/*
 * Copyright (c) 2015 Ericsson India Global Services Pvt Ltd. 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.ovsdb.hwvtepsouthbound;

import org.opendaylight.controller.md.sal.binding.api.DataBroker;
import org.opendaylight.controller.md.sal.binding.api.ReadWriteTransaction;
import org.opendaylight.controller.md.sal.common.api.clustering.CandidateAlreadyRegisteredException;
import org.opendaylight.controller.md.sal.common.api.clustering.Entity;
import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipCandidateRegistration;
import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipChange;
import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipListener;
import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipListenerRegistration;
import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipService;
import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
import org.opendaylight.controller.sal.binding.api.BindingAwareBroker.ProviderContext;
import org.opendaylight.controller.sal.binding.api.BindingAwareProvider;
import org.opendaylight.ovsdb.hwvtepsouthbound.transactions.md.TransactionInvoker;
import org.opendaylight.ovsdb.hwvtepsouthbound.transactions.md.TransactionInvokerImpl;
import org.opendaylight.ovsdb.lib.OvsdbConnection;
import org.opendaylight.ovsdb.lib.impl.OvsdbConnectionService;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.NetworkTopology;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.NetworkTopologyBuilder;
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.yangtools.yang.binding.InstanceIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Optional;
import com.google.common.util.concurrent.CheckedFuture;

public class HwvtepSouthboundProvider implements BindingAwareProvider, AutoCloseable {

    private static final Logger LOG = LoggerFactory.getLogger(HwvtepSouthboundProvider.class);
    private static final String ENTITY_TYPE = "ovsdb-hwvtepsouthbound-provider";

    public static DataBroker getDb() {
        return db;
    }

    private static DataBroker db;
    private HwvtepConnectionManager cm;
    private OvsdbConnection ovsdbConnection;
    private TransactionInvoker txInvoker;
    private EntityOwnershipService entityOwnershipService;
    private EntityOwnershipCandidateRegistration registration;
    private HwvtepsbPluginInstanceEntityOwnershipListener providerOwnershipChangeListener;

    public HwvtepSouthboundProvider(
            EntityOwnershipService entityOwnershipServiceDependency) {
        this.entityOwnershipService = entityOwnershipServiceDependency;
        registration = null;
    }

    @Override
    public void onSessionInitiated(ProviderContext session) {
        LOG.info("HwvtepSouthboundProvider Session Initiated");
        db = session.getSALService(DataBroker.class);
        txInvoker = new TransactionInvokerImpl(db);
        cm = new HwvtepConnectionManager(db, txInvoker, entityOwnershipService);
        //TODO: Add DataChange Listener

        //Register listener for entityOnwership changes
        providerOwnershipChangeListener =
                new HwvtepsbPluginInstanceEntityOwnershipListener(this,this.entityOwnershipService);
        entityOwnershipService.registerListener(ENTITY_TYPE,providerOwnershipChangeListener);

        //register instance entity to get the ownership of the provider
        Entity instanceEntity = new Entity(ENTITY_TYPE, ENTITY_TYPE);
        try {
            registration = entityOwnershipService.registerCandidate(instanceEntity);
        } catch (CandidateAlreadyRegisteredException e) {
            LOG.warn("HWVTEP Southbound Provider instance entity {} was already "
                    + "registered for {} ownership", instanceEntity, e);
        }
    }

    @Override
    public void close() throws Exception {
        LOG.info("HwvtepSouthboundProvider Closed");
        if(cm != null){
            cm.close();
            cm = null;
        }
        if(registration != null) {
            registration.close();
            registration = null;
        }
        if(providerOwnershipChangeListener != null) {
            providerOwnershipChangeListener.close();
            providerOwnershipChangeListener = null;
        }
    }

    private void initializeHwvtepTopology(LogicalDatastoreType type) {
        InstanceIdentifier<Topology> path = InstanceIdentifier
                .create(NetworkTopology.class)
                .child(Topology.class, new TopologyKey(HwvtepSouthboundConstants.HWVTEP_TOPOLOGY_ID));
        initializeTopology(type);
        ReadWriteTransaction transaction = db.newReadWriteTransaction();
        CheckedFuture<Optional<Topology>, ReadFailedException> hwvtepTp = transaction.read(type, path);
        try {
            if (!hwvtepTp.get().isPresent()) {
                TopologyBuilder tpb = new TopologyBuilder();
                tpb.setTopologyId(HwvtepSouthboundConstants.HWVTEP_TOPOLOGY_ID);
                transaction.put(type, path, tpb.build());
                transaction.submit();
            } else {
                transaction.cancel();
            }
        } catch (Exception e) {
            LOG.error("Error initializing hwvtep topology", e);
        }
    }

    private void initializeTopology(LogicalDatastoreType type) {
        ReadWriteTransaction transaction = db.newReadWriteTransaction();
        InstanceIdentifier<NetworkTopology> path = InstanceIdentifier.create(NetworkTopology.class);
        CheckedFuture<Optional<NetworkTopology>, ReadFailedException> topology = transaction.read(type,path);
        try {
            if (!topology.get().isPresent()) {
                NetworkTopologyBuilder ntb = new NetworkTopologyBuilder();
                transaction.put(type,path,ntb.build());
                transaction.submit();
            } else {
                transaction.cancel();
            }
        } catch (Exception e) {
            LOG.error("Error initializing hwvtep topology {}",e);
        }
    }

    public void handleOwnershipChange(EntityOwnershipChange ownershipChange) {
        if (ownershipChange.isOwner()) {
            LOG.info("*This* instance of HWVTEP southbound provider is set as a MASTER instance");
            LOG.info("Initialize HWVTEP topology {} in operational and config data store if not already present"
                    ,HwvtepSouthboundConstants.HWVTEP_TOPOLOGY_ID);
            initializeHwvtepTopology(LogicalDatastoreType.OPERATIONAL);
            initializeHwvtepTopology(LogicalDatastoreType.CONFIGURATION);
        } else {
            LOG.info("*This* instance of HWVTEP southbound provider is set as a SLAVE instance");
        }
        //TODO: How to make this co-exist with OvsdbSouthbound?
        if (ovsdbConnection == null) {
            ovsdbConnection = new OvsdbConnectionService();
            ovsdbConnection.registerConnectionListener(cm);
            ovsdbConnection.startOvsdbManager(HwvtepSouthboundConstants.DEFAULT_OVSDB_PORT);
        }
    }

    private class HwvtepsbPluginInstanceEntityOwnershipListener implements EntityOwnershipListener {
        private HwvtepSouthboundProvider hsp;
        private EntityOwnershipListenerRegistration listenerRegistration;

        HwvtepsbPluginInstanceEntityOwnershipListener(HwvtepSouthboundProvider hsp,
                EntityOwnershipService entityOwnershipService) {
            this.hsp = hsp;
            listenerRegistration = entityOwnershipService.registerListener(ENTITY_TYPE, this);
        }

        public void close() {
            this.listenerRegistration.close();
        }
        @Override
        public void ownershipChanged(EntityOwnershipChange ownershipChange) {
            hsp.handleOwnershipChange(ownershipChange);
        }
    }

}