/*
 * 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.
/**
 * 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.
 */
/*
 * Portions copyright (c) 2005, 2018, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * ===========================================================================
 *
 * (C) Copyright IBM Corp. 2003 All Rights Reserved.
 *
 * ===========================================================================
 */
/*
 * $Id: DOMRetrievalMethod.java 1788465 2017-03-24 15:10:51Z coheigea $
 */
package org.jcp.xml.dsig.internal.dom;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.net.URI;
import java.net.URISyntaxException;
import java.security.Provider;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import javax.xml.crypto.Data;
import javax.xml.crypto.MarshalException;
import javax.xml.crypto.NodeSetData;
import javax.xml.crypto.URIDereferencer;
import javax.xml.crypto.URIReferenceException;
import javax.xml.crypto.XMLCryptoContext;
import javax.xml.crypto.XMLStructure;
import javax.xml.crypto.dom.DOMCryptoContext;
import javax.xml.crypto.dom.DOMURIReference;
import javax.xml.crypto.dsig.Transform;
import javax.xml.crypto.dsig.XMLSignature;
import javax.xml.crypto.dsig.keyinfo.RetrievalMethod;
import javax.xml.parsers.DocumentBuilder;

import com.sun.org.apache.xml.internal.security.utils.XMLUtils;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

DOM-based implementation of RetrievalMethod.
/**
 * DOM-based implementation of RetrievalMethod.
 *
 */
public final class DOMRetrievalMethod extends DOMStructure
    implements RetrievalMethod, DOMURIReference {

    private final List<Transform> transforms;
    private String uri;
    private String type;
    private Attr here;

    
Creates a DOMRetrievalMethod containing the specified URIReference and List of Transforms. 
Params:
uri – the URI
type – the type
transforms – a list of Transforms. The list is defensively copied to prevent subsequent modification. May be null or empty.
Throws:
IllegalArgumentException – if the format of uri is invalid, as specified by Reference's URI attribute in the W3C specification for XML-Signature Syntax and Processing
NullPointerException – if uriReference is null
ClassCastException – if transforms contains any entries that are not of type Transform/**
     * Creates a {@code DOMRetrievalMethod} containing the specified
     * URIReference and List of Transforms.
     *
     * @param uri the URI
     * @param type the type
     * @param transforms a list of {@link Transform}s. The list is defensively
     *    copied to prevent subsequent modification. May be {@code null}
     *    or empty.
     * @throws IllegalArgumentException if the format of {@code uri} is
     *    invalid, as specified by Reference's URI attribute in the W3C
     *    specification for XML-Signature Syntax and Processing
     * @throws NullPointerException if {@code uriReference}
     *    is {@code null}
     * @throws ClassCastException if {@code transforms} contains any
     *    entries that are not of type {@link Transform}
     */
    public DOMRetrievalMethod(String uri, String type,
                              List<? extends Transform> transforms)
    {
        if (uri == null) {
            throw new NullPointerException("uri cannot be null");
        }
        if (transforms == null || transforms.isEmpty()) {
            this.transforms = Collections.emptyList();
        } else {
            this.transforms = Collections.unmodifiableList(
                new ArrayList<>(transforms));
            for (int i = 0, size = this.transforms.size(); i < size; i++) {
                if (!(this.transforms.get(i) instanceof Transform)) {
                    throw new ClassCastException
                        ("transforms["+i+"] is not a valid type");
                }
            }
        }
        this.uri = uri;
        if (!uri.equals("")) {
            try {
                new URI(uri);
            } catch (URISyntaxException e) {
                throw new IllegalArgumentException(e.getMessage());
            }
        }

        this.type = type;
    }

    
Creates a DOMRetrievalMethod from an element. 
Params:
rmElem – a RetrievalMethod element/**
     * Creates a {@code DOMRetrievalMethod} from an element.
     *
     * @param rmElem a RetrievalMethod element
     */
    public DOMRetrievalMethod(Element rmElem, XMLCryptoContext context,
                              Provider provider)
        throws MarshalException
    {
        // get URI and Type attributes
        uri = DOMUtils.getAttributeValue(rmElem, "URI");
        type = DOMUtils.getAttributeValue(rmElem, "Type");

        // get here node
        here = rmElem.getAttributeNodeNS(null, "URI");

        boolean secVal = Utils.secureValidation(context);

        // get Transforms, if specified
        List<Transform> newTransforms = new ArrayList<>();
        Element transformsElem = DOMUtils.getFirstChildElement(rmElem);

        if (transformsElem != null) {
            String localName = transformsElem.getLocalName();
            String namespace = transformsElem.getNamespaceURI();
            if (!"Transforms".equals(localName) || !XMLSignature.XMLNS.equals(namespace)) {
                throw new MarshalException("Invalid element name: " +
                                           namespace + ":" + localName + ", expected Transforms");
            }
            Element transformElem =
                DOMUtils.getFirstChildElement(transformsElem, "Transform", XMLSignature.XMLNS);
            while (transformElem != null) {
                String name = transformElem.getLocalName();
                namespace = transformElem.getNamespaceURI();
                if (!"Transform".equals(name) || !XMLSignature.XMLNS.equals(namespace)) {
                    throw new MarshalException("Invalid element name: " +
                                               name + ", expected Transform");
                }
                newTransforms.add
                    (new DOMTransform(transformElem, context, provider));
                if (secVal && Policy.restrictNumTransforms(newTransforms.size())) {
                    String error = "A maximum of " + Policy.maxTransforms()
                        + " transforms per Reference are allowed when"
                        + " secure validation is enabled";
                    throw new MarshalException(error);
                }
                transformElem = DOMUtils.getNextSiblingElement(transformElem);
            }
        }
        if (newTransforms.isEmpty()) {
            this.transforms = Collections.emptyList();
        } else {
            this.transforms = Collections.unmodifiableList(newTransforms);
        }
    }

    public String getURI() {
        return uri;
    }

    public String getType() {
        return type;
    }

    public List<Transform> getTransforms() {
        return transforms;
    }

    @Override
    public void marshal(Node parent, String dsPrefix, DOMCryptoContext context)
        throws MarshalException
    {
        Document ownerDoc = DOMUtils.getOwnerDocument(parent);
        Element rmElem = DOMUtils.createElement(ownerDoc, "RetrievalMethod",
                                                XMLSignature.XMLNS, dsPrefix);

        // add URI and Type attributes
        DOMUtils.setAttribute(rmElem, "URI", uri);
        DOMUtils.setAttribute(rmElem, "Type", type);

        // add Transforms elements
        if (!transforms.isEmpty()) {
            Element transformsElem = DOMUtils.createElement(ownerDoc,
                                                            "Transforms",
                                                            XMLSignature.XMLNS,
                                                            dsPrefix);
            rmElem.appendChild(transformsElem);
            for (Transform transform : transforms) {
                ((DOMTransform)transform).marshal(transformsElem,
                                                   dsPrefix, context);
            }
        }

        parent.appendChild(rmElem);

        // save here node
        here = rmElem.getAttributeNodeNS(null, "URI");
    }

    public Node getHere() {
        return here;
    }

    public Data dereference(XMLCryptoContext context)
        throws URIReferenceException
    {
        if (context == null) {
            throw new NullPointerException("context cannot be null");
        }

        /*
         * If URIDereferencer is specified in context; use it, otherwise use
         * built-in.
         */
        URIDereferencer deref = context.getURIDereferencer();
        if (deref == null) {
            deref = DOMURIDereferencer.INSTANCE;
        }

        Data data = deref.dereference(this, context);

        // pass dereferenced data through Transforms
        try {
            for (Transform transform : transforms) {
                data = ((DOMTransform)transform).transform(data, context);
            }
        } catch (Exception e) {
            throw new URIReferenceException(e);
        }

        // guard against RetrievalMethod loops
        if (data instanceof NodeSetData && Utils.secureValidation(context)
                && Policy.restrictRetrievalMethodLoops()) {
            NodeSetData nsd = (NodeSetData)data;
            Iterator<?> i = nsd.iterator();
            if (i.hasNext()) {
                Node root = (Node)i.next();
                if ("RetrievalMethod".equals(root.getLocalName())) {
                    throw new URIReferenceException(
                        "It is forbidden to have one RetrievalMethod point " +
                        "to another when secure validation is enabled");
                }
            }
        }

        return data;
    }

    public XMLStructure dereferenceAsXMLStructure(XMLCryptoContext context)
        throws URIReferenceException
    {
        DocumentBuilder db = null;
        boolean secVal = Utils.secureValidation(context);
        ApacheData data = (ApacheData)dereference(context);
        try (InputStream is = new ByteArrayInputStream(data.getXMLSignatureInput().getBytes())) {
            db = XMLUtils.createDocumentBuilder(false, secVal);
            Document doc = db.parse(is);
            Element kiElem = doc.getDocumentElement();
            if (kiElem.getLocalName().equals("X509Data")
                && XMLSignature.XMLNS.equals(kiElem.getNamespaceURI())) {
                return new DOMX509Data(kiElem);
            } else {
                return null; // unsupported
            }
        } catch (Exception e) {
            throw new URIReferenceException(e);
        }
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (!(obj instanceof RetrievalMethod)) {
            return false;
        }
        RetrievalMethod orm = (RetrievalMethod)obj;

        boolean typesEqual = type == null ? orm.getType() == null
                                           : type.equals(orm.getType());

        return uri.equals(orm.getURI()) &&
            transforms.equals(orm.getTransforms()) && typesEqual;
    }

    @Override
    public int hashCode() {
        int result = 17;
        if (type != null) {
            result = 31 * result + type.hashCode();
        }
        result = 31 * result + uri.hashCode();
        result = 31 * result + transforms.hashCode();

        return result;
    }
}