//cpp  With the support of Google AI and Grok AI
#include <SoftwareSerial.h>

//SoftwareSerial link(10, 11); // RX, TX


void setup() {

  for (int i = 2; i <= 5; i++) {
    pinMode(i, OUTPUT);
    digitalWrite(i, LOW);
  }

  Serial.begin(9600);
  Serial.println("Ready. Type 'LED 3 ON' or 'LED 4 OFF'");
}

void loop() {


  if (Serial.available()) {
      String line = Serial.readStringUntil('\n');
      line.trim();                // remove whitespace / \r

    // Very basic check if it even looks like a command
    if (!line.startsWith("LED ")) {
      // Serial.println("Not a LED command");
      return;
    }

    // Remove "LED " prefix
    String rest = line.substring(4);

    // Find space between number and ON/OFF
    int spacePos = rest.indexOf(' ');
    if (spacePos <= 0) return;

    String numStr  = rest.substring(0, spacePos);
    String cmdStr  = rest.substring(spacePos + 1);

    // Convert number
    int led_num = numStr.toInt();
    if (led_num < 2 || led_num > 5) {
      // Serial.println("Invalid LED number");
      return;
    }

    // Normalize and check command
    cmdStr.trim();
    bool turnOn;

    if (cmdStr.equalsIgnoreCase("ON")) {
      turnOn = true;
    }
    else if (cmdStr.equalsIgnoreCase("OFF")) {
      turnOn = false;
    }
    else {
      Serial.println("Invalid ON/OFF");
      return;
    }

    Operate_Pin(led_num, turnOn);

      // Optional debug
      // Serial.print("LED "); Serial.print(led_num);
      // Serial.println(turnOn ? " ON" : " OFF");


  }
}

void Operate_Pin(int pin, bool state) 
{
  digitalWrite(pin, state ? HIGH : LOW);
}