/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  package org.apache.myfaces.tobago.facelets;
  
  import org.apache.myfaces.tobago.event.TabChangeListener;
  import org.apache.myfaces.tobago.event.TabChangeSource;
  import org.apache.myfaces.tobago.event.ValueExpressionTabChangeListener;
  
  import javax.el.ValueExpression;
  import javax.faces.component.UIComponent;
  import javax.faces.view.facelets.FaceletContext;
  import javax.faces.view.facelets.TagAttribute;
  import javax.faces.view.facelets.TagAttributeException;
  import javax.faces.view.facelets.TagConfig;
  import javax.faces.view.facelets.TagException;
  import javax.faces.view.facelets.TagHandler;
  import java.io.IOException;
  
  public class TabChangeListenerHandler extends TagHandler {
  
    private Class listenerType;
  
    private final TagAttribute type;
  
    private final TagAttribute binding;
  
  
    public TabChangeListenerHandler(final TagConfig config) {
      super(config);
      binding = getAttribute("binding");
      type = getAttribute("type");
      if (type != null) {
        if (!type.isLiteral()) {
          throw new TagAttributeException(tag, type, "Must be literal");
        }
        try {
          this.listenerType = Class.forName(type.getValue());
        } catch (final Exception e) {
          throw new TagAttributeException(tag, type, e);
        }
      }
    }
  
    @Override
    public void apply(final FaceletContext faceletContext, final UIComponent parent) throws IOException {
      if (parent instanceof TabChangeSource) {
        // only process if parent was just created
        if (parent.getParent() == null) {
          final TabChangeSource changeSource = (TabChangeSource) parent;
          TabChangeListener listener = null;
          ValueExpression valueExpression = null;
          if (binding != null) {
            valueExpression = binding.getValueExpression(faceletContext, TabChangeListener.class);
            listener = (TabChangeListener) valueExpression.getValue(faceletContext);
          }
          if (listener == null) {
            try {
              listener = (TabChangeListener) listenerType.newInstance();
            } catch (final Exception e) {
              throw new TagAttributeException(tag, type, e);
            }
            if (valueExpression != null) {
              valueExpression.setValue(faceletContext, listener);
            }
          }
          if (valueExpression != null) {
            changeSource.addTabChangeListener(
                new ValueExpressionTabChangeListener(type.getValue(), valueExpression));
          } else {
            changeSource.addTabChangeListener(listener);
          }
        }
      } else {
        throw new TagException(tag, "Parent is not of type TabChangeSource, type is: " + parent);
      }
    }
  }