/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2022, 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 org.xml.sax.Attributes;
  
  import ch.qos.logback.core.joran.spi.ActionException;
  import ch.qos.logback.core.joran.spi.SaxEventInterpretationContext;
  import ch.qos.logback.core.model.Model;
  
  public abstract class BaseModelAction extends Action {
  
      Model parentModel;
      Model currentModel;
      boolean inError = false;
  
      @Override
      public void begin(SaxEventInterpretationContext saxEventInterpretationContext, String name, Attributes attributes)
              throws ActionException {
          parentModel = null;
          inError = false;
  
          if (!validPreconditions(saxEventInterpretationContext, name, attributes)) {
              inError = true;
              return;
          }
  
          currentModel = buildCurrentModel(saxEventInterpretationContext, name, attributes);
          currentModel.setTag(name);
          if (!saxEventInterpretationContext.isModelStackEmpty()) {
              parentModel = saxEventInterpretationContext.peekModel();
          }
          final int lineNumber = getLineNumber(saxEventInterpretationContext);
          currentModel.setLineNumber(lineNumber);
          saxEventInterpretationContext.pushModel(currentModel);
      }
  
      abstract protected Model buildCurrentModel(SaxEventInterpretationContext interpretationContext, String name,
              Attributes attributes);
  
      /**
       * Validate preconditions of this action.
       * 
       * By default, true is returned. Subclasses should override appropriately.
       * 
       * @param intercon
       * @param name
       * @param attributes
       * @return
       */
      protected boolean validPreconditions(SaxEventInterpretationContext intercon, String name, Attributes attributes) {
          return true;
      }
  
      @Override
      public void body(SaxEventInterpretationContext ec, String body) throws ActionException {
          if(currentModel == null) {
              throw new ActionException("current model is null. Is <configuration> element missing?");
          }
          currentModel.addText(body);
      }
  
      @Override
      public void end(SaxEventInterpretationContext saxEventInterpretationContext, String name) throws ActionException {
          if (inError)
              return;
  
          Model m = saxEventInterpretationContext.peekModel();
  
          if (m != currentModel) {
              addWarn("The object "+ m +"] at the top of the stack differs from the model [" + currentModel.idString()
                      + "] pushed earlier.");
              addWarn("This is wholly unexpected.");
          }
  
          // do not pop nor add to parent if there is no parent
          if (parentModel != null) {
              parentModel.addSubModel(currentModel);
              saxEventInterpretationContext.popModel();
          }
      }
  }