#define analogPin A0 // used to seed random function
#define runPin 12    // blink LED when running
#define pinSwitch 2  // used when lighting/extinguishing

#define minFlame 32 // lowest PWM value for 'flame'
#define lastLED endLED[3] // convenient definition to simplify code

#define myPause 12  // pause between candle levels
#define levelchange 12 // amount to change when blowing out candles
#define puffs 10 // loop when blowing out candles

#define ON  1 // definitions in code for clarity

// list of pins to which candles are attached/controlled
byte LEDPIN[] =  {  3,  5,  6,  9, 11,  10}; //  For Nano

// ==================================
void setup()
{
  // initialize random function
  randomSeed(analogRead(analogPin));

  // set up candles/ display startup sequence
  for (byte candle = 0; candle < 6; candle++) {
    pinMode(LEDPIN[candle], OUTPUT);
    analogWrite(LEDPIN[candle],   0);
  }
  // set up control (switch) pin
  pinMode(pinSwitch, INPUT_PULLUP);
}

// ==================================
void loop()
{
  byte level[] = {0, 0, 0, 0, 0, 0};
  byte candle, i, repeat;
  boolean Lit = true;

  showStatus();

  // display candles
  if (candlesLit()) {
    Lit = true; // remember that it's ok to blow out the candles

    for (byte candle = 0; candle < 6; candle++) { // there are six candles on the Nano
      level[candle] = random(minFlame, 255); // flicker is chosen randomly
      analogWrite(LEDPIN[candle], level[candle]);
      delay(myPause); // pause a bit at each lvel
    }
  }

  // blow out candles
  if (! candlesLit() && Lit) { // blow them out once!
    Lit = false; // changing this variable only executes the 'blow out' code once

    for (repeat = 0; repeat < puffs; repeat++) { // dim candle to out slowly
 
      // 'blow out' candles
      for (candle = 0; candle < 6; candle++) { // for each candle in a 'group'
        // dim out each candle
        level[candle] = constrain((level[candle] - levelchange), 0, 255);
        analogWrite(LEDPIN[candle], level[candle] );
        if(candlesLit())break; // Request to light candle received; get out quick
        delay(myPause); // short delay between changes
      }
      if(candlesLit())break; // Request to light candle received; get out quick
    }
    for (candle = 0; candle < 6; candle++) // turn off all candles
      analogWrite(LEDPIN[candle], 0);
  }
}

// ==================================
void showStatus()
{
  static unsigned long updateTime = 0;
  static unsigned int ledState = HIGH;
  int nextState = LOW;

  if (millis() >= updateTime) {
    if (ledState == HIGH) nextState = LOW;
    if (ledState == LOW)  nextState = HIGH;
    ledState = nextState;
    digitalWrite(runPin, ledState);
    updateTime = updateTime + 500;
  }
}

// ==================================
boolean candlesLit()
{
  return (digitalRead(pinSwitch) == ON);
}