/*
    * Copyright 2005 Philipp Erlacher
    *
    * 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.
   */
  package org.exolab.castor.xml.parsing;
  
  import org.apache.commons.lang3.StringUtils;
  import org.exolab.castor.xml.AttributeSet;
  import org.exolab.castor.xml.util.AttributeSetImpl;
  import org.xml.sax.AttributeList;
  import org.xml.sax.Attributes;
  import org.xml.sax.SAXException;
  
  /**
   * A helper class that takes SAX v1 AttributeList or SAX v2 attributes and converts those into
   * Castor's internal {@link AttributeSet} representation.
   * 
   * @author <a href="mailto:philipp DOT erlacher AT gmail DOT com">Philipp Erlacher</a>
   * 
   * @since 1.3.2
   */
  public class AttributeSetBuilder {
  
    /**
     * The built-in XML prefix used for xml:space, xml:lang and, as the XML 1.0 Namespaces document
     * specifies, are reserved for use by XML and XML related specs.
     **/
    private static final String XML_PREFIX = "xml";
  
    /**
     * Attribute name for default namespace declaration
     **/
    private static final String XMLNS = "xmlns";
  
    /**
     * Attribute prefix for prefixed namespace declaration.
     **/
    private final static String XMLNS_PREFIX = "xmlns:";
  
    /**
     * Length of the XMLNS prefix.
     */
    private final static int XMLNS_PREFIX_LENGTH = XMLNS_PREFIX.length();
  
    /**
     * Tool class to deal with XML name spaces.
     */
    private NamespaceHandling _namespaceHandling = null;
  
    /**
     * Creates an instance of this class.
     * 
     * @param namespaceHandling Instance of a tool class to handle XML name spaces.
     */
    public AttributeSetBuilder(NamespaceHandling namespaceHandling) {
      super();
      _namespaceHandling = namespaceHandling;
    }
  
    /**
     * Prepares a reusable {@link AttributeSet} object instance.
     * 
     * @param atts Attributes to determine the length of the reusable attribute object, can be null
     */
    private AttributeSetImpl prepareAttributeSetImpl(Attributes atts) {
      if (atts != null) {
        return new AttributeSetImpl(atts.getLength());
      }
      return new AttributeSetImpl();
    }
  
    /**
     * Processes the attributes and XML name space declarations found in the given {@link Attributes}
     * instance. XML namespace declarations are added to the set of name spaces in scope.
     * 
     * @return AttributeSet,
     * @throws SAXException If a name space associated with the prefix could not be resolved.
     */
    public AttributeSet getAttributeSet(Attributes atts) throws SAXException {
      AttributeSetImpl attributeSet = prepareAttributeSetImpl(atts);
      return processAttributes(atts, attributeSet);
    }
  
    /**
     * Processes the attributes and XML name space declarations found in the given SAX Attributes. The
     * global {@link AttributeSet} is cleared and updated with the attributes. XML name space
     * declarations are added to the set of name spaces in scope.
     * 
     * @param atts the Attributes to process (can be null).
     **/
   private AttributeSet processAttributes(Attributes atts, AttributeSetImpl attributeSet) {
     // -- process attributes
 
     if (atts == null || atts.getLength() == 0) {
       return attributeSet;
     }
 
     boolean hasQNameAtts = false;
     // -- look for any potential namespace declarations
     // -- in case namespace processing was disable
     // -- on the parser
     for (int i = 0; i < atts.getLength(); i++) {
       String attName = atts.getQName(i);
       if (StringUtils.isNotEmpty(attName)) {
         if (!attName.equals(XMLNS) && !attName.startsWith(XMLNS_PREFIX)) {
           // -- check for prefix
           if (attName.indexOf(':') < 0) {
             attributeSet.setAttribute(attName, atts.getValue(i), atts.getURI(i));
           } else
             hasQNameAtts = true;
         }
       } else {
         // -- if attName is null or empty, just process as a normal
         // -- attribute
         attName = atts.getLocalName(i);
         if (!XMLNS.equals(attName)) {
           attributeSet.setAttribute(attName, atts.getValue(i), atts.getURI(i));
         }
       }
     }
 
     // return if there are no qualified name attributes
     if (!hasQNameAtts) {
       return attributeSet;
     }
     // -- if we found any qName-only atts, process those
     for (int i = 0; i < atts.getLength(); i++) {
       String attName = atts.getQName(i);
       if (StringUtils.isNotEmpty(attName)) {
         // -- process any non-namespace qName atts
         if ((!attName.equals(XMLNS)) && (!attName.startsWith(XMLNS_PREFIX))) {
           int idx = attName.indexOf(':');
           if (idx >= 0) {
             String prefix = attName.substring(0, idx);
             attName = attName.substring(idx + 1);
             String nsURI = atts.getURI(i);
             if (StringUtils.isEmpty(nsURI)) {
               nsURI = _namespaceHandling.getNamespaceURI(prefix);
             }
             attributeSet.setAttribute(attName, atts.getValue(i), nsURI);
           }
         }
       }
       // -- else skip already processed in previous loop
     }
     return attributeSet;
   }
 
   /**
    * Processes the attributes and XML name space declarations found in the SAX v1
    * {@link AttributeList}. XML name space declarations are added to the set of XML name spaces in
    * scope.
    * 
    * 
    * @return AttributeSet An internal representation of XML attributes.
    * @throws SAXException If the XML name space associated with the prefix could not be resolved.
    */
   public AttributeSet getAttributeSet(AttributeList atts) throws SAXException {
     AttributeSetImpl attributeSet = prepareAttributeSetImpl(atts);
     return processAttributeList(atts, attributeSet);
   }
 
   /**
    * Processes the attributes and XML name space declarations found in the given SAX v1
    * AttributeList. The global AttributeSet is cleared and updated with the attribute data. XML name
    * space declarations are added to the set of XML name spaces in scope.
    * 
    * @deprecated
    * @param atts the {@link AttributeList} to process (can be null)
    **/
   private AttributeSet processAttributeList(AttributeList atts, AttributeSetImpl attributeSet)
       throws SAXException {
     if (atts == null || atts.getLength() == 0)
       return attributeSet;
 
     // -- process all namespaces first
     int attCount = 0;
     boolean[] validAtts = new boolean[atts.getLength()];
     for (int i = 0; i < validAtts.length; i++) {
       String attName = atts.getName(i);
       if (attName.equals(XMLNS)) {
         _namespaceHandling.addDefaultNamespace(atts.getValue(i));
       } else if (attName.startsWith(XMLNS_PREFIX)) {
         String prefix = attName.substring(XMLNS_PREFIX_LENGTH);
         _namespaceHandling.addNamespace(prefix, atts.getValue(i));
       } else {
         validAtts[i] = true;
         ++attCount;
       }
     }
     // -- process validAtts...if any exist
     for (int i = 0; i < validAtts.length; i++) {
       if (!validAtts[i])
         continue;
       String namespace = null;
       String attName = atts.getName(i);
       int idx = attName.indexOf(':');
       if (idx > 0) {
         String prefix = attName.substring(0, idx);
         if (!prefix.equals(XML_PREFIX)) {
           attName = attName.substring(idx + 1);
           namespace = _namespaceHandling.getNamespaceURI(prefix);
           if (namespace == null) {
             String error = "The namespace associated with " + "the prefix '" + prefix
                 + "' could not be resolved.";
             throw new SAXException(error);
 
           }
         }
       }
       attributeSet.setAttribute(attName, atts.getValue(i), namespace);
     }
     return attributeSet;
   }
 
   /**
    * Prepares a reusable AttributeSet object.
    * 
    * @deprecated
    * @param atts {@link Attributes} to determine the length of the reusable {@link AttributeSet}
    *        object (can be null).
    */
   private AttributeSetImpl prepareAttributeSetImpl(AttributeList atts) {
     if (atts == null) {
       return new AttributeSetImpl();
     }
     return new AttributeSetImpl(atts.getLength());
   }
 }