/**
 *
 * Copyright 2017-2020 Florian Schmaus, 2018 Paul Schaub.
 *
 * Licensed 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.jivesoftware.smackx.ox.element;

import java.io.ByteArrayInputStream;
import java.io.InputStream;

import javax.xml.namespace.QName;

import org.jivesoftware.smack.packet.ExtensionElement;
import org.jivesoftware.smack.packet.Stanza;
import org.jivesoftware.smack.util.StringUtils;
import org.jivesoftware.smack.util.XmlStringBuilder;

import org.jivesoftware.smack.util.stringencoder.Base64;
import org.jivesoftware.smackx.ox.util.Util;

/**
 * Class that represents an OpenPGP message.
 * The content of this elements text is an base64 encoded , OpenPGP encrypted/signed content element ({@link SignElement},
 * {@link SigncryptElement}, {@link CryptElement}).
 *
 * @see <a href="https://xmpp.org/extensions/xep-0373.html#exchange">
 *     XEP-0373: §3.1 Exchanging OpenPGP Encrypted and Signed Data</a>
 */
public class OpenPgpElement implements ExtensionElement {

    public static final String ELEMENT = "openpgp";
    public static final String NAMESPACE = "urn:xmpp:openpgp:0";
    public static final QName QNAME = new QName(NAMESPACE, ELEMENT);

    // Represents the OpenPGP message, but encoded using base64.
    private final String base64EncodedOpenPgpMessage;

    public OpenPgpElement(String base64EncodedOpenPgpMessage) {
        this.base64EncodedOpenPgpMessage = StringUtils.requireNotNullNorEmpty(base64EncodedOpenPgpMessage,
                "base64 encoded message MUST NOT be null nor empty.");
    }

    public InputStream toInputStream() {
        return new ByteArrayInputStream(
                Base64.decode(base64EncodedOpenPgpMessage.getBytes(Util.UTF8)));
    }

    /**
     * Return the OpenPGP encrypted payload.
     *
     * @return OpenPGP encrypted payload.
     */
    public String getEncryptedBase64MessageContent() {
        return base64EncodedOpenPgpMessage;
    }

    @Override
    public String getElementName() {
        return ELEMENT;
    }

    @Override
    public String getNamespace() {
        return NAMESPACE;
    }

    @Override
    public QName getQName() {
        return QNAME;
    }

    @Override
    public XmlStringBuilder toXML(org.jivesoftware.smack.packet.XmlEnvironment enclosingNamespace) {
        XmlStringBuilder xml = new XmlStringBuilder(this);
        xml.rightAngleBracket().append(base64EncodedOpenPgpMessage).closeElement(this);
        return xml;
    }

    public static OpenPgpElement fromStanza(Stanza stanza) {
        return stanza.getExtension(OpenPgpElement.class);
    }
}