/*
 * Copyright (c) 2015 - 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.netvirt.vpnmanager;

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.netvirt.vpnmanager.utilities.InterfaceUtils;
import org.opendaylight.yang.gen.v1.urn.huawei.params.xml.ns.yang.l3vpn.rev140815.vpn.interfaces.VpnInterface;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.iana._if.type.rev140508.Tunnel;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.InterfacesState;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface;
import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.rpcs.rev160406.OdlInterfaceRpcService;
import org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.l3vpn.rev130911.router.interfaces.RouterInterface;
import org.opendaylight.yangtools.concepts.ListenerRegistration;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.math.BigInteger;

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

    private ListenerRegistration<DataChangeListener> listenerRegistration;
    private final DataBroker broker;
    private VpnInterfaceManager vpnInterfaceManager;
    private OdlInterfaceRpcService interfaceManager;


    public InterfaceStateChangeListener(final DataBroker db, VpnInterfaceManager vpnInterfaceManager) {
        super(Interface.class);
        broker = db;
        this.vpnInterfaceManager = vpnInterfaceManager;
        registerListener(db);
    }

    public void setIfaceMgrRpcService(OdlInterfaceRpcService interfaceManager) {
      this.interfaceManager = interfaceManager;
    }

    @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("Interface listener Closed");
    }


    private void registerListener(final DataBroker db) {
        try {
            listenerRegistration = db.registerDataChangeListener(LogicalDatastoreType.OPERATIONAL,
                                                                 getWildCardPath(), InterfaceStateChangeListener.this, DataChangeScope.SUBTREE);
        } catch (final Exception e) {
            LOG.error("Interface DataChange listener registration failed", e);
            throw new IllegalStateException("Nexthop Manager registration Listener failed.", e);
        }
    }

    @Override
    protected void add(InstanceIdentifier<Interface> identifier, Interface intrf) {
      LOG.trace("Received interface {} up event", intrf);
      try {
        String interfaceName = intrf.getName();
        LOG.info("Received port UP event for interface {} ", interfaceName);
        org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.Interface
            configInterface = InterfaceUtils.getInterface(broker, interfaceName);
        BigInteger dpnId = BigInteger.ZERO;
        try{
            dpnId = InterfaceUtils.getDpIdFromInterface(intrf);
        }catch(Exception e){
            LOG.error("Unable to retrieve dpnId from interface operational data store for interface {}. ", intrf.getName(), e);
            return;
        }
        if (configInterface != null) {
            if (!configInterface.getType().equals(Tunnel.class)) {
                // We service only VM interfaces and Router interfaces here.
                // We donot service Tunnel Interfaces here.
                // Tunnel events are directly serviced
                // by TunnelInterfacesStateListener present as part of VpnInterfaceManager
                final VpnInterface vpnInterface = VpnUtil.getConfiguredVpnInterface(broker, interfaceName);
                if (vpnInterface != null) {
                    vpnInterfaceManager.processVpnInterfaceUp(dpnId, interfaceName, intrf.getIfIndex(), false);
                    vpnInterfaceManager.getVpnSubnetRouteHandler().onInterfaceUp(intrf);
                    handleRouterInterfacesUpEvent(interfaceName);
                }

            }
        }
      } catch (Exception e) {
        LOG.error("Exception observed in handling addition for VPN Interface {}. ", intrf.getName(), e);
      }
    }


    private InstanceIdentifier<Interface> getWildCardPath() {
        return InstanceIdentifier.create(InterfacesState.class).child(Interface.class);
    }

    @Override
    protected void remove(InstanceIdentifier<Interface> identifier, Interface intrf) {
      LOG.trace("Received interface {} down event", intrf);
      try {
        String interfaceName = intrf.getName();
        LOG.info("Received port DOWN event for interface {} ", interfaceName);
        InstanceIdentifier<VpnInterface> id = VpnUtil.getVpnInterfaceIdentifier(interfaceName);
        Optional<VpnInterface> existingVpnInterface = VpnUtil.read(broker, LogicalDatastoreType.OPERATIONAL, id);
        if (!existingVpnInterface.isPresent()) {
            LOG.error("VPN Interface operational instance not available for interface {}, ignoring interface", interfaceName);
            return;
        }
        if (intrf != null && intrf.getType() != null && intrf.getType().equals(Tunnel.class)) {
            //withdraw all prefixes in all vpns for this dpn from bgp
            // FIXME: Blocked until tunnel event[vxlan/gre] support is available
            // vpnInterfaceManager.updatePrefixesForDPN(dpId, VpnInterfaceManager.UpdateRouteAction.WITHDRAW_ROUTE);
        } else {
            BigInteger dpId = BigInteger.ZERO;
            try{
                dpId = InterfaceUtils.getDpIdFromInterface(intrf);
            }catch(Exception e){
                LOG.error("Unable to retrieve dpnId from interface operational data store for interface {}. Fetching from vpn interface op data store. ", intrf.getName(), e);
                dpId = existingVpnInterface.get().getDpnId();
            }
            vpnInterfaceManager.processVpnInterfaceDown(dpId, interfaceName, intrf.getIfIndex(), false, false);
            vpnInterfaceManager.getVpnSubnetRouteHandler().onInterfaceDown(intrf);
            handleRouterInterfacesDownEvent(interfaceName,dpId);
        }
      } catch (Exception e) {
        LOG.error("Exception observed in handling deletion of VPN Interface {}. ", intrf.getName(), e);
      }
    }

    @Override
    protected void update(InstanceIdentifier<Interface> identifier,
            Interface original, Interface update) {
      LOG.trace("Operation Interface update event - Old: {}, New: {}", original, update);
      if(original.getOperStatus().equals(Interface.OperStatus.Unknown) || update.getOperStatus().equals(Interface.OperStatus.Unknown)){
          LOG.debug("Interface state change is from/to UNKNOWN. Ignoring the update event.");
          return;
      }
      String interfaceName = update.getName();
      BigInteger dpId = InterfaceUtils.getDpIdFromInterface(update);
      if (update != null) {
          if (update.getType().equals(Tunnel.class)) {
            /*
            // FIXME: Blocked until tunnel event[vxlan/gre] support is available
            BigInteger dpnId = InterfaceUtils.getDpIdFromInterface(update);
            if(update.getOperStatus().equals(Interface.OperStatus.Up)) {
              //advertise all prefixes in all vpns for this dpn to bgp
              // vpnInterfaceManager.updatePrefixesForDPN(dpnId, VpnInterfaceManager.UpdateRouteAction.ADVERTISE_ROUTE);
              vpnInterfaceManager.getVpnSubnetRouteHandler().onInterfaceUp(update);
            } else if(update.getOperStatus().equals(Interface.OperStatus.Down)) {
              //withdraw all prefixes in all vpns for this dpn from bgp
              // vpnInterfaceManager.updatePrefixesForDPN(dpnId, VpnInterfaceManager.UpdateRouteAction.WITHDRAW_ROUTE);
              vpnInterfaceManager.getVpnSubnetRouteHandler().onInterfaceDown(update);
            }*/
          } else {
              if (update.getOperStatus().equals(Interface.OperStatus.Up)) {
                  vpnInterfaceManager.processVpnInterfaceUp(dpId, interfaceName, update.getIfIndex(), true);
                  vpnInterfaceManager.getVpnSubnetRouteHandler().onInterfaceUp(update);
              } else if (update.getOperStatus().equals(Interface.OperStatus.Down)) {
                  if (VpnUtil.isVpnInterfaceConfigured(broker, interfaceName)) {
                      vpnInterfaceManager.processVpnInterfaceDown(dpId, interfaceName, update.getIfIndex(), true,
                              false);
                      vpnInterfaceManager.getVpnSubnetRouteHandler().onInterfaceDown(update);
                  }
              }
          }
      }

    }

    void handleRouterInterfacesUpEvent(String interfaceName) {
        Optional<RouterInterface> optRouterInterface = VpnUtil.read(broker, LogicalDatastoreType.CONFIGURATION, VpnUtil.getRouterInterfaceId(interfaceName));
        if(optRouterInterface.isPresent()) {
            RouterInterface routerInterface = optRouterInterface.get();
            String routerName = routerInterface.getRouterName();
            LOG.debug("Handling UP event for router interface {} in Router {}", interfaceName, routerName);
            vpnInterfaceManager.addToNeutronRouterDpnsMap(routerName, interfaceName);
        } else {
            LOG.debug("No Router interface configured to handle UP event for {}", interfaceName);
        }
    }

    void handleRouterInterfacesDownEvent(String interfaceName,BigInteger dpnId) {
        Optional<RouterInterface> optRouterInterface = VpnUtil.read(broker, LogicalDatastoreType.CONFIGURATION, VpnUtil.getRouterInterfaceId(interfaceName));
        if(optRouterInterface.isPresent()) {
            RouterInterface routerInterface = optRouterInterface.get();
            String routerName = routerInterface.getRouterName();
            LOG.debug("Handling DOWN event for router interface {} in Router {}", interfaceName, routerName);
            vpnInterfaceManager.removeFromNeutronRouterDpnsMap(routerName, interfaceName,dpnId);
        } else {
            LOG.debug("No Router interface configured to handle  DOWN event for {}", interfaceName);
        }
    }

}