package service

import (
	"fmt"
	"net"
	"time"

	omd "git.loafle.net/overflow/model/discovery"
	omm "git.loafle.net/overflow/model/meta"
	omu "git.loafle.net/overflow/model/util"
	osm "git.loafle.net/overflow/service_matcher-go"
	ouej "git.loafle.net/overflow/util-go/encoding/json"
	"git.loafle.net/overflow_scanner/probe/discovery/session"
	"git.loafle.net/overflow_scanner/probe/internal/matcher"
)

const (
	deadline = time.Millisecond * 500
)

func scanTCP(discoverySession session.DiscoverySession, targetPort *omd.Port) error {
	hostAddress := targetPort.Host.Address
	portNumber, err := ouej.NumberToInt(targetPort.PortNumber)
	if err != nil {
		return fmt.Errorf("Service scan on %s:%s error has occurred %v ", hostAddress, targetPort.PortNumber, err)
	}
	if 9100 == portNumber {
		return nil
	}

	matchCtx := osm.NewMatchCtx(hostAddress, portNumber)
	connectors := newConnectors()
	stopChan := make(chan struct{})
	buf := make([]byte, 1024)

	var discoveredMatcher osm.Matcher
	var discoveredConnector connector

LOOP:
	for _, _connector := range connectors {
		conn, err := _connector.dial(targetPort)
		if nil != err {
			continue LOOP
		}

		if err := conn.SetReadDeadline(time.Now().Add(deadline)); nil != err {
			continue LOOP
		}
		n, err := conn.Read(buf)
		if nil != err {
			n = 0
		}

		if 0 < n {
			discoveredMatcher = hadlePrePacket(matchCtx, _connector, conn, osm.NewPacket(buf, n), stopChan)
		} else {
			conn.Close()
			discoveredMatcher = hadlePostPacket(matchCtx, _connector, targetPort, nil, stopChan)
		}

		if nil != discoveredMatcher {
			if "HTTP" == discoveredMatcher.Key() {
				hsm := matcher.GetHTTPSubMatchers()
				if _discoveredMatcher := hadlePostPacket(matchCtx, _connector, targetPort, hsm, stopChan); _discoveredMatcher != nil {
					discoveredMatcher = _discoveredMatcher
				}
			}
			discoveredConnector = _connector

			break LOOP
		}

		select {
		case <-discoverySession.StopChan():
			return nil
		default:
		}
	}

	if nil != discoveredMatcher {
		s := omd.NewService(
			targetPort,
			discoveredConnector.metaCryptoType(),
			discoveredMatcher.Key(),
		)
		s.Name = discoveredMatcher.Name(matchCtx)
		s.ServiceType = discoveredMatcher.Type()
		s.ServiceVendor = discoveredMatcher.Vendor(matchCtx)
		s.ServiceVersion = discoveredMatcher.Version(matchCtx)
		s.DiscoveredDate = omu.NowPtr()

		discoverySession.AddService(
			omm.ToMetaDiscovererType(omm.MetaDiscovererTypeEnumTCPMatcher),
			s,
			matchCtx.GetAttributes(),
		)
	} else {
		discoverySession.AddServiceUnknown(
			omm.ToMetaDiscovererType(omm.MetaDiscovererTypeEnumTCPMatcher),
			targetPort,
		)
	}

	return nil
}

func hadlePrePacket(matchCtx *osm.MatchCtx, _connector connector, conn net.Conn, packet *osm.Packet, stopChan <-chan struct{}) osm.Matcher {
	defer func() {
		conn.Close()
	}()

	matchers := matcher.GetTCPMatchers(true)
	buf := make([]byte, 1024)
	var discoveredMatcher osm.Matcher

LOOP:
	for _, _matcher := range matchers {
		matchCtx.InitAttribute()
		if err := _matcher.Match(matchCtx, 0, packet); nil != err {
			continue LOOP
		}

		packetCount := _matcher.PacketCount(matchCtx)

		if 0 == packetCount {
			return _matcher
		}

	INNER_LOOP:
		for j := 0; j < packetCount; j++ {
			_packet := _matcher.Packet(matchCtx, j)

			if err := conn.SetWriteDeadline(time.Now().Add(deadline)); nil != err {
				return nil
			}
			_, err := conn.Write(_packet.Buffer)
			if nil != err {
				return nil
			}

			if err := conn.SetReadDeadline(time.Now().Add(deadline)); nil != err {
				return nil
			}
			n, err := conn.Read(buf)
			if nil != err {
				return nil
			}

			if err := _matcher.Match(matchCtx, j+1, osm.NewPacket(buf, n)); nil == err {
				discoveredMatcher = _matcher
			} else {
				discoveredMatcher = nil
				break INNER_LOOP
			}
		}

		if nil != discoveredMatcher {
			return discoveredMatcher
		}

		select {
		case <-stopChan:
			return nil
		default:
		}
	}

	return nil
}

func hadlePostPacket(matchCtx *osm.MatchCtx, _connector connector, targetPort *omd.Port, limitedMatchers []osm.Matcher, stopChan <-chan struct{}) osm.Matcher {
	matchers := matcher.GetTCPMatchers(false)
	if nil != limitedMatchers {
		matchers = limitedMatchers
	}

	buf := make([]byte, 1024)
	var discoveredMatcher osm.Matcher

LOOP:
	for _, _matcher := range matchers {
		matchCtx.InitAttribute()
		packetCount := _matcher.PacketCount(matchCtx)
		if 0 == packetCount {
			continue LOOP
		}

		conn, err := _connector.dial(targetPort)
		if nil != err {
			return nil
		}

	INNER_LOOP:
		for j := 0; j < packetCount; j++ {
			_packet := _matcher.Packet(matchCtx, j)

			if err := conn.SetWriteDeadline(time.Now().Add(deadline)); nil != err {
				break INNER_LOOP
			}
			_, err := conn.Write(_packet.Buffer)
			if nil != err {
				break INNER_LOOP
			}

			if err := conn.SetReadDeadline(time.Now().Add(deadline)); nil != err {
				break INNER_LOOP
			}
			n, err := conn.Read(buf)
			if nil != err {
				// if !_matcher.HasResponse(matchCtx, j) {
				// 	discoveredMatcher = _matcher
				// }

				break INNER_LOOP
			}

			// log.Printf("res: %s", string(buf[:n]))

			if err := _matcher.Match(matchCtx, j+1, osm.NewPacket(buf, n)); err == nil {
				if packetCount-1 == j {
					discoveredMatcher = _matcher

					break INNER_LOOP
				}
			} else {
				break INNER_LOOP
			}
		}

		conn.Close()
		if nil != discoveredMatcher {
			return discoveredMatcher
		}

		select {
		case <-stopChan:
			return nil
		default:
		}
	}

	return nil
}