/**
    * This file Copyright (c) 2012-2013 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.jcr.wrapper;
  
  import info.magnolia.jcr.iterator.RangeIteratorImpl;
  import info.magnolia.jcr.util.NodeUtil;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.TreeMap;
  
  import javax.jcr.Node;
  import javax.jcr.NodeIterator;
  import javax.jcr.PathNotFoundException;
  import javax.jcr.Property;
  import javax.jcr.PropertyIterator;
  import javax.jcr.RepositoryException;
  
  import org.apache.commons.lang.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * This wrapper allows extending other nodes (mainly useful to extend configurations). A node can define
   * a property with the name 'extends'. Its value is either an absolute or relative path. The merge is then performed as follows:
   * <ul>
   * <li>properties are merged and values are overwritten
   * <li>sub nodes are merged, the original order is guaranteed, new nodes are added at the end of the list
   * </ul>
   * The mechanism supports multiple inheritances as such:
   * <ul>
   * <li>the node the current node inherits from can again extend a node
   * <li>nodes laying deeper in the hierarchy can extend an other node
   * </ul>
   * 
   * @see {@link InheritanceNodeWrapper} a class supporting content inheritance.
   */
  public class ExtendingNodeWrapper extends ChildWrappingNodeWrapper {
  
      protected static final String EXTENDING_NODE_PROPERTY = "extends";
      protected static final String EXTENDING_NODE_PROPERTY_OVERRIDE = "override";
  
      private static final Logger log = LoggerFactory.getLogger(ExtendingNodeWrapper.class);
  
      /**
       * Are we extending or not?
       */
      private boolean extending;
  
      /**
       * Node that is being extended.
       */
      private Node extendedNode;
  
      /**
       * Default constructor.
       */
      public ExtendingNodeWrapper(Node wrappedNode) {
          this(wrappedNode, false);
      }
  
      /**
       * Call directly for test purposes only.
       */
      public ExtendingNodeWrapper(Node wrappedNode, boolean failOnError) {
         super(wrappedNode);
 
         try {
             final boolean hasExtendingProperty = getWrappedNode().hasProperty(EXTENDING_NODE_PROPERTY);
 
             if (hasExtendingProperty) {
                 extending = true;
 
                 Property extendingNodeProperty = getWrappedNode().getProperty(EXTENDING_NODE_PROPERTY);
 
                 String extendingNodePath = extendingNodeProperty.getString();
 
                 if (StringUtils.isBlank(extendingNodePath) || extendingNodePath.equals(EXTENDING_NODE_PROPERTY_OVERRIDE)) {
                     extending = false;
                 }
 
                 if (extending) {
                     if (isExists(extendingNodePath, getWrappedNode())) {
                         // support multiple inheritance
                         if (extendingNodePath.startsWith("/")) {
                             extendedNode = getWrappedNode().getSession().getNode(extendingNodePath);
                         } else {
                             extendedNode = getWrappedNode().getNode(extendingNodePath);
                         }
                         if (!NodeUtil.isSame(getWrappedNode(), extendedNode)) {
                             extendedNode = wrapIfNeeded(extendedNode);
                         } else {
                             // nodes are the same so we will not extend.
                             extendedNode = null;
                             extending = false;
                             log.error("Node can't self-extend: " + getWrappedNode().getPath());
                         }
                     } else {
                         String message = "Can't find referenced node for value: " + wrapped;
                         log.error(message);
                         extending = false;
                         if (failOnError) {
                             throw new RuntimeException(message);
                         }
                     }
                 }
             }
 
         } catch (RepositoryException e) {
             throw new RuntimeException("Can't wrap node [" + wrapped + "]", e);
         }
     }
 
     /**
      * Does not support the extends property but chains the two nodes directly. Each node is
      * wrapped internally to ensure that each of them support the extends property for themselves.
      */
     protected ExtendingNodeWrapper(Node wrappedNode, Node extendedNode) {
         super(wrapIfNeeded(wrappedNode));
         extending = true;
         try {
             if (getWrappedNode().hasProperty(EXTENDING_NODE_PROPERTY)) {
                 Property extendingNodeProperty = getWrappedNode().getProperty(EXTENDING_NODE_PROPERTY);
 
                 // check if override is not forced
                 extending = !extendingNodeProperty.getString().equals(EXTENDING_NODE_PROPERTY_OVERRIDE);
             }
         } catch (RepositoryException e) {
             throw new RuntimeException("Can't determine extends point for node [" + wrappedNode + "]", e);
         }
         // might extend further more
         this.extendedNode = wrapIfNeeded(extendedNode);
     }
 
     @Override
     public boolean hasNode(String relPath) throws RepositoryException {
         if (getWrappedNode().hasNode(relPath)) {
             return true;
         } else if (extending && extendedNode.hasNode(relPath)) {
             return true;
         } else {
             return false;
         }
     }
 
     @Override
     public Node getNode(String relPath) throws PathNotFoundException, RepositoryException {
         if (getWrappedNode().hasNode(relPath)) {
             return wrapNode(getWrappedNode().getNode(relPath));
         } else if (extending && extendedNode.hasNode(relPath)) {
             return extendedNode.getNode(relPath);
         } else {
             throw new PathNotFoundException("Node does not exists: [" + relPath + "]");
         }
     }
 
     @Override
     public NodeIterator getNodes() throws RepositoryException {
         return this.getNodes("*");
     }
 
     @Override
     public NodeIterator getNodes(String[] nameGlobs) throws RepositoryException {
         return this.getNodes(StringUtils.join(nameGlobs, " | "));
     }
 
     @Override
     public NodeIterator getNodes(String namePattern) throws RepositoryException {
         Collection<Node> children = NodeUtil.getCollectionFromNodeIterator(getWrappedNode().getNodes());
         if (extending) {
 
             Collection<Node> extendedNodeChildren = NodeUtil.getCollectionFromNodeIterator(extendedNode.getNodes());
             Map<String, Node> merged = new LinkedHashMap<String, Node>();
 
             for (Node content : extendedNodeChildren) {
                 merged.put(content.getName(), content);
             }
             for (Node content : children) {
                 merged.put(content.getName(), content);
             }
             return new NodeIteratorImpl(wrapNodes(merged.values()));
         }
         return new NodeIteratorImpl(wrapNodes(children));
     }
 
     @Override
     public boolean hasProperty(String relPath) throws RepositoryException {
         // extending property should be hidden
         if (relPath.equals(EXTENDING_NODE_PROPERTY)) {
             return false;
         } else if (getWrappedNode().hasProperty(relPath)) {
             return true;
         } else if (extending && extendedNode.hasProperty(relPath)) {
             return true;
         } else {
             return false;
         }
     }
 
     @Override
     public Property getProperty(String relPath) throws PathNotFoundException, RepositoryException {
         // extending property should be hidden
         if (relPath.equals(EXTENDING_NODE_PROPERTY)) {
             throw new PathNotFoundException("Cannont access property [" + getWrappedNode().getPath() + "." + relPath + "]");
         } else if (getWrappedNode().hasProperty(relPath)) {
             return getWrappedNode().getProperty(relPath);
         } else if (extending && extendedNode.hasProperty(relPath)) {
             return extendedNode.getProperty(relPath);
         } else {
             throw new RepositoryException("Can't read property from extended node [" + extendedNode + "]");
         }
     }
 
     @Override
     public PropertyIterator getProperties() throws RepositoryException {
         return this.getProperties("*");
     }
 
     @Override
     public PropertyIterator getProperties(String[] nameGlobs) throws RepositoryException {
         return this.getProperties(StringUtils.join(nameGlobs, " | "));
     }
 
     @Override
     public PropertyIterator getProperties(String namePattern) throws RepositoryException {
         Collection<Property> properties = getPropertiesAsList(getWrappedNode(), namePattern);
 
         if (extending) {
             Collection<Property> inheritedProperties = getPropertiesAsList(extendedNode, namePattern);
 
             Map<String, Property> merged = new TreeMap<String, Property>();
 
             for (Property prop : inheritedProperties) {
                 merged.put(prop.getName(), prop);
             }
 
             for (Property prop : properties) {
                 merged.put(prop.getName(), prop);
             }
             return new PropertyIteratorImpl(merged.values());
         }
         return new PropertyIteratorImpl(properties);
     }
 
     @Override
     public Node wrapNode(Node node) {
         // get the same subnode of the extended content
         try {
             if (extending && extendedNode.hasNode(node.getName())) {
                 Node extendedSubNode = extendedNode.getNode(node.getName());
                 return new ExtendingNodeWrapper(node, extendedSubNode);
             }
         } catch (RepositoryException e) {
             throw new RuntimeException("Can't wrap " + node, e);
         }
         return wrapIfNeeded(node);
     }
 
     @Override
     public Node getWrappedNode() {
         if (wrapped instanceof ExtendingNodeWrapper) {
             ExtendingNodeWrapper extendingNodeWrapper = (ExtendingNodeWrapper) wrapped;
             if (!extendingNodeWrapper.extending) {
                 return extendingNodeWrapper.getWrappedNode();
             }
         }
         return wrapped;
     }
 
     @Override
     public void setWrappedNode(Node node) {
         // this wrapper can be used multiple times (multiple inheritance)
         super.wrapped = node;
     }
 
     /**
      * Check if node extends another.
      */
     public boolean isExtending() {
         return extending;
     }
 
     /**
      * Check if node exists.
      */
     private boolean isExists(String nodePath, Node parent) throws RepositoryException {
         if (nodePath.startsWith("/")) {
             return getWrappedNode().getSession().itemExists(nodePath);
         }
         return parent.hasNode(nodePath);
     }
 
     /**
      * Wraps node if needed.
      */
     private static Node wrapIfNeeded(Node node) {
         if (node instanceof ExtendingNodeWrapper) {
             return node;
         }
         return new ExtendingNodeWrapper(node);
     }
 
     private Collection<Node> wrapNodes(Collection<Node> collection) {
         Collection<Node> wrappedNodes = new ArrayList<Node>();
         for (Node node : collection) {
             wrappedNodes.add(wrapNode(node));
         }
         return wrappedNodes;
     }
 
     /**
      * Gets all properties from node and returns them as {@link java.util.List}.
      * Also filters out "extends" property.
      */
     private static List<Property> getPropertiesAsList(Node node, String namePattern) throws RepositoryException {
         List<Property> properties = new ArrayList<Property>();
         PropertyIterator it = node.getProperties(namePattern);
 
         while (it.hasNext()) {
             Property prop = (Property) it.next();
             if (!prop.getName().equals(EXTENDING_NODE_PROPERTY)) {
                 properties.add(prop);
             }
         }
         return properties;
     }
 
     private static class PropertyIteratorImpl extends RangeIteratorImpl<Property> implements PropertyIterator {
 
         public PropertyIteratorImpl(Collection<Property> properties) {
             super(properties);
         }
 
         @Override
         public Property nextProperty() {
             return super.next();
         }
     }
 
     private static class NodeIteratorImpl extends RangeIteratorImpl<Node> implements NodeIterator {
 
         public NodeIteratorImpl(Collection<Node> nodes) {
             super(nodes);
         }
 
         @Override
         public Node nextNode() {
             return super.next();
         }
     }
 
 }