import 'dart:io';

void main() {
  bool lightsOn = false;
  bool securityArmed = false;

  int thermostat = 20;
  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("Enter your choice: ");
    String? choice = stdin.readLineSync();
    
    switch (choice) {
      case "1":
        // Toggle lights on/off
        lightsOn = !lightsOn;
        print('Lights are now ${lightsOn ? "ON" : "OFF"}');
        break;

      case "2":
        // Set thermostat temperature
        stdout.write('Set thermostat temperature (15°C to 30°C): ');
        String? tempInput = stdin.readLineSync();
        int? temp = int.tryParse(tempInput!);
        if (temp == null  temp < minTemp  temp > maxTemp) {
          print('Invalid temperature! Please enter a value between 15°C and 30°C.');
        } else {
          thermostat = temp;
          print('Thermostat is set to $thermostat°C.');
        }
        break;

      case "3":
        // Arm or disarm the security system
        securityArmed = !securityArmed;
        print('Security System is now ${securityArmed ? "ARMED" : "DISARMED"}');
        break;

      case "4":
        // View system status
        String tempMessage = (thermostat > 24) ? "Warm Day" : "Cool Day";
        print("\nSystem Status:");
        print('Lights: ${lightsOn ? "ON" : "OFF"}');
        print('Thermostat: $thermostat°C');
        print('Security System: ${securityArmed ? "ARMED" : "DISARMED"}');
        print('Today is a $tempMessage.');
        break;

      case "5":
        // Exit the program
        print('Exiting the Smart Home System. Goodbye!');
        return;

      default:
        print('Invalid option. Please choose a valid number between 1 and 5.');
    }
  }
}