#include <Adafruit_NeoPixel.h>
#define PIN 8
#define N_LEDS 14
Adafruit_NeoPixel strip = Adafruit_NeoPixel(N_LEDS, PIN, NEO_GRB + NEO_KHZ800);

int photocellPin = 0;
int photocellReading;

void setup() {
  strip.begin();

  Serial.begin(9600);
}

void loop() {
  chase(strip.Color(255, 0, 0));
  chase(strip.Color(0, 255, 0));
  chase(strip.Color(0, 0, 255));

  photocellReading = analogRead(photocellPin);
  Serial.print("Analog reading = ");
  Serial.println(photocellReading);
}

static void chase(uint32_t c) {
  if(photocellReading <= 300) {
  for (uint16_t i = 0; i < strip.numPixels() + 4; i++) {
    strip.setPixelColor(i  , c);
    strip.setPixelColor(i - 4, 0);
    strip.show();
    delay(20);
  }
  }
}