package service

import (
	"fmt"
	"log"
	"net"
	"time"

	omd "git.loafle.net/overflow/model/discovery"
	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"
)

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)
	}

	info := osm.NewMatchInfo(hostAddress, portNumber)
	connectors := newConnectors()
	buf := make([]byte, 1024)

	var discoveredMatcher osm.Matcher

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

		if err := conn.SetReadDeadline(time.Now().Add(1 * time.Second)); nil != err {
			continue LOOP
		}
		n, err := conn.Read(buf)
		if nil != err {
			n = 0
		}

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

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

			break LOOP
		}
	}

	if nil != discoveredMatcher {
		log.Printf("discovered matcher: %s(%s) %v", discoveredMatcher.Name(), discoveredMatcher.Key(), discoveredMatcher)
	}

	return nil
}

func hadlePrePacket(info osm.MatchInfo, _connector connector, conn net.Conn, packet *osm.Packet) osm.Matcher {
	defer func() {
		conn.Close()
	}()

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

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

		packetCount := matcher.PacketCount()

		if 0 == packetCount {
			return matcher
		}

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

			if err := conn.SetWriteDeadline(time.Now().Add(1 * time.Second)); nil != err {
				return nil
			}
			_, err := conn.Write(_packet.Buffer)
			if nil != err {
				return nil
			}

			if err := conn.SetReadDeadline(time.Now().Add(1 * time.Second)); nil != err {
				return nil
			}
			n, err := conn.Read(buf)
			if nil != err {
				return nil
			}

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

		if nil != discoveredMatcher {
			return discoveredMatcher
		}
	}

	return nil
}

func hadlePostPacket(info osm.MatchInfo, _connector connector, targetPort *omd.Port, limitedMatchers []osm.Matcher) osm.Matcher {
	matchers := matcher.GetTCPMatchers(false)
	if nil != limitedMatchers {
		matchers = limitedMatchers
	}

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

LOOP:
	for _, matcher := range matchers {
		packetCount := matcher.PacketCount()
		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(j)

			if err := conn.SetWriteDeadline(time.Now().Add(1 * time.Second)); nil != err {
				break INNER_LOOP
			}
			_, err := conn.Write(_packet.Buffer)
			if nil != err {
				break INNER_LOOP
			}

			if err := conn.SetReadDeadline(time.Now().Add(1 * time.Second)); nil != err {
				break INNER_LOOP
			}
			n, err := conn.Read(buf)
			if nil != err {
				if !matcher.HasResponse(j) {
					discoveredMatcher = matcher
				}

				break INNER_LOOP
			}

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

			if err := matcher.Match(info, 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
		}
	}

	return nil
}