/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/**

 * 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 (c) 2005, 2018, Oracle and/or its affiliates. All rights reserved.

 */

/*

 * $Id: DOMSignedInfo.java 1820179 2018-01-04 19:09:52Z mullan $

 */

package org.jcp.xml.dsig.internal.dom;

import javax.xml.crypto.*;

import javax.xml.crypto.dsig.*;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.IOException;

import java.security.Provider;

import java.util.*;

import org.w3c.dom.Element;

import com.sun.org.apache.xml.internal.security.utils.UnsyncBufferedOutputStream;

/**

 * DOM-based implementation of SignedInfo.

 *

 */

public final class DOMSignedInfo extends DOMStructure implements SignedInfo {

    private static final com.sun.org.slf4j.internal.Logger LOG =

        com.sun.org.slf4j.internal.LoggerFactory.getLogger(DOMSignedInfo.class);

    private List<Reference> references;

    private CanonicalizationMethod canonicalizationMethod;

    private SignatureMethod signatureMethod;

    private String id;

    private Element localSiElem;

    private InputStream canonData;

    /**

     * Creates a {@code DOMSignedInfo} from the specified parameters. Use

     * this constructor when the {@code Id} is not specified.

     *

     * @param cm the canonicalization method

     * @param sm the signature method

     * @param references the list of references. The list is copied.

     * @throws NullPointerException if

     *    {@code cm}, {@code sm}, or {@code references} is

     *    {@code null}

     * @throws IllegalArgumentException if {@code references} is empty

     * @throws ClassCastException if any of the references are not of

     *    type {@code Reference}

     */

    public DOMSignedInfo(CanonicalizationMethod cm, SignatureMethod sm,

                         List<? extends Reference> references) {

        if (cm == null || sm == null || references == null) {

            throw new NullPointerException();

        }

        this.canonicalizationMethod = cm;

        this.signatureMethod = sm;

        this.references = Collections.unmodifiableList(

            new ArrayList<>(references));

        if (this.references.isEmpty()) {

            throw new IllegalArgumentException("list of references must " +

                "contain at least one entry");

        }

        for (int i = 0, size = this.references.size(); i < size; i++) {

            Object obj = this.references.get(i);

            if (!(obj instanceof Reference)) {

                throw new ClassCastException("list of references contains " +

                    "an illegal type");

            }

        }

    }

    /**

     * Creates a {@code DOMSignedInfo} from the specified parameters.

     *

     * @param cm the canonicalization method

     * @param sm the signature method

     * @param references the list of references. The list is copied.

     * @param id an optional identifer that will allow this

     *    {@code SignedInfo} to be referenced by other signatures and

     *    objects

     * @throws NullPointerException if {@code cm}, {@code sm},

     *    or {@code references} is {@code null}

     * @throws IllegalArgumentException if {@code references} is empty

     * @throws ClassCastException if any of the references are not of

     *    type {@code Reference}

     */

    public DOMSignedInfo(CanonicalizationMethod cm, SignatureMethod sm,

                         List<? extends Reference> references, String id) {

        this(cm, sm, references);

        this.id = id;

    }

    /**

     * Creates a {@code DOMSignedInfo} from an element.

     *

     * @param siElem a SignedInfo element

     */

    public DOMSignedInfo(Element siElem, XMLCryptoContext context, Provider provider)

        throws MarshalException {

        localSiElem = siElem;

        // get Id attribute, if specified

        id = DOMUtils.getAttributeValue(siElem, "Id");

        // unmarshal CanonicalizationMethod

        Element cmElem = DOMUtils.getFirstChildElement(siElem,

                                                       "CanonicalizationMethod",

                                                       XMLSignature.XMLNS);

        canonicalizationMethod = new DOMCanonicalizationMethod(cmElem, context,

                                                               provider);

        // unmarshal SignatureMethod

        Element smElem = DOMUtils.getNextSiblingElement(cmElem,

                                                        "SignatureMethod",

                                                        XMLSignature.XMLNS);

        signatureMethod = DOMSignatureMethod.unmarshal(smElem);

        boolean secVal = Utils.secureValidation(context);

        String signatureMethodAlgorithm = signatureMethod.getAlgorithm();

        if (secVal && Policy.restrictAlg(signatureMethodAlgorithm)) {

            throw new MarshalException(

                "It is forbidden to use algorithm " + signatureMethodAlgorithm +

                " when secure validation is enabled"

            );

        }

        // unmarshal References

        ArrayList<Reference> refList = new ArrayList<>(5);

        Element refElem = DOMUtils.getNextSiblingElement(smElem, "Reference", XMLSignature.XMLNS);

        refList.add(new DOMReference(refElem, context, provider));

        refElem = DOMUtils.getNextSiblingElement(refElem);

        while (refElem != null) {

            String name = refElem.getLocalName();

            String namespace = refElem.getNamespaceURI();

            if (!"Reference".equals(name) || !XMLSignature.XMLNS.equals(namespace)) {

                throw new MarshalException("Invalid element name: " +

                                           namespace + ":" + name + ", expected Reference");

            }

            refList.add(new DOMReference(refElem, context, provider));

            if (secVal && Policy.restrictNumReferences(refList.size())) {

                String error = "A maxiumum of " + Policy.maxReferences()

                    + " references per Manifest are allowed when"

                    + " secure validation is enabled";

                throw new MarshalException(error);

            }

            refElem = DOMUtils.getNextSiblingElement(refElem);

        }

        references = Collections.unmodifiableList(refList);

    }

    @Override

    public CanonicalizationMethod getCanonicalizationMethod() {

        return canonicalizationMethod;

    }

    @Override

    public SignatureMethod getSignatureMethod() {

        return signatureMethod;

    }

    @Override

    public String getId() {

        return id;

    }

    @Override

    public List<Reference> getReferences() {

        return references;

    }

    @Override

    public InputStream getCanonicalizedData() {

        return canonData;

    }

    public void canonicalize(XMLCryptoContext context, ByteArrayOutputStream bos)

        throws XMLSignatureException {

        if (context == null) {

            throw new NullPointerException("context cannot be null");

        }

        DOMSubTreeData subTree = new DOMSubTreeData(localSiElem, true);

        try (OutputStream os = new UnsyncBufferedOutputStream(bos)) {

            ((DOMCanonicalizationMethod)

                canonicalizationMethod).canonicalize(subTree, context, os);

            os.flush();

            byte[] signedInfoBytes = bos.toByteArray();

            // this whole block should only be done if LOGging is enabled

            if (LOG.isDebugEnabled()) {

                LOG.debug("Canonicalized SignedInfo:");

                StringBuilder sb = new StringBuilder(signedInfoBytes.length);

                for (int i = 0; i < signedInfoBytes.length; i++) {

                    sb.append((char)signedInfoBytes[i]);

                }

                LOG.debug(sb.toString());

                LOG.debug("Data to be signed/verified:" + Base64.getMimeEncoder().encodeToString(signedInfoBytes));

            }

            this.canonData = new ByteArrayInputStream(signedInfoBytes);

        } catch (TransformException te) {

            throw new XMLSignatureException(te);

        } catch (IOException e) {

            LOG.debug(e.getMessage(), e);

            // Impossible

        }

    }

    @Override

    public void marshal(XmlWriter xwriter, String dsPrefix, XMLCryptoContext context)

        throws MarshalException

    {

        xwriter.writeStartElement(dsPrefix, "SignedInfo", XMLSignature.XMLNS);

        XMLStructure siStruct = xwriter.getCurrentNodeAsStructure();

        localSiElem = (Element) ((javax.xml.crypto.dom.DOMStructure) siStruct).getNode();

        // append Id attribute

        xwriter.writeIdAttribute("", "", "Id", id);

        // create and append CanonicalizationMethod element

        DOMCanonicalizationMethod dcm =

            (DOMCanonicalizationMethod)canonicalizationMethod;

        dcm.marshal(xwriter, dsPrefix, context);

        // create and append SignatureMethod element

        ((AbstractDOMSignatureMethod)signatureMethod).marshal(xwriter, dsPrefix);

        // create and append Reference elements

        for (Reference reference : references) {

            // TODO - either suppress warning here, or figure out how to get rid of the cast.

            DOMReference domRef = (DOMReference)reference;

            domRef.marshal(xwriter, dsPrefix, context);

        }

        xwriter.writeEndElement(); // "SignedInfo"

    }

    @Override

    public boolean equals(Object o) {

        if (this == o) {

            return true;

        }

        if (!(o instanceof SignedInfo)) {

            return false;

        }

        SignedInfo osi = (SignedInfo)o;

        boolean idEqual = id == null ? osi.getId() == null

                                      : id.equals(osi.getId());

        return canonicalizationMethod.equals(osi.getCanonicalizationMethod())

                && signatureMethod.equals(osi.getSignatureMethod()) &&

                references.equals(osi.getReferences()) && idEqual;

    }

    @SuppressWarnings("unchecked")

    public static List<Reference> getSignedInfoReferences(SignedInfo si) {

        return si.getReferences();

    }

    @Override

    public int hashCode() {

        int result = 17;

        if (id != null) {

            result = 31 * result + id.hashCode();

        }

        result = 31 * result + canonicalizationMethod.hashCode();

        result = 31 * result + signatureMethod.hashCode();

        result = 31 * result + references.hashCode();

        return result;

    }

}