// https://forum.arduino.cc/t/frage-zu-neo-pixel-streifen/1346465

#include <Adafruit_NeoPixel.h>
#define LED_PIN       8
#define SWITCH_A_PIN  2
#define SWITCH_B_PIN  3
#define SWITCH_C_PIN  4
#define NUMPIXELS    30 // 100
#define SHORT_WAIT  100 // 25
#define LONG_WAIT  2000 // 1000

Adafruit_NeoPixel pixels(NUMPIXELS, LED_PIN, NEO_GRB + NEO_KHZ800);
bool st;

void setup()
{
  pinMode(SWITCH_A_PIN, INPUT_PULLUP);
  pinMode(SWITCH_B_PIN, INPUT_PULLUP);
  pinMode(SWITCH_C_PIN, INPUT_PULLUP);
  pixels.begin();
}

void loop()
{
  if (!digitalRead(SWITCH_A_PIN))      setA();
  else if (!digitalRead(SWITCH_B_PIN)) setB();
  else if (!digitalRead(SWITCH_C_PIN)) setC();
}

void setA()
{
  for (int j = 0; j < NUMPIXELS; j++) {
    setd(0, j);
    delay(SHORT_WAIT);
  }
  delay(LONG_WAIT);
  for (int j = 0; j < NUMPIXELS; j++) {
    setd(j, NUMPIXELS - 1);
    delay(SHORT_WAIT);
  } 
  pixels.clear();
  pixels.show();
}

void setB()
{
  for (int j = NUMPIXELS - 1; j > 0; j--) {
    setd(j - 1, NUMPIXELS - 1);
    delay(SHORT_WAIT);
  }
  delay(LONG_WAIT);
  for (int j = NUMPIXELS - 1; j > 0; j--) {
    setd(0, j - 1);
    delay(SHORT_WAIT);
  } 
  pixels.clear();
  pixels.show();
}

void setC()
{
  pixels.setPixelColor(0, pixels.Color(0, 255, 0));
  delay(SHORT_WAIT);
  pixels.show();

  pixels.setPixelColor(NUMPIXELS-1, pixels.Color(0, 255, 0));
  delay(SHORT_WAIT);
  pixels.show();
  
  delay(2*LONG_WAIT);
  pixels.clear();
  pixels.show();
}

void setd(int st, int ed)
{
  pixels.clear();
  for (int i = st; i <= ed; i++) { // For each pixel...
    pixels.setPixelColor(i, pixels.Color(0, 255, 0 ));
    //delay(5);
  }
  pixels.show();
}