import 'dart:io';

void main() {
  bool lightsOn = false;
  int thermostat = 20;
  bool securityArmed = false;

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

  while (true) {
    print('\nWelcome to the Smart Home System!');
    print('Please 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('\nEnter your choice: ');

    String? choice = stdin.readLineSync();

    if (choice == '1') {
      lightsOn = !lightsOn;
      print('Lights are now ${lightsOn ? 'ON' : 'OFF'}.');
    } else if (choice == '2') {
      stdout.write('Set thermostat temperature ($minTemp°C - $maxTemp°C): ');
      String? input = stdin.readLineSync();
      int? temp = int.tryParse(input ?? '');
      if (temp != null && temp >= minTemp && temp <= maxTemp) {
        thermostat = temp;
        print('Thermostat set to $thermostat°C.');
      } else {
        print('Invalid temperature! Please enter a value between $minTemp and $maxTemp.');
      }
    } else if (choice == '3') {
      securityArmed = !securityArmed;
      print('Security system is now ${securityArmed ? 'ARMED' : 'DISARMED'}.');
    } else if (choice == '4') {
      print('\nSystem Status:');
      print('- Lights: ${lightsOn ? 'ON' : 'OFF'}');
      String tempStatus = '';
      if (thermostat % 3 == 0 && thermostat % 5 == 0) {
        tempStatus = 'Perfect Day';
      } else if (thermostat % 3 == 0) {
        tempStatus = 'Cool Day';
      } else if (thermostat % 5 == 0) {
        tempStatus = 'Warm Day';
      }
      print('- Thermostat: $thermostat°C ${tempStatus.isNotEmpty ? '– $tempStatus' : ''}');
      print('- Security System: ${securityArmed ? 'ARMED' : 'DISARMED'}');
    } else if (choice == '5') {
      print('Exiting the system. Goodbye!');
      break;
    } else {
      print('Invalid choice! Please try again.');
    }
  }
}