#include <Adafruit_NeoPixel.h>

#define PIN            6
#define NUMPIXELS      8

Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

const int buttonPin = 2;

int currentColor = 0;

void setup() {
  strip.begin();
  strip.show();

  pinMode(buttonPin, INPUT);

  setColor(255, 0, 0);
}

void loop() {
  int buttonState = digitalRead(buttonPin);

  if (buttonState == LOW) {
    delay(50);
    changeColor();
  }
}

void setColor(uint8_t red, uint8_t green, uint8_t blue) {
  for(int i = 0; i < strip.numPixels(); i++) {
    strip.setPixelColor(i, strip.Color(red, green, blue));
  }
  strip.show();
}

void changeColor() {
  currentColor = (currentColor + 1) % 3;

  if (currentColor == 0) {
    setColor(255, 0, 0);
  } else if (currentColor == 1) {
    setColor(0, 255, 0);
  } else {
    setColor(0, 0, 255);
  }

  delay(500);
}