/*
 * Copyright 2017-present Open Networking Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.onosproject.openstacknode.impl;

import com.google.common.collect.ImmutableSet;
import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Deactivate;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.ReferenceCardinality;
import org.apache.felix.scr.annotations.Service;
import org.onlab.util.KryoNamespace;
import org.onosproject.core.ApplicationId;
import org.onosproject.core.CoreService;
import org.onosproject.openstacknode.api.NodeState;
import org.onosproject.openstacknode.api.OpenstackNode;
import org.onosproject.openstacknode.api.OpenstackNodeEvent;
import org.onosproject.openstacknode.api.OpenstackNodeStore;
import org.onosproject.openstacknode.api.OpenstackNodeStoreDelegate;
import org.onosproject.store.AbstractStore;
import org.onosproject.store.serializers.KryoNamespaces;
import org.onosproject.store.service.ConsistentMap;
import org.onosproject.store.service.MapEvent;
import org.onosproject.store.service.MapEventListener;
import org.onosproject.store.service.Serializer;
import org.onosproject.store.service.StorageService;
import org.onosproject.store.service.Versioned;
import org.slf4j.Logger;

import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.stream.Collectors;

import static com.google.common.base.Preconditions.checkArgument;
import static java.util.concurrent.Executors.newSingleThreadExecutor;
import static org.onlab.util.Tools.groupedThreads;
import static org.onosproject.openstacknode.api.NodeState.COMPLETE;
import static org.onosproject.openstacknode.api.NodeState.INCOMPLETE;
import static org.onosproject.openstacknode.api.OpenstackNodeEvent.Type.OPENSTACK_NODE_COMPLETE;
import static org.onosproject.openstacknode.api.OpenstackNodeEvent.Type.OPENSTACK_NODE_CREATED;
import static org.onosproject.openstacknode.api.OpenstackNodeEvent.Type.OPENSTACK_NODE_INCOMPLETE;
import static org.onosproject.openstacknode.api.OpenstackNodeEvent.Type.OPENSTACK_NODE_REMOVED;
import static org.onosproject.openstacknode.api.OpenstackNodeEvent.Type.OPENSTACK_NODE_UPDATED;
import static org.slf4j.LoggerFactory.getLogger;

/**
 * Implementation of openstack node store using consistent map.
 */
@Service
@Component(immediate = true)
public class DistributedOpenstackNodeStore
        extends AbstractStore<OpenstackNodeEvent, OpenstackNodeStoreDelegate>
        implements OpenstackNodeStore {

    private final Logger log = getLogger(getClass());

    private static final String ERR_NOT_FOUND = " does not exist";
    private static final String ERR_DUPLICATE = " already exists";

    private static final KryoNamespace SERIALIZER_OPENSTACK_NODE = KryoNamespace.newBuilder()
            .register(KryoNamespaces.API)
            .register(OpenstackNode.class)
            .register(DefaultOpenstackNode.class)
            .register(OpenstackNode.NodeType.class)
            .register(NodeState.class)
            .build();

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected CoreService coreService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected StorageService storageService;

    private final ExecutorService eventExecutor = newSingleThreadExecutor(
            groupedThreads(this.getClass().getSimpleName(), "event-handler", log));

    private final MapEventListener<String, OpenstackNode> osNodeMapListener =
            new OpenstackNodeMapListener();
    private ConsistentMap<String, OpenstackNode> osNodeStore;

    @Activate
    protected void activate() {
        ApplicationId appId = coreService.registerApplication("org.onosproject.openstacknode");
        osNodeStore = storageService.<String, OpenstackNode>consistentMapBuilder()
                .withSerializer(Serializer.using(SERIALIZER_OPENSTACK_NODE))
                .withName("openstack-nodestore")
                .withApplicationId(appId)
                .build();
        osNodeStore.addListener(osNodeMapListener);
        log.info("Started");
    }

    @Deactivate
    protected void deactivate() {
        osNodeStore.removeListener(osNodeMapListener);
        eventExecutor.shutdown();
        log.info("Stopped");
    }

    @Override
    public void createNode(OpenstackNode osNode) {
        osNodeStore.compute(osNode.hostname(), (hostname, existing) -> {
            final String error = osNode.hostname() + ERR_DUPLICATE;
            checkArgument(existing == null, error);
            return osNode;
        });
    }

    @Override
    public void updateNode(OpenstackNode osNode) {
        osNodeStore.compute(osNode.hostname(), (hostname, existing) -> {
            final String error = osNode.hostname() + ERR_NOT_FOUND;
            checkArgument(existing != null, error);
            return osNode;
        });
    }

    @Override
    public OpenstackNode removeNode(String hostname) {
        Versioned<OpenstackNode> osNode = osNodeStore.remove(hostname);
        if (osNode == null) {
            final String error = hostname + ERR_NOT_FOUND;
            throw new IllegalArgumentException(error);
        }
        return osNode.value();
    }

    @Override
    public Set<OpenstackNode> nodes() {
        Set<OpenstackNode> osNodes = osNodeStore.values().stream()
                .map(Versioned::value)
                .collect(Collectors.toSet());
        return ImmutableSet.copyOf(osNodes);
    }

    @Override
    public OpenstackNode node(String hostname) {
        Versioned<OpenstackNode> osNode = osNodeStore.get(hostname);
        return osNode == null ? null : osNode.value();
    }

    /**
     * An internal openstack node map listener.
     */
    private class OpenstackNodeMapListener implements MapEventListener<String, OpenstackNode> {

        @Override
        public void event(MapEvent<String, OpenstackNode> event) {
            switch (event.type()) {
                case INSERT:
                    log.debug("OpenStack node created {}", event.newValue());
                    eventExecutor.execute(() ->
                            notifyDelegate(new OpenstackNodeEvent(
                                OPENSTACK_NODE_CREATED, event.newValue().value()
                    )));
                    break;
                case UPDATE:
                    log.debug("OpenStack node updated {}", event.newValue());
                    eventExecutor.execute(() -> {
                        notifyDelegate(new OpenstackNodeEvent(
                                OPENSTACK_NODE_UPDATED,
                                event.newValue().value()
                        ));
                        if (event.newValue().value().state() == COMPLETE) {
                            notifyDelegate(new OpenstackNodeEvent(
                                    OPENSTACK_NODE_COMPLETE,
                                    event.newValue().value()
                            ));
                        } else if (event.newValue().value().state() == INCOMPLETE) {
                            notifyDelegate(new OpenstackNodeEvent(
                                    OPENSTACK_NODE_INCOMPLETE,
                                    event.newValue().value()
                            ));
                        }
                    });
                    break;
                case REMOVE:
                    log.debug("OpenStack node removed {}", event.oldValue());
                    eventExecutor.execute(() ->
                            notifyDelegate(new OpenstackNodeEvent(
                                OPENSTACK_NODE_REMOVED, event.oldValue().value()
                    )));
                    break;
                default:
                    // do nothing
                    break;
            }
        }
    }
}