/*
 * Copyright (c) 2013 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.controller.netconf.osgi;

import com.google.common.base.Optional;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.net.InetSocketAddress;
import org.opendaylight.controller.netconf.ssh.NetconfSSHServer;
import org.opendaylight.controller.netconf.ssh.authentication.AuthProvider;
import org.opendaylight.controller.netconf.util.osgi.NetconfConfigUtil;
import org.opendaylight.controller.usermanager.IUserManager;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTracker;
import org.osgi.util.tracker.ServiceTrackerCustomizer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Activator for netconf SSH bundle which creates SSH bridge between netconf client and netconf server. Activator
 * starts SSH Server in its own thread. This thread is closed when activator calls stop() method. Server opens socket
 * and listen for client connections. Each client connection creation is handled in separate
 * {@link org.opendaylight.controller.netconf.ssh.threads.SocketThread} thread.
 * This thread creates two additional threads {@link org.opendaylight.controller.netconf.ssh.threads.IOThread}
 * forwarding data from/to client.IOThread closes servers session and server connection when it gets -1 on input stream.
 * {@link org.opendaylight.controller.netconf.ssh.threads.IOThread}'s run method waits for -1 on input stream to finish.
 * All threads are daemons.
 **/
public class NetconfSSHActivator implements BundleActivator{

    private NetconfSSHServer server;
    private static final Logger logger =  LoggerFactory.getLogger(NetconfSSHActivator.class);
    private static final String EXCEPTION_MESSAGE = "Netconf ssh bridge is not available.";
    private IUserManager iUserManager;
    private BundleContext context = null;

    ServiceTrackerCustomizer<IUserManager, IUserManager> customizer = new ServiceTrackerCustomizer<IUserManager, IUserManager>(){
        @Override
        public IUserManager addingService(ServiceReference<IUserManager> reference) {
            logger.info("Service IUserManager added, let there be SSH bridge.");
            iUserManager =  context.getService(reference);
            try {
                onUserManagerFound(iUserManager);
            } catch (Exception e) {
                logger.trace("Can't start SSH server due to {}",e);
            }
            return iUserManager;
        }
        @Override
        public void modifiedService(ServiceReference<IUserManager> reference, IUserManager service) {
            logger.info("Replacing modified service IUserManager in netconf SSH.");
            server.addUserManagerService(service);
        }
        @Override
        public void removedService(ServiceReference<IUserManager> reference, IUserManager service) {
            logger.info("Removing service IUserManager from netconf SSH. " +
                    "SSH won't authenticate users until IUserManeger service will be started.");
            removeUserManagerService();
        }
    };


    @Override
    public void start(BundleContext context) throws Exception {
        this.context = context;
        listenForManagerService();
    }

    @Override
    public void stop(BundleContext context) throws Exception {
        if (server != null){
            server.stop();
            logger.trace("Netconf SSH bridge is down ...");
        }
    }
    private void startSSHServer() throws Exception {
        logger.trace("Starting netconf SSH  bridge.");
        Optional<InetSocketAddress> sshSocketAddressOptional = NetconfConfigUtil.extractSSHNetconfAddress(context, EXCEPTION_MESSAGE);
        InetSocketAddress tcpSocketAddress = NetconfConfigUtil.extractTCPNetconfAddress(context,
                EXCEPTION_MESSAGE, true);

        if (sshSocketAddressOptional.isPresent()){
            String path = NetconfConfigUtil.getPrivateKeyPath(context);
            path = path.replace("\\", "/");
            if (path.equals("")){
                throw new Exception("Missing netconf.ssh.pk.path key in configuration file.");
            }
            FileInputStream fis = null;
            try {
                fis = new FileInputStream(path);
            } catch (FileNotFoundException e){
                throw new Exception("Missing file described by netconf.ssh.pk.path key in configuration file.");
            } catch (SecurityException e){
                throw new Exception("Read access denied to file described by netconf.ssh.pk.path key in configuration file.");
            }
            AuthProvider authProvider = null;
            try {
                authProvider = new AuthProvider(iUserManager,fis);
            } catch (Exception e){
                if (fis!=null){
                    fis.close();
                }
                throw (e);
            }
            this.server = NetconfSSHServer.start(sshSocketAddressOptional.get().getPort(),tcpSocketAddress,authProvider);
            Thread serverThread = new  Thread(server,"netconf SSH server thread");
            serverThread.setDaemon(true);
            serverThread.start();
            logger.trace("Netconf SSH  bridge up and running.");
        } else {
            logger.trace("No valid connection configuration for SSH bridge found.");
            throw new Exception("No valid connection configuration for SSH bridge found.");
        }
    }
    private void onUserManagerFound(IUserManager userManager) throws Exception{
        if (server!=null && server.isUp()){
           server.addUserManagerService(userManager);
        } else {
           startSSHServer();
        }
    }
    private void removeUserManagerService(){
        this.server.removeUserManagerService();
    }
    private void listenForManagerService(){
        ServiceTracker<IUserManager, IUserManager> listenerTracker = new ServiceTracker<>(context, IUserManager.class,customizer);
        listenerTracker.open();
    }
}