package common

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"oc-discovery/conf"
	"strings"
	"sync"
	"time"

	oclib "cloud.o-forge.io/core/oc-lib"
	peer "cloud.o-forge.io/core/oc-lib/models/peer"
	"github.com/libp2p/go-libp2p/core/host"
	"github.com/libp2p/go-libp2p/core/network"
	pp "github.com/libp2p/go-libp2p/core/peer"
	"github.com/libp2p/go-libp2p/core/protocol"
)

type LongLivedStreamRecordedService[T interface{}] struct {
	*LongLivedPubSubService
	StreamRecords    map[protocol.ID]map[pp.ID]*StreamRecord[T]
	StreamMU         sync.RWMutex
	maxNodesConn     int
	isBidirectionnal bool
}

func NewStreamRecordedService[T interface{}](h host.Host, maxNodesConn int, isBidirectionnal bool) *LongLivedStreamRecordedService[T] {
	service := &LongLivedStreamRecordedService[T]{
		LongLivedPubSubService: NewLongLivedPubSubService(h),
		StreamRecords:          map[protocol.ID]map[pp.ID]*StreamRecord[T]{},
		maxNodesConn:           maxNodesConn,
		isBidirectionnal:       isBidirectionnal,
	}
	go service.StartGC(30 * time.Second)
	// Garbage collection is needed on every Map of Long-Lived Stream... it may be a top level redesigned
	go service.Snapshot(1 * time.Hour)
	return service
}

func (ix *LongLivedStreamRecordedService[T]) StartGC(interval time.Duration) {
	go func() {
		t := time.NewTicker(interval)
		defer t.Stop()
		for range t.C {
			ix.gc()
		}
	}()
}

func (ix *LongLivedStreamRecordedService[T]) gc() {
	ix.StreamMU.Lock()
	defer ix.StreamMU.Unlock()
	now := time.Now()
	streams := ix.StreamRecords[ProtocolHeartbeat]
	if streams == nil {
		ix.StreamRecords[ProtocolHeartbeat] = map[pp.ID]*StreamRecord[T]{}
		return
	}
	for pid, rec := range streams {
		if now.After(rec.HeartbeatStream.Expiry) || now.Sub(rec.LastSeen) > 2*rec.HeartbeatStream.Expiry.Sub(now) {
			for _, sstreams := range ix.StreamRecords {
				if sstreams[pid] != nil {
					sstreams[pid].Stream.Close()
					delete(sstreams, pid)
				}
			}
			ix.PubsubMu.Lock()
			if ix.LongLivedPubSubs[TopicPubSubNodeActivity] != nil {
				if b, err := json.Marshal(TopicNodeActivityPub{
					DID:          rec.HeartbeatStream.DID,
					PeerID:       pid.String(),
					NodeActivity: peer.OFFLINE,
				}); err == nil {
					ix.LongLivedPubSubs[TopicPubSubNodeActivity].Publish(context.Background(), b)
				}
			}
			ix.PubsubMu.Unlock()
		}
	}

}

func (ix *LongLivedStreamRecordedService[T]) Snapshot(interval time.Duration) {
	go func() {
		logger := oclib.GetLogger()
		t := time.NewTicker(interval)
		defer t.Stop()
		for range t.C {
			infos := ix.snapshot()
			for _, inf := range infos {
				logger.Info().Msg(" -> " + inf.DID)
			}
		}
	}()
}

// -------- Snapshot / Query --------
func (ix *LongLivedStreamRecordedService[T]) snapshot() []*StreamRecord[T] {
	ix.StreamMU.Lock()
	defer ix.StreamMU.Unlock()

	out := make([]*StreamRecord[T], 0, len(ix.StreamRecords))
	for _, streams := range ix.StreamRecords {
		for _, stream := range streams {
			out = append(out, stream)
		}
	}
	return out
}

func (ix *LongLivedStreamRecordedService[T]) HandleNodeHeartbeat(s network.Stream) {
	streams := ix.StreamRecords[ProtocolHeartbeat]
	pid, hb, err := CheckHeartbeat(ix.Host, s, ix.maxNodesConn)
	if err != nil {
		return
	}
	ix.StreamMU.Lock()
	defer ix.StreamMU.Unlock()
	if streams == nil {
		ix.StreamRecords[ProtocolHeartbeat] = map[pp.ID]*StreamRecord[T]{}
		return
	}
	// if record already seen update last seen
	if rec, ok := streams[*pid]; ok {
		rec.DID = hb.DID
		rec.Stream = s
		rec.HeartbeatStream = hb.Stream
		rec.LastSeen = time.Unix(hb.Timestamp, 0)
	}

	// si je l'handle et que je ne suis pas dans une
}

func CheckHeartbeat(h host.Host, s network.Stream, maxNodes int) (*pp.ID, *Heartbeat, error) {
	if len(h.Network().Peers()) >= maxNodes {
		return nil, nil, fmt.Errorf("too many connections, try another indexer")
	}
	defer s.Close()

	var hb Heartbeat
	if err := json.NewDecoder(s).Decode(&hb); err != nil {
		return nil, nil, err
	}
	pid, err := pp.Decode(hb.PeerID)
	hb.Stream.Stream = s // here is the long-lived bidirectionnal heart bit.
	return &pid, &hb, err
}

type StreamRecord[T interface{}] struct {
	DID             string
	HeartbeatStream *Stream
	Stream          network.Stream
	Record          T
	LastSeen        time.Time // to check expiry
}

type Stream struct {
	DID    string `json:"did"`
	Stream network.Stream
	Expiry time.Time `json:"expiry"`
}

func NewStream[T interface{}](s network.Stream, did string, record T) *Stream {
	return &Stream{
		DID:    did,
		Stream: s,
		Expiry: time.Now().UTC().Add(2 * time.Minute),
	}
}

type ProtocolStream map[protocol.ID]map[pp.ID]*Stream

func (ps ProtocolStream) Get(protocol protocol.ID) map[pp.ID]*Stream {
	if ps[protocol] == nil {
		ps[protocol] = map[pp.ID]*Stream{}
	}

	return ps[protocol]
}

func (ps ProtocolStream) Add(protocol protocol.ID, peerID *pp.ID, s *Stream) error {
	if ps[protocol] == nil {
		ps[protocol] = map[pp.ID]*Stream{}
	}
	if peerID != nil {
		if s != nil {
			ps[protocol][*peerID] = s
		} else {
			return errors.New("unable to add stream : stream missing")
		}
	}
	return nil
}

func (ps ProtocolStream) Delete(protocol protocol.ID, peerID *pp.ID) {
	if streams, ok := ps[protocol]; ok {
		if peerID != nil && streams[*peerID] != nil {
			streams[*peerID].Stream.Close()
			delete(streams, *peerID)
		} else {
			for _, s := range ps {
				for _, v := range s {
					v.Stream.Close()
				}
			}
			delete(ps, protocol)
		}
	}
}

const (
	ProtocolPublish = "/opencloud/record/publish/1.0"
	ProtocolGet     = "/opencloud/record/get/1.0"
)

var StaticIndexers []*pp.AddrInfo = []*pp.AddrInfo{}
var StreamIndexers ProtocolStream = ProtocolStream{}

func ConnectToIndexers(h host.Host, minIndexer int, maxIndexer int, myPID pp.ID) {
	logger := oclib.GetLogger()
	ctx := context.Background()
	addresses := strings.Split(conf.GetConfig().IndexerAddresses, ",")

	if len(addresses) > maxIndexer {
		addresses = addresses[0:maxIndexer]
	}

	for _, indexerAddr := range addresses {
		ad, err := pp.AddrInfoFromString(indexerAddr)
		if err != nil {
			logger.Err(err)
			continue
		}
		if h.Network().Connectedness(ad.ID) != network.Connected {
			if err := h.Connect(ctx, *ad); err != nil {
				logger.Err(err)
				continue
			}
		}
		StaticIndexers = append(StaticIndexers, ad)
		// make a privilege streams with indexer.
		for _, proto := range []protocol.ID{ProtocolPublish, ProtocolGet, ProtocolHeartbeat} {
			AddStreamProtocol(nil, StreamIndexers, h, proto, ad.ID, myPID, nil)
		}
	}
	if len(StaticIndexers) == 0 {
		panic("can't run a node with no indexers")
	}

	if len(StaticIndexers) < minIndexer {
		// TODO : ask for unknown indexer.
	}
	SendHeartbeat(ctx, ProtocolHeartbeat, h, StreamIndexers, StaticIndexers, 20) // your indexer is just like a node for the next indexer.
}

func AddStreamProtocol(ctx *context.Context, protoS ProtocolStream, h host.Host, proto protocol.ID, id pp.ID, mypid pp.ID, onStreamCreated *func(network.Stream)) ProtocolStream {
	if onStreamCreated == nil {
		f := func(s network.Stream) {
			protoS[proto][id] = &Stream{
				Stream: s,
				Expiry: time.Now().Add(2 * time.Minute),
			}
		}
		onStreamCreated = &f
	}
	f := *onStreamCreated
	if mypid > id {
		if ctx == nil {
			c := context.Background()
			ctx = &c
		}
		if protoS[proto] == nil {
			protoS[proto] = map[pp.ID]*Stream{}
		}

		if protoS[proto][id] != nil {
			protoS[proto][id].Expiry = time.Now().Add(2 * time.Minute)
		} else {
			s, err := h.NewStream(*ctx, id, proto)
			if err != nil {
				panic(err.Error())
			}
			f(s)
		}
	} else {
		h.SetStreamHandler(proto, f)
	}

	return protoS
}

type Heartbeat struct {
	Stream    *Stream `json:"stream"`
	DID       string  `json:"did"`
	PeerID    string  `json:"peer_id"`
	Timestamp int64   `json:"timestamp"`
}

type HeartbeatInfo []struct {
	Info []byte `json:"info"`
}

const ProtocolHeartbeat = "/opencloud/heartbeat/1.0"

func SendHeartbeat(ctx context.Context, proto protocol.ID, h host.Host, ps ProtocolStream, peers []*pp.AddrInfo, interval time.Duration) {
	peerID, err := oclib.GenerateNodeID()
	if err == nil {
		panic("can't heartbeat daemon failed to start")
	}
	go func() {
		t := time.NewTicker(interval)
		defer t.Stop()
		for {
			select {
			case <-t.C:
				hb := Heartbeat{
					DID:       peerID,
					PeerID:    h.ID().String(),
					Timestamp: time.Now().Unix(),
				}
				for _, ix := range peers {
					_ = sendHeartbeat(ctx, h, proto, ix, hb, ps, interval*time.Second)
				}
			case <-ctx.Done():
				return
			}
		}
	}()
}

func sendHeartbeat(ctx context.Context, h host.Host, proto protocol.ID, p *pp.AddrInfo, hb Heartbeat, ps ProtocolStream, interval time.Duration) error {
	streams := ps.Get(proto)
	if len(streams) == 0 {
		return errors.New("no stream for protocol heartbeat founded")
	}
	pss, exists := streams[p.ID]

	ctxTTL, _ := context.WithTimeout(ctx, 3*interval)
	// Connect si nécessaire
	if h.Network().Connectedness(p.ID) != network.Connected {
		_ = h.Connect(ctxTTL, *p)
		exists = false // on devra recréer le stream
	}

	// Crée le stream si inexistant ou fermé
	if !exists || pss.Stream == nil {
		s, err := h.NewStream(ctx, p.ID, proto)
		if err != nil {
			return err
		}
		pss = &Stream{
			Stream: s,
			Expiry: time.Now().UTC().Add(2 * time.Minute),
		}
		streams[p.ID] = pss
	}

	// Envoie le heartbeat
	ss := json.NewEncoder(pss.Stream)
	err := ss.Encode(&hb)
	if err != nil {
		pss.Stream.Close()
		pss.Stream = nil // recréera au prochain tick
		return err
	}
	pss.Expiry = time.Now().UTC().Add(2 * time.Minute)
	return nil
}

/*
func SearchPeer(search string) ([]*peer.Peer, error) {
	ps := []*peer.Peer{}
	access := oclib.NewRequestAdmin(oclib.LibDataEnum(oclib.PEER), nil)
	peers := access.Search(nil, search, false)
	if len(peers.Data) == 0 {
		return ps, errors.New("no self available")
	}
	for _, p := range peers.Data {
		ps = append(ps, p.(*peer.Peer))
	}
	return ps, nil
}
*/