package ftp

import (
	"strings"

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

// FTP Status codes, defined in RFC 959
const (
	statusReadyServer         = "120"
	statusOK                  = "200"
	statusNewConnectOK        = "220"
	statusSystemNameOK        = "215"
	statusCloseConnect        = "221"
	statusUnkownCMD           = "202"
	statusTlsUseOK            = "234"
	statusCloseControlConnect = "421"
	statusSyntaxErr           = "500"
	statusParamSyntaxErr      = "501"
	statusNotUseCMD           = "502"
	statusIncorrectCMD        = "503"
	statusNotLoggedIn         = "530"
	statusTlsNotUse           = "534"
	statusNeedUserId          = "332"
)

type FTPMatcher struct {
	osm.Matchers
}

func (m *FTPMatcher) Key() string {
	return "FTP"
}

func (m *FTPMatcher) Name(matchCtx *osm.MatchCtx) string {
	return "FTP"
}

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

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

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

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

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

	str := strings.Split(string(packet.Bytes()), "\r\n")[0]
	if len(str) < 4 {
		return osm.NotMatchedError()
	}
	code := str[:3]

	if index == 0 {
		switch code {
		case statusNewConnectOK, statusReadyServer:
			matchCtx.SetAttribute("comment", str[4:])
			return nil
		}
	} else if index == 1 {
		switch code {
		case statusCloseConnect, statusSyntaxErr:
			return nil
		}
	}

	return osm.NotMatchedError()
}

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

	quitStr := "QUIT\r\n"
	quitByte := make([]byte, len(quitStr))
	copy(quitByte[:], quitStr)
	m.AddPacket(osm.NewPacket(quitByte, len(quitStr)))

	return m
}