package redis

import (
	"bufio"
	"strconv"
	"strings"

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

const REDIS_PING string = "*1\r\n$4\r\nPING\r\n"
const REDIS_INFO string = "*1\r\n$4\r\nINFO\r\n"
const REDIS_QUIT string = "*1\r\n$4\r\nQUIT\r\n"

type RedisMatcher struct {
	osm.Matchers
}

func (m *RedisMatcher) Key() string {
	return "REDIS"
}

func (m *RedisMatcher) Name(matchCtx *osm.MatchCtx) string {
	name := "Redis"

	if v, ok := matchCtx.GetAttribute("protected"); ok {
		if _v, _err := strconv.ParseBool(v); nil != _err && _v {
			return name + " (protected)"
		}
	}

	if v, ok := matchCtx.GetAttribute("redis_mode"); ok {
		name = name + " " + v
	}
	if v, ok := matchCtx.GetAttribute("redis_version"); ok {
		name = name + " (" + v + ")"
	}
	return name
}

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

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

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

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

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

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

	switch index {
	case 0:
		sign := string([]rune(resp)[0])
		if len(sign) <= 0 {
			return osm.NotMatchedError()
		}

		if sign == "+" {
			if resp == "+PONG" || resp == "+OK" {
				return nil
			}
		}
		if sign == "-" {
			if resp == "-NOAUTH" || resp == "-ERR" {
				return nil
			}
		}

		protected := m.checkProtectedMode(packet)

		matchCtx.SetAttribute("protected", strconv.FormatBool(protected))
		if protected {
			return nil
		}

	case 1: // INFO
		response := string(packet.Bytes())

		if v, ok := matchCtx.GetAttribute("protected"); ok {
			if _v, _err := strconv.ParseBool(v); nil != _err && _v {
				m.parseResponse(matchCtx, response)
			}
		}

		return nil
	case 2:
		sign := string([]rune(resp)[0])
		if sign == "+" || sign == "-" {
			return nil
		}
		return nil
	default:
		return osm.NotMatchedError()
	}
	return osm.NotMatchedError()
}

func (m *RedisMatcher) checkProtectedMode(packet *osm.Packet) bool {
	var (
		compareSign = "-"
		compareMsg  = "DENIED"
	)
	str := string(packet.Bytes())

	if str == "" {
		return false
	}
	if 0 >= len(str) || len(compareMsg)+2 > len(str) {
		return false
	}

	firstCompare := str[0:1]
	seconcdCompare := str[1 : len(compareMsg)+1]

	if firstCompare != compareSign {
		return false
	}
	if seconcdCompare != compareMsg {
		return false
	}

	return true
}

func (m *RedisMatcher) parseResponse(matchCtx *osm.MatchCtx, response string) {
	scanner := bufio.NewScanner(strings.NewReader(response))
	for scanner.Scan() {
		line := scanner.Text()
		if strings.Compare(line, "") == 0 {
			break
		}
		if len(line) > 0 && strings.Contains(line, ":") {
			kv := strings.Split(line, ":")
			if len(kv[0]) > 0 && len(kv[1]) > 0 {
				matchCtx.SetAttribute(kv[0], kv[1])
			}
		}
	}
}

func (m *RedisMatcher) PacketCount(matchCtx *osm.MatchCtx) int {
	if v, ok := matchCtx.GetAttribute("protected"); ok {
		if _v, _err := strconv.ParseBool(v); nil != _err && _v {
			return 1
		}
	}

	return 3
}

func NewMatcher() osm.Matcher {

	m := &RedisMatcher{}

	m.AddPacket(osm.NewPacket([]byte(REDIS_PING), len(REDIS_PING)))
	m.AddPacket(osm.NewPacket([]byte(REDIS_INFO), len(REDIS_INFO)))
	m.AddPacket(osm.NewPacket([]byte(REDIS_QUIT), len(REDIS_QUIT)))
	return m
}