/*
 * Copyright (c) 2014 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.netconf.test.tool;

import com.google.common.base.MoreObjects.ToStringHelper;
import com.google.common.base.Optional;
import com.google.common.collect.Collections2;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.local.LocalAddress;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.util.HashedWheelTimer;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.net.BindException;
import java.net.Inet4Address;
import java.net.InetSocketAddress;
import java.net.UnknownHostException;
import java.nio.channels.AsynchronousChannelGroup;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import org.apache.sshd.common.keyprovider.KeyPairProvider;
import org.apache.sshd.common.util.security.SecurityUtils;
import org.apache.sshd.common.util.threads.ThreadUtils;
import org.opendaylight.netconf.api.capability.BasicCapability;
import org.opendaylight.netconf.api.capability.Capability;
import org.opendaylight.netconf.api.capability.YangModuleCapability;
import org.opendaylight.netconf.api.monitoring.NetconfMonitoringService;
import org.opendaylight.netconf.impl.NetconfServerDispatcherImpl;
import org.opendaylight.netconf.impl.NetconfServerSessionNegotiatorFactory;
import org.opendaylight.netconf.impl.ServerChannelInitializer;
import org.opendaylight.netconf.impl.SessionIdProvider;
import org.opendaylight.netconf.impl.osgi.AggregatedNetconfOperationServiceFactory;
import org.opendaylight.netconf.mapping.api.NetconfOperationServiceFactory;
import org.opendaylight.netconf.ssh.SshProxyServer;
import org.opendaylight.netconf.ssh.SshProxyServerConfiguration;
import org.opendaylight.netconf.ssh.SshProxyServerConfigurationBuilder;
import org.opendaylight.netconf.test.tool.config.Configuration;
import org.opendaylight.netconf.test.tool.customrpc.SettableOperationProvider;
import org.opendaylight.netconf.test.tool.monitoring.NetconfMonitoringOperationService;
import org.opendaylight.netconf.test.tool.monitoring.NetconfMonitoringOperationServiceFactory;
import org.opendaylight.netconf.test.tool.operations.DefaultOperationsCreator;
import org.opendaylight.netconf.test.tool.operations.OperationsProvider;
import org.opendaylight.netconf.test.tool.rpchandler.SettableOperationRpcProvider;
import org.opendaylight.netconf.test.tool.schemacache.SchemaSourceCache;
import org.opendaylight.yangtools.yang.common.Revision;
import org.opendaylight.yangtools.yang.model.api.Module;
import org.opendaylight.yangtools.yang.model.api.SchemaContext;
import org.opendaylight.yangtools.yang.model.repo.api.RevisionSourceIdentifier;
import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceFilter;
import org.opendaylight.yangtools.yang.model.repo.api.SchemaSourceRepresentation;
import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
import org.opendaylight.yangtools.yang.model.repo.spi.PotentialSchemaSource;
import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceListener;
import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceProvider;
import org.opendaylight.yangtools.yang.model.repo.util.FilesystemSchemaSourceCache;
import org.opendaylight.yangtools.yang.parser.repo.SharedSchemaRepository;
import org.opendaylight.yangtools.yang.parser.rfc7950.repo.TextToASTTransformer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@SuppressFBWarnings("DM_DEFAULT_ENCODING")
public class NetconfDeviceSimulator implements Closeable {

    private static final Logger LOG = LoggerFactory.getLogger(NetconfDeviceSimulator.class);

    private final NioEventLoopGroup nettyThreadgroup;
    private final HashedWheelTimer hashedWheelTimer;
    private final List<Channel> devicesChannels = Lists.newArrayList();
    private final List<SshProxyServer> sshWrappers = Lists.newArrayList();
    private final ScheduledExecutorService minaTimerExecutor;
    private final ExecutorService nioExecutor;
    private final Configuration configuration;
    private SchemaContext schemaContext;

    private boolean sendFakeSchema = false;

    public NetconfDeviceSimulator(final Configuration configuration) {
        this.configuration = configuration;
        this.nettyThreadgroup = new NioEventLoopGroup();
        this.hashedWheelTimer = new HashedWheelTimer();
        this.minaTimerExecutor = Executors.newScheduledThreadPool(configuration.getThreadPoolSize(),
                new ThreadFactoryBuilder().setNameFormat("netconf-ssh-server-mina-timers-%d").build());
        this.nioExecutor = ThreadUtils
                .newFixedThreadPool("netconf-ssh-server-nio-group", configuration.getThreadPoolSize());
    }

    private NetconfServerDispatcherImpl createDispatcher(final Set<Capability> capabilities,
            final SchemaSourceProvider<YangTextSchemaSource> sourceProvider) {

        final Set<Capability> transformedCapabilities = Sets.newHashSet(Collections2.transform(capabilities, input -> {
            if (sendFakeSchema) {
                sendFakeSchema = false;
                return new FakeCapability((YangModuleCapability) input);
            } else {
                return input;
            }
        }));
        transformedCapabilities.add(new BasicCapability("urn:ietf:params:netconf:capability:candidate:1.0"));
        final NetconfMonitoringService monitoringService1 = new DummyMonitoringService(transformedCapabilities);
        final SessionIdProvider idProvider = new SessionIdProvider();

        final NetconfOperationServiceFactory aggregatedNetconfOperationServiceFactory = createOperationServiceFactory(
            sourceProvider, transformedCapabilities, monitoringService1, idProvider);

        final Set<String> serverCapabilities = configuration.getCapabilities();

        final NetconfServerSessionNegotiatorFactory serverNegotiatorFactory = new TesttoolNegotiationFactory(
                hashedWheelTimer, aggregatedNetconfOperationServiceFactory, idProvider,
                configuration.getGenerateConfigsTimeout(),
                monitoringService1, serverCapabilities);

        final ServerChannelInitializer serverChannelInitializer =
            new ServerChannelInitializer(serverNegotiatorFactory);
        return new NetconfServerDispatcherImpl(serverChannelInitializer, nettyThreadgroup, nettyThreadgroup);
    }

    private NetconfOperationServiceFactory createOperationServiceFactory(
            final SchemaSourceProvider<YangTextSchemaSource> sourceProvider,
            final Set<Capability> transformedCapabilities, final NetconfMonitoringService monitoringService1,
            final SessionIdProvider idProvider) {
        final AggregatedNetconfOperationServiceFactory aggregatedNetconfOperationServiceFactory =
            new AggregatedNetconfOperationServiceFactory();

        final NetconfOperationServiceFactory operationProvider;
        if (configuration.isMdSal()) {
            LOG.info("using MdsalOperationProvider.");
            operationProvider = new MdsalOperationProvider(
                idProvider, transformedCapabilities, schemaContext, sourceProvider);
        } else if (configuration.isXmlConfigurationProvided()) {
            LOG.info("using SimulatedOperationProvider.");
            operationProvider = new SimulatedOperationProvider(idProvider, transformedCapabilities,
                    Optional.fromNullable(configuration.getNotificationFile()),
                    Optional.fromNullable(configuration.getInitialConfigXMLFile()));
        } else {
            LOG.info("using OperationsProvider.");
            operationProvider = new OperationsProvider(idProvider, transformedCapabilities,
                configuration.getOperationsCreator() != null ? configuration.getOperationsCreator()
                    : DefaultOperationsCreator.getDefaultOperationServiceCreator(idProvider.getCurrentSessionId()));
        }


        final NetconfMonitoringOperationServiceFactory monitoringService =
                new NetconfMonitoringOperationServiceFactory(
                        new NetconfMonitoringOperationService(monitoringService1));
        aggregatedNetconfOperationServiceFactory.onAddNetconfOperationServiceFactory(operationProvider);
        aggregatedNetconfOperationServiceFactory.onAddNetconfOperationServiceFactory(monitoringService);
        if (configuration.getRpcConfigFile() != null) {
            final SettableOperationProvider settableService =
                    new SettableOperationProvider(configuration.getRpcConfigFile());
            aggregatedNetconfOperationServiceFactory.onAddNetconfOperationServiceFactory(settableService);
        } else {
            final SettableOperationRpcProvider settableService =
                    new SettableOperationRpcProvider(configuration.getRpcHandler());
            aggregatedNetconfOperationServiceFactory.onAddNetconfOperationServiceFactory(settableService);
        }
        return aggregatedNetconfOperationServiceFactory;
    }

    public List<Integer> start() {
        LOG.info("Starting {}, {} simulated devices starting on port {}",
                configuration.getDeviceCount(), configuration.isSsh() ? "SSH" : "TCP", configuration.getStartingPort());

        final SharedSchemaRepository schemaRepo = new SharedSchemaRepository("netconf-simulator");
        final Set<Capability> capabilities = parseSchemasToModuleCapabilities(schemaRepo);

        final NetconfServerDispatcherImpl dispatcher = createDispatcher(capabilities,
            sourceIdentifier -> schemaRepo.getSchemaSource(sourceIdentifier, YangTextSchemaSource.class));

        int currentPort = configuration.getStartingPort();

        final List<Integer> openDevices = Lists.newArrayList();

        // Generate key to temp folder
        final KeyPairProvider keyPairProvider = getPemGeneratorHostKeyProvider();

        final AsynchronousChannelGroup group;
        try {
            group = AsynchronousChannelGroup.withThreadPool(nioExecutor);
        } catch (final IOException e) {
            throw new IllegalStateException("Failed to create group", e);
        }

        for (int i = 0; i < configuration.getDeviceCount(); i++) {
            if (currentPort > 65535) {
                LOG.warn("Port cannot be greater than 65535, stopping further attempts.");
                break;
            }
            final InetSocketAddress address = getAddress(configuration.getIp(), currentPort);

            final ChannelFuture server;
            if (configuration.isSsh()) {
                final InetSocketAddress bindingAddress = InetSocketAddress.createUnresolved("0.0.0.0", currentPort);
                final LocalAddress tcpLocalAddress = new LocalAddress(address.toString());

                server = dispatcher.createLocalServer(tcpLocalAddress);
                try {
                    final SshProxyServer sshServer = new SshProxyServer(
                        minaTimerExecutor, nettyThreadgroup, group);
                    sshServer.bind(getSshConfiguration(bindingAddress, tcpLocalAddress, keyPairProvider));
                    sshWrappers.add(sshServer);
                } catch (final BindException e) {
                    LOG.warn("Cannot start simulated device on {}, port already in use. Skipping.", address);
                    // Close local server and continue
                    server.cancel(true);
                    if (server.isDone()) {
                        server.channel().close();
                    }
                    continue;
                } catch (final IOException e) {
                    LOG.warn("Cannot start simulated device on {} due to IOException.", address, e);
                    break;
                } finally {
                    currentPort++;
                }

                try {
                    server.get();
                } catch (final InterruptedException e) {
                    throw new RuntimeException(e);
                } catch (final ExecutionException e) {
                    LOG.warn("Cannot start ssh simulated device on {}, skipping", address, e);
                    continue;
                }

                LOG.debug("Simulated SSH device started on {}", address);

            } else {
                server = dispatcher.createServer(address);
                currentPort++;

                try {
                    server.get();
                } catch (final InterruptedException e) {
                    throw new RuntimeException(e);
                } catch (final ExecutionException e) {
                    LOG.warn("Cannot start tcp simulated device on {}, skipping", address, e);
                    continue;
                }

                LOG.debug("Simulated TCP device started on {}", address);
            }

            devicesChannels.add(server.channel());
            openDevices.add(currentPort - 1);
        }

        if (openDevices.size() == configuration.getDeviceCount()) {
            LOG.info("All simulated devices started successfully from port {} to {}",
                    configuration.getStartingPort(), currentPort - 1);
        } else if (openDevices.size() == 0) {
            LOG.warn("No simulated devices started.");
        } else {
            LOG.warn("Not all simulated devices started successfully. Started devices ar on ports {}", openDevices);
        }

        return openDevices;
    }

    private SshProxyServerConfiguration getSshConfiguration(final InetSocketAddress bindingAddress,
            final LocalAddress tcpLocalAddress, final KeyPairProvider keyPairProvider) {
        return new SshProxyServerConfigurationBuilder()
                .setBindingAddress(bindingAddress)
                .setLocalAddress(tcpLocalAddress)
                .setAuthenticator(configuration.getAuthProvider())
                .setPublickeyAuthenticator(configuration.getPublickeyAuthenticator())
                .setKeyPairProvider(keyPairProvider)
                .setIdleTimeout(Integer.MAX_VALUE)
                .createSshProxyServerConfiguration();
    }

    private static KeyPairProvider getPemGeneratorHostKeyProvider() {
        try {
            final Path tempFile = Files.createTempFile("tempKeyNetconfTest", "suffix");
            return SecurityUtils.createGeneratorHostKeyProvider(tempFile.toAbsolutePath());
        } catch (final IOException e) {
            LOG.error("Unable to generate PEM key", e);
            throw new RuntimeException(e);
        }
    }

    private Set<Capability> parseSchemasToModuleCapabilities(final SharedSchemaRepository consumer) {
        final Set<SourceIdentifier> loadedSources = Sets.newHashSet();
        consumer.registerSchemaSourceListener(TextToASTTransformer.create(consumer, consumer));
        consumer.registerSchemaSourceListener(new SchemaSourceListener() {
            @Override
            public void schemaSourceEncountered(final SchemaSourceRepresentation schemaSourceRepresentation) {

            }

            @Override
            public void schemaSourceRegistered(final Iterable<PotentialSchemaSource<?>> potentialSchemaSources) {
                for (final PotentialSchemaSource<?> potentialSchemaSource : potentialSchemaSources) {
                    loadedSources.add(potentialSchemaSource.getSourceIdentifier());
                }
            }

            @Override
            public void schemaSourceUnregistered(final PotentialSchemaSource<?> potentialSchemaSource) {

            }
        });

        if (configuration.getSchemasDir() != null) {
            LOG.info("Loading models from directory.");
            final FilesystemSchemaSourceCache<YangTextSchemaSource> cache = new FilesystemSchemaSourceCache<>(
                consumer, YangTextSchemaSource.class, configuration.getSchemasDir());
            consumer.registerSchemaSourceListener(cache);
        } else if (configuration.getModels() != null) {
            LOG.info("Loading models from classpath.");
            final SchemaSourceCache<YangTextSchemaSource> cache = new SchemaSourceCache<>(
                    consumer, YangTextSchemaSource.class, configuration.getModels());
            consumer.registerSchemaSourceListener(cache);
        } else {
            LOG.info("Custom module loading skipped.");
        }

        configuration.getDefaultYangResources().forEach(r -> {
            final SourceIdentifier sourceIdentifier = RevisionSourceIdentifier.create(r.getModuleName(),
                Revision.ofNullable(r.getRevision()));
            registerSource(consumer, r.getResourcePath(), sourceIdentifier);
        });

        try {
            //necessary for creating mdsal data stores and operations
            this.schemaContext = consumer.createSchemaContextFactory(SchemaSourceFilter.ALWAYS_ACCEPT)
                .createSchemaContext(loadedSources).get();
        } catch (final InterruptedException | ExecutionException e) {
            throw new RuntimeException("Cannot parse schema context", e);
        }

        final Set<Capability> capabilities = Sets.newHashSet();

        for (final Module module : schemaContext.getModules()) {
            for (final Module subModule : module.getSubmodules()) {
                addModuleCapability(consumer, capabilities, subModule);
            }
            addModuleCapability(consumer, capabilities, module);
        }
        return capabilities;
    }

    private static void addModuleCapability(final SharedSchemaRepository consumer, final Set<Capability> capabilities,
                                     final Module module) {
        final SourceIdentifier moduleSourceIdentifier = RevisionSourceIdentifier.create(module.getName(),
            module.getRevision());
        try {
            final String moduleContent = new String(
                consumer.getSchemaSource(moduleSourceIdentifier, YangTextSchemaSource.class).get().read());
            capabilities.add(new YangModuleCapability(module, moduleContent));
            //IOException would be thrown in creating SchemaContext already
        } catch (final ExecutionException | InterruptedException | IOException e) {
            throw new RuntimeException("Cannot retrieve schema source for module "
                + moduleSourceIdentifier.toString() + " from schema repository", e);
        }
    }

    private static void registerSource(final SharedSchemaRepository consumer, final String resource,
                                final SourceIdentifier sourceId) {
        consumer.registerSchemaSource(sourceIdentifier -> Futures.immediateFuture(new YangTextSchemaSource(sourceId) {
            @Override
            protected ToStringHelper addToStringAttributes(final ToStringHelper toStringHelper) {
                return toStringHelper;
            }

            @Override
            public InputStream openStream() {
                return getClass().getResourceAsStream(resource);
            }
        }), PotentialSchemaSource.create(sourceId, YangTextSchemaSource.class,
            PotentialSchemaSource.Costs.IMMEDIATE.getValue()));
    }

    private static InetSocketAddress getAddress(final String ip, final int port) {
        try {
            return new InetSocketAddress(Inet4Address.getByName(ip), port);
        } catch (final UnknownHostException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void close() {
        for (final SshProxyServer sshWrapper : sshWrappers) {
            try {
                sshWrapper.close();
            } catch (final IOException e) {
                LOG.debug("Wrapper {} failed to close", sshWrapper, e);
            }
        }
        for (final Channel deviceCh : devicesChannels) {
            deviceCh.close();
        }
        nettyThreadgroup.shutdownGracefully();
        minaTimerExecutor.shutdownNow();
        nioExecutor.shutdownNow();
    }

}