/**
 * 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.
 */
package org.apache.xml.security.keys.keyresolver.implementations;

import java.security.PublicKey;
import java.security.cert.Certificate;
import java.security.cert.X509Certificate;
import java.util.Iterator;


import org.apache.xml.security.exceptions.XMLSecurityException;
import org.apache.xml.security.keys.content.x509.XMLX509SKI;
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.utils.Constants;
import org.apache.xml.security.utils.XMLUtils;
import org.w3c.dom.Element;

public class X509SKIResolver extends KeyResolverSpi {

    private static org.slf4j.Logger log =
        org.slf4j.LoggerFactory.getLogger(X509SKIResolver.class);


    /**
     * Method engineResolvePublicKey
     *
     * @param element
     * @param baseURI
     * @param storage
     * @return null if no {@link PublicKey} could be obtained
     * @throws KeyResolverException
     */
    public PublicKey engineLookupAndResolvePublicKey(
        Element element, String baseURI, StorageResolver storage
    ) throws KeyResolverException {

        X509Certificate cert = 
            this.engineLookupResolveX509Certificate(element, baseURI, storage);

        if (cert != null) {
            return cert.getPublicKey();
        }

        return null;
    }

    /**
     * Method engineResolveX509Certificate
     * @inheritDoc
     * @param element
     * @param baseURI
     * @param storage
     *
     * @throws KeyResolverException
     */
    public X509Certificate engineLookupResolveX509Certificate(
        Element element, String baseURI, StorageResolver storage
    ) throws KeyResolverException {
        if (log.isDebugEnabled()) {
            log.debug("Can I resolve " + element.getTagName() + "?");
        }	      
        if (!XMLUtils.elementIsInSignatureSpace(element, Constants._TAG_X509DATA)) {
            if (log.isDebugEnabled()) {
                log.debug("I can't");
            }
            return null;
        }
        /** Field _x509childObject[] */
        XMLX509SKI x509childObject[] = null;

        Element x509childNodes[] = null;
        x509childNodes = XMLUtils.selectDsNodes(element.getFirstChild(), Constants._TAG_X509SKI);

        if (!(x509childNodes != null && x509childNodes.length > 0)) {
            if (log.isDebugEnabled()) {
                log.debug("I can't");
            }
            return null;
        }
        try {         
            if (storage == null) {
                Object exArgs[] = { Constants._TAG_X509SKI };
                KeyResolverException ex =
                    new KeyResolverException("KeyResolver.needStorageResolver", exArgs);

                if (log.isDebugEnabled()) {
                    log.debug("", ex);
                }

                throw ex;
            }

            x509childObject = new XMLX509SKI[x509childNodes.length];

            for (int i = 0; i < x509childNodes.length; i++) {
                x509childObject[i] = new XMLX509SKI(x509childNodes[i], baseURI);
            }

            Iterator<Certificate> storageIterator = storage.getIterator();
            while (storageIterator.hasNext()) {
                X509Certificate cert = (X509Certificate)storageIterator.next();
                XMLX509SKI certSKI = new XMLX509SKI(element.getOwnerDocument(), cert);

                for (int i = 0; i < x509childObject.length; i++) {
                    if (certSKI.equals(x509childObject[i])) {
                        if (log.isDebugEnabled()) {
                            log.debug("Return PublicKey from " + cert.getSubjectX500Principal().getName());
                        }

                        return cert;
                    }
                }
            }
        } catch (XMLSecurityException ex) {
            throw new KeyResolverException("empty", ex);
        }

        return null;
    }

    /**
     * Method engineResolveSecretKey
     * @inheritDoc
     * @param element
     * @param baseURI
     * @param storage
     *
     */
    public javax.crypto.SecretKey engineLookupAndResolveSecretKey(
        Element element, String baseURI, StorageResolver storage
    ) {
        return null;
    }
}
