/*
 * 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.ode.bpel.compiler;

import java.io.IOException;
import java.net.URL;
import java.util.HashMap;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * Resolver implementation that restricts us to a known set of resources.
 */
class LocalEntityResolver implements EntityResolver {
  private static final Log __log = LogFactory.getLog(LocalEntityResolver.class);

  private final HashMap<String, URL> _mappings = new HashMap<String,URL>();
  
  public InputSource resolveEntity(String publicId, String systemId) 
    throws SAXException, IOException {
    if (__log.isTraceEnabled())
      __log.trace("resolveEntity(" + publicId + "," + systemId + ")") ;
    
    URL target = _mappings.get(systemId);
    if (target == null)
      target = _mappings.get(publicId);
    
    if (target == null) {
      if (__log.isDebugEnabled())
        __log.debug("resolveEntity(" + publicId + "," + systemId + 
            ") failed (resource not found) ");
      throw new IOException("Resource not found: " + publicId + " : "  + systemId);
    }
    
    if (__log.isDebugEnabled())
       __log.debug("resolveEntity(" + publicId + "," + systemId + 
            ") ==> target" );
    
    return new InputSource(target.openStream());
  }

  
  void register(String id, URL location) {
    if (id == null)
      throw new NullPointerException("id arg must not be null!");
    if (location == null)
      throw new NullPointerException("location arg must not be null");
    
    if (__log.isDebugEnabled())
      __log.debug("mapping " + id + " ==> " + location);
    _mappings.put(id, location);
  }
}