package netlink

import (
	"errors"
	"fmt"

	"github.com/vishvananda/netlink/nl"
)

type Filter interface {
	Attrs() *FilterAttrs
	Type() string
}

// FilterAttrs represents a netlink filter. A filter is associated with a link,
// has a handle and a parent. The root filter of a device should have a
// parent == HANDLE_ROOT.
type FilterAttrs struct {
	LinkIndex int
	Handle    uint32
	Parent    uint32
	Priority  uint16 // lower is higher priority
	Protocol  uint16 // syscall.ETH_P_*
}

func (q FilterAttrs) String() string {
	return fmt.Sprintf("{LinkIndex: %d, Handle: %s, Parent: %s, Priority: %d, Protocol: %d}", q.LinkIndex, HandleStr(q.Handle), HandleStr(q.Parent), q.Priority, q.Protocol)
}

type TcAct int32

const (
	TC_ACT_UNSPEC     TcAct = -1
	TC_ACT_OK         TcAct = 0
	TC_ACT_RECLASSIFY TcAct = 1
	TC_ACT_SHOT       TcAct = 2
	TC_ACT_PIPE       TcAct = 3
	TC_ACT_STOLEN     TcAct = 4
	TC_ACT_QUEUED     TcAct = 5
	TC_ACT_REPEAT     TcAct = 6
	TC_ACT_REDIRECT   TcAct = 7
	TC_ACT_JUMP       TcAct = 0x10000000
)

func (a TcAct) String() string {
	switch a {
	case TC_ACT_UNSPEC:
		return "unspec"
	case TC_ACT_OK:
		return "ok"
	case TC_ACT_RECLASSIFY:
		return "reclassify"
	case TC_ACT_SHOT:
		return "shot"
	case TC_ACT_PIPE:
		return "pipe"
	case TC_ACT_STOLEN:
		return "stolen"
	case TC_ACT_QUEUED:
		return "queued"
	case TC_ACT_REPEAT:
		return "repeat"
	case TC_ACT_REDIRECT:
		return "redirect"
	case TC_ACT_JUMP:
		return "jump"
	}
	return fmt.Sprintf("0x%x", a)
}

type TcPolAct int32

const (
	TC_POLICE_UNSPEC     TcPolAct = TcPolAct(TC_ACT_UNSPEC)
	TC_POLICE_OK         TcPolAct = TcPolAct(TC_ACT_OK)
	TC_POLICE_RECLASSIFY TcPolAct = TcPolAct(TC_ACT_RECLASSIFY)
	TC_POLICE_SHOT       TcPolAct = TcPolAct(TC_ACT_SHOT)
	TC_POLICE_PIPE       TcPolAct = TcPolAct(TC_ACT_PIPE)
)

func (a TcPolAct) String() string {
	switch a {
	case TC_POLICE_UNSPEC:
		return "unspec"
	case TC_POLICE_OK:
		return "ok"
	case TC_POLICE_RECLASSIFY:
		return "reclassify"
	case TC_POLICE_SHOT:
		return "shot"
	case TC_POLICE_PIPE:
		return "pipe"
	}
	return fmt.Sprintf("0x%x", a)
}

type ActionAttrs struct {
	Index   int
	Capab   int
	Action  TcAct
	Refcnt  int
	Bindcnt int
}

func (q ActionAttrs) String() string {
	return fmt.Sprintf("{Index: %d, Capab: %x, Action: %s, Refcnt: %d, Bindcnt: %d}", q.Index, q.Capab, q.Action.String(), q.Refcnt, q.Bindcnt)
}

// Action represents an action in any supported filter.
type Action interface {
	Attrs() *ActionAttrs
	Type() string
}

type GenericAction struct {
	ActionAttrs
}

func (action *GenericAction) Type() string {
	return "generic"
}

func (action *GenericAction) Attrs() *ActionAttrs {
	return &action.ActionAttrs
}

type BpfAction struct {
	ActionAttrs
	Fd   int
	Name string
}

func (action *BpfAction) Type() string {
	return "bpf"
}

func (action *BpfAction) Attrs() *ActionAttrs {
	return &action.ActionAttrs
}

type MirredAct uint8

func (a MirredAct) String() string {
	switch a {
	case TCA_EGRESS_REDIR:
		return "egress redir"
	case TCA_EGRESS_MIRROR:
		return "egress mirror"
	case TCA_INGRESS_REDIR:
		return "ingress redir"
	case TCA_INGRESS_MIRROR:
		return "ingress mirror"
	}
	return "unknown"
}

const (
	TCA_EGRESS_REDIR   MirredAct = 1 /* packet redirect to EGRESS*/
	TCA_EGRESS_MIRROR  MirredAct = 2 /* mirror packet to EGRESS */
	TCA_INGRESS_REDIR  MirredAct = 3 /* packet redirect to INGRESS*/
	TCA_INGRESS_MIRROR MirredAct = 4 /* mirror packet to INGRESS */
)

type MirredAction struct {
	ActionAttrs
	MirredAction MirredAct
	Ifindex      int
}

func (action *MirredAction) Type() string {
	return "mirred"
}

func (action *MirredAction) Attrs() *ActionAttrs {
	return &action.ActionAttrs
}

func NewMirredAction(redirIndex int) *MirredAction {
	return &MirredAction{
		ActionAttrs: ActionAttrs{
			Action: TC_ACT_STOLEN,
		},
		MirredAction: TCA_EGRESS_REDIR,
		Ifindex:      redirIndex,
	}
}

// U32 filters on many packet related properties
type U32 struct {
	FilterAttrs
	ClassId    uint32
	RedirIndex int
	Actions    []Action
}

func (filter *U32) Attrs() *FilterAttrs {
	return &filter.FilterAttrs
}

func (filter *U32) Type() string {
	return "u32"
}

type FilterFwAttrs struct {
	ClassId   uint32
	InDev     string
	Mask      uint32
	Index     uint32
	Buffer    uint32
	Mtu       uint32
	Mpu       uint16
	Rate      uint32
	AvRate    uint32
	PeakRate  uint32
	Action    TcPolAct
	Overhead  uint16
	LinkLayer int
}

// Fw filter filters on firewall marks
type Fw struct {
	FilterAttrs
	ClassId uint32
	// TODO remove nl type from interface
	Police nl.TcPolice
	InDev  string
	// TODO Action
	Mask   uint32
	AvRate uint32
	Rtab   [256]uint32
	Ptab   [256]uint32
}

func NewFw(attrs FilterAttrs, fattrs FilterFwAttrs) (*Fw, error) {
	var rtab [256]uint32
	var ptab [256]uint32
	rcellLog := -1
	pcellLog := -1
	avrate := fattrs.AvRate / 8
	police := nl.TcPolice{}
	police.Rate.Rate = fattrs.Rate / 8
	police.PeakRate.Rate = fattrs.PeakRate / 8
	buffer := fattrs.Buffer
	linklayer := nl.LINKLAYER_ETHERNET

	if fattrs.LinkLayer != nl.LINKLAYER_UNSPEC {
		linklayer = fattrs.LinkLayer
	}

	police.Action = int32(fattrs.Action)
	if police.Rate.Rate != 0 {
		police.Rate.Mpu = fattrs.Mpu
		police.Rate.Overhead = fattrs.Overhead
		if CalcRtable(&police.Rate, rtab, rcellLog, fattrs.Mtu, linklayer) < 0 {
			return nil, errors.New("TBF: failed to calculate rate table")
		}
		police.Burst = uint32(Xmittime(uint64(police.Rate.Rate), uint32(buffer)))
	}
	police.Mtu = fattrs.Mtu
	if police.PeakRate.Rate != 0 {
		police.PeakRate.Mpu = fattrs.Mpu
		police.PeakRate.Overhead = fattrs.Overhead
		if CalcRtable(&police.PeakRate, ptab, pcellLog, fattrs.Mtu, linklayer) < 0 {
			return nil, errors.New("POLICE: failed to calculate peak rate table")
		}
	}

	return &Fw{
		FilterAttrs: attrs,
		ClassId:     fattrs.ClassId,
		InDev:       fattrs.InDev,
		Mask:        fattrs.Mask,
		Police:      police,
		AvRate:      avrate,
		Rtab:        rtab,
		Ptab:        ptab,
	}, nil
}

func (filter *Fw) Attrs() *FilterAttrs {
	return &filter.FilterAttrs
}

func (filter *Fw) Type() string {
	return "fw"
}

type BpfFilter struct {
	FilterAttrs
	ClassId      uint32
	Fd           int
	Name         string
	DirectAction bool
}

func (filter *BpfFilter) Type() string {
	return "bpf"
}

func (filter *BpfFilter) Attrs() *FilterAttrs {
	return &filter.FilterAttrs
}

// GenericFilter filters represent types that are not currently understood
// by this netlink library.
type GenericFilter struct {
	FilterAttrs
	FilterType string
}

func (filter *GenericFilter) Attrs() *FilterAttrs {
	return &filter.FilterAttrs
}

func (filter *GenericFilter) Type() string {
	return filter.FilterType
}