/*
* Copyright 2008 Federal Chancellery Austria and
* Graz University of Technology
*
* 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 at.gv.egiz.bku.slcommands.impl.xsect;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

import javax.xml.crypto.Data;
import javax.xml.crypto.OctetStreamData;
import javax.xml.crypto.URIDereferencer;
import javax.xml.crypto.URIReference;
import javax.xml.crypto.URIReferenceException;
import javax.xml.crypto.XMLCryptoContext;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import at.gv.egiz.bku.utils.urldereferencer.StreamData;
import at.gv.egiz.bku.utils.urldereferencer.URLDereferencer;
import at.gv.egiz.bku.utils.urldereferencer.URLDereferencerContext;

/**
 * An URIDereferencer implementation that dereferences <code>LocRef</code>
 * references.
 * 
 * @author mcentner
 */
public class LocRefDereferencer implements URIDereferencer {

  /**
   * Logging facility.
   */
  private static Log log = LogFactory.getLog(LocRefDereferencer.class);

  /**
   * The <code>LocRef</code>-reference to be dereferenced by
   * {@link #dereference(URIReference, XMLCryptoContext)}.
   */
  protected String locRef;

  /**
   * The context to be used for dereferencing.
   */
  protected URLDereferencerContext dereferencerContext;

  /**
   * Creates a new instance of this LocRefDereferencer with the given
   * <code>dereferencerContext</code> and <code>locRef</code> reference.
   * 
   * @param dereferencerContext
   *          the context to be used for dereferencing
   * @param locRef
   *          the <code>LocRef</code>-reference (must be an absolute URI)
   * 
   * @throws URISyntaxException
   *           if <code>LocRef</code> is not an absolute URI
   */
  public LocRefDereferencer(URLDereferencerContext dereferencerContext,
      String locRef) throws URISyntaxException {

    this.dereferencerContext = dereferencerContext;

    URI locRefUri = new URI(locRef);
    if (locRefUri.isAbsolute()) {
      this.locRef = locRef;
    } else {
      throw new IllegalArgumentException(
          "Parameter 'locRef' must be an absolut URI.");
    }
  }

  /*
   * (non-Javadoc)
   * 
   * @see
   * javax.xml.crypto.URIDereferencer#dereference(javax.xml.crypto.URIReference,
   * javax.xml.crypto.XMLCryptoContext)
   */
  @Override
  public Data dereference(URIReference uriReference, XMLCryptoContext context)
      throws URIReferenceException {

    URLDereferencer dereferencer = URLDereferencer.getInstance();
    StreamData streamData;
    try {
      streamData = dereferencer.dereference(locRef, dereferencerContext);
    } catch (IOException e) {
      log.info("Failed to dereference URI'" + locRef + "'. " + e.getMessage(),
          e);
      throw new URIReferenceException("Failed to dereference URI '" + locRef
          + "'. " + e.getMessage(), e);
    }

    return new OctetStreamData(streamData.getStream(), locRef, streamData
        .getContentType());
  }

}