package sentinel

import (
	"fmt"
	"reflect"
	"time"

	"github.com/ledgerwatch/erigon/cmd/lightclient/clparams"
	"github.com/ledgerwatch/erigon/cmd/lightclient/sentinel/handlers"
	"github.com/ledgerwatch/erigon/cmd/lightclient/sentinel/proto"
	"github.com/ledgerwatch/erigon/cmd/lightclient/sentinel/proto/p2p"
	"github.com/ledgerwatch/erigon/cmd/lightclient/sentinel/proto/ssz_snappy"
	"github.com/ledgerwatch/log/v3"
	"github.com/libp2p/go-libp2p/core/peer"
	"github.com/libp2p/go-libp2p/core/protocol"
)

func (s *Sentinel) SendPingReqV1() (proto.Packet, error) {
	requestPacket := &p2p.Ping{
		Id: uint64(1),
	}
	responsePacket := &p2p.Ping{}
	return sendRequest(s, requestPacket, responsePacket, handlers.PingProtocolV1)
}

func (s *Sentinel) SendMetadataReqV1() (proto.Packet, error) {
	requestPacket := &p2p.MetadataV1{}
	responsePacket := &p2p.MetadataV1{}

	return sendRequest(s, requestPacket, responsePacket, handlers.MedataProtocolV1)
}

// TODO: add the rest of the request topics

func sendRequest(s *Sentinel, requestPacket proto.Packet, responsePacket proto.Packet, topic string) (proto.Packet, error) {
	_, peerInfo, err := connectToRandomPeer(s)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to a random peer err=%s", err)
	}

	peerId := peerInfo.ID

	reqRetryTimer := time.NewTimer(clparams.ReqTimeout)
	defer reqRetryTimer.Stop()

	retryTicker := time.NewTicker(10 * time.Millisecond)
	defer retryTicker.Stop()

	sc, err := writeRequest(s, requestPacket, peerId, topic)
	for err != nil {
		select {
		case <-s.ctx.Done():
			log.Warn("[Req] sentinel has been shut down")
			return nil, nil
		case <-reqRetryTimer.C:
			log.Warn("[Req] timeout", "topic", topic, "peer", peerId)
			return nil, err
		case <-retryTicker.C:
			sc, err = writeRequest(s, requestPacket, peerId, topic)
		}
	}

	defer sc.Close()
	log.Info("[Req] sent request", "topic", topic, "peer", peerId)

	respRetryTimer := time.NewTimer(clparams.RespTimeout)
	defer respRetryTimer.Stop()

	responsePacket, err = decodeResponse(sc, responsePacket, peerId)
	for err != nil {
		select {
		case <-s.ctx.Done():
			log.Warn("[Resp] sentinel has been shutdown")
			return nil, nil
		case <-respRetryTimer.C:
			log.Warn("[Resp] timeout", "topic", topic, "peer", peerId)
			return nil, err
		case <-retryTicker.C:
			responsePacket, err = decodeResponse(sc, responsePacket, peerId)
		}
	}

	return responsePacket, nil
}

func writeRequest(s *Sentinel, requestPacket proto.Packet, peerId peer.ID, topic string) (proto.StreamCodec, error) {
	stream, err := s.host.NewStream(s.ctx, peerId, protocol.ID(topic))
	if err != nil {
		return nil, fmt.Errorf("failed to begin stream, err=%s", err)
	}

	sc := ssz_snappy.NewStreamCodec(stream)

	if _, err := sc.WritePacket(requestPacket); err != nil {
		return nil, fmt.Errorf("failed to write packet type=%s, err=%s", reflect.TypeOf(requestPacket), err)
	}

	if err := sc.CloseWriter(); err != nil {
		return nil, fmt.Errorf("failed to close write stream, err=%s", err)
	}

	return sc, nil
}

func decodeResponse(sc proto.StreamCodec, responsePacket proto.Packet, peerId peer.ID) (proto.Packet, error) {
	code, err := sc.ReadByte()
	if err != nil {
		return nil, fmt.Errorf("failed to read code byte peer=%s, err=%s", peerId, err)
	}

	if code != 0 {
		errPacket := &proto.ErrorMessage{}
		protoCtx, err := sc.Decode(errPacket)
		if err != nil {
			return nil, fmt.Errorf("failed to decode error packet got=%s, err=%s", string(protoCtx.Raw), err)
		}
		log.Info("[Resp] got error packet", "error-message", string(errPacket.Message), "peer", peerId)
		return errPacket, nil
	}

	protoCtx, err := sc.Decode(responsePacket)
	if err != nil {
		return nil, fmt.Errorf("failed to decode packet got=%s, err=%s", string(protoCtx.Raw), err)
	}
	log.Info("[Resp] got response from", "response", responsePacket, "peer", peerId)

	return responsePacket, nil
}