/*
    * #%L
    * wcm.io
    * %%
    * Copyright (C) 2019 wcm.io
    * %%
    * Licensed 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.
   * #L%
   */
  package io.wcm.wcm.ui.granite.pathfield.impl.util;
  
  import java.util.Iterator;
  
  import org.apache.commons.collections4.Predicate;
  import org.apache.commons.collections4.iterators.FilterIterator;
  import org.apache.commons.collections4.iterators.TransformIterator;
  import org.apache.sling.api.resource.Resource;
  import org.apache.sling.api.resource.ResourceWrapper;
  import org.jetbrains.annotations.NotNull;
  
  /**
   * Wraps a resource and filters all children by given predicate.
   */
  public class PredicatedResourceWrapper extends ResourceWrapper {
  
    private final Predicate<Resource> predicate;
  
    /**
     * @param resource Resource
     * @param predicate Predicate
     */
    public PredicatedResourceWrapper(Resource resource, Predicate<Resource> predicate) {
      super(resource);
      this.predicate = predicate;
    }
  
    @Override
    public Resource getChild(@NotNull String relPath) {
      Resource child = super.getChild(relPath);
      if (child == null || !predicate.evaluate(child)) {
        return null;
      }
      return new PredicatedResourceWrapper(child, predicate);
    }
  
    @Override
    @SuppressWarnings("null")
    public Iterator<Resource> listChildren() {
      return new TransformIterator<>(new FilterIterator<>(super.listChildren(), predicate),
          obj -> new PredicatedResourceWrapper(obj, predicate));
    }
  
    @Override
    public boolean hasChildren() {
      if (!super.hasChildren()) {
        return false;
      }
      return listChildren().hasNext();
    }
  
  }