/*
* 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 com.google.common.base.Strings;
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.onlab.packet.Ethernet;
import org.onlab.packet.IPv4;
import org.onlab.packet.Ip4Address;
import org.onlab.packet.Ip4Prefix;
import org.onlab.packet.IpPrefix;
import org.onlab.packet.TpPort;
import org.onosproject.core.ApplicationId;
import org.onosproject.core.CoreService;
import org.onosproject.mastership.MastershipService;
import org.onosproject.net.flow.DefaultTrafficSelector;
import org.onosproject.net.flow.DefaultTrafficTreatment;
import org.onosproject.net.flow.TrafficSelector;
import org.onosproject.net.flowobjective.DefaultForwardingObjective;
import org.onosproject.net.flowobjective.FlowObjectiveService;
import org.onosproject.net.flowobjective.ForwardingObjective;
import org.onosproject.openstacknetworking.api.InstancePort;
import org.onosproject.openstacknetworking.api.InstancePortEvent;
import org.onosproject.openstacknetworking.api.InstancePortListener;
import org.onosproject.openstacknetworking.api.InstancePortService;
import org.onosproject.openstacknetworking.api.OpenstackNetworkEvent;
import org.onosproject.openstacknetworking.api.OpenstackNetworkListener;
import org.onosproject.openstacknetworking.api.OpenstackNetworkService;
import org.onosproject.openstacknetworking.api.OpenstackSecurityGroupEvent;
import org.onosproject.openstacknetworking.api.OpenstackSecurityGroupListener;
import org.onosproject.openstacknetworking.api.OpenstackSecurityGroupService;
import org.openstack4j.model.network.Port;
import org.openstack4j.model.network.SecurityGroup;
import org.openstack4j.model.network.SecurityGroupRule;
import org.openstack4j.openstack.networking.domain.NeutronSecurityGroupRule;
import org.slf4j.Logger;

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

import static java.util.concurrent.Executors.newSingleThreadExecutor;
import static org.onlab.util.Tools.groupedThreads;
import static org.onosproject.openstacknetworking.api.Constants.OPENSTACK_NETWORKING_APP_ID;
import static org.onosproject.openstacknetworking.api.Constants.PRIORITY_ACL_RULE;
import static org.slf4j.LoggerFactory.getLogger;

/**
 * Populates flow rules to handle OpenStack SecurityGroups.
 */
@Component(immediate = true)
public class OpenstackSecurityGroupHandler {

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

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

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected InstancePortService instancePortService;

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

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected OpenstackNetworkService osNetService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected OpenstackSecurityGroupService securityGroupService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected FlowObjectiveService flowObjectiveService;

    private final InstancePortListener instancePortListener = new InternalInstancePortListener();
    private final OpenstackNetworkListener portListener = new InternalOpenstackPortListener();
    private final OpenstackSecurityGroupListener securityGroupListener = new InternalSecurityGroupListener();
    private ApplicationId appId;

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

    private static final String PROTO_ICMP = "ICMP";
    private static final String PROTO_TCP = "TCP";
    private static final String PROTO_UDP = "UDP";
    private static final String ETHTYPE_IPV4 = "IPV4";
    private static final String EGRESS = "EGRESS";
    private static final String INGRESS = "INGRESS";
    private static final IpPrefix IP_PREFIX_ANY = Ip4Prefix.valueOf("0.0.0.0/0");

    @Activate
    protected void activate() {
        appId = coreService.registerApplication(OPENSTACK_NETWORKING_APP_ID);
        instancePortService.addListener(instancePortListener);
        securityGroupService.addListener(securityGroupListener);
        osNetService.addListener(portListener);

        log.info("Started");
    }

    @Deactivate
    protected void deactivate() {
        instancePortService.removeListener(instancePortListener);
        securityGroupService.removeListener(securityGroupListener);
        osNetService.removeListener(portListener);
        eventExecutor.shutdown();

        log.info("Stopped");
    }

    private void setSecurityGroupRules(InstancePort instPort, Port port, boolean install) {
        port.getSecurityGroups().forEach(sgId -> {
            SecurityGroup sg = securityGroupService.securityGroup(sgId);
            if (sg == null) {
                log.error("Security Group Not Found : {}", sgId);
                return;
            }
            sg.getRules().forEach(sgRule -> updateSecurityGroupRule(instPort, port, sgRule, install));
            final String action = install ? "Installed " : "Removed ";
            log.debug(action + "security group rule ID : " + sgId);
        });
    }

    private void updateSecurityGroupRule(InstancePort instPort, Port port, SecurityGroupRule sgRule, boolean install) {
        if (sgRule.getRemoteGroupId() != null && !sgRule.getRemoteGroupId().isEmpty()) {
            getRemoteInstPorts(port.getTenantId(), sgRule.getRemoteGroupId())
                .forEach(rInstPort -> {
                    populateSecurityGroupRule(sgRule, instPort, rInstPort.ipAddress().toIpPrefix(), install);
                    populateSecurityGroupRule(sgRule, rInstPort, instPort.ipAddress().toIpPrefix(), install);

                    SecurityGroupRule rSgRule = new NeutronSecurityGroupRule.SecurityGroupRuleConcreteBuilder()
                            .from(sgRule)
                            .direction(sgRule.getDirection().toUpperCase().equals(EGRESS) ? INGRESS : EGRESS).build();
                    populateSecurityGroupRule(rSgRule, instPort, rInstPort.ipAddress().toIpPrefix(), install);
                    populateSecurityGroupRule(rSgRule, rInstPort, instPort.ipAddress().toIpPrefix(), install);
                });
        } else {
            populateSecurityGroupRule(sgRule, instPort, sgRule.getRemoteIpPrefix() == null ? IP_PREFIX_ANY :
                    IpPrefix.valueOf(sgRule.getRemoteIpPrefix()), install);
        }
    }

    private void populateSecurityGroupRule(SecurityGroupRule sgRule, InstancePort instPort,
                                           IpPrefix remoteIp, boolean install) {
        ForwardingObjective.Builder foBuilder = buildFlowObjective(sgRule,
                Ip4Address.valueOf(instPort.ipAddress().toInetAddress()), remoteIp);
        if (foBuilder == null) {
            return;
        }

        if (install) {
            flowObjectiveService.forward(instPort.deviceId(), foBuilder.add());
        } else {
            flowObjectiveService.forward(instPort.deviceId(), foBuilder.remove());
        }
    }

    /**
     * Returns a set of host IP addresses engaged with supplied security group ID.
     * It only searches a VM in the same tenant boundary.
     *
     * @param tenantId tenant id
     * @param sgId security group id
     * @return set of ip addresses
     */
    private Set<InstancePort> getRemoteInstPorts(String tenantId, String sgId) {
        Set<InstancePort> remoteInstPorts;

        remoteInstPorts = osNetService.ports().stream()
                .filter(port -> port.getTenantId().equals(tenantId))
                .filter(port -> port.getSecurityGroups().contains(sgId))
                .map(port -> instancePortService.instancePort(port.getId()))
                .filter(instPort -> instPort != null && instPort.ipAddress() != null)
                .collect(Collectors.toSet());

        return Collections.unmodifiableSet(remoteInstPorts);
    }

    private ForwardingObjective.Builder buildFlowObjective(SecurityGroupRule sgRule,
                                                           Ip4Address vmIp,
                                                           IpPrefix remoteIp) {
        if (remoteIp != null && remoteIp.equals(IpPrefix.valueOf(vmIp, 32))) {
            // do nothing if the remote IP is my IP
            return null;
        }

        TrafficSelector.Builder sBuilder = DefaultTrafficSelector.builder();
        buildMatchs(sBuilder, sgRule, vmIp, remoteIp);

        return DefaultForwardingObjective.builder()
                .withSelector(sBuilder.build())
                .withTreatment(DefaultTrafficTreatment.builder().build())
                .withPriority(PRIORITY_ACL_RULE)
                .withFlag(ForwardingObjective.Flag.SPECIFIC)
                .fromApp(appId);
    }

    private void buildMatchs(TrafficSelector.Builder sBuilder, SecurityGroupRule sgRule,
                             Ip4Address vmIp, IpPrefix remoteIp) {
        buildMatchEthType(sBuilder, sgRule.getEtherType());
        buildMatchDirection(sBuilder, sgRule.getDirection(), vmIp);
        buildMatchProto(sBuilder, sgRule.getProtocol());
        buildMatchPort(sBuilder, sgRule.getProtocol(), sgRule.getDirection(),
                sgRule.getPortRangeMax() == null ? 0 : sgRule.getPortRangeMax(),
                sgRule.getPortRangeMin() == null ? 0 : sgRule.getPortRangeMin());
        buildMatchRemoteIp(sBuilder, remoteIp, sgRule.getDirection());
        if (sgRule.getRemoteGroupId() != null && sgRule.getRemoteGroupId().isEmpty()) {
            buildMatchRemoteIp(sBuilder, remoteIp, sgRule.getDirection());
        }
    }

    private void buildMatchDirection(TrafficSelector.Builder sBuilder,
                                     String direction,
                                     Ip4Address vmIp) {
        if (direction.toUpperCase().equals(EGRESS)) {
            sBuilder.matchIPSrc(IpPrefix.valueOf(vmIp, 32));
        } else {
            sBuilder.matchIPDst(IpPrefix.valueOf(vmIp, 32));
        }
    }

    private void buildMatchEthType(TrafficSelector.Builder sBuilder, String etherType) {
        // Either IpSrc or IpDst (or both) is set by default, and we need to set EthType as IPv4.
        sBuilder.matchEthType(Ethernet.TYPE_IPV4);
        if (etherType != null && !Objects.equals(etherType, "null") &&
                !etherType.toUpperCase().equals(ETHTYPE_IPV4)) {
            log.debug("EthType {} is not supported yet in Security Group", etherType);
        }
    }

    private void buildMatchRemoteIp(TrafficSelector.Builder sBuilder, IpPrefix remoteIpPrefix, String direction) {
        if (remoteIpPrefix != null && !remoteIpPrefix.getIp4Prefix().equals(IP_PREFIX_ANY)) {
            if (direction.toUpperCase().equals(EGRESS)) {
                sBuilder.matchIPDst(remoteIpPrefix);
            } else {
                sBuilder.matchIPSrc(remoteIpPrefix);
            }
        }
    }

    private void buildMatchProto(TrafficSelector.Builder sBuilder, String protocol) {
        if (protocol != null) {
            switch (protocol.toUpperCase()) {
                case PROTO_ICMP:
                    sBuilder.matchIPProtocol(IPv4.PROTOCOL_ICMP);
                    break;
                case PROTO_TCP:
                    sBuilder.matchIPProtocol(IPv4.PROTOCOL_TCP);
                    break;
                case PROTO_UDP:
                    sBuilder.matchIPProtocol(IPv4.PROTOCOL_UDP);
                    break;
                default:
            }
        }
    }

    private void buildMatchPort(TrafficSelector.Builder sBuilder, String protocol, String direction,
                                int portMin, int portMax) {
        if (portMin > 0 && portMax > 0 && portMin == portMax) {
            if (protocol.toUpperCase().equals(PROTO_TCP)) {
                if (direction.toUpperCase().equals(EGRESS)) {
                    sBuilder.matchTcpSrc(TpPort.tpPort(portMax));
                } else {
                    sBuilder.matchTcpDst(TpPort.tpPort(portMax));
                }
            } else if (protocol.toUpperCase().equals(PROTO_UDP)) {
                if (direction.toUpperCase().equals(EGRESS)) {
                    sBuilder.matchUdpSrc(TpPort.tpPort(portMax));
                } else {
                    sBuilder.matchUdpDst(TpPort.tpPort(portMax));
                }
            }
        }
    }

    private class InternalInstancePortListener implements InstancePortListener {

        @Override
        public boolean isRelevant(InstancePortEvent event) {
            InstancePort instPort = event.subject();
            return mastershipService.isLocalMaster(instPort.deviceId());
        }

        @Override
        public void event(InstancePortEvent event) {
            InstancePort instPort = event.subject();
            switch (event.type()) {
                case OPENSTACK_INSTANCE_PORT_UPDATED:
                case OPENSTACK_INSTANCE_PORT_DETECTED:
                    log.debug("Instance port detected MAC:{} IP:{}",
                            instPort.macAddress(),
                            instPort.ipAddress());
                    eventExecutor.execute(() -> {
                        setSecurityGroupRules(instPort,
                                osNetService.port(event.subject().portId()),
                                true);
                    });
                    break;
                case OPENSTACK_INSTANCE_PORT_VANISHED:
                    log.debug("Instance port vanished MAC:{} IP:{}",
                            instPort.macAddress(),
                            instPort.ipAddress());
                    eventExecutor.execute(() -> {
                        setSecurityGroupRules(instPort,
                                osNetService.port(event.subject().portId()),
                                false);
                    });
                    break;
                default:
                    break;
            }
        }
    }

    private class InternalOpenstackPortListener implements OpenstackNetworkListener {

        @Override
        public boolean isRelevant(OpenstackNetworkEvent event) {
            if (event.port() == null || !Strings.isNullOrEmpty(event.port().getId())) {
                return false;
            }
            if (event.securityGroupId() == null ||
                    securityGroupService.securityGroup(event.securityGroupId()) == null) {
                return false;
            }
            if (instancePortService.instancePort(event.port().getId()) == null) {
                return false;
            }
            return true;
        }

        @Override
        public void event(OpenstackNetworkEvent event) {
            Port osPort = event.port();
            InstancePort instPort = instancePortService.instancePort(osPort.getId());
            SecurityGroup osSg = securityGroupService.securityGroup(event.securityGroupId());

            switch (event.type()) {
                case OPENSTACK_PORT_SECURITY_GROUP_ADDED:
                    eventExecutor.execute(() -> {
                        osSg.getRules().forEach(sgRule -> {
                            updateSecurityGroupRule(instPort, osPort, sgRule, true);
                        });
                        log.info("Added security group {} to port {}",
                                event.securityGroupId(), event.port().getId());
                    });
                    break;
                case OPENSTACK_PORT_SECURITY_GROUP_REMOVED:
                    eventExecutor.execute(() -> {
                        osSg.getRules().forEach(sgRule -> {
                            updateSecurityGroupRule(instPort, osPort, sgRule, false);
                        });
                        log.info("Removed security group {} from port {}",
                                event.securityGroupId(), event.port().getId());
                    });
                    break;
                default:
                    // do nothing for the other events
                    break;
            }
        }
    }

    private class InternalSecurityGroupListener implements OpenstackSecurityGroupListener {

        @Override
        public void event(OpenstackSecurityGroupEvent event) {
            switch (event.type()) {
                case OPENSTACK_SECURITY_GROUP_RULE_CREATED:
                    SecurityGroupRule securityGroupRuleToAdd = event.securityGroupRule();
                    eventExecutor.execute(() -> {
                        securityGroupRuleAdded(securityGroupRuleToAdd);
                        log.info("Applied new security group rule {} to ports",
                                securityGroupRuleToAdd.getId());
                    });
                    break;

                case OPENSTACK_SECURITY_GROUP_RULE_REMOVED:
                    SecurityGroupRule securityGroupRuleToRemove = event.securityGroupRule();
                    eventExecutor.execute(() -> {
                        securityGroupRuleRemoved(securityGroupRuleToRemove);
                        log.info("Removed security group rule {} from ports",
                                securityGroupRuleToRemove.getId());
                    });
                    break;
                case OPENSTACK_SECURITY_GROUP_CREATED:
                case OPENSTACK_SECURITY_GROUP_REMOVED:
                default:
                    // do nothing
                    break;
            }
        }

        private void securityGroupRuleAdded(SecurityGroupRule sgRule) {
            osNetService.ports().stream()
                    .filter(port -> port.getSecurityGroups().contains(sgRule.getSecurityGroupId()))
                    .forEach(port -> {
                        updateSecurityGroupRule(
                                instancePortService.instancePort(port.getId()),
                                port, sgRule, true);
                        log.debug("Applied security group rule {} to port {}",
                                sgRule.getId(), port.getId());
                    });
        }

        private void securityGroupRuleRemoved(SecurityGroupRule sgRule) {
            osNetService.ports().stream()
                    .filter(port -> port.getSecurityGroups().contains(sgRule.getSecurityGroupId()))
                    .forEach(port -> {
                        updateSecurityGroupRule(
                                instancePortService.instancePort(port.getId()),
                                port, sgRule, false);
                        log.debug("Removed security group rule {} from port {}",
                                sgRule.getId(), port.getId());
                    });
        }
    }
}