Arduino handle serial message

/* ARDUINO MESSAGE HANDLING */

String currentMessage; // For holding the serial messages
bool isMessage = false; // True when is message is being send

// Message functions
void readChar() {
  if (Serial.available() > 0) {
    char incomingChar = (char)Serial.read();

    // Start the message
    if (incomingChar == '#' && ! isMessage)
      isMessage = true;

    // END message
    else if (incomingChar == '%' && isMessage) {
      handleMessage();
      currentMessage = "";
      isMessage = false;
    }

    // Append to the message
    else if (isMessage)
      currentMessage += incomingChar;
  }
}

void handleMessage() {
  // Set to remote control
  if (currentMessage == "REMOTE_CONTROL") {
    digitalWrite(RED_LED, HIGH);
    setRGB(remoteColor);
    mode = remote;
  }
    if (currentMessage.startsWith("SET_RED")) {
      remoteColor[0] = currentMessage.substring(currentMessage.indexOf(':') + 1).toInt();
    }
    else if (currentMessage.startsWith("SET_GREEN")) {
      remoteColor[1] = currentMessage.substring(currentMessage.indexOf(':') + 1).toInt();
    }
    else if (currentMessage.startsWith("SET_BLUE")) {
      remoteColor[2] = currentMessage.substring(currentMessage.indexOf(':') + 1).toInt();
    }
    // saving preset modes
    else if (currentMessage.startsWith("SET_PRESET")) {
      int index = currentMessage.indexOf(',');
      String presetName = currentMessage.substring(currentMessage.indexOf(':') + 1, index);
      Serial.println(presetName);
      int presetNumber = currentMessage.substring(index + 1).toInt() -1;
      remoteNames[presetNumber] = presetName;
      remotePresets[presetNumber][0] = remoteColor[0];
      remotePresets[presetNumber][1] = remoteColor[1];
      remotePresets[presetNumber][2] = remoteColor[2];
    }
      else if (currentMessage.startsWith("GET_PRESET")){
        int preset = currentMessage.substring(currentMessage.indexOf(':') + 1).toInt();
        sendPreset(preset);
        }
}