/*
 * Copyright (c) 2016 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.vpnservice.neutronvpn;

import com.google.common.base.Optional;

import org.opendaylight.controller.md.sal.binding.api.DataBroker;
import org.opendaylight.controller.md.sal.binding.api.DataChangeListener;
import org.opendaylight.controller.md.sal.common.api.data.AsyncDataBroker.DataChangeScope;
import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
import org.opendaylight.vpnservice.mdsalutil.AbstractDataChangeListener;
import org.opendaylight.vpnservice.mdsalutil.MDSALUtil;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.yang.types.rev130715.Uuid;
import org.opendaylight.yang.gen.v1.urn.opendaylight.neutron.rev150712.Neutron;
import org.opendaylight.yang.gen.v1.urn.opendaylight.neutron.subnets.rev150712.subnets.attributes.Subnets;
import org.opendaylight.yang.gen.v1.urn.opendaylight.neutron.subnets.rev150712.subnets.attributes.subnets.Subnet;
import org.opendaylight.yang.gen.v1.urn.opendaylight.vpnservice.neutronvpn.rev150602.networkmaps.NetworkMap;
import org.opendaylight.yang.gen.v1.urn.opendaylight.vpnservice.neutronvpn.rev150602.networkmaps.NetworkMapBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.vpnservice.neutronvpn.rev150602.networkmaps.NetworkMapKey;
import org.opendaylight.yangtools.concepts.ListenerRegistration;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.List;


public class NeutronSubnetChangeListener extends AbstractDataChangeListener<Subnet> implements AutoCloseable {
    private static final Logger LOG = LoggerFactory.getLogger(NeutronSubnetChangeListener.class);

    private ListenerRegistration<DataChangeListener> listenerRegistration;
    private final DataBroker broker;
    private NeutronvpnManager nvpnManager;


    public NeutronSubnetChangeListener(final DataBroker db, NeutronvpnManager nVpnMgr) {
        super(Subnet.class);
        broker = db;
        nvpnManager = nVpnMgr;
        registerListener(db);
    }

    @Override
    public void close() throws Exception {
        if (listenerRegistration != null) {
            try {
                listenerRegistration.close();
            } catch (final Exception e) {
                LOG.error("Error when cleaning up DataChangeListener.", e);
            }
            listenerRegistration = null;
        }
        LOG.info("N_Subnet listener Closed");
    }


    private void registerListener(final DataBroker db) {
        try {
            listenerRegistration = db.registerDataChangeListener(LogicalDatastoreType.CONFIGURATION,
                    InstanceIdentifier.create(Neutron.class).child(Subnets.class).child(Subnet.class),
                    NeutronSubnetChangeListener.this, DataChangeScope.SUBTREE);
        } catch (final Exception e) {
            LOG.error("Neutron Manager Subnet DataChange listener registration fail!", e);
            throw new IllegalStateException("Neutron Manager Subnet DataChange listener registration failed.", e);
        }
    }

    @Override
    protected void add(InstanceIdentifier<Subnet> identifier, Subnet input) {
        if (LOG.isTraceEnabled()) {
            LOG.trace("Adding Subnet : key: " + identifier + ", value=" + input);
        }
        handleNeutronSubnetCreated(input.getUuid(), String.valueOf(input.getCidr().getValue()), input.getNetworkId(), input.getTenantId());
    }

    @Override
    protected void remove(InstanceIdentifier<Subnet> identifier, Subnet input) {
        if (LOG.isTraceEnabled()) {
            LOG.trace("Removing subnet : key: " + identifier + ", value=" + input);
        }
        handleNeutronSubnetDeleted(input.getUuid(), input.getNetworkId(), null);
    }

    @Override
    protected void update(InstanceIdentifier<Subnet> identifier, Subnet original, Subnet update) {
        if (LOG.isTraceEnabled()) {
            LOG.trace("Updating Subnet : key: " + identifier + ", original value=" + original + ", update value=" +
                    update);
        }
        handleNeutronSubnetUpdated(update.getUuid(), update.getNetworkId(), update.getTenantId());
    }

    private void handleNeutronSubnetCreated(Uuid subnetId, String subnetIp, Uuid networkId, Uuid tenantId) {
        nvpnManager.updateSubnetNode(subnetId, subnetIp, tenantId, networkId, null, null, null);
        if (networkId != null && NeutronvpnUtils.getNeutronNetwork(broker, networkId) != null) {
            createSubnetToNetworkMapping(subnetId, networkId);
        }
    }

    private void handleNeutronSubnetDeleted(Uuid subnetId, Uuid networkId, Uuid tenantId) {
        Uuid vpnId = NeutronvpnUtils.getVpnForNetwork(broker, networkId);
        if (vpnId != null) {
            nvpnManager.removeSubnetFromVpn(vpnId, subnetId);
        }
        if (networkId != null)  {
            deleteSubnetToNetworkMapping(subnetId, networkId);
        }
        nvpnManager.deleteSubnetMapNode(subnetId);
    }

    private void handleNeutronSubnetUpdated(Uuid subnetId, Uuid networkId, Uuid tenantId) {
        Uuid oldNetworkId = NeutronvpnUtils.getSubnetmap(broker, subnetId).getNetworkId();
        if (oldNetworkId != null && !oldNetworkId.equals(networkId)) {
            deleteSubnetToNetworkMapping(subnetId, oldNetworkId);
        }
        if (networkId != null && !networkId.equals(oldNetworkId)) {
            createSubnetToNetworkMapping(subnetId, networkId);
        }
        nvpnManager.updateSubnetNode(subnetId, null, tenantId, networkId, null, null, null);
    }

    private void createSubnetToNetworkMapping(Uuid subnetId, Uuid networkId) {
        try {
            InstanceIdentifier networkMapIdentifier = NeutronvpnUtils.buildNetworkMapIdentifier(networkId);
            Optional<NetworkMap> optionalNetworkMap = NeutronvpnUtils.read(broker, LogicalDatastoreType.CONFIGURATION,
                    networkMapIdentifier);
            NetworkMapBuilder nwMapBuilder = null;
            if (optionalNetworkMap.isPresent()) {
                nwMapBuilder = new NetworkMapBuilder(optionalNetworkMap.get());
            } else {
                nwMapBuilder = new NetworkMapBuilder().setKey(new NetworkMapKey(networkId)).setNetworkId(networkId);
                LOG.debug("Adding a new network node in NetworkMaps DS for network {}", networkId.getValue());
            }
            List<Uuid> subnetIdList = nwMapBuilder.getSubnetIdList();
            if (subnetIdList == null) {
                subnetIdList = new ArrayList<>();
            }
            subnetIdList.add(subnetId);
            nwMapBuilder.setSubnetIdList(subnetIdList);
            MDSALUtil.syncWrite(broker, LogicalDatastoreType.CONFIGURATION, networkMapIdentifier, nwMapBuilder.build());
            LOG.debug("Created subnet-network mapping for subnet {} network {}", subnetId.getValue(),
                    networkId.getValue());
        } catch (Exception e) {
            LOG.error("Create subnet-network mapping failed for subnet {} network {}", subnetId.getValue(),
                    networkId.getValue());
        }
    }

    private void deleteSubnetToNetworkMapping(Uuid subnetId, Uuid networkId) {
        try {
            InstanceIdentifier networkMapIdentifier = NeutronvpnUtils.buildNetworkMapIdentifier(networkId);
            Optional<NetworkMap> optionalNetworkMap = NeutronvpnUtils.read(broker, LogicalDatastoreType.CONFIGURATION,
                    networkMapIdentifier);
            if (optionalNetworkMap.isPresent()) {
                NetworkMapBuilder nwMapBuilder = new NetworkMapBuilder(optionalNetworkMap.get());
                List<Uuid> subnetIdList = nwMapBuilder.getSubnetIdList();
                if (subnetIdList.remove(subnetId)) {
                    if (subnetIdList.size() == 0) {
                        MDSALUtil.syncDelete(broker, LogicalDatastoreType.CONFIGURATION, networkMapIdentifier);
                        LOG.debug("Deleted network node in NetworkMaps DS for network {}", subnetId.getValue(),
                                networkId.getValue());
                    } else {
                        nwMapBuilder.setSubnetIdList(subnetIdList);
                        MDSALUtil.syncWrite(broker, LogicalDatastoreType.CONFIGURATION, networkMapIdentifier,
                                nwMapBuilder.build());
                        LOG.debug("Deleted subnet-network mapping for subnet {} network {}", subnetId.getValue(),
                                networkId.getValue());
                    }
                } else {
                    LOG.error("Subnet {} is not mapped to network {}", subnetId.getValue(), networkId.getValue());
                }
            } else {
                LOG.error("network {} not present for subnet {} ", networkId, subnetId);
            }
        } catch (Exception e) {
            LOG.error("Delete subnet-network mapping failed for subnet {} network {}", subnetId.getValue(),
                    networkId.getValue());
        }
    }
}