/*
 * 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;

import com.juick.components.s2s.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import org.xmlpull.v1.XmlPullParserException;
import rocks.xmpp.core.stanza.model.Stanza;
import rocks.xmpp.util.XmppUtils;

import javax.annotation.PostConstruct;
import javax.inject.Inject;
import javax.xml.bind.JAXBException;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamWriter;
import java.io.IOException;
import java.io.StringWriter;
import java.net.ServerSocket;
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.Iterator;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ExecutorService;

/**
 * @author ugnich
 */
@Component
public class XMPPServer implements AutoCloseable {
    private static final Logger logger = LoggerFactory.getLogger(XMPPServer.class);

    @Inject
    public ExecutorService service;
    @Value("${hostname}")
    public String HOSTNAME;
    @Value("${s2s_port:5269}")
    private int s2sPort;
    @Value("${keystore}")
    public String keystore;
    @Value("${keystore_password}")
    public String keystorePassword;
    @Value("${broken_ssl_hosts}")
    public String[] brokenSSLhosts;
    @Value("${banned_hosts}")
    public String[] bannedHosts;

    private final List<ConnectionIn> inConnections = new CopyOnWriteArrayList<>();
    private final List<ConnectionOut> outConnections = new CopyOnWriteArrayList<>();
    private final List<CacheEntry> outCache = new CopyOnWriteArrayList<>();
    private final List<StanzaListener> stanzaListeners = new CopyOnWriteArrayList<>();


    private ServerSocket listener;

    @Inject
    private BasicXmppSession session;

    @PostConstruct
    public void init() {

        logger.info("component initialized");
        service.submit(() -> {
            try {
                listener = new ServerSocket(s2sPort);
                logger.info("s2s listener ready");
                while (!listener.isClosed()) {
                    if (Thread.currentThread().isInterrupted()) break;
                    Socket socket = listener.accept();
                    ConnectionIn client = new ConnectionIn(this, socket);
                    addConnectionIn(client);
                    service.submit(client);
                }
            } catch (SocketException e) {
                // shutdown
            } catch (IOException | CertificateException | NoSuchAlgorithmException | UnrecoverableKeyException | KeyStoreException | XmlPullParserException | KeyManagementException e) {
                logger.warn("xmpp exception", e);
            }
        });
    }

    @Override
    public void close() throws Exception {
        if (!listener.isClosed()) {
            listener.close();
        }
        outConnections.forEach(c -> {
            c.closeConnection();
            outConnections.remove(c);
        });
        inConnections.forEach(c -> {
            c.closeConnection();
            inConnections.remove(c);
        });
        if (!listener.isClosed()) {
            listener.close();
        }
        service.shutdown();
        logger.info("XMPP server destroyed");
    }

    public void addConnectionIn(ConnectionIn c) {
        inConnections.add(c);
    }

    public void addConnectionOut(ConnectionOut c) {
        outConnections.add(c);
    }

    public void removeConnectionIn(ConnectionIn c) {
        inConnections.remove(c);
    }

    public void removeConnectionOut(ConnectionOut c) {
        outConnections.remove(c);
    }

    public String getFromCache(String hostname) {
        final String[] cache = new String[1];
        outCache.stream().filter(c -> c.hostname != null && c.hostname.equals(hostname)).findFirst().ifPresent(c -> {
            cache[0] = c.xml;
            outCache.remove(c);
        });
        return cache[0];
    }

    public Optional<ConnectionOut> getConnectionOut(String hostname, boolean needReady) {
        return outConnections.stream().filter(c -> c.to != null &&
                c.to.equals(hostname) && (!needReady || c.streamReady)).findFirst();
    }

    public Optional<ConnectionIn> getConnectionIn(String streamID) {
        return inConnections.stream().filter(c -> c.streamID != null && c.streamID.equals(streamID)).findFirst();
    }

    public void sendOut(Stanza s) {
        try {
            StringWriter stanzaWriter = new StringWriter();
            XMLStreamWriter xmppStreamWriter = XmppUtils.createXmppStreamWriter(
                    session.getConfiguration().getXmlOutputFactory().createXMLStreamWriter(stanzaWriter));
            session.createMarshaller().marshal(s, xmppStreamWriter);
            xmppStreamWriter.flush();
            xmppStreamWriter.close();
            String xml = stanzaWriter.toString();
            logger.info("s2s (out): {}", xml);
            sendOut(s.getTo().getDomain(), xml);
        } catch (XMLStreamException | JAXBException e1) {
            logger.info("jaxb exception", e1);
        }
    }

    public void sendOut(String hostname, String xml) {
        boolean haveAnyConn = false;

        ConnectionOut connOut = null;
        for (ConnectionOut c : outConnections) {
            if (c.to != null && c.to.equals(hostname)) {
                if (c.streamReady) {
                    connOut = c;
                    break;
                } else {
                    haveAnyConn = true;
                    break;
                }
            }
        }
        if (connOut != null) {
            connOut.sendStanza(xml);
            return;
        }

        boolean haveCache = false;
        for (CacheEntry c : outCache) {
            if (c.hostname != null && c.hostname.equals(hostname)) {
                c.xml += xml;
                c.tsUpdated = System.currentTimeMillis();
                haveCache = true;
                break;
            }
        }
        if (!haveCache) {
            outCache.add(new CacheEntry(hostname, xml));
        }

        if (!haveAnyConn) {
            try {
                ConnectionOut connectionOut = new ConnectionOut(this, hostname);
                addConnectionOut(connectionOut);
                service.submit(connectionOut);
            } catch (CertificateException | UnrecoverableKeyException | NoSuchAlgorithmException | XmlPullParserException | KeyStoreException | KeyManagementException | IOException e) {
                logger.error("s2s out error", e);
            }
        }
    }

    public void startDialback(String from, String streamId, String dbKey) throws Exception {
        Optional<ConnectionOut> c = getConnectionOut(from, false);
        if (c.isPresent()) {
            c.get().sendDialbackVerify(streamId, dbKey);
        } else {
            ConnectionOut newConnection = new ConnectionOut(this, from, streamId, dbKey);
            addConnectionOut(newConnection);
            service.submit(newConnection);
        }
    }

    public void addStanzaListener(StanzaListener listener) {
        stanzaListeners.add(listener);
    }

    public void onStanzaReceived(Stanza xmlValue) {
        stanzaListeners.forEach(l -> l.stanzaReceived(xmlValue));
    }

    public BasicXmppSession getSession() {
        return session;
    }

    public List<ConnectionIn> getInConnections() {
        return inConnections;
    }

    public List<ConnectionOut> getOutConnections() {
        return outConnections;
    }
}