import 'dart:io';

// 7. Final/Const Variables: Use const for any constant values
const int MIN_TEMP = 15;
const int MAX_TEMP = 30;

// Device Status Variables (Initialized with default values)
bool lightsOn = false; // lights: off
int thermostatTemp = 20; // thermostat: 20°C
String securityStatus = 'disarmed'; // security system: disarmed

void main() {
  // 1. Main Method
  print("Welcome to the Smart Home System!");

  // 3. User Interaction: Use a loop to allow continuous interaction
  bool running = true;
  while (running) {
    displayMenu();
    
    // Read user choice
    String? choiceInput = stdin.readLineSync();
    int? choice = int.tryParse(choiceInput ?? '');

    if (choice != null) {
      // 5. Control Flow: Use if/else for choice validation
      if (choice < 1 || choice > 5) {
        print("\nInvalid choice. Please enter a number between 1 and 5.");
        continue;
      }
      
      // 5. Control Flow: Use a switch statement to handle user choices
      switch (choice) {
        case 1:
          toggleLights();
          break;
        case 2:
          setThermostatTemperature();
          break;
        case 3:
          armDisarmSecuritySystem();
          break;
        case 4:
          viewSystemStatus();
          break;
        case 5:
          running = false;
          print("\nExiting the Smart Home System. Goodbye!");
          break;
        default:
          // This should ideally not be reached due to the preceding if/else check
          print("\nInvalid choice. Please try again.");
      }
    } else {
      print("\nInvalid input. Please enter a number.");
    }
    
    if (running) {
        print("\n" + ("-" * 30)); // Separator for better readability
    }
  }
}

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");
  stdout.write("\nEnter your choice: ");
}

void toggleLights() {
  lightsOn = !lightsOn;
  // 6. String Interpolation: Using string interpolation in output
  print("Lights are now ${lightsOn ? 'ON' : 'OFF'}.");
}

void setThermostatTemperature() {
  stdout.write("Set thermostat temperature (${MIN_TEMP}°C - ${MAX_TEMP}°C): ");
  String? tempInput = stdin.readLineSync();
  int? newTemp = int.tryParse(tempInput ?? '');

  // 4. Input Validation & 8. Logical & Relational Operators: Validate user input
  if (newTemp != null && newTemp >= MIN_TEMP && newTemp <= MAX_TEMP) {
    thermostatTemp = newTemp;
    print("Thermostat set to ${thermostatTemp}°C.");
  } else {
    print("Invalid temperature. Please set a value between $MIN_TEMP°C and $MAX_TEMP°C.");
  }
}

void armDisarmSecuritySystem() {
  if (securityStatus == 'disarmed') {
    securityStatus = 'armed';
    print("Security system is now ARMED.");
  } else {
    securityStatus = 'disarmed';
    print("Security system is now DISARMED.");
  }
}

void viewSystemStatus() {
  String lightsState = lightsOn ? "ON" : "OFF";
  
  // 6. String Operations: Convert status to user-friendly message (e.g., "armed" to "ARMED")
  String securityState = securityStatus.toUpperCase();

  // 5. Control Flow: Implement a FizzBuzz-like exercise for weather status
  String weatherMessage;
  if (thermostatTemp % 3 == 0 && thermostatTemp % 5 == 0) {
    weatherMessage = "Perfect Day";
  } else if (thermostatTemp % 3 == 0) {
    weatherMessage = "Cool Day";
  } else if (thermostatTemp % 5 == 0) {
    weatherMessage = "Warm Day";
  } else {
    weatherMessage = "Normal"; // Default case
  }
  
  print("\nSystem Status:");
  // 6. String Interpolation: Displaying status with device values
  print("- Lights: $lightsState");
  print("- Thermostat: ${thermostatTemp}°C - $weatherMessage");
  print("- Security System: $securityState");
}