/*
 * Copyright 2019-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.k8snetworking.impl;

import org.onosproject.cfg.ComponentConfigService;
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.k8snetworking.api.DefaultK8sNetwork;
import org.onosproject.k8snetworking.api.K8sNetwork;
import org.onosproject.k8snetworking.api.K8sNetworkAdminService;
import org.onosproject.k8snode.api.K8sNode;
import org.onosproject.k8snode.api.K8sNodeEvent;
import org.onosproject.k8snode.api.K8sNodeListener;
import org.onosproject.k8snode.api.K8sNodeService;
import org.onosproject.mastership.MastershipService;
import org.onosproject.net.device.DeviceService;
import org.onosproject.net.driver.DriverService;
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Deactivate;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.component.annotations.ReferenceCardinality;
import org.slf4j.Logger;

import java.util.Objects;
import java.util.concurrent.ExecutorService;

import static java.util.concurrent.Executors.newSingleThreadExecutor;
import static org.onlab.util.Tools.groupedThreads;
import static org.onosproject.k8snetworking.api.Constants.K8S_NETWORKING_APP_ID;
import static org.slf4j.LoggerFactory.getLogger;

/**
 * Provides implementation of initializes the kubernetes network.
 */
@Component(immediate = true)
public class K8sNetworkHandler {

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

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

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected ComponentConfigService configService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected DeviceService deviceService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected DriverService driverService;

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

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected MastershipService mastershipService;

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

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected K8sNodeService k8sNodeService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected K8sNetworkAdminService k8sNetworkService;

    private final InternalK8sNodeListener k8sNodeListener =
            new InternalK8sNodeListener();
    private final ExecutorService eventExecutor = newSingleThreadExecutor(
            groupedThreads(this.getClass().getSimpleName(), "event-handler", log));

    private ApplicationId appId;
    private NodeId localNodeId;

    @Activate
    protected void activate() {
        appId = coreService.registerApplication(K8S_NETWORKING_APP_ID);

        localNodeId = clusterService.getLocalNode().id();
        leadershipService.runForLeadership(appId.name());
        k8sNodeService.addListener(k8sNodeListener);

        log.info("Started");
    }

    @Deactivate
    protected void deactivate() {
        k8sNodeService.removeListener(k8sNodeListener);
        leadershipService.withdraw(appId.name());
        eventExecutor.shutdown();

        log.info("Stopped");
    }

    private class InternalK8sNodeListener implements K8sNodeListener {

        private boolean isRelevantHelper() {
            return Objects.equals(localNodeId, leadershipService.getLeader(appId.name()));
        }

        @Override
        public void event(K8sNodeEvent event) {
            switch (event.type()) {
                case K8S_NODE_CREATED:
                    eventExecutor.execute(() -> processNodeCreation(event.subject()));
                    break;
                case K8S_NODE_REMOVED:
                    eventExecutor.execute(() -> processNodeRemoval(event.subject()));
                    break;
                default:
                    break;
            }
        }

        private void processNodeCreation(K8sNode k8sNode) {
            if (!isRelevantHelper()) {
                return;
            }

            K8sNetwork network = k8sNetworkService.network(k8sNode.hostname());
            if (network == null) {
                K8sNetwork.Builder nBuilder = DefaultK8sNetwork.builder()
                        .networkId(k8sNode.hostname())
                        .name(k8sNode.hostname())
                        .cidr(k8sNode.podCidr());
                k8sNetworkService.createNetwork(nBuilder.build());
            }
        }

        private void processNodeRemoval(K8sNode k8sNode) {
            if (!isRelevantHelper()) {
                return;
            }

            K8sNetwork network = k8sNetworkService.network(k8sNode.hostname());
            if (network != null) {
                k8sNetworkService.removeNetwork(k8sNode.hostname());
            }
        }
    }
}