package ssh

import (
	"bufio"
	"bytes"
	"strings"

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

type SSHMatcher struct {
	osm.Matchers
	meta osm.Metadata
}

func (ssh *SSHMatcher) Key() string {
	return "SSH"
}

func (ssh *SSHMatcher) Name() string {
	name := "SSH"
	if v, ok := ssh.meta["softwareversion"]; ok {
		name = name + " (" + v + ")"
	}
	return name
}

func (ssh *SSHMatcher) Meta() osm.Metadata {
	return ssh.meta
}

func (ssh *SSHMatcher) IsPrePacket() bool {
	return true
}

func (ssh *SSHMatcher) HasResponse(index int) bool {
	return true
}

func (ssh *SSHMatcher) IsError(info osm.MatchInfo, index int, packet *osm.Packet) bool {
	return false
}

func (ssh *SSHMatcher) Match(info osm.MatchInfo, index int, packet *osm.Packet) error {

	if packet == nil || packet.Buffer == nil || packet.Len == 0 {
		return osm.NoPacketReceivedError()
	}

	// SSH-protoversion-softwareversion SP comments CR LF
	// e.g. ) SSH-2.0-OpenSSH_7.5p1 Ubuntu-10ubuntu0.1\n
	scanner := bufio.NewScanner(bytes.NewReader(packet.Buffer))
	for scanner.Scan() {
		exchange := scanner.Text()

		if !strings.HasPrefix(exchange, "SSH") {
			return osm.NotMatchedError()
		}

		temp := strings.Split(exchange, " ")
		versions := strings.Split(temp[0], "-")

		protoversion := versions[1]
		softwareversion := versions[2]

		if strings.HasPrefix(protoversion, "1") || strings.HasPrefix(protoversion, "2") {
			ssh.meta["protoversion"] = protoversion
			ssh.meta["softwareversion"] = softwareversion

			if len(temp) > 1 {
				ssh.meta["comments"] = temp[1]
			}
			return nil
		}
		break
	}

	return osm.NotMatchedError()
}

func NewMatcher() osm.Matcher {
	m := &SSHMatcher{}
	m.meta = osm.NewMetadata()
	return m
}