package cassandra

import (
	"bytes"
	"encoding/binary"

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

type cassandra struct {
	Version uint8
	Flags   uint8
	Stream  uint16
	Opcode  uint8
	Length  uint32
}

type CassandraMatcher struct {
	osm.Matchers
}

func (m *CassandraMatcher) Key() string {
	return "CASSANDRA"
}

func (m *CassandraMatcher) Name() string {
	return "Cassandra"
}

func (m *CassandraMatcher) Meta() osm.Metadata {
	return nil
}

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

func (m *CassandraMatcher) HasResponse(index int) bool {
	return true
}

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

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

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

	reader := new(bytes.Buffer)
	reader.Write(packet.Bytes())

	c := cassandra{}
	if err := binary.Read(reader, binary.BigEndian, &c); err != nil {
		return err
	}
	if c.Version != 0x84 {
		return osm.NotMatchedError()
	}
	if c.Flags != 0x00 {
		return osm.NotMatchedError()
	}
	if c.Stream != 0x00 {
		return osm.NotMatchedError()
	}
	if c.Opcode != 0x06 {
		return osm.NotMatchedError()
	}

	return nil

}

func NewMatcher() osm.Matcher {

	m := &CassandraMatcher{}
	c := cassandra{
		Version: 4,
		Flags:   0,
		Stream:  0,
		Opcode:  5,
		Length:  0,
	}
	writer := new(bytes.Buffer)
	binary.Write(writer, binary.LittleEndian, c)

	m.AddPacket(osm.NewPacket(writer.Bytes(), writer.Len()))

	return m
}