/*
 * Copyright (C) 2008-2017, Juick
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * 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/>.
 */

package com.juick.components.s2s;

import com.juick.components.XMPPServer;
import com.juick.components.s2s.util.DialbackUtils;
import com.juick.xmpp.extensions.StreamError;
import com.juick.xmpp.extensions.StreamFeatures;
import com.juick.xmpp.utils.XmlUtils;
import org.apache.commons.text.RandomStringGenerator;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import javax.net.ssl.SSLException;
import javax.net.ssl.SSLSocket;
import java.io.EOFException;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketException;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.UnrecoverableKeyException;
import java.security.cert.CertificateException;
import java.util.UUID;

/**
 * @author ugnich
 */
public class ConnectionOut extends Connection implements Runnable {

    public boolean streamReady = false;
    public String to;
    String checkSID = null;
    String dbKey = null;
    RandomStringGenerator generator = new RandomStringGenerator.Builder().withinRange('a', 'z').build();

    public ConnectionOut(XMPPServer xmpp, String hostname) throws CertificateException, UnrecoverableKeyException, NoSuchAlgorithmException, XmlPullParserException, KeyManagementException, KeyStoreException, IOException {
        super(xmpp);
        to = hostname;
        dbKey = DialbackUtils.generateDialbackKey(generator.generate(15), to, xmpp.HOSTNAME, streamID);
    }

    public ConnectionOut(XMPPServer xmpp, String hostname, String checkSID, String dbKey) throws Exception {
        super(xmpp);
        to = hostname;
        this.checkSID = checkSID;
        this.dbKey = dbKey;
        streamID = UUID.randomUUID().toString();
    }

    void sendOpenStream() throws IOException {
        sendStanza("<?xml version='1.0'?><stream:stream xmlns='jabber:server' id='" + streamID +
                "' xmlns:stream='http://etherx.jabber.org/streams' xmlns:db='jabber:server:dialback' from='" +
                xmpp.HOSTNAME + "' to='" + to + "' version='1.0'>");
    }

    void processDialback() throws Exception {
        if (checkSID != null) {
            sendDialbackVerify(checkSID, dbKey);
        }
        sendStanza("<db:result from='" + xmpp.HOSTNAME + "' to='" + to + "'>" +
                 dbKey + "</db:result>");
    }

    @Override
    public void run() {
        logger.info("stream to {} start", to);
        try {
            socket = new Socket();
            InetSocketAddress address = DNSQueries.getServerAddress(to);
            socket.connect(address);
            restartParser();

            sendOpenStream();

            parser.next(); // stream:stream
            streamID = parser.getAttributeValue(null, "id");
            if (streamID == null || streamID.isEmpty()) {
                throw new Exception("stream to " + to + " invalid first packet");
            }

            logger.info("stream to {} {} open", to, streamID);
            xmpp.addConnectionOut(ConnectionOut.this);
            boolean xmppversionnew = parser.getAttributeValue(null, "version") != null;
            if (!xmppversionnew) {
                processDialback();
            }

            while (parser.next() != XmlPullParser.END_DOCUMENT) {
                if (parser.getEventType() != XmlPullParser.START_TAG) {
                    continue;
                }
                logParser();

                String tag = parser.getName();
                if (tag.equals("result") && parser.getNamespace().equals(NS_DB)) {
                    String type = parser.getAttributeValue(null, "type");
                    if (type != null && type.equals("valid")) {
                        streamReady = true;
                        logger.info("stream to {} {} ready", to, streamID);

                        String cache = xmpp.getFromCache(to);
                        if (cache != null) {
                            logger.info("stream to {} {} sending cache", to, streamID);
                            sendStanza(cache);
                        }

                    } else {
                        logger.info("stream to {} {} dialback fail", to, streamID);
                    }
                    XmlUtils.skip(parser);
                } else if (tag.equals("verify") && parser.getNamespace().equals(NS_DB)) {
                    String from = parser.getAttributeValue(null, "from");
                    String type = parser.getAttributeValue(null, "type");
                    String sid = parser.getAttributeValue(null, "id");
                    if (from != null && from.equals(to) && sid != null && !sid.isEmpty() && type != null) {
                        ConnectionIn c = xmpp.getConnectionIn(sid);
                        if (c != null) {
                            c.sendDialbackResult(from, type);
                        }
                    }
                    XmlUtils.skip(parser);
                } else if (tag.equals("features") && parser.getNamespace().equals(NS_STREAM)) {
                    StreamFeatures features = StreamFeatures.parse(parser);
                    if (sc != null && !isSecured() && features.STARTTLS >= 0 && !xmpp.brokenSSLhosts.contains(to)) {
                        logger.info("stream to {} {} securing", to, streamID);
                        sendStanza("<starttls xmlns=\"" + NS_TLS + "\" />");
                    } else {
                        processDialback();
                    }
                } else if (tag.equals("proceed") && parser.getNamespace().equals(NS_TLS)) {
                    try {
                        socket = sc.getSocketFactory().createSocket(socket, socket.getInetAddress().getHostAddress(),
                                socket.getPort(), true);
                        ((SSLSocket) socket).startHandshake();
                        setSecured(true);
                        logger.info("stream {} secured", streamID);
                        restartParser();
                        sendOpenStream();
                    } catch (SSLException sex) {
                        logger.error("s2s ssl error: {} {}, error {}", to, streamID, sex);
                        sendStanza("<failed xmlns\"" + NS_TLS + "\" />");
                        xmpp.removeConnectionOut(this);
                        closeConnection();
                    }
                } else if (isSecured() && tag.equals("stream") && parser.getNamespace().equals(NS_STREAM)) {
                    streamID = parser.getAttributeValue(null, "id");
                } else if (tag.equals("error")) {
                    StreamError streamError = StreamError.parse(parser);
                    logger.warn("Stream error from {}: {}", streamID, streamError.getCondition());
                    xmpp.removeConnectionOut(this);
                    closeConnection();
                } else {
                    String unhandledStanza = XmlUtils.parseToString(parser, true);
                    logger.warn("Unhandled stanza from {} {} : {}", to, streamID, unhandledStanza);
                }
            }

            logger.warn("stream to {} {} finished", to, streamID);
            xmpp.removeConnectionOut(ConnectionOut.this);
            closeConnection();
        } catch (EOFException | SocketException eofex) {
            logger.info("stream {} {} closed (dirty)", to, streamID);
            xmpp.removeConnectionOut(ConnectionOut.this);
            closeConnection();
        } catch (Exception e) {
            logger.error("s2s out exception: {} {}, exception {}", to, streamID, e);
            xmpp.removeConnectionOut(ConnectionOut.this);
            closeConnection();
        }
    }

    public void sendDialbackVerify(String sid, String key) {
        sendStanza("<db:verify from='" + xmpp.HOSTNAME + "' to='" + to + "' id='" + sid + "'>" +
                key + "</db:verify>");
    }

    @Override
    public void restartParser() throws XmlPullParserException, IOException {
        super.restartParser();
        streamID = UUID.randomUUID().toString();
    }
}