concept Chaser extends G22TradingStrategy {
  // Juicer parameters
  
  settable double maxLoss = 0.6;
  settable double pullback = 0.4;
  
  // internal
  
  persistable srecord Juicer(double maxLoss, double pullback) {}
  
  persistable class Position extends G22TradingStrategy.Position {
    settable Juicer juicer;
  }
  
  Position openPosition(int direction) {
    if (nempty(openPositions())) {
      log("Not opening a second position");
      null;
    }
    
    new Position p;
    p.juicer(new Juicer(maxLoss, pullback));
    ret openPosition(p, direction);
  }

  void start {
    if (started()) fail("Already started");
    if (currentPrice() == 0)
      ret with primed(true);
    
    // Save starting price, create price cells & digitizer
    
    startingPrice = currentPrice();
    var priceCells = makePriceCells(startingPrice);
    digitizer = new PriceDigitizer2(priceCells);
    digitizer.verbose(verbose);

    log("Starting CHASER at " + startingPrice + " +/- " + cellSize);
  }
  
  void price(double price) {
    if (currentPrice == price) ret;
    currentPrice = price;
    
    if (!started()) {
      if (primed) {
        primed(false);
        start();
      }
      ret;
    }
    
    digitizer.digitize(price);
    direction = sign(digitizedPrice()-lastDigitizedPrice());
    
    nextStep();

    if (started())
      step();
      
    print(this);
  }
  
  swappable void step {
    // Find positions to close
    
    L<G22TradingStrategy.Position> toClose = new L;
    /*for (p : p.juicer.closeReasons(p)) {
      cast p to Position;
      p.closeReason("WIN");
      log("Closing winner position at " + currentPrice + " (" + p1 + " -> " + p2 + "): " + p);
      toClose.add(p);
    }*/
    
    double p1 = lastDigitizedPrice();
    double p2 = digitizedPrice();
    direction = sign(p2-p1);
    if (direction == 0) ret;
    
    closePositions(toClose);

    // TODO: open new position

    afterStep();
  }
  
  S baseToString() {
    ret colonCombine(
      _conceptID() == 0 ? "" : "Strategy " + _conceptID(),
      "Chaser");
  }
  
  // Chaser.toString
  toString { ret baseToString(); } 
  
  Position openShort() { ret openPosition(-1); }
  Position openLong() { ret openPosition(1); }
}