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

  Map<S, RuleData> ruleData = ciMap();
  S lastOutput;
  BBRule activeRule;
  
  sclass RuleData {
    int answerIndex;
  }
  
  RuleData ruleData(BBRule rule) {
    ret getOrCreate(ruleData, rule.listName, RuleData);
  }

  *() {
    rulesByName = indexFieldAsCIMap('listName, bb_allRules());
  }
  
  *(NewWoody w) {
    copyFields(w, this, 'rulesByName, 'badRules);
  }
  
  void processInput(S input) {
    temp tempSetTL(ctxContext_var(), nu(CtxContext, +input));
    new L<BBRule> matching;
    for (BBRule r : valuesList(rulesByName))
      if (ruleExpressionMatches(r))
        matching.add(r);

    lastOutput = null;
    activeRule = first(matching);
    if (activeRule != null)
      if (cic(activeRule.answerMode, 'random))
        lastOutput = random(activeRule.answers);
      else {
        RuleData rd = ruleData(activeRule);
        lastOutput = get(activeRule.answers,
          rd.answerIndex = (rd.answerIndex+1) % l(activeRule.answers));
      }
  }

  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)];
  }
}