/**
    * Copyright 2010-2014 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.common.util.tree;
  
  import static com.google.common.collect.Lists.newArrayList;
  import static com.google.common.collect.Lists.reverse;
  import static com.google.common.collect.Lists.transform;
  import static org.kuali.common.util.base.Precondition.checkNotNull;
  
  import java.util.List;
  
  public abstract class AbstractNode<T> implements Node<T> {
  
  	/**
  	 * Return true if this is the root node (ie it has no parent)
  	 */
  	@Override
  	public boolean isRoot() {
  		return !getParent().isPresent();
  	}
  
  	/**
  	 * Return true if this is a leaf node (ie it has no children)
  	 */
  	@Override
  	public boolean isLeaf() {
  		return getChildren().isEmpty();
  	}
  
  	/**
  	 * Returns the number of levels above this node. The distance from the root to this node. If this node is the root, returns 0.
  	 */
  	@Override
  	public int getLevel() {
  		int level = 0;
  		Node<T> ancestor = this;
  		while (ancestor.getParent().isPresent()) {
  			ancestor = ancestor.getParent().get();
  			level++;
  		}
  		return level;
  	}
  
  	/**
  	 * Returns the path from the root, to get to this node. The last element in the path is this node.
  	 */
  	@Override
  	public List<Node<T>> getPath() {
  		Node<T> ancestor = this;
  		List<Node<T>> list = newArrayList();
  		list.add(ancestor);
  		while (ancestor.getParent().isPresent()) {
  			ancestor = ancestor.getParent().get();
  			list.add(ancestor);
  		}
  		return reverse(list);
  	}
  
  	/**
  	 * Returns the node elements in the path from the root, to get to this node. The last entry is the element from this node
  	 */
  	@Override
  	public List<T> getElementPath() {
  		return transform(getPath(), new NodeElementFunction<T>());
  	}
  
  	/**
  	 * Return true if this node is a child of parent
  	 */
  	@Override
  	public boolean isChild(Node<T> parent) {
  		checkNotNull(parent, "parent");
  		return parent.getChildren().contains(this);
  	}
  
  	/**
  	 * Return true if this node is a parent of child
  	 */
  	@Override
  	public boolean isParent(Node<T> child) {
  		checkNotNull(child, "child");
  		return getChildren().contains(child);
  	}
  
  	/**
  	 * Return true if this node descends from parent OR is parent
 	 */
 	@Override
 	public boolean isAncestor(Node<T> parent) {
 		checkNotNull(parent, "parent");
 		return getPath().contains(parent);
 	}
 
 }