPin, OUTPUT);
  pinMode(redLedPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(switchPin, INPUT_PULLUP);
  alarmOff();
  powerIsOff();  // just to set the power LED correctly at startup
}

void loop() {

  switch (state) {
    case NORMAL:
      if (powerIsOff()) alarmOn() ;
      break;

    case ACTIVATED:
      if (powerIsOn()) alarmOff();
      else if (buttonIsPressed()) buzzerOff() ;
      break;

    case MUTED:
      if (powerIsOn()) alarmOff();
      break;
  }
}