package ldap

import (
	"math/rand"
	"time"

	csm "git.loafle.net/commons/service_matcher-go"
	ber "gopkg.in/asn1-ber.v1"
)

const (
	ApplicationBindRequest  = 0
	ApplicationBindResponse = 1
)

type LDAPMatcher struct {
	csm.Matchers
	reqID int64
}

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

func (l *LDAPMatcher) Name() string {
	return "LDAP"
}

func (l *LDAPMatcher) Meta() csm.Metadata {
	return nil
}

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

func (l *LDAPMatcher) IsError(info csm.MatchInfo, index int, packet *csm.Packet) bool {
	return false
}

func (l *LDAPMatcher) Match(info csm.MatchInfo, index int, packet *csm.Packet) error {

	if packet == nil || packet.Buffer == nil || packet.Len == 0 {
		return csm.NoPacketReceivedError()
	}
	p := ber.DecodePacket(packet.Buffer)

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

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

	return nil
}

func NewMatcher() csm.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(csm.NewPacket(p.Bytes(), len(p.Bytes())))

	return m

}