/*
 * Copyright 2017-present 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.openstacknode.impl;

import com.google.common.base.Strings;
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.onosproject.cluster.ClusterService;
import org.onosproject.cluster.LeadershipService;
import org.onosproject.cluster.NodeId;
import org.onosproject.core.ApplicationId;
import org.onosproject.core.CoreService;
import org.onosproject.event.ListenerRegistry;
import org.onosproject.net.DeviceId;
import org.onosproject.net.config.ConfigFactory;
import org.onosproject.net.config.NetworkConfigEvent;
import org.onosproject.net.config.NetworkConfigListener;
import org.onosproject.net.config.NetworkConfigRegistry;
import org.onosproject.net.config.basics.SubjectFactories;
import org.onosproject.openstacknode.api.OpenstackNodeConfig;
import org.onosproject.openstacknode.api.OpenstackNode;
import org.onosproject.openstacknode.api.OpenstackNodeAdminService;
import org.onosproject.openstacknode.api.OpenstackNodeEvent;
import org.onosproject.openstacknode.api.OpenstackNodeListener;
import org.onosproject.openstacknode.api.OpenstackNodeService;
import org.onosproject.openstacknode.api.OpenstackNodeStore;
import org.onosproject.openstacknode.api.OpenstackNodeStoreDelegate;
import org.slf4j.Logger;

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

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
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.slf4j.LoggerFactory.getLogger;

/**
 * Service administering the inventory of openstack nodes.
 */
@Service
@Component(immediate = true)
public class OpenstackNodeManager extends ListenerRegistry<OpenstackNodeEvent, OpenstackNodeListener>
        implements OpenstackNodeService, OpenstackNodeAdminService {

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

    private static final String MSG_NODE = "OpenStack node %s %s";
    private static final String MSG_CREATED = "created";
    private static final String MSG_UPDATED = "updated";
    private static final String MSG_REMOVED = "removed";

    private static final String ERR_NULL_NODE = "OpenStack node cannot be null";
    private static final String ERR_NULL_HOSTNAME = "OpenStack node hostname cannot be null";

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected OpenstackNodeStore osNodeStore;

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

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

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected LeadershipService leadershipService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected NetworkConfigRegistry configRegistry;

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

    private final ConfigFactory configFactory =
            new ConfigFactory<ApplicationId, OpenstackNodeConfig>(
                    SubjectFactories.APP_SUBJECT_FACTORY, OpenstackNodeConfig.class, "openstacknode") {
                @Override
                public OpenstackNodeConfig createConfig() {
                    return new OpenstackNodeConfig();
                }
            };

    private final NetworkConfigListener configListener = new InternalConfigListener();
    private final OpenstackNodeStoreDelegate delegate = new InternalNodeStoreDelegate();

    private ApplicationId appId;
    private NodeId localNode;

    @Activate
    protected void activate() {
        appId = coreService.registerApplication(APP_ID);
        osNodeStore.setDelegate(delegate);

        localNode = clusterService.getLocalNode().id();
        leadershipService.runForLeadership(appId.name());

        configRegistry.registerConfigFactory(configFactory);
        configRegistry.addListener(configListener);

        readConfiguration();
        log.info("Started");
    }

    @Deactivate
    protected void deactivate() {
        osNodeStore.unsetDelegate(delegate);
        configRegistry.removeListener(configListener);
        configRegistry.unregisterConfigFactory(configFactory);

        leadershipService.withdraw(appId.name());
        eventExecutor.shutdown();

        log.info("Stopped");
    }

    @Override
    public void createNode(OpenstackNode osNode) {
        checkNotNull(osNode, ERR_NULL_NODE);
        osNodeStore.createNode(osNode);
        log.info(String.format(MSG_NODE, osNode.hostname(), MSG_CREATED));
    }

    @Override
    public void updateNode(OpenstackNode osNode) {
        checkNotNull(osNode, ERR_NULL_NODE);
        osNodeStore.updateNode(osNode);
        log.info(String.format(MSG_NODE, osNode.hostname(), MSG_UPDATED));
    }

    @Override
    public OpenstackNode removeNode(String hostname) {
        checkArgument(!Strings.isNullOrEmpty(hostname), ERR_NULL_HOSTNAME);
        OpenstackNode osNode = osNodeStore.removeNode(hostname);
        log.info(String.format(MSG_NODE, hostname, MSG_REMOVED));
        return osNode;
    }

    @Override
    public Set<OpenstackNode> nodes() {
        return osNodeStore.nodes();
    }

    @Override
    public Set<OpenstackNode> nodes(OpenstackNode.NodeType type) {
        Set<OpenstackNode> osNodes = osNodeStore.nodes().stream()
                .filter(osNode -> Objects.equals(osNode.type(), type))
                .collect(Collectors.toSet());
        return ImmutableSet.copyOf(osNodes);
    }

    @Override
    public Set<OpenstackNode> completeNodes() {
        Set<OpenstackNode> osNodes = osNodeStore.nodes().stream()
                .filter(osNode -> Objects.equals(osNode.state(), COMPLETE))
                .collect(Collectors.toSet());
        return ImmutableSet.copyOf(osNodes);
    }

    @Override
    public Set<OpenstackNode> completeNodes(OpenstackNode.NodeType type) {
        Set<OpenstackNode> osNodes = osNodeStore.nodes().stream()
                .filter(osNode -> osNode.type() == type &&
                        Objects.equals(osNode.state(), COMPLETE))
                .collect(Collectors.toSet());
        return ImmutableSet.copyOf(osNodes);
    }

    @Override
    public OpenstackNode node(String hostname) {
        return osNodeStore.node(hostname);
    }

    @Override
    public OpenstackNode node(DeviceId deviceId) {
        OpenstackNode result = osNodeStore.nodes().stream()
                .filter(osNode -> Objects.equals(osNode.intgBridge(), deviceId) ||
                        Objects.equals(osNode.ovsdb(), deviceId) ||
                        Objects.equals(osNode.routerBridge(), deviceId))
                .findFirst().orElse(null);
        return result;
    }

    private class InternalNodeStoreDelegate implements OpenstackNodeStoreDelegate {

        @Override
        public void notify(OpenstackNodeEvent event) {
            if (event != null) {
                log.trace("send openstack node event {}", event);
                process(event);
            }
        }
    }

    private void readConfiguration() {
        OpenstackNodeConfig config = configRegistry.getConfig(appId, OpenstackNodeConfig.class);
        if (config == null) {
            log.debug("No configuration found");
            return;
        }

        log.info("Read openstack node configurations...");
        Set<String> hostnames = config.openstackNodes().stream()
                .map(OpenstackNode::hostname)
                .collect(Collectors.toSet());
        nodes().stream().filter(osNode -> !hostnames.contains(osNode.hostname()))
                .forEach(osNode -> removeNode(osNode.hostname()));

        config.openstackNodes().forEach(osNode -> {
            OpenstackNode existing = node(osNode.hostname());
            if (existing == null) {
                createNode(osNode);
            } else if (!existing.equals(osNode)) {
                updateNode(osNode);
            }
        });
    }

    private class InternalConfigListener implements NetworkConfigListener {

        @Override
        public void event(NetworkConfigEvent event) {
            NodeId leaderNodeId = leadershipService.getLeader(appId.name());
            if (!Objects.equals(localNode, leaderNodeId)) {
                // do not allow to proceed without leadership
                return;
            }

            if (!event.configClass().equals(OpenstackNodeConfig.class)) {
                return;
            }

            switch (event.type()) {
                case CONFIG_ADDED:
                case CONFIG_UPDATED:
                    eventExecutor.execute(OpenstackNodeManager.this::readConfiguration);
                    break;
                default:
                    break;
            }
        }
    }
}