/*
 * Copyright  1999-2004 The Apache Software Foundation.
 *
 *  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.apache.xml.security.keys.keyresolver.implementations;



import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.security.PublicKey;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Set;

import javax.xml.parsers.ParserConfigurationException;

import org.apache.xml.security.c14n.CanonicalizationException;
import org.apache.xml.security.exceptions.XMLSecurityException;
import org.apache.xml.security.keys.content.RetrievalMethod;
import org.apache.xml.security.keys.content.x509.XMLX509Certificate;
import org.apache.xml.security.keys.keyresolver.KeyResolver;
import org.apache.xml.security.keys.keyresolver.KeyResolverException;
import org.apache.xml.security.keys.keyresolver.KeyResolverSpi;
import org.apache.xml.security.keys.storage.StorageResolver;
import org.apache.xml.security.signature.XMLSignatureInput;
import org.apache.xml.security.transforms.Transforms;
import org.apache.xml.security.utils.Constants;
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 org.xml.sax.SAXException;


/**
 * The RetrievalMethodResolver can retrieve public keys and certificates from
 * other locations. The location is specified using the ds:RetrievalMethod
 * element which points to the location. This includes the handling of raw
 * (binary) X.509 certificate which are not encapsulated in an XML structure.
 * If the retrieval process encounters an element which the
 * RetrievalMethodResolver cannot handle itself, resolving of the extracted
 * element is delegated back to the KeyResolver mechanism.
 *
 * @author $Author: raul $ modified by Dave Garcia
 */
public class RetrievalMethodResolver extends KeyResolverSpi {

   /** {@link org.apache.commons.logging} logging facility */
    static org.apache.commons.logging.Log log = 
        org.apache.commons.logging.LogFactory.getLog(
                        RetrievalMethodResolver.class.getName());

   /**
    * Method engineResolvePublicKey
    * @inheritDoc
    * @param element
    * @param BaseURI
    * @param storage
    *
    */
   public PublicKey engineLookupAndResolvePublicKey(
           Element element, String BaseURI, StorageResolver storage)
              {
	   if  (!XMLUtils.elementIsInSignatureSpace(element,
               Constants._TAG_RETRIEVALMETHOD)) {      
		   return null;
	   }

      try {
		   //Create a retrieval method over the given element
		   RetrievalMethod rm = new RetrievalMethod(element, BaseURI);
	       String type = rm.getType();		   
		   XMLSignatureInput resource=resolveInput(rm,BaseURI);			
           if (RetrievalMethod.TYPE_RAWX509.equals(type)) {
                //a raw certificate, direct parsing is done!
            	X509Certificate cert=getRawCertificate(resource);
				if (cert != null) {
			         return cert.getPublicKey();
			    }
				return null;
            };
			Element e = obtainRefrenceElement(resource); 
			return resolveKey(e,BaseURI,storage);
	  } catch (XMLSecurityException ex) {
         log.debug("XMLSecurityException", ex);
      } catch (CertificateException ex) {
         log.debug("CertificateException", ex);
      } catch (IOException ex) {
         log.debug("IOException", ex);
      } catch (ParserConfigurationException e) {
		  log.debug("ParserConfigurationException", e);
	  } catch (SAXException e) {
		 log.debug("SAXException", e);
	  } 
      return null;
   }

   static private Element obtainRefrenceElement(XMLSignatureInput resource) throws CanonicalizationException, ParserConfigurationException, IOException, SAXException, KeyResolverException {
	   Element e;
	   if (resource.isElement()){
		   e=(Element) resource.getSubNode();
	   } else if (resource.isNodeSet()) {
		   //Retrieved resource is a nodeSet
		   e=getDocumentElement(resource.getNodeSet());							   
	   } else {
		   //Retrieved resource is an inputStream
		   byte inputBytes[] = resource.getBytes();
		   e = getDocFromBytes(inputBytes);						
		   //otherwise, we parse the resource, create an Element and delegate
		   if (log.isDebugEnabled()) 
			   log.debug("we have to parse " + inputBytes.length + " bytes");
	   }
	   return e;
   }

   /**
    * Method engineResolveX509Certificate
    * @inheritDoc
    * @param element
    * @param BaseURI
    * @param storage
    *
    */
   public X509Certificate engineLookupResolveX509Certificate(
           Element element, String BaseURI, StorageResolver storage)
              {
	   if  (!XMLUtils.elementIsInSignatureSpace(element,
               Constants._TAG_RETRIEVALMETHOD)) {      
		   return null;
	   }

	   try {
         RetrievalMethod rm = new RetrievalMethod(element, BaseURI);
		 String type = rm.getType();		   
		 XMLSignatureInput resource=resolveInput(rm,BaseURI);			         
		 if (RetrievalMethod.TYPE_RAWX509.equals(type)) {
        	X509Certificate cert=getRawCertificate(resource);
            return cert;
		 } 
		 Element e = obtainRefrenceElement(resource);
		 return resolveCertificate(e,BaseURI,storage);
      } catch (XMLSecurityException ex) {
         log.debug("XMLSecurityException", ex);
      } catch (CertificateException ex) {
         log.debug("CertificateException", ex);
      } catch (IOException ex) {
         log.debug("IOException", ex);
	  } catch (ParserConfigurationException e) {
		  log.debug("ParserConfigurationException", e);
	  } catch (SAXException e) {
		 log.debug("SAXException", e);
	  } 
      return null;
   }
   
   /**
    * Retrieves a x509Certificate from the given information
    * @param e
    * @param BaseURI
    * @param storage
    * @return
    * @throws KeyResolverException 
    */
   static private X509Certificate resolveCertificate(Element e,String BaseURI,StorageResolver storage) throws KeyResolverException{
		  if (log.isDebugEnabled()) 
			  log.debug("Now we have a {" + e.getNamespaceURI() + "}"+ e.getLocalName() + " Element");
		  //An element has been provided
       	  if (e != null) { 
			  return KeyResolver.getX509Certificate(e,BaseURI, storage);		  	  
   		  }
		  return null;
   } 
   
   /**
    * Retrieves a x509Certificate from the given information
    * @param e
    * @param BaseURI
    * @param storage
    * @return
    * @throws KeyResolverException 
    */
   static private PublicKey resolveKey(Element e,String BaseURI,StorageResolver storage) throws KeyResolverException{
		  if (log.isDebugEnabled()) 
			  log.debug("Now we have a {" + e.getNamespaceURI() + "}"+ e.getLocalName() + " Element");
		  //An element has been provided
       	  if (e != null) { 
			  return KeyResolver.getPublicKey(e,BaseURI, storage);		  	  
   		  }
		  return null;
   }

   static private X509Certificate getRawCertificate(XMLSignatureInput resource) throws CanonicalizationException, IOException, CertificateException{
	   byte inputBytes[] = resource.getBytes();	   
       // if the resource stores a raw certificate, we have to handle it
       CertificateFactory certFact =CertificateFactory.getInstance(XMLX509Certificate.JCA_CERT_ID);
       X509Certificate cert =(X509Certificate) certFact.generateCertificate(new ByteArrayInputStream(inputBytes));
       return cert;
   }
   /**
    * Resolves the input from the given retrieval method 
    * @return
    * @throws XMLSecurityException 
    */
   static private XMLSignatureInput resolveInput(RetrievalMethod rm,String BaseURI) throws XMLSecurityException{
       Attr uri = rm.getURIAttr();
	   //Apply the trnasforms
       Transforms transforms = rm.getTransforms();
       ResourceResolver resRes = ResourceResolver.getInstance(uri, BaseURI);
       if (resRes != null) {
          XMLSignatureInput resource = resRes.resolve(uri, BaseURI);
          if (transforms != null) {
        	  log.debug("We have Transforms");
			  resource = transforms.performTransforms(resource);
          }		  
		  return resource;
       }
	   return null;
   }
   
   /**
    * Parses a byte array and returns the parsed Element.
    *
    * @param bytes
    * @return the Document Element after parsing bytes 
    * @throws KeyResolverException if something goes wrong
    */
   static Element getDocFromBytes(byte[] bytes) throws KeyResolverException {
      try {
         javax.xml.parsers.DocumentBuilderFactory dbf =javax.xml.parsers.DocumentBuilderFactory.newInstance();
         dbf.setNamespaceAware(true);
         javax.xml.parsers.DocumentBuilder db = dbf.newDocumentBuilder();
         org.w3c.dom.Document doc =
            db.parse(new java.io.ByteArrayInputStream(bytes));
         return doc.getDocumentElement();
      } catch (org.xml.sax.SAXException ex) {
         throw new KeyResolverException("empty", ex);
      } catch (java.io.IOException ex) {
         throw new KeyResolverException("empty", ex);
      } catch (javax.xml.parsers.ParserConfigurationException ex) {
         throw new KeyResolverException("empty", ex);
      }
   }

   /**
    * Method engineResolveSecretKey
    * @inheritDoc
    * @param element
    * @param BaseURI
    * @param storage
    *
    */
   public javax.crypto.SecretKey engineLookupAndResolveSecretKey(
           Element element, String BaseURI, StorageResolver storage)
   {
      return null;
   }
   
   static Element getDocumentElement(Set set) {
	   Iterator it=set.iterator();
	   Element e=null;
	   while (it.hasNext()) {
		   Node currentNode=(Node)it.next();
		   if (currentNode != null && Node.ELEMENT_NODE == currentNode.getNodeType()) {
			   e=(Element)currentNode;
			   break;
		   }
		   
	   }
	   List parents=new ArrayList(10);
  		
  		//Obtain all the parents of the elemnt
  		do {
  			parents.add(e);
  			Node n=e.getParentNode();
  			if (n == null || Node.ELEMENT_NODE != n.getNodeType()) {
  				break;
  			}
  			e=(Element)n;
  		} while (e!=null);
  		//Visit them in reverse order.
  		ListIterator it2=parents.listIterator(parents.size()-1);
  		Element ele=null;
  		while (it2.hasPrevious()) {
  			ele=(Element)it2.previous();
  			if (set.contains(ele)) {
  				return ele;
  			}
     	}
		return null;
   }
}

