import 'dart:io';

// Constants using final (since const can't be used with runtime values)
const double MIN_TEMP = 15.0;
const double MAX_TEMP = 30.0;

void main() {
  // Initialize device status
  bool lightsOn = false;
  double thermostatTemp = 20.0;
  bool securityArmed = false;
  
  print("=" * 50);
  print("Welcome to the Smart Home System!");
  print("=" * 50);
  
  bool running = true;
  
  while (running) {
    // Display menu
    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("Enter your choice: ");
    
    String? choice = stdin.readLineSync();
    
    // Use if/else to handle main menu choices
    if (choice == '1') {
      // Toggle lights
      lightsOn = !lightsOn;
      print("Lights are now ${lightsOn ? 'ON' : 'OFF'}.");
      
    } else if (choice == '2') {
      // Set thermostat temperature
      stdout.write("Set thermostat temperature ($MIN_TEMP°C - $MAX_TEMP°C): ");
      String? tempInput = stdin.readLineSync();
      
      if (tempInput != null) {
        double? temp = double.tryParse(tempInput);
        
        // Input validation using logical operators
        if (temp != null && temp >= MIN_TEMP && temp <= MAX_TEMP) {
          thermostatTemp = temp;
          print("Thermostat set to ${thermostatTemp}°C");
        } else {
          print("Invalid temperature! Please enter a value between $MIN_TEMP°C and $MAX_TEMP°C.");
        }
      }
      
    } else if (choice == '3') {
      // Arm/disarm security system using switch
      print("\nSecurity System Options:");
      print("1. Arm");
      print("2. Disarm");
      stdout.write("Enter your choice: ");
      
      String? secChoice = stdin.readLineSync();
      
      // Switch statement for security commands
      switch (secChoice) {
        case '1':
          securityArmed = true;
          print("Security system ARMED.");
          break;
        case '2':
          securityArmed = false;
          print("Security system DISARMED.");
          break;
        default:
          print("Invalid choice!");
      }
      
    } else if (choice == '4') {
      // View system status
      displaySystemStatus(lightsOn, thermostatTemp, securityArmed);
      
    } else if (choice == '5') {
      // Exit
      running = false;
      print("\nExiting the system. Goodbye!");
      
    } else {
      print("Invalid choice! Please enter 1-5.");
    }
  }
}

void displaySystemStatus(bool lightsOn, double temp, bool securityArmed) {
  print("\n" + "=" * 30);
  print("System Status:");
  print("- Lights: ${lightsOn ? 'ON' : 'OFF'}");
  
  // String interpolation with FizzBuzz-like exercise
  String tempMessage = "$temp°C";
  
  // Check for multiples
  bool multipleOf3 = temp % 3 == 0;
  bool multipleOf5 = temp % 5 == 0;
  
  if (multipleOf3 && multipleOf5) {
    tempMessage += " - Perfect Day!";
  } else if (multipleOf3) {
    tempMessage += " - Cool Day";
  } else if (multipleOf5) {
    tempMessage += " - Warm Day";
  }
  
  print("- Thermostat: $tempMessage");
  
  // String operations - converting to uppercase
  String securityStatus = securityArmed ? "armed" : "disarmed";
  print("- Security System: ${securityStatus.toUpperCase()}");
  print("=" * 30);
}