/*
 * Copyright 2017-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.dhcprelay.cli;

import org.apache.karaf.shell.commands.Command;
import org.onlab.packet.Ip4Address;
import org.onlab.packet.IpAddress;
import org.onlab.packet.MacAddress;
import org.onlab.packet.VlanId;
import org.onlab.util.Tools;
import org.onosproject.cli.AbstractShellCommand;
import org.onosproject.core.ApplicationId;
import org.onosproject.core.CoreService;
import org.onosproject.dhcprelay.config.DefaultDhcpRelayConfig;
import org.onosproject.dhcprelay.DhcpRelayManager;
import org.onosproject.dhcprelay.api.DhcpRelayService;
import org.onosproject.dhcprelay.config.DhcpServerConfig;
import org.onosproject.dhcprelay.store.DhcpRecord;
import org.onosproject.net.ConnectPoint;
import org.onosproject.net.Host;
import org.onosproject.net.HostId;
import org.onosproject.net.config.NetworkConfigRegistry;
import org.onosproject.net.host.HostService;

import java.util.Collection;
import java.util.function.Predicate;

/**
 * Prints DHCP server and DHCP relay status.
 */
@Command(scope = "onos", name = "dhcp-relay", description = "DHCP relay app cli.")
public class DhcpRelayCommand extends AbstractShellCommand {
    private static final String HEADER = "DHCP relay records ([D]: Directly connected):";
    private static final String NO_RECORDS = "No DHCP relay record found";
    private static final String HOST = "id=%s/%s, locations=%s%s, last-seen=%s, IPv4=%s, IPv6=%s";
    private static final String DHCP_SERVER_GW = "DHCP Server: %s, %s via %s (Mac: %s)";
    private static final String DHCP_SERVER = "DHCP Server: %s, %s (Mac: %s)";
    private static final String MISSING_SERVER_CFG = "DHCP Server info not available";
    private static final String DIRECTLY = "[D]";
    private static final String EMPTY = "";
    private static final String NA = "N/A";
    private static final String STATUS_FMT = "[%s, %s]";
    private static final String STATUS_FMT_NH = "[%s via %s, %s]";

    private static final DhcpRelayService DHCP_RELAY_SERVICE = get(DhcpRelayService.class);
    private static final NetworkConfigRegistry CFG_SERVICE = get(NetworkConfigRegistry.class);
    private static final HostService HOST_SERVICE = get(HostService.class);
    private static final CoreService CORE_SERVICE = get(CoreService.class);
    private static final ApplicationId APP_ID =
            CORE_SERVICE.getAppId(DhcpRelayManager.DHCP_RELAY_APP);


    @Override
    protected void execute() {
        DefaultDhcpRelayConfig cfg = CFG_SERVICE.getConfig(APP_ID, DefaultDhcpRelayConfig.class);
        if (cfg == null || cfg.dhcpServerConfigs().size() == 0) {
            print(MISSING_SERVER_CFG);
            return;
        }

        // DHCP server information
        // TODO: currently we pick up first DHCP server config.
        // Will use other server configs in the future.
        DhcpServerConfig serverConfig = cfg.dhcpServerConfigs().get(0);

        ConnectPoint connectPoint = serverConfig.getDhcpServerConnectPoint().orElse(null);
        Ip4Address gatewayAddress = serverConfig.getDhcpGatewayIp4().orElse(null);
        Ip4Address serverIp = serverConfig.getDhcpServerIp4().orElse(null);
        String serverMac = DHCP_RELAY_SERVICE.getDhcpServerMacAddress()
                .map(MacAddress::toString).orElse(NA);
        if (gatewayAddress != null) {
            print(DHCP_SERVER_GW, connectPoint, serverIp, gatewayAddress, serverMac);
        } else {
            print(DHCP_SERVER, connectPoint, serverIp, serverMac);
        }

        // DHCP records
        Collection<DhcpRecord> records = DHCP_RELAY_SERVICE.getDhcpRecords();
        if (records.isEmpty()) {
            print(NO_RECORDS);
            return;
        }
        print(HEADER);
        records.forEach(record -> print(HOST,
                                        record.macAddress(),
                                        record.vlanId(),
                                        record.locations(),
                                        record.directlyConnected() ? DIRECTLY : EMPTY,
                                        Tools.timeAgo(record.lastSeen()),
                                        ip4State(record),
                                        ip6State(record)));
    }

    private String ip4State(DhcpRecord record) {
        String nextHopIp = findNextHopIp(IpAddress::isIp4,
                                         record.nextHop().orElse(null),
                                         record.vlanId());
        return ipState(record.ip4Address().map(Object::toString).orElse(NA),
                       record.ip4Status().map(Object::toString).orElse(NA),
                       record.directlyConnected(),
                       nextHopIp);
    }

    private String ip6State(DhcpRecord record) {
        String nextHopIp = findNextHopIp(IpAddress::isIp6,
                                         record.nextHop().orElse(null),
                                         record.vlanId());
        return ipState(record.ip6Address().map(Object::toString).orElse(NA),
                       record.ip6Status().map(Object::toString).orElse(NA),
                       record.directlyConnected(),
                       nextHopIp);
    }

    private String ipState(String ipAddress, String status,
                           boolean directlyConnected,
                           String nextHopIp) {
        if (directlyConnected) {
            return String.format(STATUS_FMT, ipAddress, status);
        } else {
            return String.format(STATUS_FMT_NH, ipAddress, nextHopIp, status);
        }
    }

    private String findNextHopIp(Predicate<IpAddress> ipFilter, MacAddress nextHopMac, VlanId vlanId) {
        if (ipFilter == null || nextHopMac == null || vlanId == null) {
            return NA;
        }
        Host host = HOST_SERVICE.getHost(HostId.hostId(nextHopMac, vlanId));
        if (host == null) {
            return NA;
        }
        return host.ipAddresses().stream()
                .filter(ipFilter)
                .filter(ip -> !ip.isLinkLocal())
                .map(Object::toString)
                .findFirst()
                .orElse(NA);
    }
}