import 'dart:io';

void main() {
  // Smart Home Default Values
  bool lightsOn = false; // lightsOff by default
  int thermostat = 20; // default 20°C
  bool securityArmed = false; // disarmed by default

  const int minTemp = 15;
  const int maxTemp = 30;

  print("Welcome to the Smart Home System!");

  while (true) {
    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: ");
    String? input = stdin.readLineSync();
    int? choice = int.tryParse(input ?? "");

    if (choice == null) {
      print("Invalid input. Please enter a number from 1 to 5.");
      continue;
    }

    // if/else to handle user choices (as required)
    if (choice == 1 || choice == 2 || choice == 3) {
      // switch to handle device commands (as required)
      switch (choice) {
        case 1:
          lightsOn = !lightsOn;
          print("Lights are now ${lightsOn ? "ON" : "OFF"}.");
          break;

        case 2:
          int? newTemp = _readTemperature(minTemp, maxTemp);
          if (newTemp != null) {
            thermostat = newTemp;
            print("Thermostat set to $thermostat°C.");
          }
          break;

        case 3:
          stdout.write("Type 1 to ARM or 0 to DISARM: ");
          String? secInput = stdin.readLineSync();
          int? secChoice = int.tryParse(secInput ?? "");

          // logical & relational operators
          if (secChoice == 1) {
            securityArmed = true;
            print("Security System is now ARMED.");
          } else if (secChoice == 0) {
            securityArmed = false;
            print("Security System is now DISARMED.");
          } else {
            print("Invalid choice. Please type 1 or 0.");
          }
          break;
      }
    } else if (choice == 4) {
      _showStatus(lightsOn, thermostat, securityArmed);
    } else if (choice == 5) {
      print("Exiting the system. Goodbye!");
      break;
    } else {
      print("Invalid choice. Please enter a number from 1 to 5.");
    }
  }
}

int? _readTemperature(int minTemp, int maxTemp) {
  while (true) {
    stdout.write("Set thermostat temperature ($minTemp°C - $maxTemp°C): ");
    String? tempInput = stdin.readLineSync();
    int? temp = int.tryParse(tempInput ?? "");

    if (temp == null) {
      print("Invalid input. Please enter a valid number.");
      continue;
    }

    // input validation using logical & relational operators
    if (temp < minTemp || temp > maxTemp) {
      print("Temperature must be between $minTemp and $maxTemp. Try again.");
      continue;
    }

    return temp;
  }
}

void _showStatus(bool lightsOn, int thermostat, bool securityArmed) {
  // FizzBuzz-like temperature label
  String tempLabel = "";
  if (thermostat % 3 == 0 && thermostat % 5 == 0) {
    tempLabel = "Perfect Day";
  } else if (thermostat % 3 == 0) {
    tempLabel = "Cool Day";
  } else if (thermostat % 5 == 0) {
    tempLabel = "Warm Day";
  }

  // string operations: armed -> ARMED (uppercase)
  String securityText = (securityArmed ? "armed" : "disarmed").toUpperCase();

  print("\nSystem Status:");
  print("- Lights: ${lightsOn ? "ON" : "OFF"}");
  print("- Thermostat: $thermostat°C${tempLabel.isNotEmpty ? " - $tempLabel" : ""}");
  print("- Security System: $securityText");
}