/*-------------------------------------------------------------------------
    Copyright 2006 Olivier Berlanger
   
    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 net.sf.xolite.impl;
  
  
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Set;
  
  import javax.xml.namespace.NamespaceContext;
  
  
  /**
   * Default (Map based) implementation of the NamespaceContext interface.
   */
  public class MapPrefixResolver implements NamespaceContext {
  
  
      /** Map from key=prefix to URI. */
      private Map<String, String> uriMappings;
      /** Map from key=URI to set of prefixes. */
      private Map<String, Set<String>> prefixMappings;
  
  
      public MapPrefixResolver() {
          uriMappings = new HashMap<String, String>();
          prefixMappings = new HashMap<String, Set<String>>();
      }
  
  
      public void addAll(MapPrefixResolver other) {
          if (other != null) {
              String uri;
              String prefix;
              for (Iterator<String> uris = other.prefixMappings.keySet().iterator(); uris.hasNext();) {
                  uri = uris.next();
                  for (Iterator<String> prefixes = other.getPrefixes(uri); prefixes.hasNext();) {
                      prefix = prefixes.next();
                      addPrefixMapping(prefix, uri);
                  }
              }
          }
      }
  
  
      public void addPrefixMapping(String prefix, String namespaceURI) {
          if (prefix == null) throw new IllegalArgumentException("Added prefix cannot be null");
          if (namespaceURI == null) throw new IllegalArgumentException("Added Namespace URI cannot be null");
          if (uriMappings.containsKey(prefix)) {
              throw new IllegalArgumentException("MapPrefixResolver doesn't support prefix redefinition: " + prefix + "="
                      + namespaceURI + " WAS " + prefix + "=" + uriMappings.get(prefix));
          }
          uriMappings.put(prefix, namespaceURI);
          Set<String> prefixs = prefixMappings.get(namespaceURI);
          if (prefixs == null) {
              prefixs = new HashSet<String>();
              prefixMappings.put(namespaceURI, prefixs);
          }
          prefixs.add(prefix);
      }
  
  
      public void removePrefixMapping(String prefix, String namespaceURI) {
          if (prefix == null) throw new IllegalArgumentException("Removed prefix cannot be null");
          if (namespaceURI == null) throw new IllegalArgumentException("Removed Namespace URI cannot be null");
          uriMappings.remove(prefix);
          Set<String> prefixs = prefixMappings.get(namespaceURI);
          if (prefixs != null) prefixs.remove(prefix);
      }
  
  
      public void clear() {
          uriMappings.clear();
          prefixMappings.clear();
      }
  
  
      /**
       * Get namespace URI corresponding to the given prefix.
       * 
       * @see javax.xml.namespace.NamespaceContext#getNamespaceURI(java.lang.String)
       */
      public String getNamespaceURI(String prefix) {
          return uriMappings.get(prefix);
     }
 
 
     /**
      * Get the first prefix mapped to the given namespace.
      * 
      * @see javax.xml.namespace.NamespaceContext#getPrefix(java.lang.String)
      */
     public String getPrefix(String namespaceURI) {
         Set<String> prefixs = prefixMappings.get(namespaceURI);
         if (prefixs == null) return null;
         return (prefixs.isEmpty()) ? null : (String) prefixs.iterator().next();
     }
 
 
     /**
      * Get all the prefixes mapped to the given namespace.
      * 
      * @see javax.xml.namespace.NamespaceContext#getPrefixes(java.lang.String)
      */
     public Iterator<String> getPrefixes(String namespaceURI) {
         Set<String> prefixs = prefixMappings.get(namespaceURI);
         if (prefixs == null) prefixs = new HashSet<String>();
         return prefixs.iterator();
     }
 
 
 }