package network

import (
	"fmt"
	"net"

	"github.com/Azure/azure-container-networking/netio"
	"github.com/Azure/azure-container-networking/netlink"
	"github.com/Azure/azure-container-networking/network/networkutils"
	"github.com/Azure/azure-container-networking/platform"
	"github.com/pkg/errors"
	"go.uber.org/zap"
)

const (
	virtualGwIPString     = "169.254.1.1/32"
	defaultGwCidr         = "0.0.0.0/0"
	defaultGw             = "0.0.0.0"
	virtualv6GwString     = "fe80::1234:5678:9abc/128"
	defaultv6Cidr         = "::/0"
	ipv4Bits              = 32
	ipv6Bits              = 128
	ipv4FullMask          = 32
	ipv6FullMask          = 128
	defaultHostVethHwAddr = "aa:aa:aa:aa:aa:aa"
)

var errorTransparentEndpointClient = errors.New("TransparentEndpointClient Error")

func newErrorTransparentEndpointClient(err error) error {
	return errors.Wrapf(err, "%s", errorTransparentEndpointClient)
}

type TransparentEndpointClient struct {
	bridgeName        string
	hostPrimaryIfName string
	hostVethName      string
	containerVethName string
	hostPrimaryMac    net.HardwareAddr
	containerMac      net.HardwareAddr
	hostVethMac       net.HardwareAddr
	mode              string
	netlink           netlink.NetlinkInterface
	netioshim         netio.NetIOInterface
	plClient          platform.ExecClient
	netUtilsClient    networkutils.NetworkUtils
}

func NewTransparentEndpointClient(
	extIf *externalInterface,
	hostVethName string,
	containerVethName string,
	mode string,
	nl netlink.NetlinkInterface,
	nioc netio.NetIOInterface,
	plc platform.ExecClient,
) *TransparentEndpointClient {
	client := &TransparentEndpointClient{
		bridgeName:        extIf.BridgeName,
		hostPrimaryIfName: extIf.Name,
		hostVethName:      hostVethName,
		containerVethName: containerVethName,
		hostPrimaryMac:    extIf.MacAddress,
		mode:              mode,
		netlink:           nl,
		netioshim:         nioc,
		plClient:          plc,
		netUtilsClient:    networkutils.NewNetworkUtils(nl, plc),
	}

	return client
}

func (client *TransparentEndpointClient) setArpProxy(ifName string) error {
	cmd := fmt.Sprintf("echo 1 > /proc/sys/net/ipv4/conf/%v/proxy_arp", ifName)
	_, err := client.plClient.ExecuteCommand(cmd)
	return err
}

func (client *TransparentEndpointClient) AddEndpoints(epInfo *EndpointInfo) error {
	if _, err := client.netioshim.GetNetworkInterfaceByName(client.hostVethName); err == nil {
		logger.Info("Deleting old host veth", zap.String("hostVethName", client.hostVethName))
		if err = client.netlink.DeleteLink(client.hostVethName); err != nil {
			logger.Error("Failed to delete old", zap.String("hostVethName", client.hostVethName), zap.Error(err))
			return newErrorTransparentEndpointClient(err)
		}
	}

	primaryIf, err := client.netioshim.GetNetworkInterfaceByName(client.hostPrimaryIfName)
	if err != nil {
		return newErrorTransparentEndpointClient(err)
	}

	mac, err := net.ParseMAC(defaultHostVethHwAddr)
	if err != nil {
		logger.Error("Failed to parse the mac addrress", zap.String("defaultHostVethHwAddr", defaultHostVethHwAddr))
	}

	if err = client.netUtilsClient.CreateEndpoint(client.hostVethName, client.containerVethName, mac); err != nil {
		return newErrorTransparentEndpointClient(err)
	}

	defer func() {
		if err != nil {
			if delErr := client.netlink.DeleteLink(client.hostVethName); delErr != nil {
				logger.Error("Deleting veth failed on addendpoint failure", zap.Error(delErr))
			}
		}
	}()

	containerIf, err := client.netioshim.GetNetworkInterfaceByName(client.containerVethName)
	if err != nil {
		return newErrorTransparentEndpointClient(err)
	}

	client.containerMac = containerIf.HardwareAddr

	hostVethIf, err := client.netioshim.GetNetworkInterfaceByName(client.hostVethName)
	if err != nil {
		return newErrorTransparentEndpointClient(err)
	}

	client.hostVethMac = hostVethIf.HardwareAddr

	logger.Info("Setting mtu on veth interface", zap.Int("MTU", primaryIf.MTU), zap.String("hostVethName", client.hostVethName))
	if err := client.netlink.SetLinkMTU(client.hostVethName, primaryIf.MTU); err != nil {
		logger.Error("Setting mtu failed for hostveth", zap.String("hostVethName", client.hostVethName),
			zap.Error(err))
	}

	if err := client.netlink.SetLinkMTU(client.containerVethName, primaryIf.MTU); err != nil {
		logger.Error("Setting mtu failed for containerveth", zap.String("containerVethName", client.containerVethName),
			zap.Error(err))
	}

	return nil
}

func (client *TransparentEndpointClient) AddEndpointRules(epInfo *EndpointInfo) error {
	var routeInfoList []RouteInfo

	// ip route add <podip> dev <hostveth>
	// This route is needed for incoming packets to pod to route via hostveth
	for _, ipAddr := range epInfo.IPAddresses {
		var (
			routeInfo RouteInfo
			ipNet     net.IPNet
		)

		if ipAddr.IP.To4() != nil {
			ipNet = net.IPNet{IP: ipAddr.IP, Mask: net.CIDRMask(ipv4FullMask, ipv4Bits)}
		} else {
			ipNet = net.IPNet{IP: ipAddr.IP, Mask: net.CIDRMask(ipv6FullMask, ipv6Bits)}
		}
		logger.Info("Adding route for the", zap.String("ip", ipNet.String()))
		routeInfo.Dst = ipNet
		routeInfoList = append(routeInfoList, routeInfo)
	}

	if err := addRoutes(client.netlink, client.netioshim, client.hostVethName, routeInfoList); err != nil {
		return newErrorTransparentEndpointClient(err)
	}

	logger.Info("calling setArpProxy for", zap.String("hostVethName", client.hostVethName))
	if err := client.setArpProxy(client.hostVethName); err != nil {
		logger.Error("setArpProxy failed with", zap.Error(err))
		return err
	}

	return nil
}

func (client *TransparentEndpointClient) DeleteEndpointRules(ep *endpoint) {
	// ip route del <podip> dev <hostveth>
	// Deleting the route set up for routing the incoming packets to pod
	for _, ipAddr := range ep.IPAddresses {
		var (
			routeInfo RouteInfo
			ipNet     net.IPNet
		)

		if ipAddr.IP.To4() != nil {
			ipNet = net.IPNet{IP: ipAddr.IP, Mask: net.CIDRMask(ipv4FullMask, ipv4Bits)}
		} else {
			ipNet = net.IPNet{IP: ipAddr.IP, Mask: net.CIDRMask(ipv6FullMask, ipv6Bits)}
		}

		logger.Info("Deleting route for the", zap.String("ip", ipNet.String()))
		routeInfo.Dst = ipNet
		if err := deleteRoutes(client.netlink, client.netioshim, client.hostVethName, []RouteInfo{routeInfo}); err != nil {
			logger.Error("Failed to delete route on VM for the", zap.String("ip", ipNet.String()), zap.Error(err))
		}
	}
}

func (client *TransparentEndpointClient) MoveEndpointsToContainerNS(epInfo *EndpointInfo, nsID uintptr) error {
	// Move the container interface to container's network namespace.
	logger.Info("Setting link netns", zap.String("containerVethName", client.containerVethName), zap.String("NetNsPath", epInfo.NetNsPath))
	if err := client.netlink.SetLinkNetNs(client.containerVethName, nsID); err != nil {
		return newErrorTransparentEndpointClient(err)
	}

	return nil
}

func (client *TransparentEndpointClient) SetupContainerInterfaces(epInfo *EndpointInfo) error {
	if err := client.netUtilsClient.SetupContainerInterface(client.containerVethName, epInfo.IfName); err != nil {
		return err
	}

	client.containerVethName = epInfo.IfName

	return nil
}

func (client *TransparentEndpointClient) ConfigureContainerInterfacesAndRoutes(epInfo *EndpointInfo) error {
	if err := client.netUtilsClient.AssignIPToInterface(client.containerVethName, epInfo.IPAddresses); err != nil {
		return newErrorTransparentEndpointClient(err)
	}

	// ip route del 10.240.0.0/12 dev eth0 (removing kernel subnet route added by above call)
	for _, ipAddr := range epInfo.IPAddresses {
		_, ipnet, _ := net.ParseCIDR(ipAddr.String())
		routeInfo := RouteInfo{
			Dst:      *ipnet,
			Scope:    netlink.RT_SCOPE_LINK,
			Protocol: netlink.RTPROT_KERNEL,
		}
		if err := deleteRoutes(client.netlink, client.netioshim, client.containerVethName, []RouteInfo{routeInfo}); err != nil {
			return newErrorTransparentEndpointClient(err)
		}
	}

	// add route for virtualgwip
	// ip route add 169.254.1.1/32 dev eth0
	virtualGwIP, virtualGwNet, _ := net.ParseCIDR(virtualGwIPString)
	routeInfo := RouteInfo{
		Dst:   *virtualGwNet,
		Scope: netlink.RT_SCOPE_LINK,
	}
	if err := addRoutes(client.netlink, client.netioshim, client.containerVethName, []RouteInfo{routeInfo}); err != nil {
		return newErrorTransparentEndpointClient(err)
	}

	if !epInfo.SkipDefaultRoutes {
		// ip route add default via 169.254.1.1 dev eth0
		_, defaultIPNet, _ := net.ParseCIDR(defaultGwCidr)
		dstIP := net.IPNet{IP: net.ParseIP(defaultGw), Mask: defaultIPNet.Mask}
		routeInfo = RouteInfo{
			Dst: dstIP,
			Gw:  virtualGwIP,
		}
		if err := addRoutes(client.netlink, client.netioshim, client.containerVethName, []RouteInfo{routeInfo}); err != nil {
			return err
		}
	} else if err := addRoutes(client.netlink, client.netioshim, client.containerVethName, epInfo.Routes); err != nil {
		return newErrorTransparentEndpointClient(err)
	}

	// arp -s 169.254.1.1 e3:45:f4:ac:34:12 - add static arp entry for virtualgwip to hostveth interface mac
	logger.Info("Adding static arp for IP address and MAC in Container namespace",
		zap.String("address", virtualGwNet.String()), zap.Any("hostVethMac", client.hostVethMac))
	linkInfo := netlink.LinkInfo{
		Name:       client.containerVethName,
		IPAddr:     virtualGwNet.IP,
		MacAddress: client.hostVethMac,
	}

	if err := client.netlink.SetOrRemoveLinkAddress(linkInfo, netlink.ADD, netlink.NUD_PROBE); err != nil {
		return fmt.Errorf("Adding arp in container failed: %w", err)
	}

	// IPv6Mode can be ipv6NAT or dual stack overlay
	// set epInfo ipv6Mode to 'dualStackOverlay' to set ipv6Routes and ipv6NeighborEntries for Linux pod in dualStackOverlay ipam mode
	if epInfo.IPV6Mode != "" {
		if err := client.setupIPV6Routes(); err != nil {
			return err
		}
	}

	if epInfo.IPV6Mode != "" {
		return client.setIPV6NeighEntry()
	}

	return nil
}

func (client *TransparentEndpointClient) setupIPV6Routes() error {
	logger.Info("Setting up ipv6 routes in container")

	// add route for virtualgwip
	// ip -6 route add fe80::1234:5678:9abc/128 dev eth0
	virtualGwIP, virtualGwNet, _ := net.ParseCIDR(virtualv6GwString)
	gwRoute := RouteInfo{
		Dst:   *virtualGwNet,
		Scope: netlink.RT_SCOPE_LINK,
	}

	// ip -6 route add default via fe80::1234:5678:9abc dev eth0
	_, defaultIPNet, _ := net.ParseCIDR(defaultv6Cidr)
	logger.Info("defaultv6ipnet", zap.Any("defaultIPNet", defaultIPNet))
	defaultRoute := RouteInfo{
		Dst: *defaultIPNet,
		Gw:  virtualGwIP,
	}

	return addRoutes(client.netlink, client.netioshim, client.containerVethName, []RouteInfo{gwRoute, defaultRoute})
}

func (client *TransparentEndpointClient) setIPV6NeighEntry() error {
	logger.Info("Add v6 neigh entry for default gw ip")
	hostGwIP, _, _ := net.ParseCIDR(virtualv6GwString)
	linkInfo := netlink.LinkInfo{
		Name:       client.containerVethName,
		IPAddr:     hostGwIP,
		MacAddress: client.hostVethMac,
	}

	if err := client.netlink.SetOrRemoveLinkAddress(linkInfo, netlink.ADD, netlink.NUD_PERMANENT); err != nil {
		logger.Error("Failed setting neigh entry in container", zap.Error(err))
		return fmt.Errorf("Failed setting neigh entry in container: %w", err)
	}

	return nil
}

func (client *TransparentEndpointClient) DeleteEndpoints(_ *endpoint) error {
	return nil
}