import 'dart:io';

void main() {
  String lights = 'OFF';
  int thermostat = 20;
  String security = 'DISARMED';

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

  print('Welcome to the Smart Home System!');

  bool isRunning = true;
  while (isRunning) {
    print('\nPlease choose an action:');
    print('1. Toggle lights');
    print('2. Set thermostat temperature');
    print('3. Arm/disarm security system');
    print('4. View system status');
    print('5. Exit');
    stdout.write('Enter your choice: ');

    String? choice = stdin.readLineSync();

    switch (choice) {
      case '1':
        lights = (lights == 'OFF') ? 'ON' : 'OFF';
        print('Lights are now $lights.');
        break;

      case '2':
        stdout.write('Set thermostat temperature ($minTemp°C - $maxTemp°C): ');
        int? newTemp = int.tryParse(stdin.readLineSync() ?? '');

        if (newTemp == null) {
          print('Invalid input. Please enter a number.');
        } else if (newTemp < minTemp || newTemp > maxTemp) {
          print('Temperature must be between $minTemp and $maxTemp.');
        } else {
          thermostat = newTemp;
          print('Thermostat set to $thermostat°C.');
        }
        break;

      case '3':
        security = (security == 'DISARMED') ? 'ARMED' : 'DISARMED';
        print('Security system is now $security.');
        break;

      case '4':
        print('\nSystem Status:');
        print('- Lights: $lights');
        print('- Thermostat: $thermostat°C');
        print('- Security System: $security');

        if (thermostat % 3 == 0) print('Cool Day');
        if (thermostat % 5 == 0) print('Warm Day');
        if (thermostat % 2 == 0) print('Perfect Day');
        break;

      case '5':
        isRunning = false;
        print('Exiting the system. Goodbye!');
        break;

      default:
        print('Invalid choice. Please enter a number between 1 and 5.');
    }
  }
}