/*
    * 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.maven.internal.xml;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.maven.api.xml.XmlNode;
  import org.codehaus.plexus.configuration.PlexusConfiguration;
  
  /**
   * A PlexusConfiguration implementation that wraps an XmlNode instead of copying its entire hierarchy.
   * This provides better performance by avoiding deep copying of the XML structure.
   *
   * <p>This implementation supports both read and write operations. When write operations are performed,
   * new XmlNode instances are created to maintain immutability, and internal caches are cleared.</p>
   */
  public class XmlPlexusConfiguration implements PlexusConfiguration {
      private XmlNode xmlNode;
      private PlexusConfiguration[] childrenCache;
  
      public static PlexusConfiguration toPlexusConfiguration(XmlNode node) {
          return new XmlPlexusConfiguration(node);
      }
  
      public XmlPlexusConfiguration(XmlNode xmlNode) {
          this.xmlNode = xmlNode;
      }
  
      /**
       * Clears the internal cache when the XML structure is modified.
       */
      private synchronized void clearCache() {
          this.childrenCache = null;
      }
  
      /**
       * Converts a PlexusConfiguration to an XmlNode.
       */
      private XmlNode convertToXmlNode(PlexusConfiguration config) {
          // Convert attributes
          Map<String, String> attributes = new HashMap<>();
          for (String attrName : config.getAttributeNames()) {
              String attrValue = config.getAttribute(attrName);
              if (attrValue != null) {
                  attributes.put(attrName, attrValue);
              }
          }
  
          // Convert children
          List<XmlNode> children = new ArrayList<>();
          for (PlexusConfiguration child : config.getChildren()) {
              children.add(convertToXmlNode(child));
          }
  
          return XmlNode.newInstance(config.getName(), config.getValue(), attributes, children, null);
      }
  
      @Override
      public String getName() {
          return xmlNode.name();
      }
  
      public synchronized void setName(String name) {
          this.xmlNode = XmlNode.newBuilder()
                  .name(name)
                  .value(xmlNode.value())
                  .attributes(xmlNode.attributes())
                  .children(xmlNode.children())
                  .namespaceUri(xmlNode.namespaceUri())
                  .prefix(xmlNode.prefix())
                  .inputLocation(xmlNode.inputLocation())
                  .build();
          clearCache();
      }
  
      public String getValue() {
          return xmlNode.value();
      }
  
      public String getValue(String defaultValue) {
         String value = xmlNode.value();
         return value != null ? value : defaultValue;
     }
 
     public synchronized void setValue(String value) {
         this.xmlNode = XmlNode.newBuilder()
                 .name(xmlNode.name())
                 .value(value)
                 .attributes(xmlNode.attributes())
                 .children(xmlNode.children())
                 .namespaceUri(xmlNode.namespaceUri())
                 .prefix(xmlNode.prefix())
                 .inputLocation(xmlNode.inputLocation())
                 .build();
         clearCache();
     }
 
     public PlexusConfiguration setValueAndGetSelf(String value) {
         setValue(value);
         return this;
     }
 
     public synchronized void setAttribute(String name, String value) {
         Map<String, String> newAttributes = new HashMap<>(xmlNode.attributes());
         if (value == null) {
             newAttributes.remove(name);
         } else {
             newAttributes.put(name, value);
         }
         this.xmlNode = XmlNode.newBuilder()
                 .name(xmlNode.name())
                 .value(xmlNode.value())
                 .attributes(newAttributes)
                 .children(xmlNode.children())
                 .namespaceUri(xmlNode.namespaceUri())
                 .prefix(xmlNode.prefix())
                 .inputLocation(xmlNode.inputLocation())
                 .build();
         clearCache();
     }
 
     public String[] getAttributeNames() {
         return xmlNode.attributes().keySet().toArray(new String[0]);
     }
 
     public String getAttribute(String paramName) {
         return xmlNode.attribute(paramName);
     }
 
     public String getAttribute(String name, String defaultValue) {
         String value = xmlNode.attribute(name);
         return value != null ? value : defaultValue;
     }
 
     public PlexusConfiguration getChild(String child) {
         XmlNode childNode = xmlNode.child(child);
         if (childNode != null) {
             return new XmlPlexusConfiguration(childNode);
         } else {
             // Return an empty configuration object to match DefaultPlexusConfiguration behavior
             XmlNode emptyNode = XmlNode.newInstance(child, null, null, null, null);
             return new XmlPlexusConfiguration(emptyNode);
         }
     }
 
     public PlexusConfiguration getChild(int i) {
         List<XmlNode> children = xmlNode.children();
         if (i >= 0 && i < children.size()) {
             return new XmlPlexusConfiguration(children.get(i));
         }
         return null;
     }
 
     public synchronized PlexusConfiguration getChild(String child, boolean createChild) {
         XmlNode childNode = xmlNode.child(child);
         if (childNode == null) {
             if (createChild) {
                 // Create a new child node
                 XmlNode newChild = XmlNode.newInstance(child);
                 List<XmlNode> newChildren = new ArrayList<>(xmlNode.children());
                 newChildren.add(newChild);
 
                 this.xmlNode = XmlNode.newBuilder()
                         .name(xmlNode.name())
                         .value(xmlNode.value())
                         .attributes(xmlNode.attributes())
                         .children(newChildren)
                         .namespaceUri(xmlNode.namespaceUri())
                         .prefix(xmlNode.prefix())
                         .inputLocation(xmlNode.inputLocation())
                         .build();
                 clearCache();
 
                 return new XmlPlexusConfiguration(newChild);
             } else {
                 return null; // Return null when child doesn't exist and createChild=false
             }
         }
         return new XmlPlexusConfiguration(childNode);
     }
 
     public synchronized PlexusConfiguration[] getChildren() {
         if (childrenCache == null) {
             List<XmlNode> children = xmlNode.children();
             childrenCache = new PlexusConfiguration[children.size()];
             for (int i = 0; i < children.size(); i++) {
                 childrenCache[i] = new XmlPlexusConfiguration(children.get(i));
             }
         }
         return childrenCache.clone();
     }
 
     public PlexusConfiguration[] getChildren(String name) {
         List<PlexusConfiguration> result = new ArrayList<>();
         for (XmlNode child : xmlNode.children()) {
             if (name.equals(child.name())) {
                 result.add(new XmlPlexusConfiguration(child));
             }
         }
         return result.toArray(new PlexusConfiguration[0]);
     }
 
     public synchronized void addChild(PlexusConfiguration configuration) {
         // Convert PlexusConfiguration to XmlNode
         XmlNode newChild = convertToXmlNode(configuration);
         List<XmlNode> newChildren = new ArrayList<>(xmlNode.children());
         newChildren.add(newChild);
 
         this.xmlNode = XmlNode.newBuilder()
                 .name(xmlNode.name())
                 .value(xmlNode.value())
                 .attributes(xmlNode.attributes())
                 .children(newChildren)
                 .namespaceUri(xmlNode.namespaceUri())
                 .prefix(xmlNode.prefix())
                 .inputLocation(xmlNode.inputLocation())
                 .build();
         clearCache();
     }
 
     public synchronized PlexusConfiguration addChild(String name) {
         XmlNode newChild = XmlNode.newInstance(name);
         List<XmlNode> newChildren = new ArrayList<>(xmlNode.children());
         newChildren.add(newChild);
 
         this.xmlNode = XmlNode.newBuilder()
                 .name(xmlNode.name())
                 .value(xmlNode.value())
                 .attributes(xmlNode.attributes())
                 .children(newChildren)
                 .namespaceUri(xmlNode.namespaceUri())
                 .prefix(xmlNode.prefix())
                 .inputLocation(xmlNode.inputLocation())
                 .build();
         clearCache();
 
         return new XmlPlexusConfiguration(newChild);
     }
 
     public synchronized PlexusConfiguration addChild(String name, String value) {
         XmlNode newChild = XmlNode.newInstance(name, value);
         List<XmlNode> newChildren = new ArrayList<>(xmlNode.children());
         newChildren.add(newChild);
 
         this.xmlNode = XmlNode.newBuilder()
                 .name(xmlNode.name())
                 .value(xmlNode.value())
                 .attributes(xmlNode.attributes())
                 .children(newChildren)
                 .namespaceUri(xmlNode.namespaceUri())
                 .prefix(xmlNode.prefix())
                 .inputLocation(xmlNode.inputLocation())
                 .build();
         clearCache();
 
         return new XmlPlexusConfiguration(newChild);
     }
 
     public int getChildCount() {
         return xmlNode.children().size();
     }
 
     public String toString() {
         final StringBuilder buf = new StringBuilder().append('<').append(getName());
         for (final String a : getAttributeNames()) {
             buf.append(' ').append(a).append("=\"").append(getAttribute(a)).append('"');
         }
         if (getChildCount() > 0) {
             buf.append('>');
             for (int i = 0, size = getChildCount(); i < size; i++) {
                 buf.append(getChild(i));
             }
             buf.append("</").append(getName()).append('>');
         } else if (null != getValue()) {
             buf.append('>').append(getValue()).append("</").append(getName()).append('>');
         } else {
             buf.append("/>");
         }
         return buf.append('\n').toString();
     }
 }