/*
 *
 * This file is part of the iText (R) project.
    Copyright (c) 1998-2017 iText Group NV
 * Authors: Bruno Lowagie, Paulo Soares, et al.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
 * ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
 * OF THIRD PARTY RIGHTS
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Affero General Public License for more details.
 * You should have received a copy of the GNU Affero General Public License
 * along with this program; if not, see http://www.gnu.org/licenses or write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA, 02110-1301 USA, or download the license from the following URL:
 * http://itextpdf.com/terms-of-use/
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * In accordance with Section 7(b) of the GNU Affero General Public License,
 * a covered work must retain the producer line in every PDF that is created
 * or manipulated using iText.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the iText software without
 * disclosing the source code of your own applications.
 * These activities include: offering paid services to customers as an ASP,
 * serving PDFs on the fly in a web application, shipping iText with a closed
 * source product.
 *
 * For more information, please contact iText Software Corp. at this
 * address: sales@itextpdf.com
 */
package com.itextpdf.text.pdf.security;

import java.io.IOException;
import java.security.GeneralSecurityException;
import java.security.KeyStore;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Date;
import java.util.Enumeration;
import java.util.List;

import com.itextpdf.text.log.Logger;
import com.itextpdf.text.log.LoggerFactory;

/**
 * Verifies a certificate against a <code>KeyStore</code>
 * containing trusted anchors.
 */
public class RootStoreVerifier extends CertificateVerifier {
	
	/** The Logger instance */
	protected final static Logger LOGGER = LoggerFactory.getLogger(RootStoreVerifier.class);

	/** A key store against which certificates can be verified. */
	protected KeyStore rootStore = null;

	/**
	 * Creates a RootStoreVerifier in a chain of verifiers.
	 * 
	 * @param verifier
	 *            the next verifier in the chain
	 */
	public RootStoreVerifier(CertificateVerifier verifier) {
		super(verifier);
	}

	/**
	 * Sets the Key Store against which a certificate can be checked.
	 * 
	 * @param keyStore
	 *            a root store
	 */
	public void setRootStore(KeyStore keyStore) {
		this.rootStore = keyStore;
	}

	/**
	 * Verifies a single certificate against a key store (if present).
	 * 
	 * @param signCert
	 *            the certificate to verify
	 * @param issuerCert
	 *            the issuer certificate
	 * @param signDate
	 *            the date the certificate needs to be valid
	 * @return a list of <code>VerificationOK</code> objects.
	 * The list will be empty if the certificate couldn't be verified.
	 */
	public List<VerificationOK> verify(X509Certificate signCert, X509Certificate issuerCert,
			Date signDate) throws GeneralSecurityException, IOException {
		LOGGER.info("Root store verification: " + signCert.getSubjectDN().getName());
		// verify using the CertificateVerifier if root store is missing
		if (rootStore == null)
			return super.verify(signCert, issuerCert, signDate);
		try {
			List<VerificationOK> result = new ArrayList<VerificationOK>();
			// loop over the trusted anchors in the root store
			for (Enumeration<String> aliases = rootStore.aliases(); aliases.hasMoreElements();) {
				String alias = aliases.nextElement();
				try {
					if (!rootStore.isCertificateEntry(alias))
						continue;
					X509Certificate anchor = (X509Certificate) rootStore
							.getCertificate(alias);
					signCert.verify(anchor.getPublicKey());
					LOGGER.info("Certificate verified against root store");
					result.add(new VerificationOK(signCert, this.getClass(), "Certificate verified against root store."));
					result.addAll(super.verify(signCert, issuerCert, signDate));
					return result;
				} catch (GeneralSecurityException e) {
					continue;
				}
			}
			result.addAll(super.verify(signCert, issuerCert, signDate));
			return result;
		} catch (GeneralSecurityException e) {
			return super.verify(signCert, issuerCert, signDate);
		}
	}
}
