#define MAX_MESSAGE_LENGTH 64

char character = "";
static char message[MAX_MESSAGE_LENGTH];
int message_pos = 0;
String messageString;

void setup() {
  Serial.begin(9600);
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
}

void loop() {
  if(Serial.available()){
    character = Serial.read();
    if(character != '\n'){
      message[message_pos] = character;
      message_pos++;
    }else{
      message[message_pos] = '\0'; //if the message is over
      messageString = message; //save it to the output String
      message_pos = 0; //reset the char position
      Serial.println(messageString);
    }
  }

  if(messageString == "green"){
    digitalWrite(2, HIGH);
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
  }

  if(messageString == "red"){
    digitalWrite(2, LOW);
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
  }

  if(messageString == "blue"){
    digitalWrite(2, LOW);
    digitalWrite(3, LOW);
    digitalWrite(4, HIGH);
  }
  
}