package org.apache.archiva.xml;
   
   /*
    * 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.
   */
  
  import org.apache.commons.lang.StringUtils;
  import org.dom4j.Attribute;
  import org.dom4j.Document;
  import org.dom4j.DocumentException;
  import org.dom4j.Element;
  import org.dom4j.Namespace;
  import org.dom4j.Node;
  import org.dom4j.QName;
  import org.dom4j.XPath;
  import org.dom4j.io.SAXReader;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.nio.charset.Charset;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  /**
   * XMLReader - a set of common xml utility methods for reading content out of an xml file.
   */
  public class XMLReader
  {
      private URL xmlUrl;
  
      private String documentType;
  
      private Document document;
  
      private Map<String, String> namespaceMap = new HashMap<>();
  
      public XMLReader( String type, File file )
          throws XMLException
      {
          if ( !file.exists() )
          {
              throw new XMLException( "file does not exist: " + file.getAbsolutePath() );
          }
  
          if ( !file.isFile() )
          {
              throw new XMLException( "path is not a file: " + file.getAbsolutePath() );
          }
  
          if ( !file.canRead() )
          {
              throw new XMLException( "Cannot read xml file due to permissions: " + file.getAbsolutePath() );
          }
  
          try
          {
              init( type, file.toURL() );
          }
          catch ( MalformedURLException e )
          {
              throw new XMLException( "Unable to translate file " + file + " to URL: " + e.getMessage(), e );
          }
      }
  
      public XMLReader( String type, URL url )
          throws XMLException
      {
          init( type, url );
      }
  
      private void init( String type, URL url )
          throws XMLException
      {
          this.documentType = type;
          this.xmlUrl = url;
  
          SAXReader reader = new SAXReader();
 
         try (InputStream in = url.openStream())
         {
             InputStreamReader inReader = new InputStreamReader( in, Charset.forName( "UTF-8" ) );
             LatinEntityResolutionReader latinReader = new LatinEntityResolutionReader( inReader );
             this.document = reader.read( latinReader );
         }
         catch ( DocumentException e )
         {
             throw new XMLException( "Unable to parse " + documentType + " xml " + xmlUrl + ": " + e.getMessage(), e );
         }
         catch ( IOException e )
         {
             throw new XMLException( "Unable to open stream to " + url + ": " + e.getMessage(), e );
         }
 
         Element root = this.document.getRootElement();
         if ( root == null )
         {
             throw new XMLException( "Invalid " + documentType + " xml: root element is null." );
         }
 
         if ( !StringUtils.equals( root.getName(), documentType ) )
         {
             throw new XMLException(
                 "Invalid " + documentType + " xml: Unexpected root element <" + root.getName() + ">, expected <"
                     + documentType + ">" );
         }
     }
 
     public String getDefaultNamespaceURI()
     {
         Namespace namespace = this.document.getRootElement().getNamespace();
         return namespace.getURI();
     }
 
     public void addNamespaceMapping( String elementName, String uri )
     {
         this.namespaceMap.put( elementName, uri );
     }
 
     public Element getElement( String xpathExpr )
         throws XMLException
     {
         XPath xpath = createXPath( xpathExpr );
         Object evaluated = xpath.selectSingleNode( document );
 
         if ( evaluated == null )
         {
             return null;
         }
 
         if ( evaluated instanceof Element )
         {
             return (Element) evaluated;
         }
         else
         {
             // Unknown evaluated type.
             throw new XMLException( ".getElement( Expr: " + xpathExpr + " ) resulted in non-Element type -> ("
                                         + evaluated.getClass().getName() + ") " + evaluated );
         }
     }
 
     private XPath createXPath( String xpathExpr )
     {
         XPath xpath = document.createXPath( xpathExpr );
         if ( !this.namespaceMap.isEmpty() )
         {
             xpath.setNamespaceURIs( this.namespaceMap );
         }
         return xpath;
     }
 
     public boolean hasElement( String xpathExpr )
         throws XMLException
     {
         XPath xpath = createXPath( xpathExpr );
         Object evaluated = xpath.selectSingleNode( document );
 
         if ( evaluated == null )
         {
             return false;
         }
 
         return true;
     }
 
     /**
      * Remove namespaces from entire document.
      */
     public void removeNamespaces()
     {
         removeNamespaces( this.document.getRootElement() );
     }
 
     /**
      * Remove namespaces from element recursively.
      */
     @SuppressWarnings("unchecked")
     public void removeNamespaces( Element elem )
     {
         elem.setQName( QName.get( elem.getName(), Namespace.NO_NAMESPACE, elem.getQualifiedName() ) );
 
         Node n;
 
         Iterator<Node> it = elem.elementIterator();
         while ( it.hasNext() )
         {
             n = it.next();
 
             switch ( n.getNodeType() )
             {
                 case Node.ATTRIBUTE_NODE:
                     ( (Attribute) n ).setNamespace( Namespace.NO_NAMESPACE );
                     break;
                 case Node.ELEMENT_NODE:
                     removeNamespaces( (Element) n );
                     break;
             }
         }
     }
 
     public String getElementText( Node context, String xpathExpr )
         throws XMLException
     {
         XPath xpath = createXPath( xpathExpr );
         Object evaluated = xpath.selectSingleNode( context );
 
         if ( evaluated == null )
         {
             return null;
         }
 
         if ( evaluated instanceof Element )
         {
             Element evalElem = (Element) evaluated;
             return evalElem.getTextTrim();
         }
         else
         {
             // Unknown evaluated type.
             throw new XMLException( ".getElementText( Node, Expr: " + xpathExpr + " ) resulted in non-Element type -> ("
                                         + evaluated.getClass().getName() + ") " + evaluated );
         }
     }
 
     public String getElementText( String xpathExpr )
         throws XMLException
     {
         XPath xpath = createXPath( xpathExpr );
         Object evaluated = xpath.selectSingleNode( document );
 
         if ( evaluated == null )
         {
             return null;
         }
 
         if ( evaluated instanceof Element )
         {
             Element evalElem = (Element) evaluated;
             return evalElem.getTextTrim();
         }
         else
         {
             // Unknown evaluated type.
             throw new XMLException( ".getElementText( Expr: " + xpathExpr + " ) resulted in non-Element type -> ("
                                         + evaluated.getClass().getName() + ") " + evaluated );
         }
     }
 
     @SuppressWarnings("unchecked")
     public List<Element> getElementList( String xpathExpr )
         throws XMLException
     {
         XPath xpath = createXPath( xpathExpr );
         Object evaluated = xpath.evaluate( document );
 
         if ( evaluated == null )
         {
             return null;
         }
 
         /* The xpath.evaluate(Context) method can return:
          *   1) A Collection or List of dom4j Nodes. 
          *   2) A single dom4j Node.
          */
 
         if ( evaluated instanceof List )
         {
             return (List<Element>) evaluated;
         }
         else if ( evaluated instanceof Node )
         {
             List<Element> ret = new ArrayList<>();
             ret.add( (Element) evaluated );
             return ret;
         }
         else
         {
             // Unknown evaluated type.
             throw new XMLException( ".getElementList( Expr: " + xpathExpr + " ) resulted in non-List type -> ("
                                         + evaluated.getClass().getName() + ") " + evaluated );
         }
     }
 
     public List<String> getElementListText( String xpathExpr )
         throws XMLException
     {
         List<Element> elemList = getElementList( xpathExpr );
         if ( elemList == null )
         {
             return null;
         }
 
         List<String> ret = new ArrayList<>();
         for ( Iterator<Element> iter = elemList.iterator(); iter.hasNext(); )
         {
             Element listelem = iter.next();
             ret.add( listelem.getTextTrim() );
         }
         return ret;
     }
 
 }