package plugin

import (
	"fmt"
	"io/ioutil"
	"net"
	"os"
	"strings"
	"time"

	"github.com/golang/glog"

	osapi "github.com/openshift/origin/pkg/sdn/api"
	"github.com/openshift/origin/pkg/util/ipcmd"
	"github.com/openshift/origin/pkg/util/netutils"

	kapi "k8s.io/kubernetes/pkg/api"
	kapierrors "k8s.io/kubernetes/pkg/api/errors"
	utildbus "k8s.io/kubernetes/pkg/util/dbus"
	kexec "k8s.io/kubernetes/pkg/util/exec"
	"k8s.io/kubernetes/pkg/util/iptables"
	"k8s.io/kubernetes/pkg/util/sysctl"
	utilwait "k8s.io/kubernetes/pkg/util/wait"
)

const (
	// rule versioning; increment each time flow rules change
	VERSION        = 1
	VERSION_TABLE  = "table=253"
	VERSION_ACTION = "actions=note:"

	BR    = "br0"
	TUN   = "tun0"
	VXLAN = "vxlan0"

	VXLAN_PORT = "4789"
)

func getPluginVersion(multitenant bool) []string {
	if VERSION > 254 {
		panic("Version too large!")
	}
	version := fmt.Sprintf("%02X", VERSION)
	if multitenant {
		return []string{"01", version}
	}
	// single-tenant
	return []string{"00", version}
}

func (plugin *OsdnNode) getLocalSubnet() (string, error) {
	var subnet *osapi.HostSubnet
	backoff := utilwait.Backoff{
		Duration: 100 * time.Millisecond,
		Factor:   2,
		Steps:    8,
	}
	err := utilwait.ExponentialBackoff(backoff, func() (bool, error) {
		var err error
		subnet, err = plugin.osClient.HostSubnets().Get(plugin.hostName)
		if err == nil {
			return true, nil
		} else if kapierrors.IsNotFound(err) {
			glog.Warningf("Could not find an allocated subnet for node: %s, Waiting...", plugin.hostName)
			return false, nil
		} else {
			return false, err
		}
	})
	if err != nil {
		return "", fmt.Errorf("Failed to get subnet for this host: %s, error: %v", plugin.hostName, err)
	}

	if err = plugin.networkInfo.validateNodeIP(subnet.HostIP); err != nil {
		return "", fmt.Errorf("Failed to validate own HostSubnet: %v", err)
	}

	return subnet.Subnet, nil
}

func (plugin *OsdnNode) alreadySetUp(localSubnetGatewayCIDR, clusterNetworkCIDR string) bool {
	var found bool

	exec := kexec.New()
	itx := ipcmd.NewTransaction(exec, TUN)
	addrs, err := itx.GetAddresses()
	itx.EndTransaction()
	if err != nil {
		return false
	}
	found = false
	for _, addr := range addrs {
		if strings.Contains(addr, localSubnetGatewayCIDR) {
			found = true
			break
		}
	}
	if !found {
		return false
	}

	itx = ipcmd.NewTransaction(exec, TUN)
	routes, err := itx.GetRoutes()
	itx.EndTransaction()
	if err != nil {
		return false
	}
	found = false
	for _, route := range routes {
		if strings.Contains(route, clusterNetworkCIDR+" ") {
			found = true
			break
		}
	}
	if !found {
		return false
	}

	flows, err := plugin.ovs.DumpFlows()
	if err != nil {
		return false
	}
	found = false
	for _, flow := range flows {
		if !strings.Contains(flow, VERSION_TABLE) {
			continue
		}
		idx := strings.Index(flow, VERSION_ACTION)
		if idx < 0 {
			continue
		}

		// OVS note action format hex bytes separated by '.'; first
		// byte is plugin type (multi-tenant/single-tenant) and second
		// byte is flow rule version
		expected := getPluginVersion(plugin.multitenant)
		existing := strings.Split(flow[idx+len(VERSION_ACTION):], ".")
		if len(existing) >= 2 && existing[0] == expected[0] && existing[1] == expected[1] {
			found = true
			break
		}
	}
	if !found {
		return false
	}

	return true
}

func deleteLocalSubnetRoute(device, localSubnetCIDR string) {
	backoff := utilwait.Backoff{
		Duration: 100 * time.Millisecond,
		Factor:   1.25,
		Steps:    6,
	}
	err := utilwait.ExponentialBackoff(backoff, func() (bool, error) {
		itx := ipcmd.NewTransaction(kexec.New(), device)
		routes, err := itx.GetRoutes()
		if err != nil {
			return false, fmt.Errorf("could not get routes: %v", err)
		}
		for _, route := range routes {
			if strings.Contains(route, localSubnetCIDR) {
				itx.DeleteRoute(localSubnetCIDR)
				err = itx.EndTransaction()
				if err != nil {
					return false, fmt.Errorf("could not delete route: %v", err)
				}
				return true, nil
			}
		}
		return false, nil
	})

	if err != nil {
		glog.Errorf("Error removing %s route from dev %s: %v; if the route appears later it will not be deleted.", localSubnetCIDR, device, err)
	}
}

func (plugin *OsdnNode) SetupSDN() (bool, error) {
	clusterNetworkCIDR := plugin.networkInfo.ClusterNetwork.String()
	serviceNetworkCIDR := plugin.networkInfo.ServiceNetwork.String()

	localSubnetCIDR := plugin.localSubnetCIDR
	_, ipnet, err := net.ParseCIDR(localSubnetCIDR)
	localSubnetMaskLength, _ := ipnet.Mask.Size()
	localSubnetGateway := netutils.GenerateDefaultGateway(ipnet).String()

	glog.V(5).Infof("[SDN setup] node pod subnet %s gateway %s", ipnet.String(), localSubnetGateway)

	exec := kexec.New()

	if plugin.clearLbr0IptablesRule {
		// Delete docker's left-over lbr0 rule; cannot do this from
		// NewNodePlugin (where docker is cleaned up) because we need
		// localSubnetCIDR which is only valid after plugin start
		ipt := iptables.New(exec, utildbus.New(), iptables.ProtocolIpv4)
		ipt.DeleteRule(iptables.TableNAT, iptables.ChainPostrouting, "-s", localSubnetCIDR, "!", "-o", "lbr0", "-j", "MASQUERADE")
	}

	gwCIDR := fmt.Sprintf("%s/%d", localSubnetGateway, localSubnetMaskLength)
	if plugin.alreadySetUp(gwCIDR, clusterNetworkCIDR) {
		glog.V(5).Infof("[SDN setup] no SDN setup required")
		return false, nil
	}
	glog.V(5).Infof("[SDN setup] full SDN setup required")

	if err := os.MkdirAll("/run/openshift-sdn", 0700); err != nil {
		return false, err
	}
	config := fmt.Sprintf("export OPENSHIFT_CLUSTER_SUBNET=%s", clusterNetworkCIDR)
	err = ioutil.WriteFile("/run/openshift-sdn/config.env", []byte(config), 0644)
	if err != nil {
		return false, err
	}

	err = plugin.ovs.AddBridge("fail-mode=secure", "protocols=OpenFlow13")
	if err != nil {
		return false, err
	}
	_ = plugin.ovs.DeletePort(VXLAN)
	_, err = plugin.ovs.AddPort(VXLAN, 1, "type=vxlan", `options:remote_ip="flow"`, `options:key="flow"`)
	if err != nil {
		return false, err
	}
	_ = plugin.ovs.DeletePort(TUN)
	_, err = plugin.ovs.AddPort(TUN, 2, "type=internal")
	if err != nil {
		return false, err
	}

	otx := plugin.ovs.NewTransaction()
	// Table 0: initial dispatch based on in_port
	// vxlan0
	otx.AddFlow("table=0, priority=200, in_port=1, arp, nw_src=%s, nw_dst=%s, actions=move:NXM_NX_TUN_ID[0..31]->NXM_NX_REG0[],goto_table:1", clusterNetworkCIDR, localSubnetCIDR)
	otx.AddFlow("table=0, priority=200, in_port=1, ip, nw_src=%s, nw_dst=%s, actions=move:NXM_NX_TUN_ID[0..31]->NXM_NX_REG0[],goto_table:1", clusterNetworkCIDR, localSubnetCIDR)
	otx.AddFlow("table=0, priority=150, in_port=1, actions=drop")
	// tun0
	otx.AddFlow("table=0, priority=200, in_port=2, arp, nw_src=%s, nw_dst=%s, actions=goto_table:5", localSubnetGateway, clusterNetworkCIDR)
	otx.AddFlow("table=0, priority=200, in_port=2, ip, actions=goto_table:5")
	otx.AddFlow("table=0, priority=150, in_port=2, actions=drop")
	// else, from a container
	otx.AddFlow("table=0, priority=100, arp, actions=goto_table:2")
	otx.AddFlow("table=0, priority=100, ip, actions=goto_table:2")
	otx.AddFlow("table=0, priority=0, actions=drop")

	// Table 1: VXLAN ingress filtering; filled in by AddHostSubnetRules()
	// eg, "table=1, priority=100, tun_src=${remote_node_ip}, actions=goto_table:5"
	otx.AddFlow("table=1, priority=0, actions=drop")

	// Table 2: from OpenShift container; validate IP/MAC, assign tenant-id; filled in by openshift-sdn-ovs
	// eg, "table=2, priority=100, in_port=${ovs_port}, arp, nw_src=${ipaddr}, arp_sha=${macaddr}, actions=load:${tenant_id}->NXM_NX_REG0[], goto_table:5"
	//     "table=2, priority=100, in_port=${ovs_port}, ip, nw_src=${ipaddr}, actions=load:${tenant_id}->NXM_NX_REG0[], goto_table:3"
	// (${tenant_id} is always 0 for single-tenant)
	otx.AddFlow("table=2, priority=0, actions=drop")

	// Table 3: from OpenShift container; service vs non-service
	otx.AddFlow("table=3, priority=100, ip, nw_dst=%s, actions=goto_table:4", serviceNetworkCIDR)
	otx.AddFlow("table=3, priority=0, actions=goto_table:5")

	// Table 4: from OpenShift container; service dispatch; filled in by AddServiceRules()
	otx.AddFlow("table=4, priority=200, reg0=0, actions=output:2")
	// eg, "table=4, priority=100, reg0=${tenant_id}, ${service_proto}, nw_dst=${service_ip}, tp_dst=${service_port}, actions=output:2"
	otx.AddFlow("table=4, priority=0, actions=drop")

	// Table 5: general routing
	otx.AddFlow("table=5, priority=300, arp, nw_dst=%s, actions=output:2", localSubnetGateway)
	otx.AddFlow("table=5, priority=300, ip, nw_dst=%s, actions=output:2", localSubnetGateway)
	otx.AddFlow("table=5, priority=200, arp, nw_dst=%s, actions=goto_table:6", localSubnetCIDR)
	otx.AddFlow("table=5, priority=200, ip, nw_dst=%s, actions=goto_table:7", localSubnetCIDR)
	otx.AddFlow("table=5, priority=100, arp, nw_dst=%s, actions=goto_table:8", clusterNetworkCIDR)
	otx.AddFlow("table=5, priority=100, ip, nw_dst=%s, actions=goto_table:8", clusterNetworkCIDR)
	otx.AddFlow("table=5, priority=0, ip, actions=goto_table:9")
	otx.AddFlow("table=5, priority=0, arp, actions=drop")

	// Table 6: ARP to container, filled in by openshift-sdn-ovs
	// eg, "table=6, priority=100, arp, nw_dst=${container_ip}, actions=output:${ovs_port}"
	otx.AddFlow("table=6, priority=0, actions=drop")

	// Table 7: IP to container; filled in by openshift-sdn-ovs
	// eg, "table=7, priority=100, reg0=0, ip, nw_dst=${ipaddr}, actions=output:${ovs_port}"
	// eg, "table=7, priority=100, reg0=${tenant_id}, ip, nw_dst=${ipaddr}, actions=output:${ovs_port}"
	otx.AddFlow("table=7, priority=0, actions=drop")

	// Table 8: to remote container; filled in by AddHostSubnetRules()
	// eg, "table=8, priority=100, arp, nw_dst=${remote_subnet_cidr}, actions=move:NXM_NX_REG0[]->NXM_NX_TUN_ID[0..31], set_field:${remote_node_ip}->tun_dst,output:1"
	// eg, "table=8, priority=100, ip, nw_dst=${remote_subnet_cidr}, actions=move:NXM_NX_REG0[]->NXM_NX_TUN_ID[0..31], set_field:${remote_node_ip}->tun_dst,output:1"
	otx.AddFlow("table=8, priority=0, actions=drop")

	// Table 9: egress network policy dispatch; edited by updateEgressNetworkPolicyRules()
	// eg, "table=9, reg0=${tenant_id}, priority=2, ip, nw_dst=${external_cidr}, actions=drop
	otx.AddFlow("table=9, priority=0, actions=output:2")

	err = otx.EndTransaction()
	if err != nil {
		return false, err
	}

	itx := ipcmd.NewTransaction(exec, TUN)
	itx.AddAddress(gwCIDR)
	defer deleteLocalSubnetRoute(TUN, localSubnetCIDR)
	itx.SetLink("mtu", fmt.Sprint(plugin.mtu))
	itx.SetLink("up")
	itx.AddRoute(clusterNetworkCIDR, "proto", "kernel", "scope", "link")
	itx.AddRoute(serviceNetworkCIDR)
	err = itx.EndTransaction()
	if err != nil {
		return false, err
	}

	sysctl := sysctl.New()

	// Enable IP forwarding for ipv4 packets
	err = sysctl.SetSysctl("net/ipv4/ip_forward", 1)
	if err != nil {
		return false, fmt.Errorf("Could not enable IPv4 forwarding: %s", err)
	}
	err = sysctl.SetSysctl(fmt.Sprintf("net/ipv4/conf/%s/forwarding", TUN), 1)
	if err != nil {
		return false, fmt.Errorf("Could not enable IPv4 forwarding on %s: %s", TUN, err)
	}

	// Table 253: rule version; note action is hex bytes separated by '.'
	otx = plugin.ovs.NewTransaction()
	pluginVersion := getPluginVersion(plugin.multitenant)
	otx.AddFlow("%s, %s%s.%s", VERSION_TABLE, VERSION_ACTION, pluginVersion[0], pluginVersion[1])
	err = otx.EndTransaction()
	if err != nil {
		return false, err
	}

	return true, nil
}

func policyNames(policies []osapi.EgressNetworkPolicy) string {
	names := make([]string, len(policies))
	for i, policy := range policies {
		names[i] = policy.Namespace + ":" + policy.Name
	}
	return strings.Join(names, ", ")
}

func (plugin *OsdnNode) updateEgressNetworkPolicyRules(vnid uint32) error {
	otx := plugin.ovs.NewTransaction()

	policies := plugin.egressPolicies[vnid]
	namespaces := plugin.vnids.GetNamespaces(vnid)
	if len(policies) == 0 {
		otx.DeleteFlows("table=9, reg0=%d", vnid)
	} else if vnid == 0 {
		glog.Errorf("EgressNetworkPolicy in global network namespace is not allowed (%s); ignoring", policyNames(policies))
	} else if len(namespaces) > 1 {
		glog.Errorf("EgressNetworkPolicy not allowed in shared NetNamespace (%s); dropping all traffic", strings.Join(namespaces, ", "))
		otx.DeleteFlows("table=9, reg0=%d", vnid)
		otx.AddFlow("table=9, reg0=%d, priority=1, actions=drop", vnid)
	} else if len(policies) > 1 {
		glog.Errorf("multiple EgressNetworkPolicies in same network namespace (%s) is not allowed; dropping all traffic", policyNames(policies))
		otx.DeleteFlows("table=9, reg0=%d", vnid)
		otx.AddFlow("table=9, reg0=%d, priority=1, actions=drop", vnid)
	} else /* vnid != 0 && len(policies) == 1 */ {
		// Temporarily drop all outgoing traffic, to avoid race conditions while modifying the other rules
		otx.AddFlow("table=9, reg0=%d, cookie=1, priority=65535, actions=drop", vnid)
		otx.DeleteFlows("table=9, reg0=%d, cookie=0/1", vnid)

		for i, rule := range policies[0].Spec.Egress {
			priority := len(policies[0].Spec.Egress) - i

			var action string
			if rule.Type == osapi.EgressNetworkPolicyRuleAllow {
				action = "output:2"
			} else {
				action = "drop"
			}

			var dst string
			if rule.To.CIDRSelector == "0.0.0.0/0" {
				dst = ""
			} else {
				dst = fmt.Sprintf(", nw_dst=%s", rule.To.CIDRSelector)
			}

			otx.AddFlow("table=9, reg0=%d, priority=%d, ip%s, actions=%s", vnid, priority, dst, action)
		}
		otx.DeleteFlows("table=9, reg0=%d, cookie=1/1", vnid)
	}

	err := otx.EndTransaction()
	if err != nil {
		return fmt.Errorf("Error updating OVS flows for EgressNetworkPolicy: %v", err)
	}
	return nil
}

func (plugin *OsdnNode) AddHostSubnetRules(subnet *osapi.HostSubnet) error {
	glog.Infof("AddHostSubnetRules for %s", hostSubnetToString(subnet))
	otx := plugin.ovs.NewTransaction()

	otx.AddFlow("table=1, priority=100, tun_src=%s, actions=goto_table:5", subnet.HostIP)
	if vnid, ok := subnet.Annotations[osapi.FixedVnidHost]; ok {
		otx.AddFlow("table=8, priority=100, arp, nw_dst=%s, actions=load:%s->NXM_NX_TUN_ID[0..31],set_field:%s->tun_dst,output:1", subnet.Subnet, vnid, subnet.HostIP)
		otx.AddFlow("table=8, priority=100, ip, nw_dst=%s, actions=load:%s->NXM_NX_TUN_ID[0..31],set_field:%s->tun_dst,output:1", subnet.Subnet, vnid, subnet.HostIP)
	} else {
		otx.AddFlow("table=8, priority=100, arp, nw_dst=%s, actions=move:NXM_NX_REG0[]->NXM_NX_TUN_ID[0..31],set_field:%s->tun_dst,output:1", subnet.Subnet, subnet.HostIP)
		otx.AddFlow("table=8, priority=100, ip, nw_dst=%s, actions=move:NXM_NX_REG0[]->NXM_NX_TUN_ID[0..31],set_field:%s->tun_dst,output:1", subnet.Subnet, subnet.HostIP)
	}

	err := otx.EndTransaction()
	if err != nil {
		return fmt.Errorf("Error adding OVS flows for subnet: %v, %v", subnet, err)
	}
	return nil
}

func (plugin *OsdnNode) DeleteHostSubnetRules(subnet *osapi.HostSubnet) error {
	glog.Infof("DeleteHostSubnetRules for %s", hostSubnetToString(subnet))

	otx := plugin.ovs.NewTransaction()
	otx.DeleteFlows("table=1, tun_src=%s", subnet.HostIP)
	otx.DeleteFlows("table=8, ip, nw_dst=%s", subnet.Subnet)
	otx.DeleteFlows("table=8, arp, nw_dst=%s", subnet.Subnet)
	err := otx.EndTransaction()
	if err != nil {
		return fmt.Errorf("Error deleting OVS flows for subnet: %v, %v", subnet, err)
	}
	return nil
}

func (plugin *OsdnNode) AddServiceRules(service *kapi.Service, netID uint32) error {
	if !plugin.multitenant {
		return nil
	}

	glog.V(5).Infof("AddServiceRules for %v", service)

	otx := plugin.ovs.NewTransaction()
	for _, port := range service.Spec.Ports {
		otx.AddFlow(generateAddServiceRule(netID, service.Spec.ClusterIP, port.Protocol, int(port.Port)))
		err := otx.EndTransaction()
		if err != nil {
			return fmt.Errorf("Error adding OVS flows for service: %v, netid: %d, %v", service, netID, err)
		}
	}
	return nil
}

func (plugin *OsdnNode) DeleteServiceRules(service *kapi.Service) error {
	if !plugin.multitenant {
		return nil
	}

	glog.V(5).Infof("DeleteServiceRules for %v", service)

	otx := plugin.ovs.NewTransaction()
	for _, port := range service.Spec.Ports {
		otx.DeleteFlows(generateDeleteServiceRule(service.Spec.ClusterIP, port.Protocol, int(port.Port)))
		err := otx.EndTransaction()
		if err != nil {
			return fmt.Errorf("Error deleting OVS flows for service: %v, %v", service, err)
		}
	}
	return nil
}

func generateBaseServiceRule(IP string, protocol kapi.Protocol, port int) string {
	return fmt.Sprintf("table=4, %s, nw_dst=%s, tp_dst=%d", strings.ToLower(string(protocol)), IP, port)
}

func generateAddServiceRule(netID uint32, IP string, protocol kapi.Protocol, port int) string {
	baseRule := generateBaseServiceRule(IP, protocol, port)
	if netID == 0 {
		return fmt.Sprintf("%s, priority=100, actions=output:2", baseRule)
	} else {
		return fmt.Sprintf("%s, priority=100, reg0=%d, actions=output:2", baseRule, netID)
	}
}

func generateDeleteServiceRule(IP string, protocol kapi.Protocol, port int) string {
	return generateBaseServiceRule(IP, protocol, port)
}