import 'dart:io';

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

  while (true) {
    print("\n===== Smart Home 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();

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

      case '2':
        stdout.write("Enter temperature (15 - 30): ");
        int? temp = int.tryParse(stdin.readLineSync()!);

        if (temp == null || temp < 15 || temp > 30) {
          print("Invalid temperature! Must be between 15 and 30.");
        } else {
          temperature = temp;
          print("Temperature set to $temperature°C");
        }
        break;

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

      case '4':
        print("\n===== SYSTEM STATUS =====");
        print("Lights: ${lightsOn ? 'ON' : 'OFF'}");
        print("Thermostat: $temperature°C");

        // FizzBuzz-like exercise
        if (temperature % 15 == 0) {
          print("Perfect Day!");
        } else if (temperature % 3 == 0) {
          print("Cool Day!");
        } else if (temperature % 5 == 0) {
          print("Warm Day!");
        }

        print("Security: ${securityArmed ? 'ARMED' : 'DISARMED'}");
        print("===========================");
        break;

      case '5':
        print("Exiting system... Goodbye!");
        return;

      default:
        print("Invalid choice! Please try again.");
        break;
    }
  }
}