/*
 * 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.pdfbox.pdmodel.encryption;

import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * The protection policy to use to protect a document with the public key security handler.
 *
 * PDF documents are encrypted so that they can be decrypted by
 * one or more recipients. Each recipient have its own access permission.
 *
 * The following code sample shows how to protect a document using
 * the public key security handler. In this code sample, <code>doc</code> is
 * a <code>PDDocument</code> object.
 *
 * <pre>
 * PublicKeyProtectionPolicy policy = new PublicKeyProtectionPolicy();
 * PublicKeyRecipient recip = new PublicKeyRecipient();
 * AccessPermission ap = new AccessPermission();
 * ap.setCanModify(false);
 * recip.setPermission(ap);
 *
 * // load the recipient's certificate
 * InputStream inStream = new FileInputStream(certificate_path);
 * CertificateFactory cf = CertificateFactory.getInstance("X.509");
 * X509Certificate certificate = (X509Certificate)cf.generateCertificate(inStream);
 * inStream.close();
 *
 * recip.setX509(certificate); // set the recipient's certificate
 * policy.addRecipient(recip);
 * policy.setEncryptionKeyLength(128); // the document will be encrypted with 128 bits secret key
 * doc.protect(policy);
 * doc.save(out);
 * </pre>
 *
 * @see org.apache.pdfbox.pdmodel.PDDocument#protect(ProtectionPolicy)
 * @see AccessPermission
 * @see PublicKeyRecipient
 * @author Benoit Guillon
 */
public final class PublicKeyProtectionPolicy extends ProtectionPolicy
{
    private final List<PublicKeyRecipient> recipients = new ArrayList<>();
    private X509Certificate decryptionCertificate;

    /**
     * Creates a new PublicKeyProtectionPolicy with an empty recipients list.
     */
    public PublicKeyProtectionPolicy()
    {
    }

    /**
     * Adds a new recipient to the recipients list.
     * @param recipient A new recipient.
     */
    public void addRecipient(PublicKeyRecipient recipient)
    {
        recipients.add(recipient);
    }

    /**
     * Removes a recipient from the recipients list.
     * @param recipient The recipient to remove.
     * @return true If a recipient was found and removed.
     */
    public boolean removeRecipient(PublicKeyRecipient recipient)
    {
        return recipients.remove(recipient);
    }

    /**
     * Returns an iterator to browse the list of recipients.
     * Object found in this iterator are <code>PublicKeyRecipient</code>.
     * @return The recipients list iterator.
     */
    public Iterator<PublicKeyRecipient> getRecipientsIterator()
    {
        return recipients.iterator();
    }

    /**
     * Returns the decryption certificate.
     * @return the decryption certificate
     */
    public X509Certificate getDecryptionCertificate()
    {
        return decryptionCertificate;
    }

    /**
     * Sets the decryption certificate
     * @param decryptionCertificate the new decryption certificate.
     */
    public void setDecryptionCertificate(X509Certificate decryptionCertificate)
    {
        this.decryptionCertificate = decryptionCertificate;
    }

    /**
     * Returns the number of recipients
     * @return the number of recipients
     */
    public int getNumberOfRecipients()
    {
        return recipients.size();
    }
}
