// Removed: import 'dart:io' show stdin, stdout; // 'dart:io' is not supported by DartPad

void main() {
  // ─────────────── Constants ───────────────
  const int minTemp = 15;
  const int maxTemp = 30;

  // ─────────────── Device Status ───────────────
  bool lightsOn = false;
  int thermostat = 20;
  bool securityArmed = false;

  // --- Simulate interactive input for DartPad ---
  // In a real console application, stdin.readLineSync() would be used.
  // For DartPad, we provide a sequence of simulated user choices.
  final List<String> simulatedChoices = [
    "1", // Toggle Lights
    "2", // Set Thermostat
    "25", // -> Input for thermostat temp (valid)
    "4", // View System Status
    "2", // Set Thermostat (invalid)
    "10", // -> Input for thermostat temp
    "3", // Arm Security
    "4", // View System Status
    "5", // Exit
  ];
  int choiceIndex = 0;

  // ─────────────── Main Menu Loop ───────────────
  // The loop now iterates through the simulated choices
  while (choiceIndex < simulatedChoices.length) {
    print("\n========= SMART HOME SYSTEM =========");
    print("1. Toggle Lights");
    print("2. Set Thermostat Temperature");
    print("3. Arm/Disarm Security System");
    print("4. View System Status");
    print("5. Exit");

    // Replaced stdout.write with print for DartPad compatibility
    print("Enter your choice (simulated): ");

    // Get the next simulated choice
    // simulatedChoices is List<String>, so elements are guaranteed to be non-null Strings.
    String choice = simulatedChoices[choiceIndex];
    print("Simulated input: $choice"); // Display the current simulated input
    choiceIndex++; // Move to the next simulated choice for the next iteration

    // The previous check `if (choice == null) continue;` is no longer needed
    // because `choice` is now declared as a non-nullable String,
    // reflecting that elements from `simulatedChoices` are never null.

    // ─────────────── Handling Choices ───────────────
    switch (choice) {
      case "1":
        lightsOn = !lightsOn;
        print("Lights are now: ${lightsOn ? 'ON' : 'OFF'}");
        break;

      case "2":
        // Replaced stdout.write with print for DartPad compatibility
        print("Enter temperature ($minTemp – $maxTemp) (simulated): ");

        // Check if there's a subsequent simulated input for temperature
        if (choiceIndex >= simulatedChoices.length) {
          print("No more simulated inputs for temperature. Skipping.");
          break; // Exit case "2"
        }
        String? tempInput = simulatedChoices[choiceIndex];
        print("Simulated input for temperature: $tempInput");
        choiceIndex++; // Move to the next simulated choice (for the next main menu choice)

        int? newTemp = int.tryParse(tempInput);

        // Input Validation
        if (newTemp == null || newTemp < minTemp || newTemp > maxTemp) {
          print(
            "❌ Invalid temperature! Must be between $minTemp and $maxTemp.",
          );
        } else {
          thermostat = newTemp;
          print("✅ Thermostat set to $thermostat°C");
        }
        break;

      case "3":
        securityArmed = !securityArmed;
        print(
          "Security System is now: ${securityArmed ? 'ARMED' : 'DISARMED'}",
        );
        break;

      case "4":
        // FizzBuzz-like Temperature Message
        String tempMessage = "";
        if (thermostat % 3 == 0 && thermostat % 5 == 0) {
          tempMessage = "Perfect Day";
        } else if (thermostat % 3 == 0) {
          tempMessage = "Cool Day";
        } else if (thermostat % 5 == 0) {
          tempMessage = "Warm Day";
        }

        print("\n──── SYSTEM STATUS ────");
        print("Lights: ${lightsOn ? 'ON' : 'OFF'}");
        print(
          "Thermostat: $thermostat°C ${tempMessage.isNotEmpty ? '→ $tempMessage' : ''}",
        );
        print("Security: ${securityArmed ? 'ARMED' : 'DISARMED'}");

        break;

      case "5":
        print("Exiting Smart Home System... Goodbye!");
        return; // Exits the main function after the simulated sequence

      default:
        print("❌ Invalid choice, please try again.");
    }
  }
  // If the loop finishes without a '5' choice, explicitly state it.
  if (choiceIndex >= simulatedChoices.length) {
    print("\nSimulated choices exhausted. Program finished.");
  }
}