sclass RSI extends CandleBasedIndicator<Double> {

  settable int smoothingPeriod = 14;

  // For first phase

  settable double upSum;

  settable double downSum;

  settable long steps;

  // For second phase

  settable ExponentialMovingAverage up;

  settable ExponentialMovingAverage down;

  settable SimpleMovingAverage postSmoother;

  // RSI value, unsmoothed

  settable double rsi = Double.NaN;

  // RSI value, smoothed

  settable double rsiSmoothed = Double.NaN;

  // RSI values collected as ticker

  gettable TickerSequence rsiHistory = new TickerSequence("RSI");

  gettable TickerSequence rsiSmoothedHistory = new TickerSequence("RSI Smoothed");

  Double value() { ret rsiSmoothed(); }

  // Do we have enough data for a proper value calculation?

  bool complete() {

    ret steps >= length();

  }

  {

    length = 25;

    onCandleAdded((IVF1<TradingCandle>) candle -> {

      var x = candle.move();

      var u = max(x, 0.0);

      var d = neg(min(x, 0.0));

      if (!complete()) {

        upSum += u;

        downSum += d;

      } else {

        if (up == null) {

          up = new ExponentialMovingAverage(length());

          down = new ExponentialMovingAverage(length());

          up.add(upSum/steps);

          down.add(downSum/steps);

        } else {

          up().add(u);

          down().add(d);

        }

        var rs = div(up()!, down()!);

        rsi(100-100/(1+rs));

        long time = candle.endTime().toLong();

        rsiHistory?.addIfPriceChanged(rsi, time);

        if (postSmoother == null)

          postSmoother = new SimpleMovingAverage(smoothingPeriod);

        postSmoother.add(rsi);

        rsiSmoothed(postSmoother!);

        rsiSmoothedHistory?.addIfPriceChanged(rsiSmoothed, time);

      }

      ++steps;

    });

  }

  TickerSequence asTicker(L<TradingCandle> candles) {

    feed(candles);

    ret rsiHistory;

  }

  void reset :: after {

    resetFields(this, "upSum downSum steps up down postSmoother rsi rsiSmoothed rsiHistory rsiSmoothedHistory");

  }

}