/*
 * Copyright 2021-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.kubevirtnetworking.util;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.base.Strings;
import com.google.common.collect.ImmutableSet;
import io.fabric8.kubernetes.api.model.Pod;
import io.fabric8.kubernetes.client.ConfigBuilder;
import io.fabric8.kubernetes.client.DefaultKubernetesClient;
import io.fabric8.kubernetes.client.KubernetesClient;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.net.util.SubnetUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.onlab.osgi.DefaultServiceDirectory;
import org.onlab.packet.ARP;
import org.onlab.packet.Ethernet;
import org.onlab.packet.Ip4Address;
import org.onlab.packet.IpAddress;
import org.onlab.packet.MacAddress;
import org.onosproject.cfg.ConfigProperty;
import org.onosproject.kubevirtnetworking.api.DefaultKubevirtPort;
import org.onosproject.kubevirtnetworking.api.KubevirtNetwork;
import org.onosproject.kubevirtnetworking.api.KubevirtNetworkService;
import org.onosproject.kubevirtnetworking.api.KubevirtPort;
import org.onosproject.kubevirtnetworking.api.KubevirtRouter;
import org.onosproject.kubevirtnetworking.api.KubevirtRouterService;
import org.onosproject.kubevirtnode.api.KubevirtApiConfig;
import org.onosproject.kubevirtnode.api.KubevirtApiConfigService;
import org.onosproject.kubevirtnode.api.KubevirtNode;
import org.onosproject.kubevirtnode.api.KubevirtNodeService;
import org.onosproject.net.DeviceId;
import org.onosproject.net.Port;
import org.onosproject.net.PortNumber;
import org.onosproject.net.device.DeviceService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xbill.DNS.Address;

import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;

import static org.onosproject.kubevirtnetworking.api.Constants.TUNNEL_TO_TENANT_PREFIX;
import static org.onosproject.kubevirtnode.api.KubevirtNode.Type.GATEWAY;
import static org.onosproject.net.AnnotationKeys.PORT_NAME;

/**
 * An utility that used in KubeVirt networking app.
 */
public final class KubevirtNetworkingUtil {

    private static final Logger log = LoggerFactory.getLogger(KubevirtNetworkingUtil.class);

    private static final int PORT_NAME_MAX_LENGTH = 15;
    private static final String COLON_SLASH = "://";
    private static final String COLON = ":";
    private static final String OF_PREFIX = "of:";

    private static final String NETWORK_STATUS_KEY = "k8s.v1.cni.cncf.io/network-status";
    private static final String NAME = "name";
    private static final String NETWORK_PREFIX = "default/";
    private static final String MAC = "mac";
    private static final String IPS = "ips";
    private static final String BR_INT = "br-int";

    /**
     * Prevents object installation from external.
     */
    private KubevirtNetworkingUtil() {
    }

    /**
     * Obtains the boolean property value with specified property key name.
     *
     * @param properties a collection of properties
     * @param name       key name
     * @return mapping value
     */
    public static boolean getPropertyValueAsBoolean(Set<ConfigProperty> properties,
                                                    String name) {
        Optional<ConfigProperty> property =
                properties.stream().filter(p -> p.name().equals(name)).findFirst();

        return property.map(ConfigProperty::asBoolean).orElse(false);
    }

    /**
     * Re-structures the OVS port name.
     * The length of OVS port name should be not large than 15.
     *
     * @param portName original port name
     * @return re-structured OVS port name
     */
    public static String structurePortName(String portName) {

        // The size of OVS port name should not be larger than 15
        if (portName.length() > PORT_NAME_MAX_LENGTH) {
            return StringUtils.substring(portName, 0, PORT_NAME_MAX_LENGTH);
        }

        return portName;
    }

    /**
     * Generates string format based on the given string length list.
     *
     * @param stringLengths a list of string lengths
     * @return string format (e.g., %-28s%-15s%-24s%-20s%-15s)
     */
    public static String genFormatString(List<Integer> stringLengths) {
        StringBuilder fsb = new StringBuilder();
        stringLengths.forEach(length -> {
            fsb.append("%-");
            fsb.append(length);
            fsb.append("s");
        });
        return fsb.toString();
    }

    /**
     * Auto generates DPID from the given name.
     *
     * @param name name
     * @return auto generated DPID
     */
    public static String genDpidFromName(String name) {
        if (name != null) {
            String hexString = Integer.toHexString(name.hashCode());
            return OF_PREFIX + Strings.padStart(hexString, 16, '0');
        }

        return null;
    }

    /**
     * Prints out the JSON string in pretty format.
     *
     * @param mapper     Object mapper
     * @param jsonString JSON string
     * @return pretty formatted JSON string
     */
    public static String prettyJson(ObjectMapper mapper, String jsonString) {
        try {
            Object jsonObject = mapper.readValue(jsonString, Object.class);
            return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(jsonObject);
        } catch (IOException e) {
            log.debug("Json string parsing exception caused by {}", e);
        }
        return null;
    }

    /**
     * Obtains valid IP addresses of the given subnet.
     *
     * @param cidr CIDR
     * @return set of IP addresses
     */
    public static Set<IpAddress> getSubnetIps(String cidr) {
        SubnetUtils utils = new SubnetUtils(cidr);
        utils.setInclusiveHostCount(false);
        SubnetUtils.SubnetInfo info = utils.getInfo();
        Set<String> allAddresses =
                new HashSet<>(Arrays.asList(info.getAllAddresses()));

        if (allAddresses.size() > 2) {
            allAddresses.remove(info.getLowAddress());
            allAddresses.remove(info.getHighAddress());
        }

        return allAddresses.stream()
                .map(IpAddress::valueOf).collect(Collectors.toSet());
    }

    /**
     * Calculate the broadcast address from given IP address and subnet prefix length.
     *
     * @param ipAddr       IP address
     * @param prefixLength subnet prefix length
     * @return broadcast address
     */
    public static String getBroadcastAddr(String ipAddr, int prefixLength) {
        String subnet = ipAddr + "/" + prefixLength;
        SubnetUtils utils = new SubnetUtils(subnet);
        return utils.getInfo().getBroadcastAddress();
    }

    /**
     * Generates endpoint URL by referring to scheme, ipAddress and port.
     *
     * @param scheme    scheme
     * @param ipAddress IP address
     * @param port      port number
     * @return generated endpoint URL
     */
    public static String endpoint(KubevirtApiConfig.Scheme scheme, IpAddress ipAddress, int port) {
        StringBuilder endpoint = new StringBuilder();
        String protocol = org.apache.commons.lang3.StringUtils.lowerCase(scheme.name());

        endpoint.append(protocol);
        endpoint.append(COLON_SLASH);
        endpoint.append(ipAddress.toString());
        endpoint.append(COLON);
        endpoint.append(port);

        return endpoint.toString();
    }

    /**
     * Generates endpoint URL by referring to scheme, ipAddress and port.
     *
     * @param apiConfig kubernetes API config
     * @return generated endpoint URL
     */
    public static String endpoint(KubevirtApiConfig apiConfig) {
        return endpoint(apiConfig.scheme(), apiConfig.ipAddress(), apiConfig.port());
    }

    /**
     * Obtains workable kubernetes client.
     *
     * @param config kubernetes API config
     * @return kubernetes client
     */
    public static KubernetesClient k8sClient(KubevirtApiConfig config) {
        if (config == null) {
            log.warn("Kubernetes API server config is empty.");
            return null;
        }

        String endpoint = endpoint(config);

        ConfigBuilder configBuilder = new ConfigBuilder().withMasterUrl(endpoint);

        if (config.scheme() == KubevirtApiConfig.Scheme.HTTPS) {
            configBuilder.withTrustCerts(true)
                    .withCaCertData(config.caCertData())
                    .withClientCertData(config.clientCertData())
                    .withClientKeyData(config.clientKeyData());
        }

        return new DefaultKubernetesClient(configBuilder.build());
    }

    /**
     * Obtains workable kubernetes client.
     *
     * @param service kubernetes API service
     * @return kubernetes client
     */
    public static KubernetesClient k8sClient(KubevirtApiConfigService service) {
        KubevirtApiConfig config = service.apiConfig();
        if (config == null) {
            log.error("Failed to find valid kubernetes API configuration.");
            return null;
        }

        KubernetesClient client = k8sClient(config);

        if (client == null) {
            log.error("Failed to connect to kubernetes API server.");
            return null;
        }

        return client;
    }

    /**
     * Obtains the hex string of the given segment ID with fixed padding.
     *
     * @param segIdStr segment identifier string
     * @return hex string with padding
     */
    public static String segmentIdHex(String segIdStr) {
        int segId = Integer.parseInt(segIdStr);
        return String.format("%06x", segId).toLowerCase();
    }

    /**
     * Obtains the tunnel port number with the given network and node.
     *
     * @param network kubevirt network
     * @param node    kubevirt node
     * @return tunnel port number
     */
    public static PortNumber tunnelPort(KubevirtNetwork network, KubevirtNode node) {
        switch (network.type()) {
            case VXLAN:
                return node.vxlanPort();
            case GRE:
                return node.grePort();
            case GENEVE:
                return node.genevePort();
            default:
                break;
        }
        return null;
    }

    /**
     * Obtains the kubevirt port from kubevirt POD.
     *
     * @param nodeService kubevirt node service
     * @param networks set of existing kubevirt networks
     * @param pod      kubevirt POD
     * @return kubevirt ports attached to the POD
     */
    public static Set<KubevirtPort> getPorts(KubevirtNodeService nodeService,
                                             Set<KubevirtNetwork> networks, Pod pod) {
        try {
            Map<String, String> annots = pod.getMetadata().getAnnotations();
            if (annots == null) {
                return ImmutableSet.of();
            }

            if (!annots.containsKey(NETWORK_STATUS_KEY)) {
                return ImmutableSet.of();
            }

            String networkStatusStr = annots.get(NETWORK_STATUS_KEY);

            if (networkStatusStr == null) {
                return ImmutableSet.of();
            }

            KubevirtPort.Builder builder = DefaultKubevirtPort.builder();

            KubevirtNode node = nodeService.node(pod.getSpec().getNodeName());

            if (node != null) {
                builder.deviceId(node.intgBridge());
            }

            JSONArray networkStatus = new JSONArray(networkStatusStr);
            Set<KubevirtPort> ports = new HashSet<>();

            for (int i = 0; i < networkStatus.length(); i++) {
                JSONObject object = networkStatus.getJSONObject(i);
                String name = object.getString(NAME);
                KubevirtNetwork network = networks.stream()
                        .filter(n -> (NETWORK_PREFIX + n.name()).equals(name) || (n.name()).equals(name))
                        .findAny().orElse(null);
                if (network != null) {
                    String mac = object.getString(MAC);

                    builder.macAddress(MacAddress.valueOf(mac))
                            .networkId(network.networkId());

                    ports.add(builder.build());
                }
            }

            return ports;

        } catch (JSONException e) {
            log.error("Failed to parse network status object", e);
        }

        return ImmutableSet.of();
    }

    /**
     * Obtains the tunnel bridge to tenant bridge patch port number.
     *
     * @param node    kubevirt node
     * @param network kubevirt network
     * @return patch port number
     */
    public static PortNumber tunnelToTenantPort(KubevirtNode node, KubevirtNetwork network) {
        if (network.segmentId() == null) {
            return null;
        }

        if (node.tunBridge() == null) {
            return null;
        }

        String tunToTenantPortName = TUNNEL_TO_TENANT_PREFIX + segmentIdHex(network.segmentId());
        return portNumber(node.tunBridge(), tunToTenantPortName);
    }

    /**
     * Obtains the tunnel port number of the given node.
     *
     * @param node    kubevirt node
     * @param network kubevirt network
     * @return tunnel port number
     */
    public static PortNumber tunnelPort(KubevirtNode node, KubevirtNetwork network) {
        if (network.segmentId() == null) {
            return null;
        }

        if (node.tunBridge() == null) {
            return null;
        }

        switch (network.type()) {
            case VXLAN:
                return node.vxlanPort();
            case GRE:
                return node.grePort();
            case GENEVE:
                return node.genevePort();
            case FLAT:
            case VLAN:
            default:
                // do nothing
                return null;
        }
    }

    public static String parseResourceName(String resource) {
        try {
            JSONObject json = new JSONObject(resource);
            return json.getJSONObject("metadata").getString("name");
        } catch (JSONException e) {
            log.error("");
        }
        return "";
    }

    public static PortNumber portNumber(DeviceId deviceId, String portName) {
        DeviceService deviceService = DefaultServiceDirectory.getService(DeviceService.class);
        Port port = deviceService.getPorts(deviceId).stream()
                .filter(p -> p.isEnabled() &&
                        Objects.equals(p.annotations().value(PORT_NAME), portName))
                .findAny().orElse(null);
        return port != null ? port.number() : null;
    }

    /**
     * Returns the gateway node for the specified kubevirt router.
     * Among gateways, only one gateway would act as a gateway per perter.
     * Currently gateway node is selected based on modulo operation with router hashcode.
     *
     * @param nodeService kubevirt node service
     * @param router      kubevirt router
     * @return elected gateway node
     */
    public static KubevirtNode gatewayNodeForSpecifiedRouter(KubevirtNodeService nodeService,
                                                             KubevirtRouter router) {
        //TODO: enhance election logic for a better load balancing

        int numOfGateways = nodeService.completeNodes(GATEWAY).size();
        if (numOfGateways == 0) {
            return null;
        }
        return (KubevirtNode) nodeService.completeNodes(GATEWAY).toArray()[router.hashCode() % numOfGateways];
    }

    /**
     * Returns the mac address of the router.
     *
     * @param router kubevirt router
     * @return macc address of the router
     */
    public static MacAddress getRouterMacAddress(KubevirtRouter router) {
        if (router.mac() == null) {
            log.warn("Failed to get mac address of router {}", router.name());
        }

        return router.mac();
    }

    /**
     * Returns the snat ip address with specified router.
     *
     * @param routerService     router service
     * @param internalNetworkId internal network id which is associated with the router
     * @return snat ip address if exist, null otherwise
     */
    public static IpAddress getRouterSnatIpAddress(KubevirtRouterService routerService,
                                                    String internalNetworkId) {
        KubevirtRouter router = routerService.routers().stream()
                .filter(r -> r.internal().contains(internalNetworkId))
                .findAny().orElse(null);

        if (router == null) {
            return null;
        }

        String routerSnatIp = router.external().keySet().stream().findAny().orElse(null);

        if (routerSnatIp == null) {
            return null;
        }

        return Ip4Address.valueOf(routerSnatIp);
    }

    /**
     * Returns the kubevirt router with specified kubevirt port.
     *
     * @param routerService kubevirt router service
     * @param kubevirtPort  kubevirt port
     * @return kubevirt router
     */
    public static KubevirtRouter getRouterForKubevirtPort(KubevirtRouterService routerService,
                                                          KubevirtPort kubevirtPort) {
        if (kubevirtPort.ipAddress() != null) {
            return routerService.routers().stream()
                    .filter(r -> r.internal().contains(kubevirtPort.networkId()))
                    .findAny().orElse(null);
        }
        return null;
    }

    /**
     * Returns the kubevirt router with specified kubevirt network.
     *
     * @param routerService kubevirt router service
     * @param kubevirtNetwork kubevirt network
     * @return kubevirt router
     */
    public static KubevirtRouter getRouterForKubevirtNetwork(KubevirtRouterService routerService,
                                                             KubevirtNetwork kubevirtNetwork) {
        return routerService.routers().stream()
                .filter(router -> router.internal().contains(kubevirtNetwork.networkId()))
                .findAny().orElse(null);
    }

    /**
     * Returns the external patch port number with specified gateway.
     *
     * @param deviceService device service
     * @param gatewayNode gateway node
     * @return external patch port number
     */
    public static PortNumber externalPatchPortNum(DeviceService deviceService, KubevirtNode gatewayNode) {
        String gatewayBridgeName = gatewayNode.gatewayBridgeName();
        if (gatewayBridgeName == null) {
            log.warn("No external interface is attached to gateway {}", gatewayNode.hostname());
            return null;
        }

        String patchPortName = "int-to-" + gatewayBridgeName;
        Port port = deviceService.getPorts(gatewayNode.intgBridge()).stream()
                .filter(p -> p.isEnabled() &&
                        Objects.equals(p.annotations().value(PORT_NAME), patchPortName))
                .findAny().orElse(null);

        return port != null ? port.number() : null;
    }

    /**
     * Returns the kubevirt external network with specified router.
     *
     * @param networkService kubevirt network service
     * @param router kubevirt router
     * @return external network
     */
    public static KubevirtNetwork getExternalNetworkByRouter(KubevirtNetworkService networkService,
                                                             KubevirtRouter router) {
        String networkId = router.external().values().stream().findAny().orElse(null);
        if (networkId == null) {
            return null;
        }

        return networkService.network(networkId);
    }

    /**
     * Resolve a DNS with the given DNS server and hostname.
     *
     * @param hostname      hostname to be resolved
     * @return resolved IP address
     */
    public static IpAddress resolveHostname(String hostname) {
        try {
            InetAddress addr = Address.getByName(hostname);
            return IpAddress.valueOf(IpAddress.Version.INET, addr.getAddress());
        } catch (UnknownHostException e) {
            log.warn("Failed to resolve IP address of host {}", hostname);
        }
        return null;
    }

    /**
     * Builds a GARP packet using the given source MAC and source IP address.
     *
     * @param srcMac source MAC address
     * @param srcIp  source IP address
     * @return GARP packet
     */
    public static Ethernet buildGarpPacket(MacAddress srcMac, IpAddress srcIp) {
        if (srcMac == null || srcIp == null) {
            return null;
        }

        Ethernet ethernet = new Ethernet();
        ethernet.setDestinationMACAddress(MacAddress.BROADCAST);
        ethernet.setSourceMACAddress(srcMac);
        ethernet.setEtherType(Ethernet.TYPE_ARP);

        ARP arp = new ARP();
        arp.setOpCode(ARP.OP_REPLY);
        arp.setProtocolType(ARP.PROTO_TYPE_IP);
        arp.setHardwareType(ARP.HW_TYPE_ETHERNET);

        arp.setProtocolAddressLength((byte) Ip4Address.BYTE_LENGTH);
        arp.setHardwareAddressLength((byte) Ethernet.DATALAYER_ADDRESS_LENGTH);

        arp.setSenderHardwareAddress(srcMac.toBytes());
        arp.setTargetHardwareAddress(MacAddress.BROADCAST.toBytes());

        arp.setSenderProtocolAddress(srcIp.toOctets());
        arp.setTargetProtocolAddress(srcIp.toOctets());

        ethernet.setPayload(arp);

        return ethernet;
    }
}