void setup() {
  Serial.begin(9600); // Start serial communication at 9600 baud
  while (!Serial);    // Wait for Serial to be ready (useful for boards like Arduino Leonardo)
  Serial.println("Serial Shell Ready. Type 'help' for commands.");

  // Set GPIO pins 2-9 as OUTPUT (adjust if necessary for your board)
  for (int pin = 2; pin <= 9; pin++) {
    pinMode(pin, OUTPUT);
    digitalWrite(pin, HIGH); // Ensure pins start HIGH
  }
}

void loop() {
  static String inputBuffer = ""; // Buffer to store incoming data
  
  // Check if data is available on the serial port
  if (Serial.available()) {
    char incomingChar = Serial.read(); // Read one character
    
    // Check for end of command
    if (incomingChar == '\n' || incomingChar == '\r') {
      if (inputBuffer.length() > 0) {
        processCommand(inputBuffer); // Process the full command
        inputBuffer = "";            // Clear the buffer
      }
    } else {
      inputBuffer += incomingChar;   // Append character to buffer
    }
  }
}

void processCommand(String command) {
  command.trim(); // Remove leading/trailing whitespace
  if (command == "help") {
    Serial.println("Available Commands:");
    Serial.println(" - help: Show this help message");
    Serial.println(" - led_on: Turn the onboard LED on");
    Serial.println(" - led_off: Turn the onboard LED off");
    Serial.println(" - status: Get the LED status");
    Serial.println(" - reboot <pin> [time]: Set a GPIO LOW for specified time (default 1s)");
  } else if (command.startsWith("reboot ")) {
    handleRebootCommand(command);
  } else if (command == "led_on") {
    digitalWrite(LED_BUILTIN, HIGH);
    Serial.println("LED is ON.");
  } else if (command == "led_off") {
    digitalWrite(LED_BUILTIN, LOW);
    Serial.println("LED is OFF.");
  } else if (command == "status") {
    if (digitalRead(LED_BUILTIN) == HIGH) {
      Serial.println("LED is currently ON.");
    } else {
      Serial.println("LED is currently OFF.");
    }
  } else {
    Serial.println("Unknown command. Type 'help' for a list of commands.");
  }
}

void handleRebootCommand(String command) {
  // Parse arguments (e.g., "reboot 5 2000")
  int firstSpace = command.indexOf(' ');
  int secondSpace = command.indexOf(' ', firstSpace + 1);

  // Extract pin number and optional time
  int pin = command.substring(firstSpace + 1, secondSpace).toInt();
  int duration = (secondSpace != -1) ? command.substring(secondSpace + 1).toInt() : 1000;

  // Validate pin range (2-9 for GPIOs on most Arduino boards)
  if (pin < 2 || pin > 9) {
    Serial.println("Invalid pin number. Use a number between 2 and 9.");
    return;
  }

  // Validate duration
  if (duration <= 0) {
    Serial.println("Invalid duration. Must be greater than 0.");
    return;
  }

  // Execute command
  Serial.print("Rebooting GPIO ");
  Serial.print(pin);
  Serial.print(" for ");
  Serial.print(duration);
  Serial.println(" ms...");
  digitalWrite(pin, LOW);
  delay(duration);
  digitalWrite(pin, HIGH);
  Serial.println("Done.");
}