/*
 * 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.openstacknetworking.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.onosproject.core.ApplicationId;
import org.onosproject.core.CoreService;
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.onosproject.net.flow.instructions.Instruction;
import org.onosproject.net.flowobjective.ForwardingObjective;
import org.onosproject.net.flowobjective.Objective;
import org.onosproject.openstacknetworking.api.Constants;
import org.onosproject.openstacknetworking.api.OpenstackFlowRuleService;
import org.onosproject.openstacknode.OpenstackNode;
import org.onosproject.openstacknode.OpenstackNodeEvent;
import org.onosproject.openstacknode.OpenstackNodeListener;
import org.onosproject.openstacknode.OpenstackNodeService;
import org.slf4j.Logger;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import static org.onlab.util.Tools.groupedThreads;
import static org.onosproject.openstacknetworking.api.Constants.OPENSTACK_NETWORKING_APP_ID;
import static org.slf4j.LoggerFactory.getLogger;

/**
 * Sets flow rules directly using FlowRuleService.
 */
@Service
@Component(immediate = true)
public class OpenstackFlowRuleManager implements OpenstackFlowRuleService {

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

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

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

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

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected OpenstackNodeService osNodeService;

    private final ExecutorService deviceEventExecutor =
            Executors.newSingleThreadExecutor(groupedThreads("openstacknetworking", "device-event"));
    private final InternalOpenstackNodeListener internalNodeListener = new InternalOpenstackNodeListener();

    private ApplicationId appId;

    @Activate
    protected void activate() {
        appId = coreService.registerApplication(OPENSTACK_NETWORKING_APP_ID);
        coreService.registerApplication(OPENSTACK_NETWORKING_APP_ID);
        osNodeService.addListener(internalNodeListener);

        log.info("Started");
    }

    @Deactivate
    protected void deactivate() {
        osNodeService.removeListener(internalNodeListener);
        deviceEventExecutor.shutdown();

        log.info("Stopped");
    }

    @Override
    public void forward(DeviceId deviceId, ForwardingObjective forwardingObjective, int tableType) {
        TrafficTreatment.Builder treatment = DefaultTrafficTreatment.builder();

        forwardingObjective.treatment().allInstructions().stream()
                .filter(i -> i.type() != Instruction.Type.NOACTION).forEach(treatment::add);

        FlowRule.Builder ruleBuilder = DefaultFlowRule.builder()
                .forDevice(deviceId)
                .withSelector(forwardingObjective.selector())
                .withTreatment(treatment.build())
                .withPriority(forwardingObjective.priority())
                .fromApp(forwardingObjective.appId())
                .forTable(tableType);

        if (forwardingObjective.permanent()) {
            ruleBuilder.makePermanent();
        } else {
            ruleBuilder.makeTemporary(FLOW_RULE_TIME_OUT);
        }

        if (forwardingObjective.op().equals(Objective.Operation.ADD)) {
            applyRules(true, ruleBuilder.build());
        } else {
            applyRules(false, ruleBuilder.build());
        }
    }

    private void applyRules(boolean install, FlowRule flowRule) {
        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 privision vni or forwarding table");
            }
        }));
    }

    private void initializePipeline(DeviceId deviceId) {
        connectTables(deviceId, Constants.SRC_VNI_TABLE, Constants.ACL_TABLE);
        connectTables(deviceId, Constants.ACL_TABLE, Constants.JUMP_TABLE);
        setUpTableMissEntry(deviceId, Constants.ACL_TABLE);
        setupJumpTable(deviceId);
    }

    private 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();

        applyRules(true, flowRule);
    }

    private 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();

        applyRules(true, flowRule);
    }

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

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

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

        applyRules(true, flowRule);

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

        treatment.transition(Constants.FORWARDING_TABLE);

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

        applyRules(true, flowRule);
    }

    private class InternalOpenstackNodeListener implements OpenstackNodeListener {

        @Override
        public void event(OpenstackNodeEvent event) {
            OpenstackNode osNode = event.subject();
            // TODO check leadership of the node and make only the leader process

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

                    });
                    break;
                case INCOMPLETE:
                    log.warn("{} is changed to INCOMPLETE state", osNode);
                    break;
                case INIT:
                case DEVICE_CREATED:
                default:
                    break;
            }
        }

        private void processCompleteNode(OpenstackNode osNode) {
            if (osNode.type().equals(OpenstackNodeService.NodeType.COMPUTE)) {
                initializePipeline(osNode.intBridge());
            }
        }
    }
}