const int ledPins[] = {8, 9, 10, 11};   

void setup() {
  Serial.begin(115200); 
  for (int i = 0; i < 4; i++) {
    pinMode(ledPins[i], OUTPUT);  
  }
}

void loop() {
  if (Serial.available()) {
    String state = Serial.readString();
    state.trim();

    if (state == "red" || state == "Red" || state == "RED") {
      digitalWrite(ledPins[0], HIGH);
      digitalWrite(ledPins[1], LOW);
      digitalWrite(ledPins[2], LOW);
      digitalWrite(ledPins[3], LOW);

    } else if (state == "green" || state == "Green" || state == "GREEN") {
      digitalWrite(ledPins[0], LOW);
      digitalWrite(ledPins[1], HIGH);
      digitalWrite(ledPins[2], LOW);
      digitalWrite(ledPins[3], LOW);

    } else if (state == "blue" || state == "Blue" || state == "BLUE") {
      digitalWrite(ledPins[0], LOW);
      digitalWrite(ledPins[1], LOW);
      digitalWrite(ledPins[2], HIGH);
      digitalWrite(ledPins[3], LOW);
      
    } else if (state == "yellow" || state == "Yellow" || state == "YELLOW") {
      digitalWrite(ledPins[0], LOW);
      digitalWrite(ledPins[1], LOW);
      digitalWrite(ledPins[2], LOW);
      digitalWrite(ledPins[3], HIGH);
    
    } else if (state == "all" || state == "All" || state == "ALL") {
      digitalWrite(ledPins[0], HIGH);
      digitalWrite(ledPins[1], HIGH);
      digitalWrite(ledPins[2], HIGH);
      digitalWrite(ledPins[3], HIGH); // turns ON all LEDs
    
    } else if (state == "off" || state == "Off" || state == "OFF") {
      digitalWrite(ledPins[0], LOW);
      digitalWrite(ledPins[1], LOW);
      digitalWrite(ledPins[2], LOW);
      digitalWrite(ledPins[3], LOW); // turns OFF any LED that is ON
    }

  }
}