import 'dart:io'; 
void main() { 
// Initialize devices with default values 
bool lightsOn = false; 
int thermostatTemp = 20; 
bool securityArmed = false; 
// Constants 
const int minTemp = 15; 
const int maxTemp = 30; 
print('| Welcome to the Smart Home System! |'); 
// Main loop for user interaction 
while (true) { 
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('\nEnter your choice: '); 
String? choice = stdin.readLineSync(); 
    // Handle user choice 
    if (choice == '1') { 
      // Toggle lights 
      lightsOn = !lightsOn; 
      print('Lights are now ${lightsOn ? 'ON' : 'OFF'}.'); 
       
    } else if (choice == '2') { 
      // Set thermostat temperature 
      while (true) { 
        stdout.write('Set thermostat temperature (${minTemp}°C – ${maxTemp}°C): '); 
        String? tempInput = stdin.readLineSync(); 
         
        try { 
          int temp = int.parse(tempInput!); 
           
          if (temp >= minTemp && temp <= maxTemp) { 
            thermostatTemp = temp; 
            print('Thermostat set to ${temp}°C.'); 
            break; 
          } else { 
            print('Invalid temperature! Please enter a value between $minTemp and 
$maxTemp.'); 
          } 
        } catch (e) { 
          print('Invalid input! Please enter a valid number.'); 
        } 
      } 
       
    } else if (choice == '3') { 
      // Arm/disarm security system 
      securityArmed = !securityArmed; 
      print('Security system is now ${securityArmed ? 'ARMED' : 'DISARMED'}.'); 
       
    } else if (choice == '4') { 
      // View system status 
      print('System Status:'); 
       
      // Lights status 
      print('- Lights: ${lightsOn ? 'ON' : 'OFF'}'); 
       
      // Thermostat status with FizzBuzz-like exercise 
      String dayMessage = ''; 
      if (thermostatTemp % 3 == 0 && thermostatTemp % 5 == 0) { 
        dayMessage = ' - Perfect Day'; 
      } else if (thermostatTemp % 3 == 0) { 
        dayMessage = ' - Cool Day'; 
      } else if (thermostatTemp % 5 == 0) { 
        dayMessage = ' - Warm Day'; 
      } 
       
      print('- Thermostat: ${thermostatTemp}°C$dayMessage'); 
       
// Security system status (converted to uppercase) 
String securityStatus = securityArmed ? 'ARMED' : 'DISARMED'; 
print('- Security System: $securityStatus'); 
} else if (choice == '5') { 
// Exit program 
print('Exiting the system. Goodbye!'); 
break; 
} else { 
print('Invalid choice! Please enter a number between 1 and 5.'); 
} 
print(''); // Empty line for better readability 
} 
}