import 'dart:io';

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

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

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

  while (running) {
    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('\nEnter your choice: ');
    String choice = stdin.readLineSync()?.trim() ?? '';

    if (choice == '1') {
      print('\nLights control:');
      print('1. Turn ON');
      print('2. Turn OFF');
      stdout.write('Choose (1/2): ');
      String lightChoice = stdin.readLineSync()?.trim() ?? '';
      switch (lightChoice) {
        case '1':
          lightsOn = true;
          print('Lights are now ON.');
          break;
        case '2':
          lightsOn = false;
          print('Lights are now OFF.');
          break;
        default:
          print('Invalid option. Lights unchanged.');
      }
    } else if (choice == '2') {
      print('\nThermostat control:');
      print('1. Set temperature');
      stdout.write('Choose: ');
      String tChoice = stdin.readLineSync()?.trim() ?? '';
      switch (tChoice) {
        case '1':
          int newTemp = _readTempInRange();
          thermostat = newTemp;
          print('Thermostat set to ${thermostat}°C.');
          break;
        default:
          print('Invalid option. Thermostat unchanged.');
      }
    } else if (choice == '3') {
      print('\nSecurity System:');
      print('1. Arm');
      print('2. Disarm');
      stdout.write('Choose (1/2): ');
      String secChoice = stdin.readLineSync()?.trim() ?? '';
      switch (secChoice) {
        case '1':
          securityArmed = true;
          print('Security system is now ARMED.');
          break;
        case '2':
          securityArmed = false;
          print('Security system is now DISARMED.');
          break;
        default:
          print('Invalid option. Security unchanged.');
      }
    } else if (choice == '4') {
      String lightsStr = lightsOn ? 'ON' : 'OFF';
      String secStr = (securityArmed ? 'armed' : 'disarmed').toUpperCase();
      String label = _tempLabel(thermostat);

      print('\nSystem Status:');
      print('- Lights: $lightsStr');
      print('- Thermostat: ${thermostat}°C${label.isEmpty ? '' : ' – $label'}');
      print('- Security System: $secStr');
    } else if (choice == '5') {
      running = false;
      print('Exiting the system. Goodbye!');
    } else {
      print('Invalid choice. Please try again.');
    }
  }
}

int _readTempInRange() {
  while (true) {
    stdout.write('Enter temperature ($minTemp°C – $maxTemp°C): ');
    String input = stdin.readLineSync()?.trim() ?? '';
    int? value = int.tryParse(input);
    if (value != null && value >= minTemp && value <= maxTemp) {
      return value;
    }
    print('Invalid temperature! Please enter a value between $minTemp and $maxTemp.');
  }
}

String _tempLabel(int t) {
  bool mult3 = t % 3 == 0;
  bool mult5 = t % 5 == 0;

  if (mult3 && mult5) return 'Perfect Day';
  if (mult3) return 'Cool Day';
  if (mult5) return 'Warm Day';
  return '';
}