/*
 * Copyright 2005 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.
 *
 */
/*
 * Portions copyright 2005 Sun Microsystems, Inc. All rights reserved.
 */
/*
 * =========================================================================== 
 *
 * (C) Copyright IBM Corp. 2003 All Rights Reserved.
 *
 * ===========================================================================
 */
/*
 * $Id: DOMReference.java 647272 2008-04-11 19:22:21Z mullan $
 */
package org.jcp.xml.dsig.internal.dom;

import javax.xml.crypto.*;
import javax.xml.crypto.dsig.*;
import javax.xml.crypto.dom.DOMCryptoContext;
import javax.xml.crypto.dom.DOMURIReference;

import java.io.*;
import java.net.URI;
import java.net.URISyntaxException;
import java.security.*;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

import org.jcp.xml.dsig.internal.DigesterOutputStream;
import org.apache.xml.security.exceptions.Base64DecodingException;
import org.apache.xml.security.signature.XMLSignatureInput;
import org.apache.xml.security.utils.Base64;
import org.apache.xml.security.utils.UnsyncBufferedOutputStream;

/**
 * DOM-based implementation of Reference.
 *
 * @author Sean Mullan
 * @author Joyce Leung
 */
public final class DOMReference extends DOMStructure 
    implements Reference, DOMURIReference {

   /**
    * Look up useC14N11 system property. If true, an explicit C14N11 transform
    * will be added if necessary when generating the signature. See section
    * 3.1.1 of http://www.w3.org/2007/xmlsec/Drafts/xmldsig-core/ for more info.
    *
    * If true, overrides the same property if set in the XMLSignContext.
    */
    private static boolean useC14N11 = false;
    static {
	try {
            useC14N11 = Boolean.getBoolean("org.apache.xml.security.useC14N11");
        } catch (Exception e) {
            // ignore exceptions
       }
    }

    private static Logger log = Logger.getLogger("org.jcp.xml.dsig.internal.dom");

    private final DigestMethod digestMethod;
    private final String id;
    private final List transforms;
    private List allTransforms;
    private final Data appliedTransformData;
    private Attr here;
    private final String uri;
    private final String type;
    private byte[] digestValue;
    private byte[] calcDigestValue;
    private Element refElem;
    private boolean digested = false;
    private boolean validated = false;
    private boolean validationStatus;
    private Data derefData;
    private InputStream dis;
    private MessageDigest md;
    private Provider provider;

    /**
     * Creates a <code>Reference</code> from the specified parameters.
     *
     * @param uri the URI (may be null)
     * @param type the type (may be null)
     * @param dm the digest method
     * @param transforms a list of {@link Transform}s. The list
     *    is defensively copied to protect against subsequent modification.
     *    May be <code>null</code> or empty.
     * @param id the reference ID (may be <code>null</code>)
     * @return a <code>Reference</code>
     * @throws NullPointerException if <code>dm</code> is <code>null</code>
     * @throws ClassCastException if any of the <code>transforms</code> are
     *    not of type <code>Transform</code>
     */
    public DOMReference(String uri, String type, DigestMethod dm, 
	List transforms, String id, Provider provider) {
	this(uri, type, dm, null, null, transforms, id, null, provider);
    }

    public DOMReference(String uri, String type, DigestMethod dm, 
	List appliedTransforms, Data result, List transforms, String id,
	Provider provider) {
	this(uri, type, dm, appliedTransforms, 
	     result, transforms, id, null, provider);
    }

    public DOMReference(String uri, String type, DigestMethod dm, 
	List appliedTransforms, Data result, List transforms, String id, 
	byte[] digestValue, Provider provider) {
	if (dm == null) {
	    throw new NullPointerException("DigestMethod must be non-null");
	}
	this.allTransforms = new ArrayList();
        if (appliedTransforms != null) {
            List transformsCopy = new ArrayList(appliedTransforms);
            for (int i = 0, size = transformsCopy.size(); i < size; i++) {
                if (!(transformsCopy.get(i) instanceof Transform)) {
                    throw new ClassCastException
                        ("appliedTransforms["+i+"] is not a valid type");
                }
            }
            this.allTransforms = transformsCopy;
        }
        if (transforms == null) {
	    this.transforms = Collections.EMPTY_LIST;
        } else {
            List transformsCopy = new ArrayList(transforms);
            for (int i = 0, size = transformsCopy.size(); i < size; i++) {
                if (!(transformsCopy.get(i) instanceof Transform)) {
                    throw new ClassCastException
                        ("transforms["+i+"] is not a valid type");
                }
            }
	    this.transforms = transformsCopy;
	    this.allTransforms.addAll(transformsCopy);
        }
	this.digestMethod = dm;
	this.uri = uri;
        if ((uri != null) && (!uri.equals(""))) {
            try {
                new URI(uri);
            } catch (URISyntaxException e) {
                throw new IllegalArgumentException(e.getMessage());
            }
        }
	this.type = type;
	this.id = id;
	if (digestValue != null) {
	    this.digestValue = (byte[]) digestValue.clone();
	    this.digested = true;
	}
	this.appliedTransformData = result;
	this.provider = provider;
    }
 
    /**
     * Creates a <code>DOMReference</code> from an element.
     *
     * @param refElem a Reference element
     */
    public DOMReference(Element refElem, XMLCryptoContext context, 
	Provider provider) throws MarshalException {
        // unmarshal Transforms, if specified
        Element nextSibling = DOMUtils.getFirstChildElement(refElem);
        List transforms = new ArrayList(5);
        if (nextSibling.getLocalName().equals("Transforms")) {
	    Element transformElem = DOMUtils.getFirstChildElement(nextSibling);
	    while (transformElem != null) {
                transforms.add
		    (new DOMTransform(transformElem, context, provider));
	        transformElem = DOMUtils.getNextSiblingElement(transformElem);
	    }
            nextSibling = DOMUtils.getNextSiblingElement(nextSibling);
	}

        // unmarshal DigestMethod
        Element dmElem = nextSibling;
        this.digestMethod = DOMDigestMethod.unmarshal(dmElem);

        // unmarshal DigestValue
	try {
	    Element dvElem = DOMUtils.getNextSiblingElement(dmElem);
	    this.digestValue = Base64.decode(dvElem);
	} catch (Base64DecodingException bde) {
	    throw new MarshalException(bde);
	}

	// unmarshal attributes
        this.uri = DOMUtils.getAttributeValue(refElem, "URI");
        this.id = DOMUtils.getAttributeValue(refElem, "Id");

        this.type = DOMUtils.getAttributeValue(refElem, "Type");
	this.here = refElem.getAttributeNodeNS(null, "URI");
	this.refElem = refElem;
	this.transforms = transforms;
	this.allTransforms = transforms;
	this.appliedTransformData = null;
	this.provider = provider;
    }

    public DigestMethod getDigestMethod() {
	return digestMethod;
    }

    public String getId() {
	return id;
    }

    public String getURI() {
	return uri;
    }

    public String getType() {
	return type;
    }

    public List getTransforms() {
	return Collections.unmodifiableList(allTransforms);
    }

    public byte[] getDigestValue() {
	return (digestValue == null ? null : (byte[]) digestValue.clone());
    }

    public byte[] getCalculatedDigestValue() {
	return (calcDigestValue == null ? null 
		: (byte[]) calcDigestValue.clone());
    }

    public void marshal(Node parent, String dsPrefix, DOMCryptoContext context)
	throws MarshalException {
	if (log.isLoggable(Level.FINE)) {
            log.log(Level.FINE, "Marshalling Reference");
	}
        Document ownerDoc = DOMUtils.getOwnerDocument(parent);

        refElem = DOMUtils.createElement
            (ownerDoc, "Reference", XMLSignature.XMLNS, dsPrefix);

	// set attributes
	DOMUtils.setAttributeID(refElem, "Id", id);
        DOMUtils.setAttribute(refElem, "URI", uri);
        DOMUtils.setAttribute(refElem, "Type", type);

	// create and append Transforms element
	if (!allTransforms.isEmpty()) {
            Element transformsElem = DOMUtils.createElement
		(ownerDoc, "Transforms", XMLSignature.XMLNS, dsPrefix);
	    refElem.appendChild(transformsElem);
	    for (int i = 0, size = allTransforms.size(); i < size; i++) {
	        DOMStructure transform = 
		    (DOMStructure) allTransforms.get(i);
	        transform.marshal(transformsElem, dsPrefix, context);
	    }
	}

	// create and append DigestMethod element
	((DOMDigestMethod) digestMethod).marshal(refElem, dsPrefix, context);

	// create and append DigestValue element
	if (log.isLoggable(Level.FINE)) {
	    log.log(Level.FINE, "Adding digestValueElem");
	}
        Element digestValueElem = DOMUtils.createElement
            (ownerDoc, "DigestValue", XMLSignature.XMLNS, dsPrefix);
	if (digestValue != null) {
            digestValueElem.appendChild
	        (ownerDoc.createTextNode(Base64.encode(digestValue)));
	}
        refElem.appendChild(digestValueElem);

	parent.appendChild(refElem);
	here = refElem.getAttributeNodeNS(null, "URI");
    }

    public void digest(XMLSignContext signContext) 
	throws XMLSignatureException {
	Data data = null;
	if (appliedTransformData == null) {
	    data = dereference(signContext);
	} else {
	    data = appliedTransformData;
	}
	digestValue = transform(data, signContext);

	// insert digestValue into DigestValue element
	String encodedDV = Base64.encode(digestValue);
	if (log.isLoggable(Level.FINE)) {
	    log.log(Level.FINE, "Reference object uri = " + uri);
	}
        Element digestElem = DOMUtils.getLastChildElement(refElem);
	if (digestElem == null) {
	    throw new XMLSignatureException("DigestValue element expected");
	}
	DOMUtils.removeAllChildren(digestElem);
	digestElem.appendChild
	    (refElem.getOwnerDocument().createTextNode(encodedDV));

	digested = true;
	if (log.isLoggable(Level.FINE)) {
	    log.log(Level.FINE, "Reference digesting completed");
	}
    }

    public boolean validate(XMLValidateContext validateContext)
        throws XMLSignatureException {
	if (validateContext == null) {
	    throw new NullPointerException("validateContext cannot be null");
	}
	if (validated) {
	    return validationStatus;
	}
	Data data = dereference(validateContext);
	calcDigestValue = transform(data, validateContext);

	if (log.isLoggable(Level.FINE)) {
	    log.log(Level.FINE, "Expected digest: " 
		+ Base64.encode(digestValue));
	    log.log(Level.FINE, "Actual digest: " 
		+ Base64.encode(calcDigestValue));
	}

	validationStatus = Arrays.equals(digestValue, calcDigestValue);
	validated = true;
	return validationStatus;
    }

    public Data getDereferencedData() {
	return derefData;
    }

    public InputStream getDigestInputStream() {
	return dis;
    }

    private Data dereference(XMLCryptoContext context) 
	throws XMLSignatureException {
        Data data = null;

	// use user-specified URIDereferencer if specified; otherwise use deflt
	URIDereferencer deref = context.getURIDereferencer();
	if (deref == null) {
	    deref = DOMURIDereferencer.INSTANCE;
	}
	try {
            data = deref.dereference(this, context);
	    if (log.isLoggable(Level.FINE)) {
                log.log(Level.FINE, "URIDereferencer class name: "
                    + deref.getClass().getName());
                log.log(Level.FINE, "Data class name: "
                    + data.getClass().getName());
            }
        } catch (URIReferenceException ure) {
	    throw new XMLSignatureException(ure);
        }

	return data;
    }

    private byte[] transform(Data dereferencedData, 
	XMLCryptoContext context) throws XMLSignatureException {

	if (md == null) {
	    try {
	        md = MessageDigest.getInstance
		    (((DOMDigestMethod) digestMethod).getMessageDigestAlgorithm());
	    } catch (NoSuchAlgorithmException nsae) {
	        throw new XMLSignatureException(nsae);
	    }
	}
	md.reset();
	DigesterOutputStream dos;
	Boolean cache = (Boolean)
            context.getProperty("javax.xml.crypto.dsig.cacheReference");
        if (cache != null && cache.booleanValue() == true) {
            this.derefData = copyDerefData(dereferencedData);
            dos = new DigesterOutputStream(md, true);
        } else {
            dos = new DigesterOutputStream(md);
        }
	OutputStream os = new UnsyncBufferedOutputStream(dos);
        Data data = dereferencedData;
        for (int i = 0, size = transforms.size(); i < size; i++) {
	    DOMTransform transform = (DOMTransform) transforms.get(i);
	    try {
                if (i < size - 1) {
                    data = transform.transform(data, context);
                } else {
                    data = transform.transform(data, context, os);
                }
	    } catch (TransformException te) {
		throw new XMLSignatureException(te);
	    }
        }
	
	try {
	    if (data != null) {
	        XMLSignatureInput xi;
	        // explicitly use C14N 1.1 when generating signature
		// first check system property, then context property
		boolean c14n11 = useC14N11;
		String c14nalg = CanonicalizationMethod.INCLUSIVE;
	        if (context instanceof XMLSignContext) {
		    if (!c14n11) {
	                Boolean prop = (Boolean) context.getProperty
			    ("org.apache.xml.security.useC14N11");
		        c14n11 = (prop != null && prop.booleanValue() == true);
			if (c14n11) {
		            c14nalg = "http://www.w3.org/2006/12/xml-c14n11";
			}
		    } else {
		        c14nalg = "http://www.w3.org/2006/12/xml-c14n11";
		    }
		}
	        if (data instanceof ApacheData) {
	            xi = ((ApacheData) data).getXMLSignatureInput();
	        } else if (data instanceof OctetStreamData) {
	            xi = new XMLSignatureInput
			(((OctetStreamData)data).getOctetStream());
	        } else if (data instanceof NodeSetData) {
		    TransformService spi = null;
		    try {
		        spi = TransformService.getInstance(c14nalg, "DOM");
		    } catch (NoSuchAlgorithmException nsae) {
		        spi = TransformService.getInstance
		            (c14nalg, "DOM", provider);
		    }
                    data = spi.transform(data, context);
	            xi = new XMLSignatureInput
		        (((OctetStreamData)data).getOctetStream());
	        } else {
	            throw new XMLSignatureException("unrecognized Data type");
	        }
	        if (context instanceof XMLSignContext && c14n11
		    && !xi.isOctetStream() && !xi.isOutputStreamSet()) {
		    DOMTransform t = new DOMTransform
			(TransformService.getInstance(c14nalg, "DOM"));
		    Element transformsElem = null;
		    String dsPrefix = DOMUtils.getSignaturePrefix(context);
		    if (allTransforms.isEmpty()) {
            		transformsElem = DOMUtils.createElement(
			    refElem.getOwnerDocument(), 
			    "Transforms", XMLSignature.XMLNS, dsPrefix);
	    		refElem.insertBefore(transformsElem, 
			    DOMUtils.getFirstChildElement(refElem));
		    } else {
	            	transformsElem = DOMUtils.getFirstChildElement(refElem);
		    }
        	    t.marshal(transformsElem, dsPrefix, (DOMCryptoContext) context);
		    allTransforms.add(t);
	            xi.updateOutputStream(os, true);
		} else {
	            xi.updateOutputStream(os);
		}
	    }
	    os.flush();
	    if (cache != null && cache.booleanValue() == true) {
                this.dis = dos.getInputStream();
            }
            return dos.getDigestValue();
	} catch (Exception e) {
	    throw new XMLSignatureException(e);
	}
    }

    public Node getHere() {
	return here;
    }

    public boolean equals(Object o) {
	if (this == o) {
            return true;
	}

        if (!(o instanceof Reference)) {
            return false;
	}
        Reference oref = (Reference) o;

	boolean idsEqual = (id == null ? oref.getId() == null :
	    id.equals(oref.getId()));
	boolean urisEqual = (uri == null ? oref.getURI() == null :
	    uri.equals(oref.getURI()));
	boolean typesEqual = (type == null ? oref.getType() == null :
	    type.equals(oref.getType()));
	boolean digestValuesEqual = 
	    Arrays.equals(digestValue, oref.getDigestValue());

	return (digestMethod.equals(oref.getDigestMethod()) && idsEqual &&
	    urisEqual && typesEqual && allTransforms.equals(oref.getTransforms()));
    }

    public int hashCode() {
	assert false : "hashCode not designed";
	return 47;
    }

    boolean isDigested() {
	return digested;
    }

    private static Data copyDerefData(Data dereferencedData) {
        if (dereferencedData instanceof ApacheData) {
            // need to make a copy of the Data
            ApacheData ad = (ApacheData) dereferencedData;
            XMLSignatureInput xsi = ad.getXMLSignatureInput();
            if (xsi.isNodeSet()) {
                try {
                    final Set s = xsi.getNodeSet();
                    return new NodeSetData() {
                        public Iterator iterator() { return s.iterator(); }
                    };
                } catch (Exception e) {
                    // log a warning
                            log.log(Level.WARNING,
                        "cannot cache dereferenced data: " + e);
                    return null;
                }
            } else if (xsi.isElement()) {
                return new DOMSubTreeData
                    (xsi.getSubNode(), xsi.isExcludeComments());
            } else if (xsi.isOctetStream() || xsi.isByteArray()) {
                try {
                return new OctetStreamData
                  (xsi.getOctetStream(), xsi.getSourceURI(), xsi.getMIMEType());
                } catch (IOException ioe) {
                    // log a warning
                            log.log(Level.WARNING,
                        "cannot cache dereferenced data: " + ioe);
                    return null;
                }
            }
        }
        return dereferencedData;
    }
}