import 'dart:io';

/// Encapsulates the state and logic for the smart home devices.
class SmartHomeSystem {
  // 2. Device Status: Initialize each device with default values.
  bool lightsOn = false; // Lights (can be on or off)
  int thermostatTemp = 20; // Thermostat (default 20°C)
  bool securityArmed = false; // Security System (can be armed or disarmed)

  /// The minimum and maximum allowable temperature for the thermostat.
  static const int minTemp = 15;
  static const int maxTemp = 30;

  // --- Core Device Control Methods ---

  /// Toggles the light status.
  String toggleLights() {
    lightsOn = !lightsOn;
    return lightsOn ? "Lights **turned ON**." : "Lights **turned OFF**.";
  }

  /// Arms the security system.
  String armSecurity() {
    if (!securityArmed) {
      securityArmed = true;
      return "Security System **ARMED**.";
    }
    return "Security System is already armed.";
  }

  /// Disarms the security system.
  String disarmSecurity() {
    if (securityArmed) {
      securityArmed = false;
      return "Security System **DISARMED**.";
    }
    return "Security System is already disarmed.";
  }

  /// Sets the thermostat temperature with validation.
  String setTemperature(String input) {
    try {
      final int newTemp = int.parse(input.trim());

      // 4. Input Validation: Temperature range check.
      if (newTemp < minTemp || newTemp > maxTemp) {
        return "⚠️ Error: Temperature must be between $minTemp°C and $maxTemp°C. Please try again.";
      }

      thermostatTemp = newTemp;
      return "Thermostat set to **$thermostatTemp°C** successfully.";
    } on FormatException {
      return "⚠️ Error: Invalid input. Please enter a valid number for the temperature.";
    }
  }

  // --- Status Display Method ---

  /// Displays the current status of all devices and applies FizzBuzz-like logic.
  String getSystemStatus() {
    // 6. String Interpolation and Operations:
    final lightStatus = lightsOn ? "ON" : "OFF";
    final securityStatus = securityArmed ? "ARMED" : "DISARMED";

    // 5. Control Flow: FizzBuzz-like exercise
    String tempMessage;
    final isMultipleOf3 = thermostatTemp % 3 == 0;
    final isMultipleOf5 = thermostatTemp % 5 == 0;

    if (isMultipleOf3 && isMultipleOf5) {
      tempMessage = "Perfect Day! (Multiple of 3 and 5)";
    } else if (isMultipleOf3) {
      tempMessage = "Cool Day! (Multiple of 3)";
    } else if (isMultipleOf5) {
      tempMessage = "Warm Day! (Multiple of 5)";
    } else {
      tempMessage = "Standard Temperature.";
    }

    return """
--- Current System Status ---
💡 Lights: **$lightStatus**
🌡️ Thermostat: **$thermostatTemp°C** ($tempMessage)
🔒 Security System: **$securityStatus**
---------------------------
""";
  }
}

// --- Main Application Logic ---

// 1. Main Method: The program starts here.
void main() {
  final SmartHomeSystem system = SmartHomeSystem();
  bool running = true;
  
  print("Welcome to the **Dart Smart Home CLI**!");
  print("Use 'status' to view devices or 'help' for options.");
  
  // 3. User Interaction: Use a loop for continuous interaction.
  while (running) {
    print("\n--------------------------");
    stdout.write("Enter command (e.g., lights on, temp 25, exit): ");
    final String? input = stdin.readLineSync();
    
    if (input == null || input.trim().isEmpty) {
      continue;
    }

    // Process the input command
    final List<String> parts = input.trim().toLowerCase().split(' ');
    final String primaryCommand = parts[0];
    final String? secondaryCommand = parts.length > 1 ? parts[1] : null;

    // 5. Control Flow: Use if/else statements to handle user choices (main menu)
    if (primaryCommand == 'exit') {
      running = false;
      print("👋 Shutting down Smart Home system. Goodbye!");
      break;
    } else if (primaryCommand == 'status') {
      print(system.getSystemStatus());
    } else if (primaryCommand == 'help') {
      _displayHelp();
    } else {
      // 5. Control Flow: Use a switch statement to handle device commands
      switch (primaryCommand) {
        case 'lights':
          if (secondaryCommand == 'on' || secondaryCommand == 'off' || secondaryCommand == 'toggle') {
            print(system.toggleLights());
          } else {
            print("⚠️ Invalid lights command. Try: lights on/off or lights toggle.");
          }
          break;
        case 'temp':
        case 'thermostat':
          if (secondaryCommand != null) {
            print(system.setTemperature(secondaryCommand));
          } else {
            print("⚠️ Missing temperature value. Try: temp 25 (range ${SmartHomeSystem.minTemp}-${SmartHomeSystem.maxTemp}°C).");
          }
          break;
        case 'security':
          if (secondaryCommand == 'arm') {
            print(system.armSecurity());
          } else if (secondaryCommand == 'disarm') {
            print(system.disarmSecurity());
          } else {
            print("⚠️ Invalid security command. Try: security arm or security disarm.");
          }
          break;
        default:
          print("Command **'$primaryCommand'** not recognized. Type 'help' for options.");
          break;
      }
    }
  }
}

/// Helper function to display command options.
void _displayHelp() {
  print("""
--- Available Commands ---
* **lights [on/off/toggle]**: Control the house lights.
* **temp [15-30]**: Set the thermostat temperature.
* **security [arm/disarm]**: Control the security system.
* **status**: View the current state of all devices.
* **exit**: Close the Smart Home application.
--------------------------
""");
}
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