Handling different variable types as commands - c++

Question

I'm building an Arduino sketch, where i want to communicate with my arduino to control a neorgb strip by adafruit, which is a strip with in my case 60 RGB LEDs with each LED is adressable.
I got it to work with a simple if construct to check if I send the command "off" to switch the whole strip of or I send a hex code for a specific color.
That works fine, but now I want to also dim the brightness of the strip, my function to dim every color component works fine but I need a way to trigger it with a command. My problem is that I don't know how I can handle it if I sent a specific string (in this case "off"), a hex color code or a percentage to dimm my strip.
Also another question is why I need to enter " off" in the serial monitor for the sketch to turn of my strip.
My whole code looks like this:
#include <Adafruit_NeoPixel.h>
//Vars
int stripPin = 6; //NeoPixel Strip Pin
int numberLED = 60; //How many LEDs?
int maxBrightness = 50; //maximum Brightness
String incoming;
Adafruit_NeoPixel strip = Adafruit_NeoPixel(numberLED, stripPin, NEO_GRB + NEO_KHZ800);
void setup() {
// put your setup code here, to run once:
strip.setBrightness(maxBrightness);
strip.begin();
strip.show(); //Clear Strip
Serial.begin(9600);
}
void loop() {
if (Serial.available() > 0) { //Listening for Commands
incoming = Serial.readString();
if (incoming == "off ") { //if command is "off", switch strip of
setStripColor(0,0,0);
}
else{
// Get rid of '#' and convert it to integer
long number = (long) strtol( &incoming[1], NULL, 16);
// Split them up into r, g, b values
long r = number >> 16;
long g = number >> 8 & 0xFF;
long b = number & 0xFF;
setStripColor(r,g,b); //Set Color for whole Strip
strip.show();
}
Serial.println(incoming);
}
delay(10);
}
int setStripColor(int redValue, int greenValue, int blueValue) //Set Color for whole strip
{
for(int i = 0; i < numberLED; i++ ){
strip.setPixelColor(i, redValue,greenValue,blueValue);
}
}
int dim(int color, int dimVal) //Dim color to dimVal in percent
{
color = color / 100 * dimVal;
return color;
}