/*
 * 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.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.K8sFlowRuleService;
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.net.DeviceId;
import org.onosproject.net.flow.DefaultFlowRule;
import org.onosproject.net.flow.DefaultTrafficSelector;
import org.onosproject.net.flow.DefaultTrafficTreatment;
import org.onosproject.net.flow.FlowRule;
import org.onosproject.net.flow.FlowRuleOperations;
import org.onosproject.net.flow.FlowRuleOperationsContext;
import org.onosproject.net.flow.FlowRuleService;
import org.onosproject.net.flow.TrafficSelector;
import org.onosproject.net.flow.TrafficTreatment;
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 java.util.concurrent.Executors;

import static org.onlab.util.Tools.groupedThreads;
import static org.onosproject.k8snetworking.api.Constants.ACL_EGRESS_TABLE;
import static org.onosproject.k8snetworking.api.Constants.ACL_INGRESS_TABLE;
import static org.onosproject.k8snetworking.api.Constants.ARP_TABLE;
import static org.onosproject.k8snetworking.api.Constants.DEFAULT_GATEWAY_MAC;
import static org.onosproject.k8snetworking.api.Constants.DHCP_TABLE;
import static org.onosproject.k8snetworking.api.Constants.FORWARDING_TABLE;
import static org.onosproject.k8snetworking.api.Constants.JUMP_TABLE;
import static org.onosproject.k8snetworking.api.Constants.K8S_NETWORKING_APP_ID;
import static org.onosproject.k8snetworking.api.Constants.PRIORITY_SNAT_RULE;
import static org.onosproject.k8snetworking.api.Constants.ROUTING_TABLE;
import static org.onosproject.k8snetworking.api.Constants.STAT_INBOUND_TABLE;
import static org.onosproject.k8snetworking.api.Constants.STAT_OUTBOUND_TABLE;
import static org.onosproject.k8snetworking.api.Constants.VTAG_TABLE;
import static org.onosproject.k8snetworking.api.Constants.VTAP_INBOUND_TABLE;
import static org.onosproject.k8snetworking.api.Constants.VTAP_OUTBOUND_TABLE;
import static org.slf4j.LoggerFactory.getLogger;

/**
 * Sets flow rules directly using FlowRuleService.
 */
@Component(immediate = true, service = K8sFlowRuleService.class)
public class K8sFlowRuleManager implements K8sFlowRuleService {

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

    private static final int DROP_PRIORITY = 0;
    private static final int HIGH_PRIORITY = 30000;
    private static final int TIMEOUT_SNAT_RULE = 60;

    @Reference(cardinality = ReferenceCardinality.MANDATORY)
    protected FlowRuleService flowRuleService;

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

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

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

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

    private final ExecutorService deviceEventExecutor =
            Executors.newSingleThreadExecutor(groupedThreads(
                    getClass().getSimpleName(), "device-event"));
    private final K8sNodeListener internalNodeListener = new InternalK8sNodeListener();

    private ApplicationId appId;
    private NodeId localNodeId;

    @Activate
    protected void activate() {
        appId = coreService.registerApplication(K8S_NETWORKING_APP_ID);
        coreService.registerApplication(K8S_NETWORKING_APP_ID);
        k8sNodeService.addListener(internalNodeListener);
        localNodeId = clusterService.getLocalNode().id();
        leadershipService.runForLeadership(appId.name());
        k8sNodeService.completeNodes().forEach(node ->
                                        initializePipeline(node.intgBridge()));

        log.info("Started");
    }

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

        log.info("Stopped");
    }

    @Override
    public void setRule(ApplicationId appId, DeviceId deviceId,
                        TrafficSelector selector, TrafficTreatment treatment,
                        int priority, int tableType, boolean install) {
        FlowRule.Builder flowRuleBuilder = DefaultFlowRule.builder()
                .forDevice(deviceId)
                .withSelector(selector)
                .withTreatment(treatment)
                .withPriority(priority)
                .fromApp(appId)
                .forTable(tableType);

        if (priority == PRIORITY_SNAT_RULE) {
            flowRuleBuilder.makeTemporary(TIMEOUT_SNAT_RULE);
        } else {
            flowRuleBuilder.makePermanent();
        }

        applyRule(flowRuleBuilder.build(), install);
    }

    @Override
    public void setUpTableMissEntry(DeviceId deviceId, int table) {
        TrafficSelector.Builder selector = DefaultTrafficSelector.builder();
        TrafficTreatment.Builder treatment = DefaultTrafficTreatment.builder();

        treatment.drop();

        FlowRule flowRule = DefaultFlowRule.builder()
                .forDevice(deviceId)
                .withSelector(selector.build())
                .withTreatment(treatment.build())
                .withPriority(DROP_PRIORITY)
                .fromApp(appId)
                .makePermanent()
                .forTable(table)
                .build();

        applyRule(flowRule, true);
    }

    @Override
    public void connectTables(DeviceId deviceId, int fromTable, int toTable) {
        TrafficSelector.Builder selector = DefaultTrafficSelector.builder();
        TrafficTreatment.Builder treatment = DefaultTrafficTreatment.builder();

        treatment.transition(toTable);

        FlowRule flowRule = DefaultFlowRule.builder()
                .forDevice(deviceId)
                .withSelector(selector.build())
                .withTreatment(treatment.build())
                .withPriority(DROP_PRIORITY)
                .fromApp(appId)
                .makePermanent()
                .forTable(fromTable)
                .build();

        applyRule(flowRule, true);
    }

    private void applyRule(FlowRule flowRule, boolean install) {
        FlowRuleOperations.Builder flowOpsBuilder = FlowRuleOperations.builder();

        flowOpsBuilder = install ? flowOpsBuilder.add(flowRule) : flowOpsBuilder.remove(flowRule);

        flowRuleService.apply(flowOpsBuilder.build(new FlowRuleOperationsContext() {
            @Override
            public void onSuccess(FlowRuleOperations ops) {
                log.debug("Provisioned vni or forwarding table");
            }

            @Override
            public void onError(FlowRuleOperations ops) {
                log.debug("Failed to provision vni or forwarding table");
            }
        }));
    }

    protected void initializePipeline(DeviceId deviceId) {
        // for inbound table transition
        connectTables(deviceId, STAT_INBOUND_TABLE, VTAP_INBOUND_TABLE);
        connectTables(deviceId, VTAP_INBOUND_TABLE, DHCP_TABLE);

        // for DHCP and vTag table transition
        connectTables(deviceId, DHCP_TABLE, VTAG_TABLE);

        // for vTag and ARP table transition
        connectTables(deviceId, VTAG_TABLE, ARP_TABLE);

        // for ARP and ACL table transition
        connectTables(deviceId, ARP_TABLE, ACL_INGRESS_TABLE);

        // for ACL and JUMP table transition
        connectTables(deviceId, ACL_EGRESS_TABLE, JUMP_TABLE);

        // for JUMP table transition
        // we need JUMP table for bypassing routing table which contains large
        // amount of flow rules which might cause performance degradation during
        // table lookup
        setupJumpTable(deviceId);

        // for outbound table transition
        connectTables(deviceId, STAT_OUTBOUND_TABLE, VTAP_OUTBOUND_TABLE);
        connectTables(deviceId, VTAP_OUTBOUND_TABLE, FORWARDING_TABLE);
    }

    private void setupJumpTable(DeviceId deviceId) {
        TrafficSelector.Builder selector = DefaultTrafficSelector.builder();
        TrafficTreatment.Builder treatment = DefaultTrafficTreatment.builder();

        selector.matchEthDst(DEFAULT_GATEWAY_MAC);
        treatment.transition(ROUTING_TABLE);

        FlowRule flowRule = DefaultFlowRule.builder()
                .forDevice(deviceId)
                .withSelector(selector.build())
                .withTreatment(treatment.build())
                .withPriority(HIGH_PRIORITY)
                .fromApp(appId)
                .makePermanent()
                .forTable(JUMP_TABLE)
                .build();

        applyRule(flowRule, true);

        selector = DefaultTrafficSelector.builder();
        treatment = DefaultTrafficTreatment.builder();

        treatment.transition(STAT_OUTBOUND_TABLE);

        flowRule = DefaultFlowRule.builder()
                .forDevice(deviceId)
                .withSelector(selector.build())
                .withTreatment(treatment.build())
                .withPriority(DROP_PRIORITY)
                .fromApp(appId)
                .makePermanent()
                .forTable(JUMP_TABLE)
                .build();

        applyRule(flowRule, true);
    }

    private class InternalK8sNodeListener implements K8sNodeListener {
        private boolean isRelevantHelper() {
            return Objects.equals(localNodeId, leadershipService.getLeader(appId.name()));
        }

        @Override
        public void event(K8sNodeEvent event) {
            K8sNode k8sNode = event.subject();

            switch (event.type()) {
                case K8S_NODE_COMPLETE:
                    deviceEventExecutor.execute(() -> {
                        log.info("COMPLETE node {} is detected", k8sNode.hostname());

                        if (!isRelevantHelper()) {
                            return;
                        }

                        initializePipeline(k8sNode.intgBridge());
                    });
                    break;
                case K8S_NODE_CREATED:
                default:
                    // do nothing
                    break;
            }
        }
    }
}