/**
 * 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.
 */
/*
 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
 */
/*
 * $Id: DOMURIDereferencer.java 1231033 2012-01-13 12:12:12Z coheigea $
 */
package org.apache.jcp.xml.dsig.internal.dom;

import org.apache.xml.security.Init;
import org.apache.xml.security.signature.XMLSignatureInput;
import org.apache.xml.security.utils.XMLUtils;
import org.apache.xml.security.utils.resolver.ResourceResolver;
import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

import javax.xml.crypto.Data;
import javax.xml.crypto.URIDereferencer;
import javax.xml.crypto.URIReference;
import javax.xml.crypto.URIReferenceException;
import javax.xml.crypto.XMLCryptoContext;
import javax.xml.crypto.dom.DOMCryptoContext;
import javax.xml.crypto.dom.DOMURIReference;

/**
 * DOM-based implementation of URIDereferencer.
 *
 * @author Sean Mullan
 */
public class DOMURIDereferencer implements URIDereferencer {

  static final URIDereferencer INSTANCE = new DOMURIDereferencer();

  private DOMURIDereferencer() {
    // need to call org.apache.xml.security.Init.init()
    // before calling any apache security code
    Init.init();
  }

  public Data dereference(URIReference uriRef, XMLCryptoContext context)
    throws URIReferenceException {

    if (uriRef == null) {
      throw new NullPointerException("uriRef cannot be null");
    }
    if (context == null) {
      throw new NullPointerException("context cannot be null");
    }

    DOMURIReference domRef = (DOMURIReference) uriRef;
    Attr uriAttr = (Attr) domRef.getHere();
    String uri = uriRef.getURI();
    DOMCryptoContext dcc = (DOMCryptoContext) context;
    String baseURI = context.getBaseURI();

    Boolean secureValidation = (Boolean)
      context.getProperty("org.apache.jcp.xml.dsig.secureValidation");
    boolean secVal = false;
    if (secureValidation != null && secureValidation.booleanValue()) {
      secVal = true;
    }

    // Check if same-document URI and already registered on the context
    if (uri != null && uri.length() != 0 && uri.charAt(0) == '#') {
      String id = uri.substring(1);

      if (id.startsWith("xpointer(id(")) {
        int i1 = id.indexOf('\'');
        int i2 = id.indexOf('\'', i1 + 1);
        id = id.substring(i1 + 1, i2);
      }

      Node referencedElem = dcc.getElementById(id);
      if (referencedElem != null) {
        if (secVal) {
          Element start = referencedElem.getOwnerDocument().getDocumentElement();
          if (!XMLUtils.protectAgainstWrappingAttack(start, (Element) referencedElem, id)) {
            String error = "Multiple Elements with the same ID " + id + " were detected";
            throw new URIReferenceException(error);
          }
        }

        XMLSignatureInput result = new XMLSignatureInput(referencedElem);
        if (!uri.substring(1).startsWith("xpointer(id(")) {
          result.setExcludeComments(true);
        }

        result.setMIMEType("text/xml");
        if (baseURI != null && baseURI.length() > 0) {
          result.setSourceURI(baseURI.concat(uriAttr.getNodeValue()));
        } else {
          result.setSourceURI(uriAttr.getNodeValue());
        }
        return new ApacheNodeSetData(result);
      }
    }

    try {
      ResourceResolver apacheResolver =
        ResourceResolver.getInstance(uriAttr, baseURI, secVal);
      XMLSignatureInput in = apacheResolver.resolve(uriAttr, baseURI);
      if (in.isOctetStream()) {
        return new ApacheOctetStreamData(in);
      } else {
        return new ApacheNodeSetData(in);
      }
    } catch (Exception e) {
      throw new URIReferenceException(e);
    }
  }
}