import 'dart:io';

void main() {
  // Constants for temperature range
  const int minTemp = 15;
  const int maxTemp = 30;

  // Default device states
  bool lightsOn = false;
  int temperature = 20;
  bool securityArmed = false;

  while (true) {
    print('\n=== Smart Home Automation System ===');
    print('1. Turn lights ON/OFF');
    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();

    if (choice == '5') {
      print('Exiting Smart Home System...');
      break;
    }

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

      case '2':
        stdout.write('Enter temperature ($minTemp - $maxTemp): ');
        int? newTemp = int.tryParse(stdin.readLineSync() ?? '');
        if (newTemp != null && newTemp >= minTemp && newTemp <= maxTemp) {
          temperature = newTemp;
          print('Temperature set to $temperature°C.');
        } else {
          print('Invalid input! Please enter a value between $minTemp and $maxTemp.');
        }
        break;

      case '3':
        securityArmed = !securityArmed;
        print('Security system is now ${securityArmed ? 'ARMED' : 'DISARMED'}.');
        break;

      case '4':
        String tempMessage = '';
        if (temperature % 3 == 0 && temperature % 5 == 0) {
          tempMessage = 'Perfect Day';
        } else if (temperature % 3 == 0) {
          tempMessage = 'Cool Day';
        } else if (temperature % 5 == 0) {
          tempMessage = 'Warm Day';
        }

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

      default:
        print('Invalid option. Please try again.');
    }
  }
}