package de.pixart.messenger.xmpp;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.SystemClock;
import android.security.KeyChain;
import android.support.annotation.NonNull;
import android.util.Base64;
import android.util.Log;
import android.util.Pair;
import android.util.SparseArray;

import org.xmlpull.v1.XmlPullParserException;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ConnectException;
import java.net.IDN;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.MalformedURLException;
import java.net.Socket;
import java.net.URL;
import java.net.UnknownHostException;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.Principal;
import java.security.PrivateKey;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.Random;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.regex.Matcher;

import javax.net.ssl.KeyManager;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.X509KeyManager;
import javax.net.ssl.X509TrustManager;

import de.pixart.messenger.Config;
import de.pixart.messenger.R;
import de.pixart.messenger.crypto.DomainHostnameVerifier;
import de.pixart.messenger.crypto.XmppDomainVerifier;
import de.pixart.messenger.crypto.axolotl.AxolotlService;
import de.pixart.messenger.crypto.sasl.Anonymous;
import de.pixart.messenger.crypto.sasl.DigestMd5;
import de.pixart.messenger.crypto.sasl.External;
import de.pixart.messenger.crypto.sasl.Plain;
import de.pixart.messenger.crypto.sasl.SaslMechanism;
import de.pixart.messenger.crypto.sasl.ScramSha1;
import de.pixart.messenger.crypto.sasl.ScramSha256;
import de.pixart.messenger.entities.Account;
import de.pixart.messenger.entities.Message;
import de.pixart.messenger.entities.ServiceDiscoveryResult;
import de.pixart.messenger.generator.IqGenerator;
import de.pixart.messenger.persistance.FileBackend;
import de.pixart.messenger.services.MemorizingTrustManager;
import de.pixart.messenger.services.MessageArchiveService;
import de.pixart.messenger.services.NotificationService;
import de.pixart.messenger.services.XmppConnectionService;
import de.pixart.messenger.utils.CryptoHelper;
import de.pixart.messenger.utils.Namespace;
import de.pixart.messenger.utils.Patterns;
import de.pixart.messenger.utils.Resolver;
import de.pixart.messenger.utils.SSLSocketHelper;
import de.pixart.messenger.utils.SocksSocketFactory;
import de.pixart.messenger.utils.XmlHelper;
import de.pixart.messenger.xml.Element;
import de.pixart.messenger.xml.Tag;
import de.pixart.messenger.xml.TagWriter;
import de.pixart.messenger.xml.XmlReader;
import de.pixart.messenger.xmpp.forms.Data;
import de.pixart.messenger.xmpp.forms.Field;
import de.pixart.messenger.xmpp.jingle.OnJinglePacketReceived;
import de.pixart.messenger.xmpp.jingle.stanzas.JinglePacket;
import de.pixart.messenger.xmpp.stanzas.AbstractAcknowledgeableStanza;
import de.pixart.messenger.xmpp.stanzas.AbstractStanza;
import de.pixart.messenger.xmpp.stanzas.IqPacket;
import de.pixart.messenger.xmpp.stanzas.MessagePacket;
import de.pixart.messenger.xmpp.stanzas.PresencePacket;
import de.pixart.messenger.xmpp.stanzas.csi.ActivePacket;
import de.pixart.messenger.xmpp.stanzas.csi.InactivePacket;
import de.pixart.messenger.xmpp.stanzas.streammgmt.AckPacket;
import de.pixart.messenger.xmpp.stanzas.streammgmt.EnablePacket;
import de.pixart.messenger.xmpp.stanzas.streammgmt.RequestPacket;
import de.pixart.messenger.xmpp.stanzas.streammgmt.ResumePacket;
import rocks.xmpp.addr.Jid;

public class XmppConnection implements Runnable {

    private static final int PACKET_IQ = 0;
    private static final int PACKET_MESSAGE = 1;
    private static final int PACKET_PRESENCE = 2;
    public final OnIqPacketReceived registrationResponseListener = new OnIqPacketReceived() {
        @Override
        public void onIqPacketReceived(Account account, IqPacket packet) {
            if (packet.getType() == IqPacket.TYPE.RESULT) {
                account.setOption(Account.OPTION_REGISTER, false);
                throw new StateChangingError(Account.State.REGISTRATION_SUCCESSFUL);
            } else {
                final List<String> PASSWORD_TOO_WEAK_MSGS = Arrays.asList(
                        "The password is too weak",
                        "Please use a longer password.");
                Element error = packet.findChild("error");
                Account.State state = Account.State.REGISTRATION_FAILED;
                mXmppConnectionService.deleteAccount(account);
                if (error != null) {
                    if (error.hasChild("text")) {
                        errorMessage = error.findChildContent("text");
                        Log.d(Config.LOGTAG, "Error creating account : " + error.findChildContent("text"));
                    }
                    if (error.hasChild("conflict")) {
                        state = Account.State.REGISTRATION_CONFLICT;
                    } else if (error.hasChild("resource-constraint")
                            && "wait".equals(error.getAttribute("type"))) {
                        state = Account.State.REGISTRATION_PLEASE_WAIT;
                    } else if (error.hasChild("not-acceptable")
                            && PASSWORD_TOO_WEAK_MSGS.contains(error.findChildContent("text"))) {
                        state = Account.State.REGISTRATION_PASSWORD_TOO_WEAK;
                    }
                }
                Log.d(Config.LOGTAG, "Delete account because of error " + error);
                throw new StateChangingError(state);
            }
        }
    };
    protected final Account account;
    private final Features features = new Features(this);
    private final HashMap<Jid, ServiceDiscoveryResult> disco = new HashMap<>();
    private final SparseArray<AbstractAcknowledgeableStanza> mStanzaQueue = new SparseArray<>();
    private final Hashtable<String, Pair<IqPacket, OnIqPacketReceived>> packetCallbacks = new Hashtable<>();
    private final Set<OnAdvancedStreamFeaturesLoaded> advancedStreamFeaturesLoadedListeners = new HashSet<>();
    private final XmppConnectionService mXmppConnectionService;
    private Socket socket;
    private XmlReader tagReader;
    private TagWriter tagWriter = new TagWriter();
    private boolean shouldAuthenticate = true;
    private boolean inSmacksSession = false;
    private boolean isBound = false;
    private Element streamFeatures;
    private String streamId = null;
    private int smVersion = 3;
    private int stanzasReceived = 0;
    private int stanzasSent = 0;
    private long lastPacketReceived = 0;
    private long lastPingSent = 0;
    private long lastConnect = 0;
    private long lastSessionStarted = 0;
    private long lastDiscoStarted = 0;
    private boolean isMamPreferenceAlways = false;
    private AtomicInteger mPendingServiceDiscoveries = new AtomicInteger(0);
    private AtomicBoolean mWaitForDisco = new AtomicBoolean(true);
    private AtomicBoolean mWaitingForSmCatchup = new AtomicBoolean(false);
    private AtomicInteger mSmCatchupMessageCounter = new AtomicInteger(0);
    private boolean mInteractive = false;
    private int attempt = 0;
    public static String errorMessage = null;
    private OnPresencePacketReceived presenceListener = null;
    private OnJinglePacketReceived jingleListener = null;
    private OnIqPacketReceived unregisteredIqListener = null;
    private OnMessagePacketReceived messageListener = null;
    private OnStatusChanged statusListener = null;
    private OnBindListener bindListener = null;
    private OnMessageAcknowledged acknowledgedListener = null;
    private SaslMechanism saslMechanism;
    private URL redirectionUrl = null;
    private String verifiedHostname = null;
    private volatile Thread mThread;
    private CountDownLatch mStreamCountDownLatch;


    public XmppConnection(final Account account, final XmppConnectionService service) {
        this.account = account;
        this.mXmppConnectionService = service;
    }

    private static void fixResource(Context context, Account account) {
        String resource = account.getResource();
        int fixedPartLength = context.getString(R.string.app_name).length() + 1; //include the trailing dot
        int randomPartLength = 4; // 3 bytes
        if (resource != null && resource.length() > fixedPartLength + randomPartLength) {
            if (validBase64(resource.substring(fixedPartLength, fixedPartLength + randomPartLength))) {
                account.setResource(resource.substring(0, fixedPartLength + randomPartLength));
            }
        }
    }

    private static boolean validBase64(String input) {
        try {
            return Base64.decode(input, Base64.URL_SAFE).length == 3;
        } catch (Throwable throwable) {
            return false;
        }
    }

    private void changeStatus(final Account.State nextStatus) {
        synchronized (this) {
            if (Thread.currentThread().isInterrupted()) {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": not changing status to " + nextStatus + " because thread was interrupted");
                return;
            }
            if (account.getStatus() != nextStatus) {
                if ((nextStatus == Account.State.OFFLINE)
                        && (account.getStatus() != Account.State.CONNECTING)
                        && (account.getStatus() != Account.State.ONLINE)
                        && (account.getStatus() != Account.State.DISABLED)) {
                    return;
                }
                if (nextStatus == Account.State.ONLINE) {
                    this.attempt = 0;
                }
                account.setStatus(nextStatus);
            } else {
                return;
            }
        }
        if (statusListener != null) {
            statusListener.onStatusChanged(account);
        }
    }

    public void prepareNewConnection() {
        this.lastConnect = SystemClock.elapsedRealtime();
        this.lastPingSent = SystemClock.elapsedRealtime();
        this.lastDiscoStarted = Long.MAX_VALUE;
        this.mWaitingForSmCatchup.set(false);
        this.changeStatus(Account.State.CONNECTING);
    }

    public boolean isWaitingForSmCatchup() {
        return mWaitingForSmCatchup.get();
    }

    public void incrementSmCatchupMessageCounter() {
        this.mSmCatchupMessageCounter.incrementAndGet();
    }

    protected void connect() {
        if (mXmppConnectionService.areMessagesInitialized()) {
            mXmppConnectionService.resetSendingToWaiting(account);
        }
        Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": connecting");
        features.encryptionEnabled = false;
        inSmacksSession = false;
        isBound = false;
        this.attempt++;
        this.verifiedHostname = null; //will be set if user entered hostname is being used or hostname was verified with dnssec
        try {
            Socket localSocket;
            shouldAuthenticate = !account.isOptionSet(Account.OPTION_REGISTER);
            this.changeStatus(Account.State.CONNECTING);
            final boolean useTor = mXmppConnectionService.useTorToConnect() || account.isOnion();
            final boolean extended = mXmppConnectionService.showExtendedConnectionOptions();
            if (Config.XMPP_IP != null && Config.XMPP_Ports != null) {
                Integer[] XMPP_Port = Config.XMPP_Ports;
                Integer Port = XMPP_Port[new Random().nextInt(XMPP_Port.length)];
                localSocket = new Socket();
                try {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": connect to " + Config.XMPP_IP + ":" + Port);
                    localSocket.connect(new InetSocketAddress(Config.XMPP_IP, Port), Config.SOCKET_TIMEOUT * 1000);
                } catch (IOException e) {
                    throw new UnknownHostException();
                }
                try {
                    startXmpp(localSocket);
                } catch (InterruptedException e) {
                    Log.d(Config.LOGTAG,account.getJid().asBareJid()+": thread was interrupted before beginning stream");
                    return;
                } catch (Exception e) {
                    throw new IOException(e.getMessage());
                }
            } else if (useTor) {
                String destination;
                if (account.getHostname().isEmpty() || account.isOnion()) {
                    destination = account.getServer();
                } else {
                    destination = account.getHostname();
                    this.verifiedHostname = destination;
                }
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": connect to " + destination + " via Tor");
                localSocket = SocksSocketFactory.createSocketOverTor(destination, account.getPort());
                try {
                    startXmpp(localSocket);
                } catch (InterruptedException e) {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": thread was interrupted before beginning stream");
                    return;
                } catch (Exception e) {
                    throw new IOException(e.getMessage());
                }
            } else {
                final String domain = account.getJid().getDomain();
                final List<Resolver.Result> results;
                final boolean hardcoded = extended && !account.getHostname().isEmpty();
                if (hardcoded) {
                    results = Resolver.fromHardCoded(account.getHostname(), account.getPort());
                } else {
                    results = Resolver.resolve(domain);
                }
                if (Thread.currentThread().isInterrupted()) {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": Thread was interrupted");
                    return;
                }
                if (results.size() == 0) {
                    Log.e(Config.LOGTAG, account.getJid().asBareJid() + ": Resolver results were empty");
                    return;
                }
                final Resolver.Result storedBackupResult;
                if (hardcoded) {
                    storedBackupResult = null;
                } else {
                    storedBackupResult = mXmppConnectionService.databaseBackend.findResolverResult(domain);
                    if (storedBackupResult != null && !results.contains(storedBackupResult)) {
                        results.add(storedBackupResult);
                        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": loaded backup resolver result from db: " + storedBackupResult);
                    }
                }
                for (Iterator<Resolver.Result> iterator = results.iterator(); iterator.hasNext(); ) {
                    final Resolver.Result result = iterator.next();
                    if (Thread.currentThread().isInterrupted()) {
                        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": Thread was interrupted");
                        return;
                    }
                    try {
                        // if tls is true, encryption is implied and must not be started
                        features.encryptionEnabled = result.isDirectTls();
                        verifiedHostname = result.isAuthenticated() ? result.getHostname().toString() : null;
                        Log.d(Config.LOGTAG, "verified hostname " + verifiedHostname);
                        final InetSocketAddress addr;
                        if (result.getIp() != null) {
                            addr = new InetSocketAddress(result.getIp(), result.getPort());
                            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString()
                                    + ": using values from resolver " + (result.getHostname() == null ? "" : result.getHostname().toString()
                                    + "/") + result.getIp().getHostAddress() + ":" + result.getPort() + " tls: " + features.encryptionEnabled);
                        } else {
                            addr = new InetSocketAddress(IDN.toASCII(result.getHostname().toString()), result.getPort());
                            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString()
                                    + ": using values from resolver "
                                    + result.getHostname().toString() + ":" + result.getPort() + " tls: " + features.encryptionEnabled);
                        }

                        if (!features.encryptionEnabled) {
                            localSocket = new Socket();
                            localSocket.connect(addr, Config.SOCKET_TIMEOUT * 1000);
                        } else {
                            final TlsFactoryVerifier tlsFactoryVerifier = getTlsFactoryVerifier();
                            localSocket = tlsFactoryVerifier.factory.createSocket();

                            if (localSocket == null) {
                                throw new IOException("could not initialize ssl socket");
                            }

                            SSLSocketHelper.setSecurity((SSLSocket) localSocket);
                            SSLSocketHelper.setHostname((SSLSocket) localSocket, account.getServer());
                            SSLSocketHelper.setApplicationProtocol((SSLSocket) localSocket, "xmpp-client");

                            localSocket.connect(addr, Config.SOCKET_TIMEOUT * 1000);

                            if (!tlsFactoryVerifier.verifier.verify(account.getServer(), verifiedHostname, ((SSLSocket) localSocket).getSession())) {
                                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": TLS certificate verification failed");
                                FileBackend.close(localSocket);
                                throw new StateChangingException(Account.State.TLS_ERROR);
                            }
                        }
                        localSocket.setSoTimeout(Config.SOCKET_TIMEOUT * 1000);
                        if (startXmpp(localSocket)) {
                            localSocket.setSoTimeout(0); //reset to 0; once the connection is established we don’t want this
                            if (!hardcoded && !result.equals(storedBackupResult)) {
                                mXmppConnectionService.databaseBackend.saveResolverResult(domain, result);
                            }
                            break; // successfully connected to server that speaks xmpp
                        } else {
                            FileBackend.close(localSocket);
                            throw new StateChangingException(Account.State.STREAM_OPENING_ERROR);
                        }
                    } catch (final StateChangingException e) {
                        if (!iterator.hasNext()) {
                            throw e;
                        }
                    } catch (InterruptedException e) {
                        Log.d(Config.LOGTAG,account.getJid().asBareJid()+": thread was interrupted before beginning stream");
                        return;
                    } catch (final Throwable e) {
                        Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": " + e.getMessage() + "(" + e.getClass().getName() + ")");
                        if (!iterator.hasNext()) {
                            throw new UnknownHostException();
                        }
                    }
                }
            }
            processStream();
        } catch (final SecurityException e) {
            this.changeStatus(Account.State.MISSING_INTERNET_PERMISSION);
        } catch (final StateChangingException e) {
            this.changeStatus(e.state);
        } catch (final UnknownHostException | ConnectException e) {
            this.changeStatus(Account.State.SERVER_NOT_FOUND);
        } catch (final SocksSocketFactory.SocksProxyNotFoundException e) {
            this.changeStatus(Account.State.TOR_NOT_AVAILABLE);
        } catch (final IOException | XmlPullParserException e) {
            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": " + e.getMessage());
            this.changeStatus(Account.State.OFFLINE);
            this.attempt = Math.max(0, this.attempt - 1);
        } finally {
            if (!Thread.currentThread().isInterrupted()) {
                forceCloseSocket();
            } else {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": not force closing socket because thread was interrupted");
            }
        }
    }

    /**
     * Starts xmpp protocol, call after connecting to socket
     *
     * @return true if server returns with valid xmpp, false otherwise
     */
    private boolean startXmpp(Socket socket) throws Exception {
        if (Thread.currentThread().isInterrupted()) {
            throw new InterruptedException();
        }
        this.socket = socket;
        tagReader = new XmlReader();
        if (tagWriter != null) {
            tagWriter.forceClose();
        }
        tagWriter = new TagWriter();
        tagWriter.setOutputStream(socket.getOutputStream());
        tagReader.setInputStream(socket.getInputStream());
        tagWriter.beginDocument();
        sendStartStream();
        final Tag tag = tagReader.readTag();
        if (Thread.currentThread().isInterrupted()) {
            throw new InterruptedException();
        }
        if (socket instanceof SSLSocket) {
            SSLSocketHelper.log(account, (SSLSocket) socket);
        }
        return tag != null && tag.isStart("stream");
    }

    private TlsFactoryVerifier getTlsFactoryVerifier() throws NoSuchAlgorithmException, KeyManagementException, IOException {
        final SSLContext sc = SSLSocketHelper.getSSLContext();
        MemorizingTrustManager trustManager = this.mXmppConnectionService.getMemorizingTrustManager();
        KeyManager[] keyManager;
        if (account.getPrivateKeyAlias() != null && account.getPassword().isEmpty()) {
            keyManager = new KeyManager[]{new MyKeyManager()};
        } else {
            keyManager = null;
        }
        String domain = account.getJid().getDomain();
        sc.init(keyManager, new X509TrustManager[]{mInteractive ? trustManager.getInteractive(domain) : trustManager.getNonInteractive(domain)}, mXmppConnectionService.getRNG());
        final SSLSocketFactory factory = sc.getSocketFactory();
        final DomainHostnameVerifier verifier = trustManager.wrapHostnameVerifier(new XmppDomainVerifier(), mInteractive);
        return new TlsFactoryVerifier(factory, verifier);
    }

    @Override
    public void run() {
        synchronized (this) {
            this.mThread = Thread.currentThread();
            if (this.mThread.isInterrupted()) {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": aborting connect because thread was interrupted");
                return;
            }
            forceCloseSocket();
        }
        connect();
    }

    private void processStream() throws XmlPullParserException, IOException {
        final CountDownLatch streamCountDownLatch = new CountDownLatch(1);
        this.mStreamCountDownLatch = streamCountDownLatch;
        Tag nextTag = tagReader.readTag();
        while (nextTag != null && !nextTag.isEnd("stream")) {
            if (nextTag.isStart("error")) {
                processStreamError(nextTag);
            } else if (nextTag.isStart("features")) {
                processStreamFeatures(nextTag);
            } else if (nextTag.isStart("proceed")) {
                switchOverToTls();
            } else if (nextTag.isStart("success")) {
                final String challenge = tagReader.readElement(nextTag).getContent();
                try {
                    saslMechanism.getResponse(challenge);
                } catch (final SaslMechanism.AuthenticationException e) {
                    Log.e(Config.LOGTAG, String.valueOf(e));
                    throw new StateChangingException(Account.State.UNAUTHORIZED);
                }
                Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": logged in");
                account.setKey(Account.PINNED_MECHANISM_KEY,
                        String.valueOf(saslMechanism.getPriority()));
                tagReader.reset();
                sendStartStream();
                final Tag tag = tagReader.readTag();
                if (tag != null && tag.isStart("stream")) {
                    processStream();
                } else {
                    throw new StateChangingException(Account.State.STREAM_OPENING_ERROR);
                }
                break;
            } else if (nextTag.isStart("failure")) {
                final Element failure = tagReader.readElement(nextTag);
                if (Namespace.SASL.equals(failure.getNamespace())) {
                    final String text = failure.findChildContent("text");
                    if (failure.hasChild("account-disabled") && text != null) {
                        Matcher matcher = Patterns.AUTOLINK_WEB_URL.matcher(text);
                        if (matcher.find()) {
                            try {
                                URL url = new URL(text.substring(matcher.start(), matcher.end()));
                                if (url.getProtocol().equals("https")) {
                                    this.redirectionUrl = url;
                                    throw new StateChangingException(Account.State.PAYMENT_REQUIRED);
                                }
                            } catch (MalformedURLException e) {
                                throw new StateChangingException(Account.State.UNAUTHORIZED);
                            }
                        }
                    }
                    throw new StateChangingException(Account.State.UNAUTHORIZED);
                } else if (Namespace.TLS.equals(failure.getNamespace())) {
                    throw new StateChangingException(Account.State.TLS_ERROR);
                } else {
                    throw new StateChangingException(Account.State.INCOMPATIBLE_SERVER);
                }
            } else if (nextTag.isStart("challenge")) {
                final String challenge = tagReader.readElement(nextTag).getContent();
                final Element response = new Element("response", Namespace.SASL);
                try {
                    response.setContent(saslMechanism.getResponse(challenge));
                } catch (final SaslMechanism.AuthenticationException e) {
                    // TODO: Send auth abort tag.
                    Log.e(Config.LOGTAG, e.toString());
                }
                tagWriter.writeElement(response);
            } else if (nextTag.isStart("enabled")) {
                final Element enabled = tagReader.readElement(nextTag);
                if ("true".equals(enabled.getAttribute("resume"))) {
                    this.streamId = enabled.getAttribute("id");
                    Log.d(Config.LOGTAG, account.getJid().asBareJid().toString()
                            + ": stream management(" + smVersion
                            + ") enabled (resumable)");
                } else {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid().toString()
                            + ": stream management(" + smVersion + ") enabled");
                }
                this.stanzasReceived = 0;
                this.inSmacksSession = true;
                final RequestPacket r = new RequestPacket(smVersion);
                tagWriter.writeStanzaAsync(r);
            } else if (nextTag.isStart("resumed")) {
                this.inSmacksSession = true;
                this.isBound = true;
                this.tagWriter.writeStanzaAsync(new RequestPacket(smVersion));
                lastPacketReceived = SystemClock.elapsedRealtime();
                final Element resumed = tagReader.readElement(nextTag);
                final String h = resumed.getAttribute("h");
                try {
                    ArrayList<AbstractAcknowledgeableStanza> failedStanzas = new ArrayList<>();
                    final boolean acknowledgedMessages;
                    synchronized (this.mStanzaQueue) {
                        final int serverCount = Integer.parseInt(h);
                        if (serverCount < stanzasSent) {
                            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString()
                                    + ": session resumed with lost packages");
                            stanzasSent = serverCount;
                        } else {
                            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": session resumed");
                        }
                        acknowledgedMessages = acknowledgeStanzaUpTo(serverCount);
                        for (int i = 0; i < this.mStanzaQueue.size(); ++i) {
                            failedStanzas.add(mStanzaQueue.valueAt(i));
                        }
                        mStanzaQueue.clear();
                    }
                    if (acknowledgedMessages) {
                        mXmppConnectionService.updateConversationUi();
                    }
                    Log.d(Config.LOGTAG, "resending " + failedStanzas.size() + " stanzas");
                    for (AbstractAcknowledgeableStanza packet : failedStanzas) {
                        if (packet instanceof MessagePacket) {
                            MessagePacket message = (MessagePacket) packet;
                            mXmppConnectionService.markMessage(account,
                                    message.getTo().asBareJid(),
                                    message.getId(),
                                    Message.STATUS_UNSEND);
                        }
                        sendPacket(packet);
                    }
                } catch (final NumberFormatException ignored) {
                }
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": online with resource " + account.getResource());
                changeStatus(Account.State.ONLINE);
            } else if (nextTag.isStart("r")) {
                tagReader.readElement(nextTag);
                if (Config.EXTENDED_SM_LOGGING) {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": acknowledging stanza #" + this.stanzasReceived);
                }
                final AckPacket ack = new AckPacket(this.stanzasReceived, smVersion);
                tagWriter.writeStanzaAsync(ack);
            } else if (nextTag.isStart("a")) {
                boolean accountUiNeedsRefresh = false;
                synchronized (NotificationService.CATCHUP_LOCK) {
                    if (mWaitingForSmCatchup.compareAndSet(true, false)) {
                        final int messageCount = mSmCatchupMessageCounter.get();
                        final int pendingIQs = packetCallbacks.size();
                        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": SM catchup complete (messages=" + messageCount + ", pending IQs=" + pendingIQs + ")");
                        accountUiNeedsRefresh = true;
                        if (messageCount > 0) {
                            mXmppConnectionService.getNotificationService().finishBacklog(true, account);
                        }
                    }
                }
                if (accountUiNeedsRefresh) {
                    mXmppConnectionService.updateAccountUi();
                }
                final Element ack = tagReader.readElement(nextTag);
                lastPacketReceived = SystemClock.elapsedRealtime();
                try {
                    final boolean acknowledgedMessages;
                    synchronized (this.mStanzaQueue) {
                        final int serverSequence = Integer.parseInt(ack.getAttribute("h"));
                        acknowledgedMessages = acknowledgeStanzaUpTo(serverSequence);
                    }
                    if (acknowledgedMessages) {
                        mXmppConnectionService.updateConversationUi();
                    }
                } catch (NumberFormatException | NullPointerException e) {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": server send ack without sequence number");
                }
            } else if (nextTag.isStart("failed")) {
                Element failed = tagReader.readElement(nextTag);
                try {
                    final int serverCount = Integer.parseInt(failed.getAttribute("h"));
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": resumption failed but server acknowledged stanza #" + serverCount);
                    final boolean acknowledgedMessages;
                    synchronized (this.mStanzaQueue) {
                        acknowledgedMessages = acknowledgeStanzaUpTo(serverCount);
                    }
                    if (acknowledgedMessages) {
                        mXmppConnectionService.updateConversationUi();
                    }
                } catch (NumberFormatException | NullPointerException e) {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": resumption failed");
                }
                resetStreamId();
                sendBindRequest();
            } else if (nextTag.isStart("iq")) {
                processIq(nextTag);
            } else if (nextTag.isStart("message")) {
                processMessage(nextTag);
            } else if (nextTag.isStart("presence")) {
                processPresence(nextTag);
            }
            nextTag = tagReader.readTag();
        }
        if (nextTag != null && nextTag.isEnd("stream")) {
            streamCountDownLatch.countDown();
        }
    }

    private boolean acknowledgeStanzaUpTo(int serverCount) {
        if (serverCount > stanzasSent) {
            Log.e(Config.LOGTAG, "server acknowledged more stanzas than we sent. serverCount=" + serverCount + ", ourCount=" + stanzasSent);
        }
        boolean acknowledgedMessages = false;
        for (int i = 0; i < mStanzaQueue.size(); ++i) {
            if (serverCount >= mStanzaQueue.keyAt(i)) {
                if (Config.EXTENDED_SM_LOGGING) {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": server acknowledged stanza #" + mStanzaQueue.keyAt(i));
                }
                AbstractAcknowledgeableStanza stanza = mStanzaQueue.valueAt(i);
                if (stanza instanceof MessagePacket && acknowledgedListener != null) {
                    MessagePacket packet = (MessagePacket) stanza;
                    acknowledgedMessages |= acknowledgedListener.onMessageAcknowledged(account, packet.getId());
                }
                mStanzaQueue.removeAt(i);
                i--;
            }
        }
        return acknowledgedMessages;
    }

    private @NonNull
    Element processPacket(final Tag currentTag, final int packetType) throws XmlPullParserException, IOException {
        Element element;
        switch (packetType) {
            case PACKET_IQ:
                element = new IqPacket();
                break;
            case PACKET_MESSAGE:
                element = new MessagePacket();
                break;
            case PACKET_PRESENCE:
                element = new PresencePacket();
                break;
            default:
                throw new AssertionError("Should never encounter invalid type");
        }
        element.setAttributes(currentTag.getAttributes());
        Tag nextTag = tagReader.readTag();
        if (nextTag == null) {
            throw new IOException("interrupted mid tag");
        }
        while (!nextTag.isEnd(element.getName())) {
            if (!nextTag.isNo()) {
                final Element child = tagReader.readElement(nextTag);
                final String type = currentTag.getAttribute("type");
                if (packetType == PACKET_IQ
                        && "jingle".equals(child.getName())
                        && ("set".equalsIgnoreCase(type) || "get"
                        .equalsIgnoreCase(type))) {
                    element = new JinglePacket();
                    element.setAttributes(currentTag.getAttributes());
                }
                element.addChild(child);
            }
            nextTag = tagReader.readTag();
            if (nextTag == null) {
                throw new IOException("interrupted mid tag");
            }
        }
        if (stanzasReceived == Integer.MAX_VALUE) {
            resetStreamId();
            throw new IOException("time to restart the session. cant handle >2 billion pcks");
        }
        if (inSmacksSession) {
            ++stanzasReceived;
        } else if (features.sm()) {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": not counting stanza(" + element.getClass().getSimpleName() + "). Not in smacks session.");
        }
        lastPacketReceived = SystemClock.elapsedRealtime();
        if (Config.BACKGROUND_STANZA_LOGGING && mXmppConnectionService.checkListeners()) {
            Log.d(Config.LOGTAG, "[background stanza] " + element);
        }
        return element;
    }

    private void processIq(final Tag currentTag) throws XmlPullParserException, IOException {
        final IqPacket packet = (IqPacket) processPacket(currentTag, PACKET_IQ);

        if (!packet.valid()) {
            Log.e(Config.LOGTAG, "encountered invalid iq from='" + packet.getFrom() + "' to='" + packet.getTo() + "'");
            return;
        }

        if (packet instanceof JinglePacket) {
            if (this.jingleListener != null) {
                this.jingleListener.onJinglePacketReceived(account, (JinglePacket) packet);
            }
        } else {
            OnIqPacketReceived callback = null;
            synchronized (this.packetCallbacks) {
                if (packetCallbacks.containsKey(packet.getId())) {
                    final Pair<IqPacket, OnIqPacketReceived> packetCallbackDuple = packetCallbacks.get(packet.getId());
                    // Packets to the server should have responses from the server
                    if (packetCallbackDuple.first.toServer(account)) {
                        if (packet.fromServer(account)) {
                            callback = packetCallbackDuple.second;
                            packetCallbacks.remove(packet.getId());
                        } else {
                            Log.e(Config.LOGTAG, account.getJid().asBareJid().toString() + ": ignoring spoofed iq packet");
                        }
                    } else {
                        if (packet.getFrom() != null && packet.getFrom().equals(packetCallbackDuple.first.getTo())) {
                            callback = packetCallbackDuple.second;
                            packetCallbacks.remove(packet.getId());
                        } else {
                            Log.e(Config.LOGTAG, account.getJid().asBareJid().toString() + ": ignoring spoofed iq packet");
                        }
                    }
                } else if (packet.getType() == IqPacket.TYPE.GET || packet.getType() == IqPacket.TYPE.SET) {
                    callback = this.unregisteredIqListener;
                }
            }
            if (callback != null) {
                try {
                    callback.onIqPacketReceived(account, packet);
                } catch (StateChangingError error) {
                    throw new StateChangingException(error.state);
                }
            }
        }
    }

    private void processMessage(final Tag currentTag) throws XmlPullParserException, IOException {
        final MessagePacket packet = (MessagePacket) processPacket(currentTag, PACKET_MESSAGE);
        if (!packet.valid()) {
            Log.e(Config.LOGTAG, "encountered invalid message from='" + packet.getFrom() + "' to='" + packet.getTo() + "'");
            return;
        }
        this.messageListener.onMessagePacketReceived(account, packet);
    }

    private void processPresence(final Tag currentTag) throws XmlPullParserException, IOException {
        PresencePacket packet = (PresencePacket) processPacket(currentTag, PACKET_PRESENCE);
        if (!packet.valid()) {
            Log.e(Config.LOGTAG, "encountered invalid presence from='" + packet.getFrom() + "' to='" + packet.getTo() + "'");
            return;
        }
        this.presenceListener.onPresencePacketReceived(account, packet);
    }

    private void sendStartTLS() throws IOException {
        final Tag startTLS = Tag.empty("starttls");
        startTLS.setAttribute("xmlns", Namespace.TLS);
        tagWriter.writeTag(startTLS);
    }

    private void switchOverToTls() throws XmlPullParserException, IOException {
        tagReader.readTag();
        try {
            final TlsFactoryVerifier tlsFactoryVerifier = getTlsFactoryVerifier();
            final InetAddress address = socket == null ? null : socket.getInetAddress();

            if (address == null) {
                throw new IOException("could not setup ssl");
            }

            final SSLSocket sslSocket = (SSLSocket) tlsFactoryVerifier.factory.createSocket(socket, address.getHostAddress(), socket.getPort(), true);

            if (sslSocket == null) {
                throw new IOException("could not initialize ssl socket");
            }

            SSLSocketHelper.setSecurity(sslSocket);
            SSLSocketHelper.setHostname(sslSocket, account.getServer());
            SSLSocketHelper.setApplicationProtocol(sslSocket, "xmpp-client");

            if (!tlsFactoryVerifier.verifier.verify(account.getServer(), this.verifiedHostname, sslSocket.getSession())) {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": TLS certificate verification failed");
                throw new StateChangingException(Account.State.TLS_ERROR);
            }
            tagReader.setInputStream(sslSocket.getInputStream());
            tagWriter.setOutputStream(sslSocket.getOutputStream());
            sendStartStream();
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": TLS connection established");
            features.encryptionEnabled = true;
            final Tag tag = tagReader.readTag();
            if (tag != null && tag.isStart("stream")) {
                SSLSocketHelper.log(account, sslSocket);
                processStream();
            } else {
                throw new StateChangingException(Account.State.STREAM_OPENING_ERROR);
            }
            sslSocket.close();
        } catch (final NoSuchAlgorithmException | KeyManagementException e1) {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": TLS certificate verification failed");
            throw new StateChangingException(Account.State.TLS_ERROR);
        }
    }

    private void processStreamFeatures(final Tag currentTag) throws XmlPullParserException, IOException {
        this.streamFeatures = tagReader.readElement(currentTag);
        final boolean isSecure = features.encryptionEnabled || Config.ALLOW_NON_TLS_CONNECTIONS || account.isOnion();
        final boolean needsBinding = !isBound && !account.isOptionSet(Account.OPTION_REGISTER);
        if (this.streamFeatures.hasChild("starttls") && !features.encryptionEnabled) {
            sendStartTLS();
        } else if (this.streamFeatures.hasChild("register") && account.isOptionSet(Account.OPTION_REGISTER)) {
            if (isSecure) {
                sendRegistryRequest();
            } else {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": unable to find STARTTLS for registration process " + XmlHelper.printElementNames(this.streamFeatures));
                throw new StateChangingException(Account.State.INCOMPATIBLE_SERVER);
            }
        } else if (!this.streamFeatures.hasChild("register") && account.isOptionSet(Account.OPTION_REGISTER)) {
            throw new StateChangingException(Account.State.REGISTRATION_NOT_SUPPORTED);
        } else if (this.streamFeatures.hasChild("mechanisms") && shouldAuthenticate && isSecure) {
            authenticate();
        } else if (this.streamFeatures.hasChild("sm", "urn:xmpp:sm:" + smVersion) && streamId != null) {
            if (Config.EXTENDED_SM_LOGGING) {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": resuming after stanza #" + stanzasReceived);
            }
            final ResumePacket resume = new ResumePacket(this.streamId, stanzasReceived, smVersion);
            this.mSmCatchupMessageCounter.set(0);
            this.mWaitingForSmCatchup.set(true);
            this.tagWriter.writeStanzaAsync(resume);
        } else if (needsBinding) {
            if (this.streamFeatures.hasChild("bind") && isSecure) {
                sendBindRequest();
            } else {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": unable to find bind feature " + XmlHelper.printElementNames(this.streamFeatures));
                throw new StateChangingException(Account.State.INCOMPATIBLE_SERVER);
            }
        }
    }

    private void authenticate() throws IOException {
        final List<String> mechanisms = extractMechanisms(streamFeatures
                .findChild("mechanisms"));
        final Element auth = new Element("auth", Namespace.SASL);
        if (mechanisms.contains("EXTERNAL") && account.getPrivateKeyAlias() != null) {
            saslMechanism = new External(tagWriter, account, mXmppConnectionService.getRNG());
        } else if (mechanisms.contains("SCRAM-SHA-256")) {
            saslMechanism = new ScramSha256(tagWriter, account, mXmppConnectionService.getRNG());
        } else if (mechanisms.contains("SCRAM-SHA-1")) {
            saslMechanism = new ScramSha1(tagWriter, account, mXmppConnectionService.getRNG());
        } else if (mechanisms.contains("PLAIN") && !account.getJid().getDomain().equals("nimbuzz.com")) {
            saslMechanism = new Plain(tagWriter, account);
        } else if (mechanisms.contains("DIGEST-MD5")) {
            saslMechanism = new DigestMd5(tagWriter, account, mXmppConnectionService.getRNG());
        } else if (mechanisms.contains("ANONYMOUS")) {
            saslMechanism = new Anonymous(tagWriter, account, mXmppConnectionService.getRNG());
        }
        if (saslMechanism != null) {
            final int pinnedMechanism = account.getKeyAsInt(Account.PINNED_MECHANISM_KEY, -1);
            if (pinnedMechanism > saslMechanism.getPriority()) {
                Log.e(Config.LOGTAG, "Auth failed. Authentication mechanism " + saslMechanism.getMechanism() +
                        " has lower priority (" + String.valueOf(saslMechanism.getPriority()) +
                        ") than pinned priority (" + pinnedMechanism +
                        "). Possible downgrade attack?");
                throw new StateChangingException(Account.State.DOWNGRADE_ATTACK);
            }
            Log.d(Config.LOGTAG, account.getJid().toString() + ": Authenticating with " + saslMechanism.getMechanism());
            auth.setAttribute("mechanism", saslMechanism.getMechanism());
            if (!saslMechanism.getClientFirstMessage().isEmpty()) {
                auth.setContent(saslMechanism.getClientFirstMessage());
            }
            tagWriter.writeElement(auth);
        } else {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": unable to find SASL mechanism " + saslMechanism.toString());
            throw new StateChangingException(Account.State.INCOMPATIBLE_SERVER);
        }
    }

    private List<String> extractMechanisms(final Element stream) {
        final ArrayList<String> mechanisms = new ArrayList<>(stream
                .getChildren().size());
        for (final Element child : stream.getChildren()) {
            mechanisms.add(child.getContent());
        }
        return mechanisms;
    }

    private void sendRegistryRequest() {
        final IqPacket register = new IqPacket(IqPacket.TYPE.GET);
        register.query("jabber:iq:register");
        register.setTo(Jid.of(account.getServer()));
        sendUnmodifiedIqPacket(register, (account, packet) -> {
            if (packet.getType() == IqPacket.TYPE.TIMEOUT) {
                return;
            }
            if (packet.getType() == IqPacket.TYPE.ERROR) {
                throw new StateChangingError(Account.State.REGISTRATION_FAILED);
            }
            final Element query = packet.query("jabber:iq:register");
            if (query.hasChild("username") && (query.hasChild("password"))) {
                final IqPacket register1 = new IqPacket(IqPacket.TYPE.SET);
                final Element username = new Element("username").setContent(account.getUsername());
                final Element password = new Element("password").setContent(account.getPassword());
                register1.query("jabber:iq:register").addChild(username);
                register1.query().addChild(password);
                register1.setFrom(account.getJid().asBareJid());
                sendUnmodifiedIqPacket(register1, registrationResponseListener, true);
            } else if (query.hasChild("x", Namespace.DATA)) {
                final Data data = Data.parse(query.findChild("x", Namespace.DATA));
                final Element blob = query.findChild("data", "urn:xmpp:bob");
                final String id = packet.getId();
                InputStream is;
                if (blob != null) {
                    try {
                        final String base64Blob = blob.getContent();
                        final byte[] strBlob = Base64.decode(base64Blob, Base64.DEFAULT);
                        is = new ByteArrayInputStream(strBlob);
                    } catch (Exception e) {
                        is = null;
                    }
                } else {
                    try {
                        Field field = data.getFieldByName("url");
                        URL url = field != null && field.getValue() != null ? new URL(field.getValue()) : null;
                        is = url != null ? url.openStream() : null;
                    } catch (IOException e) {
                        is = null;
                    }
                }
                if (is != null) {
                    Bitmap captcha = BitmapFactory.decodeStream(is);
                    try {
                        if (mXmppConnectionService.displayCaptchaRequest(account, id, data, captcha)) {
                            return;
                        }
                    } catch (Exception e) {
                        throw new StateChangingError(Account.State.REGISTRATION_FAILED);
                    }
                }
                throw new StateChangingError(Account.State.REGISTRATION_FAILED);
            } else if (query.hasChild("instructions") || query.hasChild("x", Namespace.OOB)) {
                final String instructions = query.findChildContent("instructions");
                final Element oob = query.findChild("x", Namespace.OOB);
                final String url = oob == null ? null : oob.findChildContent("url");
                if (url != null) {
                    setAccountCreationFailed(url);
                } else if (instructions != null) {
                    Matcher matcher = Patterns.AUTOLINK_WEB_URL.matcher(instructions);
                    if (matcher.find()) {
                        setAccountCreationFailed(instructions.substring(matcher.start(), matcher.end()));
                    }
                }
                throw new StateChangingError(Account.State.REGISTRATION_FAILED);
            }
        }, true);
    }


    private void setAccountCreationFailed(String url) {
        if (url != null) {
            try {
                this.redirectionUrl = new URL(url);
                if (this.redirectionUrl.getProtocol().equals("https")) {
                    throw new StateChangingError(Account.State.REGISTRATION_WEB);
                }
            } catch (MalformedURLException e) {
                //fall through
            }
        }
        throw new StateChangingError(Account.State.REGISTRATION_FAILED);
    }

    public URL getRedirectionUrl() {
        return this.redirectionUrl;
    }

    public void resetEverything() {
        resetAttemptCount(true);
        resetStreamId();
        clearIqCallbacks();
        this.stanzasSent = 0;
        mStanzaQueue.clear();
        this.redirectionUrl = null;
        synchronized (this.disco) {
            disco.clear();
        }
    }

    private void sendBindRequest() {
        try {
            mXmppConnectionService.restoredFromDatabaseLatch.await();
        } catch (InterruptedException e) {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": interrupted while waiting for DB restore during bind");
            return;
        }
        clearIqCallbacks();
        if (account.getJid().isBareJid()) {
            account.setResource(this.createNewResource());
        } else {
            fixResource(mXmppConnectionService, account);
        }
        final IqPacket iq = new IqPacket(IqPacket.TYPE.SET);
        final String resource = Config.USE_RANDOM_RESOURCE_ON_EVERY_BIND ? nextRandomId() : account.getResource();
        iq.addChild("bind", Namespace.BIND).addChild("resource").setContent(resource);
        this.sendUnmodifiedIqPacket(iq, (account, packet) -> {
            if (packet.getType() == IqPacket.TYPE.TIMEOUT) {
                return;
            }
            final Element bind = packet.findChild("bind");
            if (bind != null && packet.getType() == IqPacket.TYPE.RESULT) {
                isBound = true;
                final Element jid = bind.findChild("jid");
                if (jid != null && jid.getContent() != null) {
                    try {
                        Jid assignedJid = Jid.ofEscaped(jid.getContent());
                        if (!account.getJid().getDomain().equals(assignedJid.getDomain())) {
                            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": server tried to re-assign domain to " + assignedJid.getDomain());
                            throw new StateChangingError(Account.State.BIND_FAILURE);
                        }
                        if (account.setJid(assignedJid)) {
                            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": jid changed during bind. updating database");
                            mXmppConnectionService.databaseBackend.updateAccount(account);
                        }
                        if (streamFeatures.hasChild("session")
                                && !streamFeatures.findChild("session").hasChild("optional")) {
                            sendStartSession();
                        } else {
                            sendPostBindInitialization();
                        }
                        return;
                    } catch (final IllegalArgumentException e) {
                        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": server reported invalid jid (" + jid.getContent() + ") on bind");
                    }
                } else {
                    Log.d(Config.LOGTAG, account.getJid() + ": disconnecting because of bind failure. (no jid)");
                }
            } else {
                Log.d(Config.LOGTAG, account.getJid() + ": disconnecting because of bind failure (" + packet.toString());
            }
            final Element error = packet.findChild("error");
            if (packet.getType() == IqPacket.TYPE.ERROR && error != null && error.hasChild("conflict")) {
                account.setResource(createNewResource());
            }
            throw new StateChangingError(Account.State.BIND_FAILURE);
        }, true);
    }

    private void clearIqCallbacks() {
        final IqPacket failurePacket = new IqPacket(IqPacket.TYPE.TIMEOUT);
        final ArrayList<OnIqPacketReceived> callbacks = new ArrayList<>();
        synchronized (this.packetCallbacks) {
            if (this.packetCallbacks.size() == 0) {
                return;
            }
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": clearing " + this.packetCallbacks.size() + " iq callbacks");
            final Iterator<Pair<IqPacket, OnIqPacketReceived>> iterator = this.packetCallbacks.values().iterator();
            while (iterator.hasNext()) {
                Pair<IqPacket, OnIqPacketReceived> entry = iterator.next();
                callbacks.add(entry.second);
                iterator.remove();
            }
        }
        for (OnIqPacketReceived callback : callbacks) {
            try {
                callback.onIqPacketReceived(account, failurePacket);
            } catch (StateChangingError error) {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": caught StateChangingError(" + error.state.toString() + ") while clearing callbacks");
                //ignore
            }
        }
        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": done clearing iq callbacks. " + this.packetCallbacks.size() + " left");
    }

    public void sendDiscoTimeout() {
        if (mWaitForDisco.compareAndSet(true, false)) {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": finalizing bind after disco timeout");
            finalizeBind();
        }
    }

    private void sendStartSession() {
        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": sending legacy session to outdated server");
        final IqPacket startSession = new IqPacket(IqPacket.TYPE.SET);
        startSession.addChild("session", "urn:ietf:params:xml:ns:xmpp-session");
        this.sendUnmodifiedIqPacket(startSession, (account, packet) -> {
            if (packet.getType() == IqPacket.TYPE.RESULT) {
                sendPostBindInitialization();
            } else if (packet.getType() != IqPacket.TYPE.TIMEOUT) {
                throw new StateChangingError(Account.State.SESSION_FAILURE);
            }
        }, true);
    }

    private void sendPostBindInitialization() {
        smVersion = 0;
        if (streamFeatures.hasChild("sm", "urn:xmpp:sm:3")) {
            smVersion = 3;
        } else if (streamFeatures.hasChild("sm", "urn:xmpp:sm:2")) {
            smVersion = 2;
        }
        if (smVersion != 0) {
            synchronized (this.mStanzaQueue) {
                final EnablePacket enable = new EnablePacket(smVersion);
                tagWriter.writeStanzaAsync(enable);
                stanzasSent = 0;
                mStanzaQueue.clear();
            }
        }
        features.carbonsEnabled = false;
        features.blockListRequested = false;
        synchronized (this.disco) {
            this.disco.clear();
        }
        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": starting service discovery");
        mPendingServiceDiscoveries.set(0);
        if (smVersion == 0 || Patches.DISCO_EXCEPTIONS.contains(account.getJid().getDomain())) {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": do not wait for service discovery");
            mWaitForDisco.set(false);
        } else {
            mWaitForDisco.set(true);
        }
        lastDiscoStarted = SystemClock.elapsedRealtime();
        mXmppConnectionService.scheduleWakeUpCall(Config.CONNECT_DISCO_TIMEOUT, account.getUuid().hashCode());
        Element caps = streamFeatures.findChild("c");
        final String hash = caps == null ? null : caps.getAttribute("hash");
        final String ver = caps == null ? null : caps.getAttribute("ver");
        ServiceDiscoveryResult discoveryResult = null;
        if (hash != null && ver != null) {
            discoveryResult = mXmppConnectionService.getCachedServiceDiscoveryResult(new Pair<>(hash, ver));
        }
        final boolean requestDiscoItemsFirst = !account.isOptionSet(Account.OPTION_LOGGED_IN_SUCCESSFULLY);
        if (requestDiscoItemsFirst) {
            sendServiceDiscoveryItems(Jid.of(account.getServer()));
            getAdHocFeatures(Jid.of(account.getServer()));
        }
        if (discoveryResult == null) {
            sendServiceDiscoveryInfo(Jid.of(account.getServer()));
        } else {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": server caps came from cache");
            disco.put(Jid.of(account.getServer()), discoveryResult);
        }
        discoverMamPreferences();
        sendServiceDiscoveryInfo(account.getJid().asBareJid());
        if (!requestDiscoItemsFirst) {
            sendServiceDiscoveryItems(Jid.of(account.getServer()));
            getAdHocFeatures(Jid.of(account.getServer()));
        }

        if (!mWaitForDisco.get()) {
            finalizeBind();
        }
        this.lastSessionStarted = SystemClock.elapsedRealtime();
    }

    private void sendServiceDiscoveryInfo(final Jid jid) {
        mPendingServiceDiscoveries.incrementAndGet();
        final IqPacket iq = new IqPacket(IqPacket.TYPE.GET);
        iq.setTo(jid);
        iq.query("http://jabber.org/protocol/disco#info");
        this.sendIqPacket(iq, (account, packet) -> {
            if (packet.getType() == IqPacket.TYPE.RESULT) {
                boolean advancedStreamFeaturesLoaded;
                synchronized (XmppConnection.this.disco) {
                    ServiceDiscoveryResult result = new ServiceDiscoveryResult(packet);
                    if (jid.equals(Jid.of(account.getServer()))) {
                        mXmppConnectionService.databaseBackend.insertDiscoveryResult(result);
                    }
                    disco.put(jid, result);
                    advancedStreamFeaturesLoaded = disco.containsKey(Jid.of(account.getServer()))
                            && disco.containsKey(account.getJid().asBareJid());
                }
                if (advancedStreamFeaturesLoaded && (jid.equals(Jid.of(account.getServer())) || jid.equals(account.getJid().asBareJid()))) {
                    enableAdvancedStreamFeatures();
                }
            } else {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": could not query disco info for " + jid.toString());
            }
            if (packet.getType() != IqPacket.TYPE.TIMEOUT) {
                if (mPendingServiceDiscoveries.decrementAndGet() == 0
                        && mWaitForDisco.compareAndSet(true, false)) {
                    finalizeBind();
                }
            }
        });
    }

    private void discoverMamPreferences() {
        IqPacket request = new IqPacket(IqPacket.TYPE.GET);
        request.addChild("prefs", MessageArchiveService.Version.MAM_2.namespace);
        sendIqPacket(request, (account, response) -> {
            if (response.getType() == IqPacket.TYPE.RESULT) {
                Element prefs = response.findChild("prefs", MessageArchiveService.Version.MAM_2.namespace);
                isMamPreferenceAlways = "always".equals(prefs == null ? null : prefs.getAttribute("default"));
            }
        });
    }

    public boolean isMamPreferenceAlways() {
        return isMamPreferenceAlways;
    }

    private void finalizeBind() {
        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": online with resource " + account.getResource());
        if (bindListener != null) {
            bindListener.onBind(account);
        }
        changeStatus(Account.State.ONLINE);
    }

    private void enableAdvancedStreamFeatures() {
        if (getFeatures().carbons() && !features.carbonsEnabled) {
            sendEnableCarbons();
        }
        if (getFeatures().blocking() && !features.blockListRequested) {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": Requesting block list");
            this.sendIqPacket(getIqGenerator().generateGetBlockList(), mXmppConnectionService.getIqParser());
        }
        for (final OnAdvancedStreamFeaturesLoaded listener : advancedStreamFeaturesLoadedListeners) {
            listener.onAdvancedStreamFeaturesAvailable(account);
        }
    }

    private void sendServiceDiscoveryItems(final Jid server) {
        mPendingServiceDiscoveries.incrementAndGet();
        final IqPacket iq = new IqPacket(IqPacket.TYPE.GET);
        iq.setTo(Jid.ofDomain(server.getDomain()));
        iq.query("http://jabber.org/protocol/disco#items");
        this.sendIqPacket(iq, (account, packet) -> {
            if (packet.getType() == IqPacket.TYPE.RESULT) {
                HashSet<Jid> items = new HashSet<Jid>();
                final List<Element> elements = packet.query().getChildren();
                for (final Element element : elements) {
                    if (element.getName().equals("item")) {
                        final Jid jid = InvalidJid.getNullForInvalid(element.getAttributeAsJid("jid"));
                        if (jid != null && !jid.equals(Jid.of(account.getServer()))) {
                            items.add(jid);
                        }
                    }
                }
                for (Jid jid : items) {
                    sendServiceDiscoveryInfo(jid);
                }
            } else {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": could not query disco items of " + server);
            }
            if (packet.getType() != IqPacket.TYPE.TIMEOUT) {
                if (mPendingServiceDiscoveries.decrementAndGet() == 0
                        && mWaitForDisco.compareAndSet(true, false)) {
                    finalizeBind();
                }
            }
        });
    }

    private void getAdHocFeatures(final Jid server) {
        mPendingServiceDiscoveries.incrementAndGet();
        IqPacket iq = new IqPacket(IqPacket.TYPE.GET);
        iq.setTo(Jid.ofDomain(server.getDomain()));
        iq.setFrom(Jid.of(account.getJid().asBareJid()));
        iq.setAttribute("query", "jabber:client");
        final Element query = iq.addChild("query", "http://jabber.org/protocol/disco#items");
        query.setAttribute("node", "http://jabber.org/protocol/commands");
        this.sendIqPacket(iq, (account, packet) -> {
            if (packet.getType() == IqPacket.TYPE.RESULT) {
                final List<Element> elements = packet.query().getChildren();
                for (final Element element : elements) {
                    if (element.getName().equals("item")) {
                        final Jid jid = InvalidJid.getNullForInvalid(element.getAttributeAsJid("jid"));
                        if (jid != null && jid.equals(Jid.of(account.getServer()))) {
                            final String node = element.getAttribute("node");
                            if (node.equals("invite")) {
                                features.adhocinvite = true;
                                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": query disco commands of " + server + " was successful for node " + node);
                            }
                        }
                    }
                }
            } else {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": could not query disco commands of " + server);
            }
            if (packet.getType() != IqPacket.TYPE.TIMEOUT) {
                if (mPendingServiceDiscoveries.decrementAndGet() == 0
                        && mWaitForDisco.compareAndSet(true, false)) {
                    finalizeBind();
                }
            }
        });
    }

    public void getAdHocInviteUrl(final Jid server) {
        IqPacket iqPacket = new IqPacket(IqPacket.TYPE.SET);
        iqPacket.setTo(Jid.ofDomain(server.getDomain()));
        iqPacket.setFrom(Jid.of(account.getJid().asBareJid()));
        iqPacket.setContent("jabber:client");
        final Element command = iqPacket.addChild("command", "http://jabber.org/protocol/commands");
        command.setAttribute("node", "invite");
        command.setAttribute("action", "execute");
        Log.d(Config.LOGTAG, "AdHoc URL command " + iqPacket);
        this.sendIqPacket(iqPacket, (account, packet) -> {
            Log.d(Config.LOGTAG, "AdHoc URL packet " + packet);
            if (packet.getType() == IqPacket.TYPE.RESULT) {
                final List<Element> elements = packet.command().getChildren();
                for (final Element element : elements) {
                    features.adhocinviteURI = element.getContent();
                    Log.d(Config.LOGTAG, "Commands URI: " + features.adhocinviteURI);
                }
            } else {
                features.adhocinviteURI = "";
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": could not query disco commands of " + server);
            }
            if (packet.getType() != IqPacket.TYPE.TIMEOUT) {
                if (mPendingServiceDiscoveries.decrementAndGet() == 0
                        && mWaitForDisco.compareAndSet(true, false)) {
                    finalizeBind();
                }
            }
        });
    }

    private void sendEnableCarbons() {
        final IqPacket iq = new IqPacket(IqPacket.TYPE.SET);
        iq.addChild("enable", "urn:xmpp:carbons:2");
        this.sendIqPacket(iq, new OnIqPacketReceived() {

            @Override
            public void onIqPacketReceived(final Account account, final IqPacket packet) {
                if (!packet.hasChild("error")) {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid()
                            + ": successfully enabled carbons");
                    features.carbonsEnabled = true;
                } else {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid()
                            + ": error enableing carbons " + packet.toString());
                }
            }
        });
    }

    private void processStreamError(final Tag currentTag) throws XmlPullParserException, IOException {
        final Element streamError = tagReader.readElement(currentTag);
        if (streamError == null) {
            return;
        }
        if (streamError.hasChild("conflict")) {
            account.setResource(createNewResource());
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": switching resource due to conflict (" + account.getResource() + ")");
            throw new IOException();
        } else if (streamError.hasChild("host-unknown")) {
            throw new StateChangingException(Account.State.HOST_UNKNOWN);
        } else if (streamError.hasChild("policy-violation")) {
            final String text = streamError.findChildContent("text");
            if (text != null) {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": policy violation. " + text);
            }
            throw new StateChangingException(Account.State.POLICY_VIOLATION);
        } else {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": stream error " + streamError.toString());
            throw new StateChangingException(Account.State.STREAM_ERROR);
        }
    }

    private void sendStartStream() throws IOException {
        final Tag stream = Tag.start("stream:stream");
        stream.setAttribute("to", account.getServer());
        stream.setAttribute("version", "1.0");
        stream.setAttribute("xml:lang", "en");
        stream.setAttribute("xmlns", "jabber:client");
        stream.setAttribute("xmlns:stream", "http://etherx.jabber.org/streams");
        tagWriter.writeTag(stream);
    }

    private String createNewResource() {
        return mXmppConnectionService.getString(R.string.app_name) + '.' + nextRandomId(true);
    }

    private String nextRandomId() {
        return nextRandomId(false);
    }

    private String nextRandomId(boolean s) {
        return CryptoHelper.random(s ? 3 : 9, mXmppConnectionService.getRNG());
    }

    public String sendIqPacket(final IqPacket packet, final OnIqPacketReceived callback) {
        packet.setFrom(account.getJid());
        return this.sendUnmodifiedIqPacket(packet, callback, false);
    }

    public synchronized String sendUnmodifiedIqPacket(final IqPacket packet, final OnIqPacketReceived callback, boolean force) {
        if (packet.getId() == null) {
            packet.setAttribute("id", nextRandomId());
        }
        if (callback != null) {
            synchronized (this.packetCallbacks) {
                packetCallbacks.put(packet.getId(), new Pair<>(packet, callback));
            }
        }
        this.sendPacket(packet, force);
        return packet.getId();
    }

    public void sendMessagePacket(final MessagePacket packet) {
        this.sendPacket(packet);
    }

    public void sendPresencePacket(final PresencePacket packet) {
        this.sendPacket(packet);
    }

    private synchronized void sendPacket(final AbstractStanza packet) {
        sendPacket(packet, false);
    }

    private synchronized void sendPacket(final AbstractStanza packet, final boolean force) {
        if (stanzasSent == Integer.MAX_VALUE) {
            resetStreamId();
            disconnect(true);
            return;
        }
        synchronized (this.mStanzaQueue) {
            if (force || isBound) {
                tagWriter.writeStanzaAsync(packet);
            } else {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + " do not write stanza to unbound stream " + packet.toString());
            }
            if (packet instanceof AbstractAcknowledgeableStanza) {
                AbstractAcknowledgeableStanza stanza = (AbstractAcknowledgeableStanza) packet;
                if (this.mStanzaQueue.size() != 0) {
                    int currentHighestKey = this.mStanzaQueue.keyAt(this.mStanzaQueue.size() - 1);
                    if (currentHighestKey != stanzasSent) {
                        throw new AssertionError("Stanza count messed up");
                    }
                }
                ++stanzasSent;
                this.mStanzaQueue.append(stanzasSent, stanza);
                if (stanza instanceof MessagePacket && stanza.getId() != null && inSmacksSession) {
                    if (Config.EXTENDED_SM_LOGGING) {
                        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": requesting ack for message stanza #" + stanzasSent);
                    }
                    tagWriter.writeStanzaAsync(new RequestPacket(this.smVersion));
                }
            }
        }
    }

    public void sendPing() {
        if (!r()) {
            final IqPacket iq = new IqPacket(IqPacket.TYPE.GET);
            iq.setFrom(account.getJid());
            iq.addChild("ping", "urn:xmpp:ping");
            this.sendIqPacket(iq, null);
        }
        this.lastPingSent = SystemClock.elapsedRealtime();
    }

    public void setOnMessagePacketReceivedListener(
            final OnMessagePacketReceived listener) {
        this.messageListener = listener;
    }

    public void setOnUnregisteredIqPacketReceivedListener(
            final OnIqPacketReceived listener) {
        this.unregisteredIqListener = listener;
    }

    public void setOnPresencePacketReceivedListener(
            final OnPresencePacketReceived listener) {
        this.presenceListener = listener;
    }

    public void setOnJinglePacketReceivedListener(
            final OnJinglePacketReceived listener) {
        this.jingleListener = listener;
    }

    public void setOnStatusChangedListener(final OnStatusChanged listener) {
        this.statusListener = listener;
    }

    public void setOnBindListener(final OnBindListener listener) {
        this.bindListener = listener;
    }

    public void setOnMessageAcknowledgeListener(final OnMessageAcknowledged listener) {
        this.acknowledgedListener = listener;
    }

    public void addOnAdvancedStreamFeaturesAvailableListener(final OnAdvancedStreamFeaturesLoaded listener) {
        this.advancedStreamFeaturesLoadedListeners.add(listener);
    }

    private void forceCloseSocket() {
        if (socket != null) {
            try {
                socket.close();
            } catch (IOException e) {
                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": io exception " + e.getMessage() + " during force close");
            }
        } else {
            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": socket was null during force close");
        }
    }

    public void interrupt() {
        if (this.mThread != null) {
            this.mThread.interrupt();
        }
    }

    public void disconnect(final boolean force) {
        interrupt();
        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": disconnecting force=" + Boolean.toString(force));
        if (force) {
            forceCloseSocket();
        } else {
            final TagWriter currentTagWriter = this.tagWriter;
            if (currentTagWriter.isActive()) {
                currentTagWriter.finish();
                final Socket currentSocket = this.socket;
                final CountDownLatch streamCountDownLatch = this.mStreamCountDownLatch;
                try {
                    currentTagWriter.await(1, TimeUnit.SECONDS);
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": closing stream");
                    currentTagWriter.writeTag(Tag.end("stream:stream"));
                    if (streamCountDownLatch != null) {
                        if (streamCountDownLatch.await(1, TimeUnit.SECONDS)) {
                            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": remote ended stream");
                        } else {
                            Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": remote has not closed socket. force closing");
                        }
                    }
                } catch (InterruptedException e) {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": interrupted while gracefully closing stream");
                } catch (final IOException e) {
                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": io exception during disconnect (" + e.getMessage() + ")");
                } finally {
                    FileBackend.close(currentSocket);
                }
            } else {
                forceCloseSocket();
            }
        }
    }

    public void resetStreamId() {
        this.streamId = null;
    }

    public List<Entry<Jid, ServiceDiscoveryResult>> findDiscoItemsByFeature(final String feature) {
        synchronized (this.disco) {
            final List<Entry<Jid, ServiceDiscoveryResult>> items = new ArrayList<>();
            for (final Entry<Jid, ServiceDiscoveryResult> cursor : this.disco.entrySet()) {
                if (cursor.getValue().getFeatures().contains(feature)) {
                    items.add(cursor);
                }
            }
            return items;
        }
    }

    public Jid findDiscoItemByFeature(final String feature) {
        final List<Entry<Jid, ServiceDiscoveryResult>> items = findDiscoItemsByFeature(feature);
        if (items.size() >= 1) {
            return items.get(0).getKey();
        }
        return null;
    }

    public boolean r() {
        if (getFeatures().sm()) {
            this.tagWriter.writeStanzaAsync(new RequestPacket(smVersion));
            return true;
        } else {
            return false;
        }
    }

    public List<String> getMucServersWithholdAccount() {
        List<String> servers = getMucServers();
        servers.remove(account.getServer());
        return servers;
    }

    public List<String> getMucServers() {
        List<String> servers = new ArrayList<>();
        synchronized (this.disco) {
            for (final Entry<Jid, ServiceDiscoveryResult> cursor : disco.entrySet()) {
                final ServiceDiscoveryResult value = cursor.getValue();
                if (value.getFeatures().contains("http://jabber.org/protocol/muc")
                        && value.hasIdentity("conference", "text")
                        && !value.getFeatures().contains("jabber:iq:gateway")
                        && !value.hasIdentity("conference", "irc")) {
                    servers.add(cursor.getKey().toString());
                }
            }
        }
        return servers;
    }

    public String getMucServer() {
        List<String> servers = getMucServers();
        return servers.size() > 0 ? servers.get(0) : null;
    }

    public int getTimeToNextAttempt() {
        final int interval = Math.min((int) (25 * Math.pow(1.3, attempt)), 300);
        final int secondsSinceLast = (int) ((SystemClock.elapsedRealtime() - this.lastConnect) / 1000);
        return interval - secondsSinceLast;
    }

    public int getAttempt() {
        return this.attempt;
    }

    public Features getFeatures() {
        return this.features;
    }

    public long getLastSessionEstablished() {
        final long diff = SystemClock.elapsedRealtime() - this.lastSessionStarted;
        return System.currentTimeMillis() - diff;
    }

    public long getLastConnect() {
        return this.lastConnect;
    }

    public long getLastPingSent() {
        return this.lastPingSent;
    }

    public long getLastDiscoStarted() {
        return this.lastDiscoStarted;
    }

    public long getLastPacketReceived() {
        return this.lastPacketReceived;
    }

    public void sendActive() {
        this.sendPacket(new ActivePacket());
    }

    public void sendInactive() {
        this.sendPacket(new InactivePacket());
    }

    public void resetAttemptCount(boolean resetConnectTime) {
        this.attempt = 0;
        if (resetConnectTime) {
            this.lastConnect = 0;
        }
    }

    public void setInteractive(boolean interactive) {
        this.mInteractive = interactive;
    }

    public Identity getServerIdentity() {
        synchronized (this.disco) {
            ServiceDiscoveryResult result = disco.get(Jid.ofDomain(account.getJid().getDomain()));
            if (result == null) {
                return Identity.UNKNOWN;
            }
            for (final ServiceDiscoveryResult.Identity id : result.getIdentities()) {
                if (id.getType().equals("im") && id.getCategory().equals("server") && id.getName() != null) {
                    switch (id.getName()) {
                        case "Prosody":
                            return Identity.PROSODY;
                        case "ejabberd":
                            return Identity.EJABBERD;
                        case "Slack-XMPP":
                            return Identity.SLACK;
                    }
                }
            }
        }
        return Identity.UNKNOWN;
    }

    private IqGenerator getIqGenerator() {
        return mXmppConnectionService.getIqGenerator();
    }

    public enum Identity {
        FACEBOOK,
        SLACK,
        EJABBERD,
        PROSODY,
        NIMBUZZ,
        UNKNOWN
    }

    private static class TlsFactoryVerifier {
        private final SSLSocketFactory factory;
        private final DomainHostnameVerifier verifier;

        TlsFactoryVerifier(final SSLSocketFactory factory, final DomainHostnameVerifier verifier) throws IOException {
            this.factory = factory;
            this.verifier = verifier;
            if (factory == null || verifier == null) {
                throw new IOException("could not setup ssl");
            }
        }
    }

    private class MyKeyManager implements X509KeyManager {
        @Override
        public String chooseClientAlias(String[] strings, Principal[] principals, Socket socket) {
            return account.getPrivateKeyAlias();
        }

        @Override
        public String chooseServerAlias(String s, Principal[] principals, Socket socket) {
            return null;
        }

        @Override
        public X509Certificate[] getCertificateChain(String alias) {
            Log.d(Config.LOGTAG, "getting certificate chain");
            try {
                return KeyChain.getCertificateChain(mXmppConnectionService, alias);
            } catch (Exception e) {
                Log.d(Config.LOGTAG, e.getMessage());
                return new X509Certificate[0];
            }
        }

        @Override
        public String[] getClientAliases(String s, Principal[] principals) {
            final String alias = account.getPrivateKeyAlias();
            return alias != null ? new String[]{alias} : new String[0];
        }

        @Override
        public String[] getServerAliases(String s, Principal[] principals) {
            return new String[0];
        }

        @Override
        public PrivateKey getPrivateKey(String alias) {
            try {
                return KeyChain.getPrivateKey(mXmppConnectionService, alias);
            } catch (Exception e) {
                return null;
            }
        }
    }

    private class StateChangingError extends Error {
        private final Account.State state;

        public StateChangingError(Account.State state) {
            this.state = state;
        }
    }

    private class StateChangingException extends IOException {
        private final Account.State state;

        public StateChangingException(Account.State state) {
            this.state = state;
        }
    }

    public class Features {
        public boolean adhocinvite;
        public String adhocinviteURI;
        XmppConnection connection;
        private boolean carbonsEnabled = false;
        private boolean encryptionEnabled = false;
        private boolean blockListRequested = false;

        public Features(final XmppConnection connection) {
            this.connection = connection;
        }

        private boolean hasDiscoFeature(final Jid server, final String feature) {
            synchronized (XmppConnection.this.disco) {
                return connection.disco.containsKey(server) &&
                        connection.disco.get(server).getFeatures().contains(feature);
            }
        }

        public boolean carbons() {
            return hasDiscoFeature(Jid.of(account.getServer()), "urn:xmpp:carbons:2");
        }

        public boolean bookmarksConversion() {
            return hasDiscoFeature(account.getJid().asBareJid(), Namespace.BOOKMARKS_CONVERSION) && pepPublishOptions();
        }

        public boolean avatarConversion() {
            return hasDiscoFeature(account.getJid().asBareJid(), Namespace.AVATAR_CONVERSION) && pepPublishOptions();
        }

        public boolean blocking() {
            return hasDiscoFeature(Jid.of(account.getServer()), Namespace.BLOCKING);
        }

        public boolean spamReporting() {
            return hasDiscoFeature(Jid.of(account.getServer()), "urn:xmpp:reporting:reason:spam:0");
        }

        public boolean flexibleOfflineMessageRetrieval() {
            return hasDiscoFeature(Jid.of(account.getServer()), Namespace.FLEXIBLE_OFFLINE_MESSAGE_RETRIEVAL);
        }

        public boolean register() {
            return hasDiscoFeature(Jid.of(account.getServer()), Namespace.REGISTER);
        }

        public boolean sm() {
            return streamId != null
                    || (connection.streamFeatures != null && connection.streamFeatures.hasChild("sm"));
        }

        public boolean csi() {
            return connection.streamFeatures != null && connection.streamFeatures.hasChild("csi", "urn:xmpp:csi:0");
        }

        public boolean pep() {
            synchronized (XmppConnection.this.disco) {
                ServiceDiscoveryResult info = disco.get(account.getJid().asBareJid());
                return info != null && info.hasIdentity("pubsub", "pep");
            }
        }

        public boolean pepPersistent() {
            synchronized (XmppConnection.this.disco) {
                ServiceDiscoveryResult info = disco.get(account.getJid().asBareJid());
                return info != null && info.getFeatures().contains("http://jabber.org/protocol/pubsub#persistent-items");
            }
        }

        public boolean pepPublishOptions() {
            return hasDiscoFeature(account.getJid().asBareJid(), Namespace.PUBSUB_PUBLISH_OPTIONS);
        }

        public boolean pepOmemoWhitelisted() {
            return hasDiscoFeature(account.getJid().asBareJid(), AxolotlService.PEP_OMEMO_WHITELISTED);
        }

        public boolean mam() {
            return MessageArchiveService.Version.has(getAccountFeatures());
        }

        public List<String> getAccountFeatures() {
            ServiceDiscoveryResult result = connection.disco.get(account.getJid().asBareJid());
            return result == null ? Collections.emptyList() : result.getFeatures();
        }

        public boolean push() {
            return hasDiscoFeature(account.getJid().asBareJid(), "urn:xmpp:push:0")
                    || hasDiscoFeature(Jid.of(account.getServer()), "urn:xmpp:push:0");
        }

        public boolean rosterVersioning() {
            return connection.streamFeatures != null && connection.streamFeatures.hasChild("ver");
        }

        public void setBlockListRequested(boolean value) {
            this.blockListRequested = value;
        }

        public boolean p1S3FileTransfer() {
            return hasDiscoFeature(Jid.of(account.getServer()), Namespace.P1_S3_FILE_TRANSFER);
        }

        public boolean httpUpload(long filesize) {
            if (Config.DISABLE_HTTP_UPLOAD) {
                return false;
            } else {
                for (String namespace : new String[]{Namespace.HTTP_UPLOAD, Namespace.HTTP_UPLOAD_LEGACY}) {
                    List<Entry<Jid, ServiceDiscoveryResult>> items = findDiscoItemsByFeature(namespace);
                    if (items.size() > 0) {
                        try {
                            long maxsize = Long.parseLong(items.get(0).getValue().getExtendedDiscoInformation(namespace, "max-file-size"));
                            if (filesize <= maxsize) {
                                return true;
                            } else {
                                Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": http upload is not available for files with size " + filesize + " (max is " + maxsize + ")");
                                return false;
                            }
                        } catch (Exception e) {
                            return true;
                        }
                    }
                }
                return false;
            }
        }

        public boolean useLegacyHttpUpload() {
            return findDiscoItemByFeature(Namespace.HTTP_UPLOAD) == null && findDiscoItemByFeature(Namespace.HTTP_UPLOAD_LEGACY) != null;
        }

        public long getMaxHttpUploadSize() {
            for (String namespace : new String[]{Namespace.HTTP_UPLOAD, Namespace.HTTP_UPLOAD_LEGACY}) {
                List<Entry<Jid, ServiceDiscoveryResult>> items = findDiscoItemsByFeature(namespace);
                if (items.size() > 0) {
                    try {
                        return Long.parseLong(items.get(0).getValue().getExtendedDiscoInformation(namespace, "max-file-size"));
                    } catch (Exception e) {
                        //ignored
                    }
                }
            }
            return -1;
        }

        public boolean stanzaIds() {
            return hasDiscoFeature(account.getJid().asBareJid(), Namespace.STANZA_IDS);
        }
    }
}