/**
    * 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 ch.qos.logback.core.joran.spi.InterpretationContext;
  import ch.qos.logback.core.joran.spi.ActionException;
  import ch.qos.logback.core.util.OptionHelper;
  import ch.qos.logback.core.spi.PropertyDefiner;
  import org.xml.sax.Attributes;
  
  /**
   * Instantiate class for define property value. Get future property name and
   * property definer class from attributes. Some property definer properties
   * could be used. After defining put new property to context.
   * 
   * @author Aleksey Didik
   */
  public class DefinePropertyAction extends Action {
  
    String propertyName;
    PropertyDefiner definer;
    boolean inError;
  
    public void begin(InterpretationContext ec, String localName,
        Attributes attributes) throws ActionException {
      // reset variables
      propertyName = null;
      definer = null;
      inError = false;
  
      // read future property name
      propertyName = attributes.getValue(NAME_ATTRIBUTE);
      if (OptionHelper.isEmpty(propertyName)) {
        addError("Missing property name for property definer. Near [" + localName
            + "] line " + getLineNumber(ec));
        inError = true;
        return;
      }
  
      // read property definer class name
      String className = attributes.getValue(CLASS_ATTRIBUTE);
      if (OptionHelper.isEmpty(className)) {
        addError("Missing class name for property definer. Near [" + localName
            + "] line " + getLineNumber(ec));
        inError = true;
        return;
      }
  
      // try to instantiate property definer
      try {
        addInfo("About to instantiate property definer of type [" + className
            + "]");
        definer = (PropertyDefiner) OptionHelper.instantiateByClassName(
            className, PropertyDefiner.class, context);
        definer.setContext(context);
        ec.pushObject(definer);
      } catch (Exception oops) {
        inError = true;
        addError("Could not create an PropertyDefiner of type [" + className
            + "].", oops);
        throw new ActionException(oops);
      }
    }
  
    /**
     * Now property definer is initialized by all properties and we can put
     * property value to context
     */
    public void end(InterpretationContext ec, String name) {
      if (inError) {
        return;
      }
  
      Object o = ec.peekObject();
  
      if (o != definer) {
        addWarn("The object at the of the stack is not the property definer for property named ["
            + propertyName + "] pushed earlier.");
      } else {
        addInfo("Popping property definer for property named [" + propertyName
            + "] from the object stack");
        ec.popObject();
        // let's put defined property and value to context but only if it is
        // not null
        String propertyValue = definer.getPropertyValue();
        if(propertyValue != null) {
          context.putProperty(propertyName, propertyValue);
        }
     }
   }
 }