#include <FastLED.h>

constexpr uint8_t DATA_PIN {16};
constexpr unsigned int NUM_LEDS {16};
CRGB leds[NUM_LEDS];

class Scenario {   // Interface
public:
  virtual int tuwas() { return 0; }
};

class ScRandom : public Scenario {
private:
  unsigned long delay_milli;
  unsigned long last_millis {0};

public:
  ScRandom(unsigned long dm) : delay_milli {dm} {}

  virtual int tuwas() override {
    unsigned long m = millis();
    if ((m - last_millis) < delay_milli) { return 0; }
    Serial.println("In ScRandom");
    last_millis = m;
    for (size_t i = 0; i < NUM_LEDS; ++i) { leds[i] = CRGB(random8(), random8(), random8()); }
    FastLED.show();
    return 1;
  }
};

class ScPrint : public Scenario {
private:
  Print& output;

public:
  ScPrint(Print& stream) : output {stream} {}
  virtual int tuwas() override {
    output.print("In ScPrint: Ich tu was...");
    output.println("aber nicht leuchten");
    return 0;
  }
};

Scenario* scenarios[] {new ScRandom {200}, new ScPrint {Serial}};

void setup() {
  Serial.begin(115200);
  FastLED.addLeds<WS2812, DATA_PIN, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(255);
  FastLED.clear();
}

void loop() {
  if (scenarios[0]->tuwas()) {
    scenarios[1]->tuwas();
  }
}