import 'dart:io';

bool lightsOn = false;
int thermostatTemp = 20;
bool securityArmed = false;

const int minTemp = 15;
const int maxTemp = 30;

void main() {
  print('Welcome to the Smart Home System!');
  String? choice;

  do {
    displayMenu();
    choice = stdin.readLineSync();
    handleChoice(choice);
  } while (choice != '5');
}

void displayMenu() {
  print('\nChoose an action:');
  print('1. Toggle lights');
  print('2. Set thermostat');
  print('3. Arm/disarm security');
  print('4. View status');
  print('5. Exit');
  stdout.write('Your choice: ');
}

void handleChoice(String? choice) {
  if (choice == null) return;

  if (choice == '1') {
    lightsOn = !lightsOn;
    print('Lights are now ${lightsOn ? 'ON' : 'OFF'}.');
  } else if (choice == '2') {
    stdout.write('Enter temperature ($minTemp–$maxTemp): ');
    int? temp = int.tryParse(stdin.readLineSync() ?? '');
    if (temp != null && temp >= minTemp && temp <= maxTemp) {
      thermostatTemp = temp;
      print('Thermostat set to $thermostatTemp°C.');
    } else {
      print('Invalid temperature.');
    }
  } else if (choice == '3') {
    securityArmed = !securityArmed;
    print('Security system is now ${securityArmed ? 'ARMED' : 'DISARMED'}.');
  } else if (choice == '4') {
    showStatus();
  } else if (choice == '5') {
    print('Exiting system. Goodbye!');
  } else {
    print('Invalid choice.');
  }
}

void showStatus() {
  print('\n--- System Status ---');
  print('Lights: ${lightsOn ? 'ON' : 'OFF'}');
  print('Thermostat: $thermostatTemp°C');
  print('Security: ${securityArmed ? 'ARMED' : 'DISARMED'}');

  String message = '';
  if (thermostatTemp % 3 == 0 && thermostatTemp % 5 == 0) {
    message = 'Perfect Day';
  } else if (thermostatTemp % 3 == 0) {
    message = 'Cool Day';
  } else if (thermostatTemp % 5 == 0) {
    message = 'Warm Day';
  }

  if (message.isNotEmpty) print(message);
}