package ldap

import (
	"math/rand"
	"time"

	osm "git.loafle.net/overflow/service_matcher-go"
	ber "gopkg.in/asn1-ber.v1"
)

const (
	ApplicationBindRequest  = 0
	ApplicationBindResponse = 1
)

type LDAPMatcher struct {
	osm.Matchers
	reqID int64
}

func (m *LDAPMatcher) Key() string {
	return "LDAP"
}

func (m *LDAPMatcher) Name(matchCtx *osm.MatchCtx) string {
	return "LDAP"
}

func (m *LDAPMatcher) IsPrePacket() bool {
	return false
}

func (m *LDAPMatcher) IsError(matchCtx *osm.MatchCtx, index int, packet *osm.Packet) bool {
	return false
}

func (m *LDAPMatcher) Match(matchCtx *osm.MatchCtx, index int, packet *osm.Packet) error {

	if packet == nil || !packet.Valid() {
		return osm.NoPacketReceivedError()
	}
	p := ber.DecodePacket(packet.Buffer)

	if nil == p || nil == p.Children || len(p.Children) <= 1 {
		return osm.NotMatchedError()
	}

	respID, ok := p.Children[0].Value.(int64)
	if !ok {
		return osm.NotMatchedError()
	}
	if respID != m.reqID {
		return osm.NotMatchedError()
	}

	if p.Children[1].Tag != ApplicationBindResponse {
		return osm.NotMatchedError()
	}

	return nil
}

func NewMatcher() osm.Matcher {

	m := &LDAPMatcher{}

	rand.Seed(time.Now().UnixNano())
	m.reqID = rand.Int63n(1000)
	p := ber.Encode(ber.ClassUniversal, ber.TypeConstructed, ber.TagSequence, nil, "LDAP Request")

	p.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, m.reqID, "MessageID"))
	bindRequest := ber.Encode(ber.ClassApplication, ber.TypeConstructed, ApplicationBindRequest, nil, "Bind Request")
	bindRequest.AppendChild(ber.NewInteger(ber.ClassUniversal, ber.TypePrimitive, ber.TagInteger, 2, "Version"))
	bindRequest.AppendChild(ber.NewString(ber.ClassUniversal, ber.TypePrimitive, ber.TagOctetString, "LOAFLEOVERFLOW", "User Name"))
	bindRequest.AppendChild(ber.NewString(ber.ClassContext, ber.TypePrimitive, 0, "LOAFLEOVERFLOW", "Password"))
	p.AppendChild(bindRequest)

	m.AddPacket(osm.NewPacket(p.Bytes(), len(p.Bytes())))

	return m

}