// A is the value type we get for each candle

asclass CandleBasedIndicator<A> extends MetaWithChangeListeners {

  replace Candle with TradingCandle.

  // Number of candles we need to look back to

  settable int length = 20;

  event candleAdded(Candle candle);

  event candleRemoved(Candle candle);

  // get current indicator value

  abstract A value aka get();

  simplyCached SimpleCircularBuffer<Candle> candles() {

    ret new SimpleCircularBuffer(candlesNeeded());

  }

  int candlesNeeded() { ret length; }

  Candle lastCandle() { ret candles().last(); }

  selfType feed(TradingCandleMaker candleMaker) {

    if (candleMaker != null)

      // TODO: cut list down first

      for (candle : candleMaker.candles())

        add(candle);

    this;

  }

  selfType add aka feed(Iterable<TradingCandle> candles) {

    fOr (candle : candles)

      add(candle);

    this;

  }

  // Can add candles twice, will automatically ignore the second time

  selfType add aka feed(TradingCandle candle) {

    if (candle.ongoing()) this;

    if (lastCandle() != null && lessOrEq(candle.startTime, lastCandle().startTime))

      this;

    while (candles().size() > max(length-1, 0))

      candleRemoved(candles().remove());

    candles().add(candle);

    candleAdded(candle);

    this;

  }

  void reset {

    resetFields(this, "candles_cache");

  }

  selfType emptyClone() {

    var clone = shallowNonTransientClone(this);

    clone.reset();

    ret clone;

  }

}