import 'dart:io';

// 7. Final/Const Variables: Use const for temperature constraints
const int MIN_TEMP = 15;
const int MAX_TEMP = 30;

// 2. Device Status: Global variables for device states
bool lightsOn = false; // default: off
int thermostatTemp = 20; // default: 20°C
String securityStatus = 'disarmed'; // default: disarmed

// Function to read user input
String? readInput() {
  stdout.write('Enter your choice: ');
  return stdin.readLineSync();
}

// Function to read and validate temperature input
int? readTemperature() {
  stdout.write('Set thermostat temperature ($MIN_TEMP°C - $MAX_TEMP°C): ');
  String? input = stdin.readLineSync();
  try {
    int temp = int.parse(input!);
    // 8. Logical & Relational Operators: Validate input range
    if (temp >= MIN_TEMP && temp <= MAX_TEMP) {
      return temp;
    } else {
      print('Invalid temperature. Please choose a value between $MIN_TEMP°C and $MAX_TEMP°C.');
      return null;
    }
  } catch (e) {
    print('Invalid input. Please enter a whole number for the temperature.');
    return null;
  }
}

// Function to display the main menu
void displayMenu() {
  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');
}

// Function to display the system status (including FizzBuzz-like logic)
void viewStatus() {
  // 5. Implement a FizzBuzz-like exercise
  String tempMessage = '';
  
  // Check for multiples of 3
  if (thermostatTemp % 3 == 0) {
    tempMessage += 'Cool Day';
  }
  
  // Check for multiples of 5
  if (thermostatTemp % 5 == 0) {
    if (tempMessage == 'Cool Day') {
      tempMessage = 'Perfect Day'; // Multiple of both 3 and 5
    } else {
      tempMessage += 'Warm Day';
    }
  }

  // 6. String Interpolation and Operations:
  print('\nSystem Status:');
  // Use string interpolation to show state
  print('Lights: ${lightsOn ? 'ON' : 'OFF'}');
  print('Thermostat: $thermostatTemp°C ${tempMessage.trim()}');
  // Use string operation (toUpperCase)
  print('Security System: ${securityStatus.toUpperCase()}');
}

// 1. Main Method: Program entry point
void main() {
  print('Welcome to the Smart Home Automation System CLI!');

  // 3. User Interaction: Use a loop for continuous interaction
  while (true) {
    displayMenu();
    String? choice = readInput();

    // 5. Control Flow: Use if/else for main control
    if (choice == '5') {
      print('Exiting the system. Goodbye!');
      break;
    } else if (choice == '4') {
      viewStatus();
    } else {
      // 5. Control Flow: Use switch for device commands
      switch (choice) {
        case '1': // Toggle lights
          lightsOn = !lightsOn;
          print('Lights are now ${lightsOn ? 'ON' : 'OFF'}.');
          break;
        case '2': // Set thermostat temperature
          int? newTemp = readTemperature();
          if (newTemp != null) {
            thermostatTemp = newTemp;
            print('Thermostat set to $thermostatTemp°C.');
          }
          break;
        case '3': // Arm/disarm security system
          if (securityStatus == 'disarmed') {
            securityStatus = 'armed';
            print('Security system is now ARMED.');
          } else {
            securityStatus = 'disarmed';
            print('Security system is now DISARMED.');
          }
          break;
        default:
          print('Invalid choice. Please select an option from 1 to 5.');
      }
    }
  }
}