package telnet

import (
	osm "git.loafle.net/overflow/service_matcher-go"
)

const (
	WILL = 251
	WONT = 252
	DO   = 253
	DONT = 254
	CMD  = 255
)

type TelnetMatcher struct {
	osm.Matchers
}

func (m *TelnetMatcher) Key() string {
	return "TELNET"
}

func (m *TelnetMatcher) Name(matchCtx *osm.MatchCtx) string {
	return "Telnet"
}

func (m *TelnetMatcher) IsPrePacket() bool {
	return true
}

func (m *TelnetMatcher) HasResponse(matchCtx *osm.MatchCtx, index int) bool {
	return true
}

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

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

	if packet == nil || !packet.Valid() {
		return osm.NoPacketReceivedError()
	}

	buf := make([]byte, 0, 0)
	count := 0

	for i := 0; i < packet.Len; i++ {
		if packet.Buffer[i] > 0 {
			buf = append(buf, packet.Buffer[i])
		} else if count > 2 {
			break
		} else {
			count++
		}
	}

	for idx := 0; idx < len(buf); idx += 3 {
		if buf[idx] == CMD && (buf[idx+1] == DO || buf[idx+1] == WONT || buf[idx+1] == WILL || buf[idx+1] == DONT) {
			return nil
		}
	}

	return osm.NotMatchedError()
}

func NewMatcher() osm.Matcher {
	m := &TelnetMatcher{}

	m.AddPacket(osm.NewPacket([]byte{CMD, DO, 37}, 3))

	return m
}