package net.i2p.i2ptunnel;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Collections;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.concurrent.Executors;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;


import net.i2p.I2PAppContext;
import net.i2p.app.*;
import static net.i2p.app.ClientAppState.*;
import net.i2p.client.I2PSession;
import net.i2p.client.I2PSessionException;
import net.i2p.data.DataHelper;
import net.i2p.util.FileSuffixFilter;
import net.i2p.util.FileUtil;
import net.i2p.util.I2PAppThread;
import net.i2p.util.Log;
import net.i2p.util.OrderedProperties;
import net.i2p.util.SecureDirectory;
import net.i2p.util.SystemVersion;

/**
 * Coordinate a set of tunnels within the JVM, loading and storing their config
 * to disk, and building new ones as requested.
 *
 * This is the entry point from clients.config.
 */
public class TunnelControllerGroup implements ClientApp {
    private final Log _log;
    private volatile ClientAppState _state;
    private final I2PAppContext _context;
    private final ClientAppManager _mgr;
    private static volatile TunnelControllerGroup _instance;
    static final String DEFAULT_CONFIG_FILE = "i2ptunnel.config";
    private static final String CONFIG_DIR = "i2ptunnel.config.d";
    private static final String PREFIX = "tunnel.";

    private final List<TunnelController> _controllers;
    private final ReadWriteLock _controllersLock;
    // locking: this
    private boolean _controllersLoaded;
    private final String _configFile;
    private final String _configDirectory;

    private static final String REGISTERED_NAME = "i2ptunnel";

    /**
     * Map of I2PSession to a Set of TunnelController objects
     * using the session (to prevent closing the session until
     * no more tunnels are using it)
     *
     */
    private final Map<I2PSession, Set<TunnelController>> _sessions;

    /**
     *  We keep a pool of socket handlers for all clients,
     *  as there is no need for isolation on the client side.
     *  Extending classes may use it for other purposes.
     *
     *  May also be used by servers, carefully,
     *  as there is no limit on threads.
     */
    private ThreadPoolExecutor _executor;
    private static final AtomicLong _executorThreadCount = new AtomicLong();
    private final Object _executorLock = new Object();
    /** how long to wait before dropping an idle thread */
    private static final long HANDLER_KEEPALIVE_MS = 2*60*1000;


    /**
     *  In I2PAppContext will instantiate if necessary and always return non-null.
     *  As of 0.9.4, when in RouterContext, will return null
     *  if the TCG has not yet been started by the router.
     *  As of 0.9.41, that's true for Android as well.
     *
     *  In Android, this should be used for all calls except from LoadClientsJob,
     *  as we do not want to instantiate TCG too early. Android must do null
     *  checks on the return value.
     *
     *  @throws IllegalArgumentException if unable to load from i2ptunnel.config
     */
    public static TunnelControllerGroup getInstance() {
        synchronized (TunnelControllerGroup.class) {
            if (_instance == null) {
                if (!SystemVersion.isAndroid()) {
                    I2PAppContext ctx = I2PAppContext.getGlobalContext();
                    if (!ctx.isRouterContext()) {
                        _instance = new TunnelControllerGroup(ctx, null, null);
                        _instance.startup();
                    }
                } // else wait for the router to start it
            }
            return _instance;
        }
    }

    /**
     *  In I2PAppContext will instantiate if necessary and always return non-null.
     *  When in RouterContext, will return null (except in Android)
     *  if the TCG has not yet been started by the router.
     *  In Android, if the old instance uses a stale context, it will replace it.
     *
     *  In Android, this should only be called from LoadClientsJob, as we do not
     *  want to instantiate TCG too early.
     *
     *  @throws IllegalArgumentException if unable to load from i2ptunnel.config
     *  @since 0.9.41
     */
    public static TunnelControllerGroup getInstance(I2PAppContext ctx) {
        synchronized (TunnelControllerGroup.class) {
            if (_instance == null) {
                if (SystemVersion.isAndroid() || !ctx.isRouterContext()) {
                    _instance = new TunnelControllerGroup(ctx, null, null);
                    _instance.startup();
                } // else wait for the router to start it
            } else {
                if (SystemVersion.isAndroid() && _instance._context != ctx) {
                    ctx.logManager().getLog(TunnelControllerGroup.class).warn("Old context in TCG");
                    _instance.shutdown();
                    _instance = new TunnelControllerGroup(ctx, null, null);
                 }
            }
            return _instance;
        }
    }

    /**
     *  Instantiation only. Caller must call startup().
     *  Config file problems will not throw exception until startup().
     *
     *  @param mgr may be null
     *  @param args zero or one args, which may be one config file or one config
     *  directory. If not absolute will be relative to the context's config dir,
     *              if empty or null, the default is i2ptunnel.config for a
     *              config file and i2ptunnel.config.d for a config directory
     *  @throws IllegalArgumentException if too many args
     *  @since 0.9.4
     */
    public TunnelControllerGroup(I2PAppContext context, ClientAppManager mgr, String[] args) {
        _state = UNINITIALIZED;
        _context = context;
        _mgr = mgr;
        _log = _context.logManager().getLog(TunnelControllerGroup.class);
        _controllers = new ArrayList<TunnelController>();
        _controllersLock = new ReentrantReadWriteLock(true);
        if (args == null || args.length <= 0) {
            _configFile = DEFAULT_CONFIG_FILE;
            _configDirectory = CONFIG_DIR;
        } else if (args.length == 1) {
            String[] answer = setupArguments(args);
            _configFile = answer[0];
            _configDirectory = answer[1];
        } else {
            throw new IllegalArgumentException("Usage: TunnelControllerGroup [filename] [configdirectory] ");
        }
        _sessions = new HashMap<I2PSession, Set<TunnelController>>(4);
        synchronized (TunnelControllerGroup.class) {
            if (_instance == null) {
                _instance = this;
            } else {
                _log.logAlways(Log.WARN, "New TunnelControllerGroup, now you have two");
                if (_log.shouldLog(Log.WARN))
                    _log.warn("I did it", new Exception());
            }
        }
        _state = INITIALIZED;
    }

    /**
     * Reads argument list and returns two strings that can be used to
     * instantiate _configFile and _configDirectory. After calling this
     * method, the returned Strings must be assigned to _configFile and
     * _configDirectory.
     *
     * @param args must be the args passed to TunnelControllerGroup.
     * @return an array of exactly 2 strings, where [0] is the the value for
     * _configFile and [1] is the value for _configDirectory
    */
    private String[] setupArguments(String args[]){
        String configFile = DEFAULT_CONFIG_FILE;
        String configDirectory = CONFIG_DIR;
        File check = new File(args[0]);
        if (!check.isAbsolute())
            check = new File(_context.getConfigDir(), args[0]);
        if (check.isFile()) {
            configFile = args[0];
        } else if (check.isDirectory()) {
            configDirectory = args[0];
        }
        return new String[]{configFile, configDirectory};
    }

    /**
     *  @param args one arg, the config file, if not absolute will be relative to the context's config dir,
     *              if no args, the default is i2ptunnel.config
     *  @throws IllegalArgumentException if unable to load from config from file
     */
    public static void main(String args[]) {
        synchronized (TunnelControllerGroup.class) {
            if (_instance != null) return; // already loaded through the web
            _instance = new TunnelControllerGroup(I2PAppContext.getGlobalContext(), null, args);
            _instance.startup();
        }
    }

    /**
     *  Helper
     *  @since 0.9.49
     */
    public I2PAppContext getContext() {
        return _context;
    }

    /**
     *  ClientApp interface
     *  @throws IllegalArgumentException if unable to load config from file
     *  @since 0.9.4
     */
    public void startup() {
        File configFile = new File(_configFile);
        if (!configFile.isAbsolute())
            configFile = new File(_context.getConfigDir(), _configFile);
        try {
            if (_log.shouldInfo())
                _log.info("Configuring tunnels from " + configFile);
            loadControllers(configFile);
        } catch (IllegalArgumentException iae) {
            if (DEFAULT_CONFIG_FILE.equals(configFile.getName()) && !_context.isRouterContext()) {
                // for i2ptunnel command line
                synchronized (this) {
                    _controllersLoaded = true;
                }
                _log.logAlways(Log.WARN, "Not in router context and no preconfigured tunnels");
            } else {
                throw iae;
            }
        }
        startControllers();
        if (_mgr != null)
            _mgr.register(this);
            // RouterAppManager registers its own shutdown hook
        else
            _context.addShutdownTask(new Shutdown());
    }

    /**
     *  ClientApp interface
     *  @since 0.9.4
     */
    public ClientAppState getState() {
        return _state;
    }

    /**
     *  ClientApp interface
     *  @since 0.9.4
     */
    public String getName() {
        return REGISTERED_NAME;
    }

    /**
     *  ClientApp interface
     *  @since 0.9.4
     */
    public String getDisplayName() {
        return REGISTERED_NAME;
    }

    /**
     *  @since 0.9.4
     */
    private void changeState(ClientAppState state) {
        changeState(state, null);
    }

    /**
     *  @since 0.9.4
     */
    private synchronized void changeState(ClientAppState state, Exception e) {
        _state = state;
        if (_mgr != null)
            _mgr.notify(this, state, null, e);
    }

    /**
     *  Warning - destroys the singleton!
     *  @since 0.8.8
     */
    private class Shutdown implements Runnable {
        public void run() {
            shutdown();
        }
    }

    /**
     *  ClientApp interface
     *  @since 0.9.4
     */
    public void shutdown(String[] args) {
        shutdown();
    }

    /**
     *  Warning - destroys the singleton!
     *  Caller must root a new context before calling instance() or main() again.
     *  Agressively kill and null everything to reduce memory usage in the JVM
     *  after stopping, and to recognize what must be reinitialized on restart (Android)
     *
     *  @since 0.8.8
     */
    public synchronized void shutdown() {
        if (_state != STARTING && _state != RUNNING)
            return;
        changeState(STOPPING);
        if (_mgr != null)
            _mgr.unregister(this);
        unloadControllers();
        synchronized (TunnelControllerGroup.class) {
            if (_instance == this)
                _instance = null;
        }
        killClientExecutor();
        changeState(STOPPED);
    }

    /**
     * Detects whether a migration to split configuration files should/will/has
     * happened based on the platform and installation type. Does not tell
     * whether a migration has actually occurred.
     *
     * @returns true if a migration is relevant to the platform, false if not
     * @since 0.9.42
     */
    private boolean shouldMigrate() {
        try {
            if (_context.isRouterContext()) {
                if (!SystemVersion.isAndroid()) {
                    if (!_context.getConfigDir().getCanonicalPath().equals(_context.getBaseDir().getCanonicalPath())) {
                        return true;
                    }
                }
            }
        } catch (IOException ioe) {}
        return false;
    }

    /**
     * Load up all of the tunnels configured in the given file.
     * Prior to 0.9.20, also started the tunnels.
     * As of 0.9.20, does not start the tunnels, you must call startup()
     * or getInstance() instead of loadControllers().
     *
     * DEPRECATED for use outside this class. Use startup() or getInstance().
     *
     * @throws IllegalArgumentException if unable to load from file
     */
    public synchronized void loadControllers(File cfgFile) {
        if (_controllersLoaded)
            return;

        loadControllers(cfgFile, shouldMigrate());
    }

    /**
     * @param shouldMigrate migrate to, and load from, i2ptunnel.config.d
     * @since 0.9.42
     * @throws IllegalArgumentException if unable to load from file
     */
    private synchronized void loadControllers(File cfgFile, boolean shouldMigrate) {
        if (_log.shouldInfo())
            _log.info("Getting controllers from config file " + cfgFile);
        File dir = new SecureDirectory(_context.getConfigDir(), CONFIG_DIR);
        List<Properties> props = null;
        if (cfgFile.exists()) {
            try {
                props = loadConfig(cfgFile);
                if (shouldMigrate && !dir.exists()) {
                    boolean ok = migrate(props, cfgFile, dir);
                    if (!ok) {
                        shouldMigrate = false;
                    } else {
                        _log.logAlways(Log.WARN, "Migrated tunnel configurations to " + dir +
                                                 " from " + cfgFile);
                    }
                } else {
                    _log.logAlways(Log.WARN, "Not migrating tunnel configurations");
                }
            } catch (IOException ioe) {
                if (_log.shouldLog(Log.ERROR))
                    _log.error("Unable to load the controllers from " + cfgFile.getAbsolutePath());
                throw new IllegalArgumentException("Unable to load the controllers from " + cfgFile, ioe);
            }
        } else if (!shouldMigrate) {
                throw new IllegalArgumentException("Unable to load the controllers from " + cfgFile);
        }
        _controllersLock.writeLock().lock();
        try {
            if (shouldMigrate && dir.isDirectory()) {
                List<File> fileList = listFiles();
                for (File f : fileList) {
                    try {
                        props = loadConfig(f);
                        if (!props.isEmpty()) {
                            for (Properties cfg : props) {
                                String type = cfg.getProperty("type");
                                if (type == null)
                                    continue;
                                TunnelController controller = new TunnelController(cfg, "");
                                _controllers.add(controller);
                            }
                            if (_log.shouldLog(Log.INFO)) {
                                _log.info("Loaded application config from " + f.toString());
                            }
                        } else {
                            if (_log.shouldLog(Log.ERROR))
                                _log.error("Error loading the client app properties from " + f);
                        }
                    } catch (IOException ioe) {
                        if (_log.shouldLog(Log.ERROR))
                            _log.error("Error loading the client app properties from " + f + ' '+ ioe);
                    }
                }
            } else if (props != null) {
                // use what we got from i2ptunnel.config
                for (Properties cfg : props) {
                    String type = cfg.getProperty("type");
                    if (type == null)
                        continue;
                    TunnelController controller = new TunnelController(cfg, "");
                    _controllers.add(controller);
                }
            }
        } finally {
            _controllersLock.writeLock().unlock();
        }

        _controllersLoaded = true;
        int i = _controllers.size();
        if (i > 0) {
            if (_log.shouldLog(Log.INFO))
                _log.info(i + " controllers loaded from " + cfgFile);
        } else {
            _log.logAlways(Log.WARN, "No i2ptunnel configurations found in " + cfgFile + " or " + dir);
        }
    }

    /*
     * Migrate tunnels from file to individual files in dir
     *
     * @return success
     * @since 0.9.42
     */
    private boolean migrate(List<Properties> tunnels, File from, File dir) {
        if (!dir.isDirectory() && !dir.mkdirs())
            return false;
        boolean ok = true;
        int i = 0;
        for (Properties props : tunnels) {
            String tname = props.getProperty("name");
            if (tname == null)
                tname = "tunnel";
            else
                tname = sanitize(tname);
            String name = i + "-" + tname + "-i2ptunnel.config";
            if (i < 10)
                name = '0' + name;
            File f = new File(dir, name);
            props.setProperty(TunnelController.PROP_CONFIG_FILE, f.getAbsolutePath());
            try {
                DataHelper.storeProps(props, f);
            } catch (IOException ioe) {
                if (_log.shouldLog(Log.ERROR))
                    _log.error("Error migrating the i2ptunnel configuration to " + f, ioe);
                ok = false;
            }
            i++;
        }
        if (ok) {
            if (!FileUtil.rename(from, new File(from.getAbsolutePath() + ".bak")))
                from.delete();
        }
        return ok;
    }

    /**
     * Start all of the tunnels. Must call loadControllers() first.
     * @since 0.9.20
     */
    private synchronized void startControllers() {
        changeState(STARTING);
        I2PAppThread startupThread = new I2PAppThread(new StartControllers(), "Startup tunnels");
        startupThread.start();
        changeState(RUNNING);
    }

    private class StartControllers implements Runnable {
        public void run() {
            synchronized(TunnelControllerGroup.this) {
                _controllersLock.readLock().lock();
                try {
                    if (_controllers.size() <= 0) {
                        _log.logAlways(Log.WARN, "No configured tunnels to start");
                        return;
                    }
                    for (TunnelController controller : _controllers) {
                        if (controller.getStartOnLoad())
                            controller.startTunnelBackground();
                    }
                } finally {
                    _controllersLock.readLock().unlock();
                }
            }
        }
    }

    /**
     * Stop all tunnels, reload config, and restart those configured to do so.
     * WARNING - Does NOT simply reload the configuration!!! This is probably not what you want.
     * This does not return or clear the controller messages.
     *
     * @throws IllegalArgumentException if unable to reload config file
     */
    public synchronized void reloadControllers() {
        unloadControllers();
        File cfgFile = new File(_configFile);
        if (!cfgFile.isAbsolute())
            cfgFile = new File(_context.getConfigDir(), _configFile);
        loadControllers(cfgFile);
        startControllers();
    }

    /**
     * Stop and remove reference to all known tunnels (but dont delete any config
     * file or do other silly things)
     *
     */
    public synchronized void unloadControllers() {
        if (!_controllersLoaded)
            return;

        _controllersLock.writeLock().lock();
        try {
            destroyAllControllers();
            _controllers.clear();
        } finally {
            _controllersLock.writeLock().unlock();
        }

        _controllersLoaded = false;
        if (_log.shouldLog(Log.INFO))
            _log.info("All controllers stopped and unloaded");
    }

    /**
     * Add the given tunnel to the set of known controllers (but dont add it to
     * a config file or start it or anything)
     *
     */
    public synchronized void addController(TunnelController controller) {
        _controllersLock.writeLock().lock();
        try {
            _controllers.add(controller);
        } finally {
            _controllersLock.writeLock().unlock();
        }
    }

    /**
     * Stop and remove the given tunnel.
     * Side effect - clears all messages the controller.
     * Does NOT delete the configuration - must call saveConfig() or removeConfig() also.
     *
     * @return list of messages from the controller as it is stopped
     */
    public synchronized List<String> removeController(TunnelController controller) {
        if (controller == null) return new ArrayList<String>();
        controller.stopTunnel();
        List<String> msgs = controller.clearMessages();
        _controllersLock.writeLock().lock();
        try {
            _controllers.remove(controller);
        } finally {
            _controllersLock.writeLock().unlock();
        }
        msgs.add("Tunnel " + controller.getName() + " removed");
        return msgs;
    }

    /**
     * Stop all tunnels. May be restarted.
     * Side effect - clears all messages from all controllers.
     *
     * @return list of messages the tunnels generate when stopped
     */
    public synchronized List<String> stopAllControllers() {
        List<String> msgs = new ArrayList<String>();
        _controllersLock.readLock().lock();
        try {
            for (TunnelController controller : _controllers) {
                controller.stopTunnel();
                msgs.addAll(controller.clearMessages());
            }
            if (_log.shouldLog(Log.INFO))
                _log.info(_controllers.size() + " controllers stopped");
        } finally {
            _controllersLock.readLock().unlock();
        }
        return msgs;
    }

    /**
     *  Stop all tunnels. They may not be restarted, you must reload.
     *  Caller must synch. Caller must clear controller list.
     *
     *  @since 0.9.17
     */
    private void destroyAllControllers() {
        for (TunnelController controller : _controllers) {
            controller.destroyTunnel();
        }
        if (_log.shouldLog(Log.INFO))
            _log.info(_controllers.size() + " controllers stopped");
    }

    /**
     * Start all tunnels.
     * Side effect - clears all messages from all controllers.
     *
     * @return list of messages the tunnels generate when started
     */
    public synchronized List<String> startAllControllers() {
        List<String> msgs = new ArrayList<String>();
        _controllersLock.readLock().lock();
        try {
            for (TunnelController controller : _controllers) {
                controller.startTunnelBackground();
                msgs.addAll(controller.clearMessages());
            }

            if (_log.shouldLog(Log.INFO))
                _log.info(_controllers.size() + " controllers started");
        } finally {
            _controllersLock.readLock().unlock();
        }
        return msgs;
    }

    /**
     * Restart all tunnels.
     * Side effect - clears all messages from all controllers.
     *
     * @return list of messages the tunnels generate when restarted
     */
    public synchronized List<String> restartAllControllers() {
        List<String> msgs = new ArrayList<String>();
        _controllersLock.readLock().lock();
        try {
            for (TunnelController controller : _controllers) {
                controller.restartTunnel();
                msgs.addAll(controller.clearMessages());
            }
            if (_log.shouldLog(Log.INFO))
                _log.info(_controllers.size() + " controllers restarted");
        } finally {
            _controllersLock.readLock().unlock();
        }
        return msgs;
    }

    /**
     * Fetch and clear all outstanding messages from any of the known tunnels.
     *
     * @return list of messages the tunnels have generated
     */
    public List<String> clearAllMessages() {
        List<String> msgs = new ArrayList<String>();
        _controllersLock.readLock().lock();
        try {
            for (TunnelController controller : _controllers) {
                msgs.addAll(controller.clearMessages());
            }
        } finally {
            _controllersLock.readLock().unlock();
        }
        return msgs;
    }

    /**
     * Save the configuration of all known tunnels to the default config
     * file
     *
     * @deprecated use saveConfig(TunnelController) or removeConfig(TunnelController)
     */
    @Deprecated
    public void saveConfig() throws IOException {
        _controllersLock.readLock().lock();
        if (shouldMigrate()) {
            try {
                for (TunnelController controller : _controllers) {
                    saveConfig(controller);
                }
            } finally {
                _controllersLock.readLock().unlock();
            }
        } else {
            try {
                File cfgFile = new File(_configFile);
                if (!cfgFile.isAbsolute())
                    cfgFile = new File(_context.getConfigDir(), _configFile);
                saveConfig(cfgFile);
            } finally {
                _controllersLock.readLock().unlock();
            }
        }
    }

    /**
     * Save the configuration of all known tunnels to the given file
     * @deprecated
     */
    @Deprecated
    public synchronized void saveConfig(String cfgFile) throws IOException {
        saveConfig(new File(cfgFile));
    }

    /**
     * Save the configuration of all known tunnels to the given file.
     * Side effect: for split config, sets "confFile" property to absolute path.
     * @since 0.9.42
     */
    private synchronized void saveConfig(File cfgFile) throws IOException {
        File parent = cfgFile.getParentFile();
        if (parent != null && !parent.exists())
            parent.mkdirs();
        Properties map = new OrderedProperties();
        _controllersLock.readLock().lock();
        try {
            int i = 0;
            for (TunnelController controller : _controllers) {
                Properties cur = controller.getConfig(PREFIX + i + ".");
                map.putAll(cur);
                i++;
            }
            map.setProperty(TunnelController.PROP_CONFIG_FILE, cfgFile.getAbsolutePath());
        } finally {
            _controllersLock.readLock().unlock();
        }
        DataHelper.storeProps(map, cfgFile);
    }

    /**
     * Save the configuration of this tunnel only, may be new.
     * Side effect: for split config, sets "confFile" property to absolute path.
     * @since 0.9.42
     */
    public synchronized void saveConfig(TunnelController tc) throws IOException {
        if (!shouldMigrate()){
            saveConfig();
            return;
        }
        if (_log.shouldInfo())
            _log.info("Saving tunnel configuration for " + tc);
        Properties inputController = new OrderedProperties();
        inputController.putAll(tc.getConfig(""));
        File cfgFile = assureConfigFile(tc);
        inputController.setProperty(TunnelController.PROP_CONFIG_FILE, cfgFile.getAbsolutePath());
        DataHelper.storeProps(inputController, cfgFile);
        tc.setConfig(inputController, "");
    }

    /**
     * Remove the configuration of this tunnel only
     * @since 0.9.42
     */
    public synchronized void removeConfig(TunnelController tc) throws IOException {
        File cfgFile = assureConfigFile(tc);
        if (!FileUtil.rename(cfgFile, new File(cfgFile.getAbsolutePath() + ".bak")))
            if (! cfgFile.delete())
                if (_log.shouldLog(Log.WARN))
                    _log.warn("could not delete config file" + cfgFile.toString());
        if (!shouldMigrate())
            saveConfig();
    }

    /** From i2psnark Storage.java */
    private static final char[] ILLEGAL = new char[] {
        '<', '>', ':', '"', '/', '\\', '|', '?', '*',
        0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
        16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
        0x7f,
        0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
        0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
        0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
        0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
        // unicode newlines
        0x2028, 0x2029
    };

    /**
     * Replace problematic characters in file name
     * @since 0.9.42
     */
    private static String sanitize(String rv) {
        for (int i = 0; i < ILLEGAL.length; i++) {
            if (rv.indexOf(ILLEGAL[i]) >= 0)
                rv = rv.replace(ILLEGAL[i], '_');
        }
        return rv;
    }

    /**
     * return the config File associated with a TunnelController or a default
     * File based on the tunnel name.
     *
     * @since 0.9.42
     * @return the File ready for use
     */
    private synchronized File assureConfigFile(TunnelController tc) throws IOException {
        File file = tc.getConfigFile();
        if (file != null)
            return file;
        Properties inputController = tc.getConfig("");
        String fileName = inputController.getProperty("name");
        if (fileName == null)
            fileName = "New Tunnel";
        else
            fileName = sanitize(fileName);
        String configFileName = _controllers.size() + "-" + fileName + "-i2ptunnel.config";
        if (_controllers.size() < 10)
            configFileName = '0' + configFileName;
        File folder = new File(_configDirectory);
        if (!folder.isAbsolute())
            folder = new File(_context.getConfigDir(), _configDirectory);
        file = new File(folder, configFileName);
        tc.setConfigFile(file);
        return file;
    }

    /**
     * List all the config files in the config directory, or the monolithic
     * config file, if they exist
     *
     * @return non-null list of files, sorted
     * @since 0.9.42
     */
    private List<File> listFiles() {
        File folder = new File(_configDirectory);
        if (!folder.isAbsolute())
            folder = new File(_context.getConfigDir(), _configDirectory);
        if (_log.shouldLog(Log.INFO))
            _log.info("Seeking controller configs in " + folder.toString());
        File[] listOfFiles = folder.listFiles(new FileSuffixFilter(".config"));
        List<File> files = new ArrayList<File>();
        if (listOfFiles != null && listOfFiles.length > 0){
            for (File afile : listOfFiles) {
                files.add(afile);
                if (_log.shouldLog(Log.INFO))
                    _log.info("Found controller config " + afile.toString());
            }
            Collections.sort(files);
        } else {
            File cfgFile = new File(_configFile);
            if (!cfgFile.isAbsolute())
                cfgFile = new File(_context.getConfigDir(), _configFile);
            files.add(cfgFile);
        }
        return files;
    }

    /**
     * Load up the config data from either type of config file automatically.
     * Side effect: for split config, sets "confFile" property to absolute path.
     *
     * @return non-null, properties loaded, one for each tunnel
     * @throws IOException if unable to load from file
     * @since 0.9.42
     */
    private synchronized List<Properties> loadConfig(File cfgFile) throws IOException {
        Properties config = new Properties();
        DataHelper.loadProps(config, cfgFile);
        for (String key : config.stringPropertyNames()) {
            if (key.startsWith(PREFIX)) {
                if (_log.shouldDebug())
                    _log.debug("Found monolithic config file " + cfgFile);
                return splitMonolithicConfig(config);
            } else {
                if (_log.shouldDebug())
                    _log.debug("Found split config file " + cfgFile);
                List<Properties> rv = new ArrayList<Properties>(1);
                config.setProperty(TunnelController.PROP_CONFIG_FILE, cfgFile.getAbsolutePath());
                rv.add(config);
                return rv;
            }
        }
        throw new IOException("No config found in " + cfgFile);
    }

    /**
     * Split up the config data loaded from a single file, this is the old version for the
     * numbered config file, into properties one for each tunnel.
     *
     * @return non-null, properties loaded, one for each tunnel
     * @throws IOException if unable to load from file
     * @since 0.9.42
     */
    private List<Properties> splitMonolithicConfig(Properties config) throws IOException {
        List<Properties> rv = new ArrayList<Properties>();
        int i = 0;
        while (true) {
            String prefix = PREFIX + i + ".";
            Properties p = new OrderedProperties();
            for (Map.Entry<Object, Object> e : config.entrySet()) {
                String key = (String) e.getKey();
                if (key.startsWith(prefix)) {
                    key = key.substring(prefix.length());
                    String val = (String) e.getValue();
                    p.setProperty(key, val);
                }
            }
            if (p.isEmpty())
                break;
            rv.add(p);
            i++;
        }
        return rv;
    }

    /**
     * Retrieve a list of tunnels known.
     *
     * Side effect: if the tunnels have not been loaded from config yet, they
     * will be.
     *
     * @return list of TunnelController objects
     * @throws IllegalArgumentException if unable to load config from file
     */
    public List<TunnelController> getControllers() {
        List<TunnelController> rv = new ArrayList<TunnelController>();
        File cfgFile = new File(_configFile);
        if (!cfgFile.isAbsolute())
            cfgFile = new File(_context.getConfigDir(), _configFile);
        rv.addAll(getControllers(cfgFile));
        return rv;
     }

    /**
     * Retrieve a list of tunnels known.
     *
     * Side effect: if the tunnels have not been loaded from config yet, they
     * will be.
     *
     * @return list of TunnelController objects
     * @throws IllegalArgumentException if unable to load config from file
     * @since 0.9.42
     */
    private List<TunnelController> getControllers(File cfgFile) {
        synchronized (this) {
            if (!_controllersLoaded)
                loadControllers(cfgFile);
        }

        _controllersLock.readLock().lock();
        try {
            List<TunnelController> rv = new ArrayList<TunnelController>(_controllers);
            return rv;
        } finally {
            _controllersLock.readLock().unlock();
        }
    }


    /**
     * Note the fact that the controller is using the session so that
     * it isn't destroyed prematurely.
     *
     */
    void acquire(TunnelController controller, I2PSession session) {
        synchronized (_sessions) {
            Set<TunnelController> owners = _sessions.get(session);
            if (owners == null) {
                owners = new HashSet<TunnelController>(2);
                _sessions.put(session, owners);
            }
            owners.add(controller);
        }
        if (_log.shouldLog(Log.INFO))
            _log.info("Acquiring session " + session + " for " + controller);

    }

    /**
     * Note the fact that the controller is no longer using the session, and if
     * no other controllers are using it, destroy the session.
     *
     */
    void release(TunnelController controller, I2PSession session) {
        boolean shouldClose = false;
        synchronized (_sessions) {
            Set<TunnelController> owners = _sessions.get(session);
            if (owners != null) {
                owners.remove(controller);
                if (owners.isEmpty()) {
                    if (_log.shouldLog(Log.INFO))
                        _log.info("After releasing session " + session + " by " + controller + ", no more owners remain");
                    shouldClose = true;
                    _sessions.remove(session);
                } else {
                    if (_log.shouldLog(Log.INFO))
                        _log.info("After releasing session " + session + " by " + controller + ", " + owners.size() + " owners remain");
                    shouldClose = false;
                }
            } else {
                if (_log.shouldLog(Log.WARN))
                    _log.warn("After releasing session " + session + " by " + controller + ", no owners were even known?!");
                shouldClose = true;
            }
        }
        if (shouldClose) {
            try {
                session.destroySession();
                if (_log.shouldLog(Log.INFO))
                    _log.info("Session destroyed: " + session);
            } catch (I2PSessionException ise) {
                if (_log.shouldLog(Log.ERROR))
                    _log.error("Error closing the client session", ise);
            }
        }
    }

    /**
     *  @return non-null
     *  @since 0.8.8 Moved from I2PTunnelClientBase in 0.9.18
     */
    ThreadPoolExecutor getClientExecutor() {
        synchronized (_executorLock) {
            if (_executor == null)
                _executor = new CustomThreadPoolExecutor();
        }
        return _executor;
    }

    /**
     *  @since 0.8.8 Moved from I2PTunnelClientBase in 0.9.18
     */
    private void killClientExecutor() {
        synchronized (_executorLock) {
            if (_executor != null) {
                _executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy());
                _executor.shutdownNow();
                _executor = null;
            }
        }
        // kill the shared client, so that on restart in android
        // we won't latch onto the old one
        I2PTunnelClientBase.killSharedClient();
    }

    /**
     *  Not really needed for now but in case we want to add some hooks like afterExecute().
     *  Package private for fallback in case TCG.getInstance() is null, never instantiated
     *  but a plugin still needs it... should be rare.
     *
     *  @since 0.9.18 Moved from I2PTunnelClientBase
     */
    static class CustomThreadPoolExecutor extends ThreadPoolExecutor {
        public CustomThreadPoolExecutor() {
             super(0, Integer.MAX_VALUE, HANDLER_KEEPALIVE_MS, TimeUnit.MILLISECONDS,
                   new SynchronousQueue<Runnable>(), new CustomThreadFactory());
        }
    }

    /**
     *  Just to set the name and set Daemon
     *  @since 0.9.18 Moved from I2PTunnelClientBase
     */
    private static class CustomThreadFactory implements ThreadFactory {
        public Thread newThread(Runnable r) {
            Thread rv = Executors.defaultThreadFactory().newThread(r);
            rv.setName("I2PTunnel Client Runner " + _executorThreadCount.incrementAndGet());
            rv.setDaemon(true);
            return rv;
        }
    }
}
