/*
 * Copyright 2015 Open Networking Laboratory
 *
 * 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.store.intent.impl;

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.cluster.ClusterService;
import org.onosproject.net.intent.BatchWrite;
import org.onosproject.net.intent.Intent;
import org.onosproject.net.intent.IntentData;
import org.onosproject.net.intent.IntentEvent;
import org.onosproject.net.intent.IntentState;
import org.onosproject.net.intent.IntentStore;
import org.onosproject.net.intent.IntentStoreDelegate;
import org.onosproject.net.intent.Key;
import org.onosproject.store.AbstractStore;
import org.onosproject.store.cluster.messaging.ClusterCommunicationService;
import org.onosproject.store.impl.EventuallyConsistentMap;
import org.onosproject.store.impl.EventuallyConsistentMapEvent;
import org.onosproject.store.impl.EventuallyConsistentMapImpl;
import org.onosproject.store.impl.EventuallyConsistentMapListener;
import org.onosproject.store.impl.MultiValuedTimestamp;
import org.onosproject.store.impl.SystemClockTimestamp;
import org.onosproject.store.serializers.KryoNamespaces;
import org.slf4j.Logger;

import java.util.List;
import java.util.stream.Collectors;

import static org.slf4j.LoggerFactory.getLogger;

/**
 * Manages inventory of Intents in a distributed data store that uses optimistic
 * replication and gossip based techniques.
 */
@Component(immediate = false, enabled = false)
@Service
public class GossipIntentStore
        extends AbstractStore<IntentEvent, IntentStoreDelegate>
        implements IntentStore {

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

    // Map of intent key => current intent state
    private EventuallyConsistentMap<Key, IntentData> currentState;

    // Map of intent key => pending intent operation
    private EventuallyConsistentMap<Key, IntentData> pending;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected ClusterCommunicationService clusterCommunicator;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected ClusterService clusterService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected PartitionService partitionService;

    @Activate
    public void activate() {
        KryoNamespace.Builder intentSerializer = KryoNamespace.newBuilder()
                .register(KryoNamespaces.API)
                .register(IntentData.class)
                .register(MultiValuedTimestamp.class)
                .register(SystemClockTimestamp.class);

        currentState = new EventuallyConsistentMapImpl<>("intent-current",
                                                         clusterService,
                                                         clusterCommunicator,
                                                         intentSerializer,
                                                         new IntentDataLogicalClockManager<>());

        pending = new EventuallyConsistentMapImpl<>("intent-pending",
                                                    clusterService,
                                                    clusterCommunicator,
                                                    intentSerializer, // TODO
                                                    new IntentDataClockManager<>());

        currentState.addListener(new InternalIntentStatesListener());
        pending.addListener(new InternalPendingListener());

        log.info("Started");
    }

    @Deactivate
    public void deactivate() {
        currentState.destroy();
        pending.destroy();

        log.info("Stopped");
    }

    @Override
    public long getIntentCount() {
        return currentState.size();
    }

    @Override
    public Iterable<Intent> getIntents() {
        return currentState.values().stream()
                .map(IntentData::intent)
                .collect(Collectors.toList());
    }

    @Override
    public IntentState getIntentState(Key intentKey) {
        IntentData data = currentState.get(intentKey);
        if (data != null) {
            return data.state();
        }
        return null;
    }

    @Override
    public List<Intent> getInstallableIntents(Key intentKey) {
        IntentData data = currentState.get(intentKey);
        if (data != null) {
            return data.installables();
        }
        return null;
    }

    @Override
    public List<BatchWrite.Operation> batchWrite(BatchWrite batch) {
        // Deprecated
        return null;
    }

    @Override
    public void write(IntentData newData) {
        log.debug("writing intent {}", newData);

        // Only the master is modifying the current state. Therefore assume
        // this always succeeds
        currentState.put(newData.key(), newData);

        // if current.put succeeded
        pending.remove(newData.key(), newData);

        /*try {
            notifyDelegate(IntentEvent.getEvent(newData));
        } catch (IllegalArgumentException e) {
            //no-op
            log.trace("ignore this exception: {}", e);
        }*/
    }

    @Override
    public void batchWrite(Iterable<IntentData> updates) {
        updates.forEach(this::write);
    }

    @Override
    public Intent getIntent(Key key) {
        IntentData data = currentState.get(key);
        if (data != null) {
            return data.intent();
        }
        return null;
    }

    @Override
    public IntentData getIntentData(Key key) {
        return currentState.get(key);
    }

    @Override
    public void addPending(IntentData data) {
        log.debug("new call to pending {}", data);
        if (data.version() == null) {
            log.debug("updating timestamp");
            data.setVersion(new SystemClockTimestamp());
        }
        pending.put(data.key(), data);
    }

    @Override
    public boolean isMaster(Intent intent) {
        return partitionService.isMine(intent.key());
    }

    private void notifyDelegateIfNotNull(IntentEvent event) {
        if (event != null) {
            notifyDelegate(event);
        }
    }

    private final class InternalIntentStatesListener implements
            EventuallyConsistentMapListener<Key, IntentData> {
        @Override
        public void event(
                EventuallyConsistentMapEvent<Key, IntentData> event) {
            if (event.type() == EventuallyConsistentMapEvent.Type.PUT) {
                IntentEvent externalEvent;
                IntentData intentData = event.value();

                try {
                    externalEvent = IntentEvent.getEvent(intentData.state(), intentData.intent());
                } catch (IllegalArgumentException e) {
                    externalEvent = null;
                }

                notifyDelegateIfNotNull(externalEvent);
            }
        }
    }

    private final class InternalPendingListener implements
            EventuallyConsistentMapListener<Key, IntentData> {
        @Override
        public void event(
                EventuallyConsistentMapEvent<Key, IntentData> event) {
            if (event.type() == EventuallyConsistentMapEvent.Type.PUT) {
                // The pending intents map has been updated. If we are master for
                // this intent's partition, notify the Manager that it should do
                // some work.
                if (isMaster(event.value().intent())) {
                    if (delegate != null) {
                        delegate.process(event.value());
                    }
                }

                try {
                    notifyDelegate(IntentEvent.getEvent(event.value()));
                } catch (IllegalArgumentException e) {
                    //no-op
                    log.trace("ignore this exception: {}", e);
                }
            }
        }
    }

}