/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v1.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package ch.qos.logback.core.joran.action;
  
  import java.util.Map;
  
  import org.xml.sax.Attributes;
  
  import ch.qos.logback.core.CoreConstants;
  import ch.qos.logback.core.boolex.EventEvaluator;
  import ch.qos.logback.core.joran.spi.InterpretationContext;
  import ch.qos.logback.core.spi.LifeCycle;
  import ch.qos.logback.core.util.OptionHelper;
  
  abstract public class AbstractEventEvaluatorAction extends Action {
  
    EventEvaluator evaluator;
    boolean inError = false;
  
    /**
     * Instantiates an evaluator of the given class and sets its name.
     */
    public void begin(InterpretationContext ec, String name, Attributes attributes) {
      // Let us forget about previous errors (in this instance)
      inError = false;
      evaluator = null;
  
      String className = attributes.getValue(CLASS_ATTRIBUTE);
      if (OptionHelper.isEmpty(className)) {
        className = defaultClassName();
        addInfo("Assuming default evaluator class [" + className + "]");
      }
  
      if (OptionHelper.isEmpty(className)) {
        className = defaultClassName();
        inError = true;
        addError("Mandatory \"" + CLASS_ATTRIBUTE
            + "\" attribute not set for <evaluator>");
        return;
      }
  
      String evaluatorName = attributes.getValue(Action.NAME_ATTRIBUTE);
      if (OptionHelper.isEmpty(evaluatorName)) {
        inError = true;
        addError("Mandatory \"" + NAME_ATTRIBUTE
            + "\" attribute not set for <evaluator>");
        return;
      }
      try {
        evaluator = (EventEvaluator) OptionHelper.instantiateByClassName(
            className, ch.qos.logback.core.boolex.EventEvaluator.class, context);
  
        evaluator.setContext(this.context);
        evaluator.setName(evaluatorName);
  
        ec.pushObject(evaluator);
        addInfo("Adding evaluator named [" + evaluatorName
            + "] to the object stack");
  
      } catch (Exception oops) {
        inError = true;
        addError("Could not create evaluator of type " + className + "].", oops);
      }
    }
  
    /**
     * Returns a default class name in case the class attribute is not specified
     * 
     * @return
     */
    abstract protected String defaultClassName();
  
    /**
     * Once the children elements are also parsed, now is the time to activate the
     * evaluator options.
     */
    @SuppressWarnings("unchecked")
    public void end(InterpretationContext ec, String e) {
      if (inError) {
        return;
      }
  
      if (evaluator instanceof LifeCycle) {
        ((LifeCycle) evaluator).start();
        addInfo("Starting evaluator named [" + evaluator.getName() + "]");
      }
  
      Object o = ec.peekObject();
 
     if (o != evaluator) {
       addWarn("The object on the top the of the stack is not the evaluator pushed earlier.");
     } else {
       ec.popObject();
 
       try {
         Map<String, EventEvaluator> evaluatorMap = (Map<String, EventEvaluator>) context
             .getObject(CoreConstants.EVALUATOR_MAP);
         if(evaluatorMap == null) {
           addError("Could not find EvaluatorMap");
         } else {
           evaluatorMap.put(evaluator.getName(), evaluator);
         }
       } catch (Exception ex) {
         addError("Could not set evaluator named [" + evaluator + "].", ex);
       }
     }
   }
 
   public void finish(InterpretationContext ec) {
   }
 }