Kind words night light on an Arduino Uno

// Kind words night light: a warm night light that turns on when the room goes
// dark and says something nice on its little screen. Press the button for
// another kind word.
//
//   light sensor  module AO -> A0, VCC -> 5 V, GND -> GND
//   glow          8 WS2812B LEDs in a ring, DIN <- 330 ohms <- pin 6
//   LCD           16x2 with an I2C backpack: SDA -> A4, SCL -> A5
//   button        pin 2 -> button -> GND        (INPUT_PULLUP)
//
// A gift for Mother's Day or Father's Day, for a new baby's room, or for a
// grandparent who likes a light on in the hall. When the room goes dark the
// ring fades up to a soft amber and the screen shows one of the notes in
// NOTES. The screen's backlight turns off after half a minute so it does not
// keep anyone awake, and a press of the button brings it back with the next
// note.
//
// Amber, with very little blue, is the kindest color for a night light: it
// is easy on sleepy eyes and still enough to find the door by.
//
// Things to try. Drag the light sensor's slider down to make it night. Press
// the button. Write your own NOTES, two lines of 16 letters each.

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Adafruit_NeoPixel.h>

const int BUTTON_PIN = 2;
const int LEDS = 8;
const int DARK_ABOVE = 700;    // A0 reading: night above this
const int LIGHT_BELOW = 600;   // and day below this
const unsigned long SCREEN_MS = 30000UL;

LiquidCrystal_I2C lcd(0x27, 16, 2);
Adafruit_NeoPixel glow(LEDS, 6, NEO_GRB + NEO_KHZ800);

const char *NOTES[][2] = {
  {"You are loved", "Sleep well"},
  {"Proud of you,", "always"},
  {"Thank you for", "all you do"},
  {"Sweet dreams", "See you soon"},
  {"You make home", "feel like home"},
};
const int COUNT = sizeof(NOTES) / sizeof(NOTES[0]);

bool night = false;
int note = 0;
unsigned long noteAt = 0;
bool screenOn = false;

void say(int n) {
  lcd.backlight();
  lcd.clear();
  lcd.print(NOTES[n][0]);
  lcd.setCursor(0, 1);
  lcd.print(NOTES[n][1]);
  screenOn = true;
  noteAt = millis();
  Serial.print("Kind word: ");
  Serial.print(NOTES[n][0]);
  Serial.print(" ");
  Serial.println(NOTES[n][1]);
}

void amber(int level) {
  for (int i = 0; i < LEDS; i++) glow.setPixelColor(i, level, level * 2 / 5, level / 20);
  glow.show();
}

void setup() {
  Serial.begin(9600);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  glow.begin();
  glow.show();
  lcd.init();
  lcd.noBacklight();
  Serial.println("Night light waiting for the dark");
}

void loop() {
  int light = analogRead(A0);
  if (!night && light > DARK_ABOVE) {
    night = true;
    Serial.println("Good night: light on");
    for (int v = 0; v <= 160; v += 4) {
      amber(v);
      delay(25);
    }
    say(note);
  } else if (night && light < LIGHT_BELOW) {
    night = false;
    amber(0);
    lcd.clear();
    lcd.noBacklight();
    screenOn = false;
    note = (note + 1) % COUNT;   // a new note tomorrow night
    Serial.println("Good morning: light off");
  }

  if (night && digitalRead(BUTTON_PIN) == LOW) {
    note = (note + 1) % COUNT;
    say(note);
    while (digitalRead(BUTTON_PIN) == LOW) delay(10);
  }
  if (screenOn && millis() - noteAt >= SCREEN_MS) {
    lcd.noBacklight();
    screenOn = false;
  }
  delay(20);
}