import 'dart:io';

// 2. Device Status: Initialize device states
bool lightsOn = false;
int thermostatTemp = 20; // Default 20°C
bool securityArmed = false;

// Function to display the system status (Requirement 5)
void displayStatus() {
  print('\n--- System Status ---');
  print('Lights: ${lightsOn ? 'ON' : 'OFF'}');
  print('Thermostat: $thermostatTemp°C');
  print('Security System: ${securityArmed ? 'ARMED' : 'DISARMED'}');
  print('---------------------\n');
}

// 1. Main Method: The program starts here (Requirement 1)
void main() {
  print('Welcome to the Smart Home Automation System CLI!');

  // 3. User Interaction: Loop for continuous interaction (Requirement 3, Control Flow)
  while (true) {
    print('Please select an option:');
    print('  1. Toggle Lights (Currently: ${lightsOn ? 'ON' : 'OFF'})');
    print('  2. Set Thermostat Temperature (Current: $thermostatTemp°C)');
    print('  3. Toggle Security System (Currently: ${securityArmed ? 'ARMED' : 'DISARMED'})');
    print('  4. View System Status');
    print('  5. Exit Program');

    stdout.write('Your choice: ');
    // Read and parse the user's choice
    final choice = stdin.readLineSync();
    
    // 5. Control Flow: Use if/else to handle menu options (Requirement 5)
    if (choice == '1') {
      lightsOn = !lightsOn; // Toggle the state (Requirement 3)
      print('Lights are now ${lightsOn ? 'ON' : 'OFF'}!');
    } else if (choice == '2') {
      stdout.write('Enter new temperature (15°C - 30°C): ');
      final tempInput = stdin.readLineSync();
      // Use try-catch for robust conversion
      try {
        final newTemp = int.parse(tempInput ?? '');
        // 4. Input Validation: Check temperature range (Requirement 4)
        if (newTemp >= 15 && newTemp <= 30) {
          thermostatTemp = newTemp;
          print('Thermostat set to $thermostatTemp°C!');
        } else {
          print('❌ Invalid temperature. Must be between 15°C and 30°C.');
        }
      } catch (_) {
        print('❌ Invalid input. Please enter a number.');
      }
    } else if (choice == '3') {
      securityArmed = !securityArmed; // Toggle the state (Requirement 3)
      print('Security System is now ${securityArmed ? 'ARMED' : 'DISARMED'}!');
    } else if (choice == '4') {
      displayStatus();
    } else if (choice == '5') {
      print('Exiting the Smart Home Automation Program. Goodbye!');
      break; // Exit the loop (Requirement 3)
    } else {
      print('❌ Invalid choice. Please select an option from 1 to 5.');
    }
  }
}