/*
 * 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.bgpcep.pcep.topology.provider;

import static java.util.Objects.requireNonNull;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.util.concurrent.FluentFuture;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.MoreExecutors;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import org.checkerframework.checker.lock.qual.GuardedBy;
import org.opendaylight.bgpcep.pcep.topology.provider.config.PCEPTopologyConfiguration;
import org.opendaylight.bgpcep.pcep.topology.provider.config.PCEPTopologyProviderDependencies;
import org.opendaylight.bgpcep.pcep.topology.spi.stats.TopologySessionStatsRegistry;
import org.opendaylight.mdsal.binding.api.WriteTransaction;
import org.opendaylight.mdsal.common.api.CommitInfo;
import org.opendaylight.mdsal.common.api.LogicalDatastoreType;
import org.opendaylight.protocol.pcep.PCEPDispatcherDependencies;
import org.opendaylight.protocol.pcep.PCEPPeerProposal;
import org.opendaylight.protocol.pcep.PCEPSession;
import org.opendaylight.protocol.pcep.PCEPSessionListener;
import org.opendaylight.protocol.pcep.PCEPSessionListenerFactory;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.pcep.stats.rev171113.PcepSessionState;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.pcep.types.rev181109.open.object.open.TlvsBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.AddLspArgs;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.EnsureLspOperationalInput;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.OperationResult;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.RemoveLspArgs;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.TearDownSessionInput;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.TopologyTypes1;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.TopologyTypes1Builder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.TriggerSyncArgs;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.UpdateLspArgs;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.topology.pcep.rev181109.topology.pcep.type.TopologyPcepBuilder;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.NodeId;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.TopologyId;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.Topology;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.TopologyBuilder;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.TopologyKey;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.Node;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.NodeKey;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.TopologyTypesBuilder;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.opendaylight.yangtools.yang.binding.KeyedInstanceIdentifier;
import org.opendaylight.yangtools.yang.common.RpcError;
import org.opendaylight.yangtools.yang.common.RpcResult;
import org.opendaylight.yangtools.yang.common.RpcResultBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

final class ServerSessionManager implements PCEPSessionListenerFactory, TopologySessionRPCs, PCEPPeerProposal,
        TopologySessionStatsRegistry {
    private static final Logger LOG = LoggerFactory.getLogger(ServerSessionManager.class);
    private static final long DEFAULT_HOLD_STATE_NANOS = TimeUnit.MINUTES.toNanos(5);
    private static final String FAILURE_MSG = "Failed to find session";
    @VisibleForTesting
    final AtomicBoolean isClosed = new AtomicBoolean(false);
    @GuardedBy("this")
    private final Map<NodeId, TopologySessionListener> nodes = new HashMap<>();
    @GuardedBy("this")
    private final Map<NodeId, TopologyNodeState> state = new HashMap<>();
    private final TopologySessionListenerFactory listenerFactory;
    private final InstanceIdentifier<Topology> topology;
    private final PCEPStatefulPeerProposal peerProposal;
    private final short rpcTimeout;
    private final PCEPTopologyProviderDependencies dependenciesProvider;
    private final PCEPDispatcherDependencies pcepDispatcherDependencies;

    ServerSessionManager(
            final PCEPTopologyProviderDependencies dependenciesProvider,
            final TopologySessionListenerFactory listenerFactory,
            final PCEPTopologyConfiguration configDependencies) {
        this.dependenciesProvider = requireNonNull(dependenciesProvider);
        this.topology = requireNonNull(configDependencies.getTopology());
        this.listenerFactory = requireNonNull(listenerFactory);
        this.peerProposal = PCEPStatefulPeerProposal
                .createStatefulPeerProposal(this.dependenciesProvider.getDataBroker(), this.topology);
        this.rpcTimeout = configDependencies.getRpcTimeout();
        this.pcepDispatcherDependencies = new PCEPDispatcherDependenciesImpl(this, configDependencies);
    }

    private static NodeId createNodeId(final InetAddress addr) {
        return new NodeId("pcc://" + addr.getHostAddress());
    }

    /**
     * Create Base Topology.
     */
    synchronized void instantiateServiceInstance() {
        final TopologyKey key = InstanceIdentifier.keyOf(this.topology);
        final TopologyId topologyId = key.getTopologyId();
        final WriteTransaction tx = this.dependenciesProvider.getDataBroker().newWriteOnlyTransaction();
        tx.mergeParentStructurePut(LogicalDatastoreType.OPERATIONAL, this.topology, new TopologyBuilder().withKey(key)
                .setTopologyId(topologyId).setTopologyTypes(new TopologyTypesBuilder()
                        .addAugmentation(TopologyTypes1.class, new TopologyTypes1Builder().setTopologyPcep(
                                new TopologyPcepBuilder().build()).build()).build())
                .setNode(new ArrayList<>()).build());
        try {
            tx.commit().get();
            LOG.info("PCEP Topology {} created successfully.", topologyId.getValue());
            ServerSessionManager.this.isClosed.set(false);
        } catch (final ExecutionException | InterruptedException throwable) {
            LOG.error("Failed to create PCEP Topology {}.", topologyId.getValue(), throwable);
            ServerSessionManager.this.isClosed.set(true);
        }
    }

    synchronized void releaseNodeState(final TopologyNodeState nodeState, final PCEPSession session,
            final boolean persistNode) {
        if (this.isClosed.get()) {
            LOG.error("Session Manager has already been closed.");
            return;
        }
        this.nodes.remove(createNodeId(session.getRemoteAddress()));
        if (nodeState != null) {
            LOG.debug("Node {} unbound", nodeState.getNodeId());
            nodeState.released(persistNode);
        }
    }

    synchronized TopologyNodeState takeNodeState(final InetAddress address,
            final TopologySessionListener sessionListener, final boolean retrieveNode) {
        final NodeId id = createNodeId(address);
        if (this.isClosed.get()) {
            LOG.error("Server Session Manager is closed. Unable to create topology node {} with listener {}",
                    id, sessionListener);
            return null;
        }

        LOG.debug("Node {} requested by listener {}", id, sessionListener);
        TopologyNodeState ret = this.state.get(id);

        if (ret == null) {
            ret = new TopologyNodeState(this.dependenciesProvider.getDataBroker(), this.topology, id,
                    DEFAULT_HOLD_STATE_NANOS);
            LOG.debug("Created topology node {} for id {} at {}", ret, id, ret.getNodeId());
            this.state.put(id, ret);
        }
        // if another listener requests the same session, close it
        final TopologySessionListener existingSessionListener = this.nodes.get(id);
        if (existingSessionListener != null && !sessionListener.equals(existingSessionListener)) {
            LOG.error("New session listener {} is in conflict with existing session listener {} on node {},"
                    + " closing the existing one.", existingSessionListener, sessionListener, id);
            existingSessionListener.close();
        }
        ret.taken(retrieveNode);
        this.nodes.put(id, sessionListener);
        LOG.debug("Node {} bound to listener {}", id, sessionListener);
        return ret;
    }

    @Override
    public PCEPSessionListener getSessionListener() {
        return this.listenerFactory.createTopologySessionListener(this);
    }

    private synchronized TopologySessionListener checkSessionPresence(final NodeId nodeId) {
        // Get the listener corresponding to the node
        final TopologySessionListener l = this.nodes.get(nodeId);
        if (l == null) {
            LOG.debug("Session for node {} not found", nodeId);
            return null;
        }
        return l;
    }

    @Override
    public synchronized ListenableFuture<OperationResult> addLsp(final AddLspArgs input) {
        final TopologySessionListener l = checkSessionPresence(input.getNode());
        return l != null ? l.addLsp(input) : OperationResults.UNSENT.future();
    }

    @Override
    public synchronized ListenableFuture<OperationResult> removeLsp(final RemoveLspArgs input) {
        final TopologySessionListener l = checkSessionPresence(input.getNode());
        return l != null ? l.removeLsp(input) : OperationResults.UNSENT.future();
    }

    @Override
    public synchronized ListenableFuture<OperationResult> updateLsp(final UpdateLspArgs input) {
        final TopologySessionListener l = checkSessionPresence(input.getNode());
        return l != null ? l.updateLsp(input) : OperationResults.UNSENT.future();
    }

    @Override
    public synchronized ListenableFuture<OperationResult> ensureLspOperational(final EnsureLspOperationalInput input) {
        final TopologySessionListener l = checkSessionPresence(input.getNode());
        return l != null ? l.ensureLspOperational(input) : OperationResults.UNSENT.future();
    }

    @Override
    public synchronized ListenableFuture<OperationResult> triggerSync(final TriggerSyncArgs input) {
        final TopologySessionListener l = checkSessionPresence(input.getNode());
        return l != null ? l.triggerSync(input) : OperationResults.UNSENT.future();
    }

    @Override
    public ListenableFuture<RpcResult<Void>> tearDownSession(final TearDownSessionInput input) {
        final TopologySessionListener listener = checkSessionPresence(input.getNode());
        if (listener == null) {
            return RpcResultBuilder.<Void>failed().withError(RpcError.ErrorType.RPC,
                    FAILURE_MSG).buildFuture();
        }

        return listener.tearDownSession(input);
    }

    synchronized FluentFuture<? extends CommitInfo> closeServiceInstance() {
        if (this.isClosed.getAndSet(true)) {
            LOG.error("Session Manager has already been closed.");
            return CommitInfo.emptyFluentFuture();
        }
        for (final TopologySessionListener node : this.nodes.values()) {
            node.close();
        }
        this.nodes.clear();
        for (final TopologyNodeState topologyNodeState : this.state.values()) {
            topologyNodeState.close();
        }
        this.state.clear();

        final WriteTransaction t = this.dependenciesProvider.getDataBroker().newWriteOnlyTransaction();
        t.delete(LogicalDatastoreType.OPERATIONAL, this.topology);
        final FluentFuture<? extends CommitInfo> future = t.commit();
        future.addCallback(new FutureCallback<CommitInfo>() {
            @Override
            public void onSuccess(final CommitInfo result) {
                LOG.debug("Topology {} removed", ServerSessionManager.this.topology);
            }

            @Override
            public void onFailure(final Throwable throwable) {
                LOG.warn("Failed to remove Topology {}", ServerSessionManager.this.topology, throwable);
            }
        }, MoreExecutors.directExecutor());
        return future;
    }

    @Override
    public void setPeerSpecificProposal(final InetSocketAddress address, final TlvsBuilder openBuilder) {
        requireNonNull(address);
        final byte[] speakerId = this.pcepDispatcherDependencies.getSpeakerIdMapping().get(address.getAddress());
        this.peerProposal.setPeerProposal(createNodeId(address.getAddress()), openBuilder, speakerId);
    }

    short getRpcTimeout() {
        return this.rpcTimeout;
    }

    @Override
    public synchronized void bind(final KeyedInstanceIdentifier<Node, NodeKey> nodeId,
            final PcepSessionState sessionState) {
        this.dependenciesProvider.getStateRegistry().bind(nodeId, sessionState);
    }

    @Override
    public synchronized void unbind(final KeyedInstanceIdentifier<Node, NodeKey> nodeId) {
        this.dependenciesProvider.getStateRegistry().unbind(nodeId);
    }

    PCEPDispatcherDependencies getPCEPDispatcherDependencies() {
        return this.pcepDispatcherDependencies;
    }
}