package netlink

import (
	"fmt"
	"net"
	"strings"
)

// Scope is an enum representing a route scope.
type Scope uint8

type NextHopFlag int

const (
	RT_FILTER_PROTOCOL uint64 = 1 << (1 + iota)
	RT_FILTER_SCOPE
	RT_FILTER_TYPE
	RT_FILTER_TOS
	RT_FILTER_IIF
	RT_FILTER_OIF
	RT_FILTER_DST
	RT_FILTER_SRC
	RT_FILTER_GW
	RT_FILTER_TABLE
	RT_FILTER_HOPLIMIT
	RT_FILTER_PRIORITY
	RT_FILTER_MARK
	RT_FILTER_MASK
	RT_FILTER_REALM
)

type Destination interface {
	Family() int
	Decode([]byte) error
	Encode() ([]byte, error)
	String() string
	Equal(Destination) bool
}

type Encap interface {
	Type() int
	Decode([]byte) error
	Encode() ([]byte, error)
	String() string
	Equal(Encap) bool
}

//Protocol describe what was the originator of the route
type RouteProtocol int

// Route represents a netlink route.
type Route struct {
	LinkIndex        int
	ILinkIndex       int
	Scope            Scope
	Dst              *net.IPNet
	Src              net.IP
	Gw               net.IP
	MultiPath        []*NexthopInfo
	Protocol         RouteProtocol
	Priority         int
	Family           int
	Table            int
	Type             int
	Tos              int
	Flags            int
	MPLSDst          *int
	NewDst           Destination
	Encap            Encap
	Via              Destination
	Realm            int
	MTU              int
	Window           int
	Rtt              int
	RttVar           int
	Ssthresh         int
	Cwnd             int
	AdvMSS           int
	Reordering       int
	Hoplimit         int
	InitCwnd         int
	Features         int
	RtoMin           int
	InitRwnd         int
	QuickACK         int
	Congctl          string
	FastOpenNoCookie int
}

func (r Route) String() string {
	elems := []string{}
	if len(r.MultiPath) == 0 {
		elems = append(elems, fmt.Sprintf("Ifindex: %d", r.LinkIndex))
	}
	if r.MPLSDst != nil {
		elems = append(elems, fmt.Sprintf("Dst: %d", r.MPLSDst))
	} else {
		elems = append(elems, fmt.Sprintf("Dst: %s", r.Dst))
	}
	if r.NewDst != nil {
		elems = append(elems, fmt.Sprintf("NewDst: %s", r.NewDst))
	}
	if r.Encap != nil {
		elems = append(elems, fmt.Sprintf("Encap: %s", r.Encap))
	}
	if r.Via != nil {
		elems = append(elems, fmt.Sprintf("Via: %s", r.Via))
	}
	elems = append(elems, fmt.Sprintf("Src: %s", r.Src))
	if len(r.MultiPath) > 0 {
		elems = append(elems, fmt.Sprintf("Gw: %s", r.MultiPath))
	} else {
		elems = append(elems, fmt.Sprintf("Gw: %s", r.Gw))
	}
	elems = append(elems, fmt.Sprintf("Flags: %s", r.ListFlags()))
	elems = append(elems, fmt.Sprintf("Table: %d", r.Table))
	elems = append(elems, fmt.Sprintf("Realm: %d", r.Realm))
	return fmt.Sprintf("{%s}", strings.Join(elems, " "))
}

func (r Route) Equal(x Route) bool {
	return r.LinkIndex == x.LinkIndex &&
		r.ILinkIndex == x.ILinkIndex &&
		r.Scope == x.Scope &&
		ipNetEqual(r.Dst, x.Dst) &&
		r.Src.Equal(x.Src) &&
		r.Gw.Equal(x.Gw) &&
		nexthopInfoSlice(r.MultiPath).Equal(x.MultiPath) &&
		r.Protocol == x.Protocol &&
		r.Priority == x.Priority &&
		r.Realm == x.Realm &&
		r.Table == x.Table &&
		r.Type == x.Type &&
		r.Tos == x.Tos &&
		r.Hoplimit == x.Hoplimit &&
		r.Flags == x.Flags &&
		(r.MPLSDst == x.MPLSDst || (r.MPLSDst != nil && x.MPLSDst != nil && *r.MPLSDst == *x.MPLSDst)) &&
		(r.NewDst == x.NewDst || (r.NewDst != nil && r.NewDst.Equal(x.NewDst))) &&
		(r.Via == x.Via || (r.Via != nil && r.Via.Equal(x.Via))) &&
		(r.Encap == x.Encap || (r.Encap != nil && r.Encap.Equal(x.Encap)))
}

func (r *Route) SetFlag(flag NextHopFlag) {
	r.Flags |= int(flag)
}

func (r *Route) ClearFlag(flag NextHopFlag) {
	r.Flags &^= int(flag)
}

type flagString struct {
	f NextHopFlag
	s string
}

// RouteUpdate is sent when a route changes - type is RTM_NEWROUTE or RTM_DELROUTE

// NlFlags is only non-zero for RTM_NEWROUTE, the following flags can be set:
//   - unix.NLM_F_REPLACE - Replace existing matching config object with this request
//   - unix.NLM_F_EXCL - Don't replace the config object if it already exists
//   - unix.NLM_F_CREATE - Create config object if it doesn't already exist
//   - unix.NLM_F_APPEND - Add to the end of the object list
type RouteUpdate struct {
	Type    uint16
	NlFlags uint16
	Route
}

type NexthopInfo struct {
	LinkIndex int
	Hops      int
	Gw        net.IP
	Flags     int
	NewDst    Destination
	Encap     Encap
	Via       Destination
}

func (n *NexthopInfo) String() string {
	elems := []string{}
	elems = append(elems, fmt.Sprintf("Ifindex: %d", n.LinkIndex))
	if n.NewDst != nil {
		elems = append(elems, fmt.Sprintf("NewDst: %s", n.NewDst))
	}
	if n.Encap != nil {
		elems = append(elems, fmt.Sprintf("Encap: %s", n.Encap))
	}
	if n.Via != nil {
		elems = append(elems, fmt.Sprintf("Via: %s", n.Via))
	}
	elems = append(elems, fmt.Sprintf("Weight: %d", n.Hops+1))
	elems = append(elems, fmt.Sprintf("Gw: %s", n.Gw))
	elems = append(elems, fmt.Sprintf("Flags: %s", n.ListFlags()))
	return fmt.Sprintf("{%s}", strings.Join(elems, " "))
}

func (n NexthopInfo) Equal(x NexthopInfo) bool {
	return n.LinkIndex == x.LinkIndex &&
		n.Hops == x.Hops &&
		n.Gw.Equal(x.Gw) &&
		n.Flags == x.Flags &&
		(n.NewDst == x.NewDst || (n.NewDst != nil && n.NewDst.Equal(x.NewDst))) &&
		(n.Encap == x.Encap || (n.Encap != nil && n.Encap.Equal(x.Encap)))
}

type nexthopInfoSlice []*NexthopInfo

func (n nexthopInfoSlice) Equal(x []*NexthopInfo) bool {
	if len(n) != len(x) {
		return false
	}
	for i := range n {
		if n[i] == nil || x[i] == nil {
			return false
		}
		if !n[i].Equal(*x[i]) {
			return false
		}
	}
	return true
}

// ipNetEqual returns true iff both IPNet are equal
func ipNetEqual(ipn1 *net.IPNet, ipn2 *net.IPNet) bool {
	if ipn1 == ipn2 {
		return true
	}
	if ipn1 == nil || ipn2 == nil {
		return false
	}
	m1, _ := ipn1.Mask.Size()
	m2, _ := ipn2.Mask.Size()
	return m1 == m2 && ipn1.IP.Equal(ipn2.IP)
}