sclass NewWoody {
  transient Map<S, BBRule> rulesByName;
  transient new L<BBRule> badRules;

  Map<S, RuleData> ruleData = ciMap();
  S lastOutput;
  BBRule lastRule, activeRule, gotoRule;
  S prefix = "BB | ";
  
  sclass RuleData {
    int answerIndex;
  }
  
  RuleData ruleData(BBRule rule) {
    ret getOrCreate(ruleData, rule.listName, RuleData.class);
  }

  *() {
    if (!DynamicObject_isLoading())
      rulesByName = indexFieldAsCIMap('listName, bb_allRules());
  }
  
  *(NewWoody w) { initFrom(w); }
  
  void initFrom(NewWoody w) {
    copyFields(w, this, 'rulesByName, 'badRules);
  }
  
  void processInput(S input) {
    lastRule = null;
    lastOutput = null;

    temp tempSetTL(ctxContext_var(), nu(CtxContext, +input));
    new L<BBRule> matching;
    if (nempty(input))
      for (BBRule r : valuesList(rulesByName))
        if (ruleExpressionMatches(r))
          matching.add(r);

    setActiveRule(or(first(matching), activeRule));
    repeat 10 {
      gotoRule = null;
      doRule();
      if (gotoRule == null) break;
      setActiveRule(gotoRule);
    }
  }
  
  void doRule {
    if (activeRule != null)
      if (cic(activeRule.answerMode, 'random)) // TODO: mark seen
        setOutput(random(activeRule.answers));
      else if (cic(activeRule.answerMode, 'switch)) {
        for (S s : activeRule.answers) {
          LS l = splitAtDoubleArrow(s);
          if (l(l) == 2 && print(first(l), ctxEvalCondition(first(l)))) {
            setOutput(second(l));
            break;
          }
        }
      } else {
        // loop
        RuleData rd = ruleData(activeRule);
        setOutput(get(activeRule.answers,
          rd.answerIndex %= max(1, l(activeRule.answers))));
        ++rd.answerIndex;
      }
  }

  bool ruleExpressionMatches(BBRule r) {  
    if (empty(r.expression)) false;
    try {
      ret ctxEvalCondition(r.expression);
    } catch print e {
      badRules.add(r);
      rulesByName.remove(r.listName);
      false;
    }
  }
  
  L<BBRule> listsMatchingInput(S input) {
    temp tempSetTL(ctxContext_var(), nu(CtxContext, +input));
    ret [BBRule r : valuesList(rulesByName) | ruleExpressionMatches(r)];
  }
  
  void setOutput(S s) {
    new Matches m;
    if (swic_trim(trim(lastLine(s)), "goto:", m)) {
      S ruleName = prefix + m.rest();
      gotoRule = rulesByName.get(ruleName);
      print("Goto: " + ruleName + " (" + yesNo(gotoRule != null) + ")");
      s = dropLastLine(s);
    }
    lastOutput = appendSpaceIfNempty(lastOutput) + s;
  }
  
  void setActiveRule(BBRule rule) {
    activeRule = lastRule = or(rule, activeRule);
  }
}