import 'dart:io';

void main() {
  // Const values (final/const requirement)
  const int minTemp = 15;
  const int maxTemp = 30;

  // Default device values
  bool lightsOn = false;      // lightsOff by default
  int thermostat = 20;        // 20°C by default
  bool securityArmed = false; // disarmed by default

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

  while (true) {
    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: ');
    final String choiceInput = stdin.readLineSync() ?? '';
    final int? choice = int.tryParse(choiceInput);

    if (choice == null) {
      print('Invalid input. Please enter a number (1-5).');
      continue;
    }

    // if/else requirement for user choices
    if (choice == 1) {
      // switch requirement for device commands
      switch ('lights') {
        case 'lights':
          lightsOn = !lightsOn;
          print('Lights are now ${lightsOn ? 'ON' : 'OFF'}.');
          break;
      }
    } else if (choice == 2) {
      switch ('thermostat') {
        case 'thermostat':
          int? temp;
          while (true) {
            stdout.write('Set thermostat temperature ($minTemp°C - $maxTemp°C): ');
            final String tempInput = stdin.readLineSync() ?? '';
            temp = int.tryParse(tempInput);

            // Logical & relational operators for validation
            if (temp != null && temp >= minTemp && temp <= maxTemp) {
              thermostat = temp;
              print('Thermostat set to ${thermostat}°C.');
              break;
            } else {
              print('Invalid temperature. Please enter a value between $minTemp and $maxTemp.');
            }
          }
          break;
      }
    } else if (choice == 3) {
      switch ('security') {
        case 'security':
          // Toggle armed/disarmed
          securityArmed = !securityArmed;

          // String operations requirement (e.g., "armed" -> "ARMED")
          final String statusText = (securityArmed ? 'armed' : 'disarmed').toUpperCase();
          print('Security System is now $statusText.');
          break;
      }
    } else if (choice == 4) {
      // Display system status with string interpolation
      final String lightsStatus = lightsOn ? 'ON' : 'OFF';
      final String securityStatus = (securityArmed ? 'armed' : 'disarmed').toUpperCase();

      // FizzBuzz-like requirement for temperature status
      final bool multipleOf3 = thermostat % 3 == 0;
      final bool multipleOf5 = thermostat % 5 == 0;
      String tempLabel = '';
      if (multipleOf3 && multipleOf5) {
        tempLabel = ' - Perfect Day';
      } else if (multipleOf3) {
        tempLabel = ' - Cool Day';
      } else if (multipleOf5) {
        tempLabel = ' - Warm Day';
      }

      print('\nSystem Status:');
      print('- Lights: $lightsStatus');
      print('- Thermostat: ${thermostat}°C$tempLabel');
      print('- Security System: $securityStatus');
    } else if (choice == 5) {
      print('Exiting the system. Goodbye!');
      break;
    } else {
      print('Invalid choice. Please enter a number from 1 to 5.');
    }
  }
}