package relay

import (
	"encoding/json"
	"fmt"
	"net/http"
	"sync"
	"time"

	// "github.com/gorilla/mux"
	"github.com/hashicorp/memberlist"
	"github.com/pion/webrtc/v4"
)

// PeerInfo represents information about an SFU peer
type PeerInfo struct {
	NodeID    string          `json:"nodeId"`
	Zone      string          `json:"zone"`
	PublicIP  string          `json:"publicIp"`
	PrivateIP string          `json:"privateIp,omitempty"`
	Streams   map[string]bool `json:"streams"` // streamID -> isOrigin
}

// StreamInfo tracks a stream's origin and local subscribers
type StreamInfo struct {
	ID            string
	OriginPeerID  string
	IsLocal       bool
	Publisher     *webrtc.PeerConnection
	Subscribers   map[string]*webrtc.PeerConnection
	InterPeerConn map[string]*webrtc.PeerConnection // connections to other SFU peers
	mu            sync.RWMutex
}

// DistributedSFU manages streams and peer communication
type DistributedSFU struct {
	nodeID     string
	zone       string
	publicIP   string
	privateIP  string
	streams    map[string]*StreamInfo
	peers      map[string]*PeerInfo
	memberlist *memberlist.Memberlist
	mu         sync.RWMutex
	config     webrtc.Configuration
}

// NewDistributedSFU creates a new distributed SFU instance
func NewDistributedSFU(nodeID, zone, publicIP, privateIP string, seeds []string) (*DistributedSFU, error) {
	sfu := &DistributedSFU{
		nodeID:    nodeID,
		zone:      zone,
		publicIP:  publicIP,
		privateIP: privateIP,
		streams:   make(map[string]*StreamInfo),
		peers:     make(map[string]*PeerInfo),
		config: webrtc.Configuration{
			ICEServers: []webrtc.ICEServer{
				{URLs: []string{"stun:stun.l.google.com:19302"}},
			},
		},
	}

	// Configure memberlist for peer discovery
	config := memberlist.DefaultLANConfig()
	config.Name = nodeID
	config.BindAddr = privateIP
	config.AdvertiseAddr = publicIP

	// Add delegate for handling peer updates
	config.Delegate = &peerDelegate{sfu: sfu}

	// Initialize memberlist
	list, err := memberlist.Create(config)
	if err != nil {
		return nil, err
	}

	// Join the cluster if seeds are provided
	if len(seeds) > 0 {
		_, err = list.Join(seeds)
		if err != nil {
			return nil, err
		}
	}

	sfu.memberlist = list
	return sfu, nil
}

// peerDelegate implements memberlist.Delegate
type peerDelegate struct {
	sfu *DistributedSFU
}

// NodeMeta returns metadata about the current node
func (d *peerDelegate) NodeMeta(limit int) []byte {
	meta := PeerInfo{
		NodeID:    d.sfu.nodeID,
		Zone:      d.sfu.zone,
		PublicIP:  d.sfu.publicIP,
		PrivateIP: d.sfu.privateIP,
		Streams:   make(map[string]bool),
	}

	d.sfu.mu.RLock()
	for id, info := range d.sfu.streams {
		meta.Streams[id] = info.IsLocal
	}
	d.sfu.mu.RUnlock()

	data, _ := json.Marshal(meta)
	return data
}

// NotifyMsg handles peer updates
func (d *peerDelegate) NotifyMsg(msg []byte) {
	var peer PeerInfo
	if err := json.Unmarshal(msg, &peer); err != nil {
		return
	}

	d.sfu.mu.Lock()
	d.sfu.peers[peer.NodeID] = &peer

	// Check for new streams we don't have locally
	for streamID, isOrigin := range peer.Streams {
		if isOrigin {
			if _, exists := d.sfu.streams[streamID]; !exists {
				// Initialize inter-peer connection for this stream
				d.sfu.initInterPeerStream(streamID, peer.NodeID)
			}
		}
	}
	d.sfu.mu.Unlock()
}

// initInterPeerStream sets up connection to another SFU for a stream
func (sfu *DistributedSFU) initInterPeerStream(streamID, peerID string) {
	stream := &StreamInfo{
		ID:            streamID,
		OriginPeerID:  peerID,
		IsLocal:       false,
		Subscribers:   make(map[string]*webrtc.PeerConnection),
		InterPeerConn: make(map[string]*webrtc.PeerConnection),
	}

	// Create peer connection to the origin SFU
	pc, err := webrtc.NewPeerConnection(sfu.config)
	if err != nil {
		return
	}

	stream.InterPeerConn[peerID] = pc
	sfu.streams[streamID] = stream

	// Setup inter-peer WebRTC connection
	go sfu.establishInterPeerConnection(streamID, peerID, pc)
}

// establishInterPeerConnection handles WebRTC signaling between SFU peers
func (sfu *DistributedSFU) establishInterPeerConnection(streamID, peerID string, pc *webrtc.PeerConnection) {
	// This would typically involve making an HTTP request to the peer's control endpoint
	// to exchange SDP offers/answers and ICE candidates
	peerInfo := sfu.peers[peerID]

	// Example endpoint URL construction
	peerURL := fmt.Sprintf("http://%s:8080/peer/%s/stream/%s",
		peerInfo.PublicIP, sfu.nodeID, streamID)

	// Handle incoming tracks from peer
	pc.OnTrack(func(remoteTrack *webrtc.TrackRemote, receiver *webrtc.RTPReceiver) {
		sfu.mu.RLock()
		stream := sfu.streams[streamID]
		sfu.mu.RUnlock()

		// Forward the track to local subscribers
		stream.mu.RLock()
		for _, subscriber := range stream.Subscribers {
			localTrack, err := webrtc.NewTrackLocalStaticRTP(
				remoteTrack.Codec().RTPCodecCapability,
				remoteTrack.ID(),
				remoteTrack.StreamID(),
			)
			if err != nil {
				continue
			}

			if _, err := subscriber.AddTrack(localTrack); err != nil {
				continue
			}

			go func() {
				for {
					packet, _, err := remoteTrack.ReadRTP()
					if err != nil {
						return
					}
					if err := localTrack.WriteRTP(packet); err != nil {
						return
					}
				}
			}()
		}
		stream.mu.RUnlock()
	})

	// Implement SDP exchange with peer
	// ... (signaling implementation)
}

// HandleWHIPPublish now includes peer notification
func (sfu *DistributedSFU) HandleWHIPPublish(w http.ResponseWriter, r *http.Request) {
	streamID := mux.Vars(r)["streamID"]

	// Create stream info
	stream := &StreamInfo{
		ID:            streamID,
		IsLocal:       true,
		Subscribers:   make(map[string]*webrtc.PeerConnection),
		InterPeerConn: make(map[string]*webrtc.PeerConnection),
	}

	// ... (rest of WHIP publish logic)

	// Notify other peers about the new stream
	sfu.broadcastStreamUpdate(streamID, true)
}

// HandleWHEPSubscribe now checks both local and remote streams
func (sfu *DistributedSFU) HandleWHEPSubscribe(w http.ResponseWriter, r *http.Request) {
	streamID := mux.Vars(r)["streamID"]

	sfu.mu.RLock()
	stream, exists := sfu.streams[streamID]
	sfu.mu.RUnlock()

	if !exists {
		// Check if any peer has this stream
		if peer := sfu.findStreamPeer(streamID); peer != nil {
			// Initialize inter-peer connection if needed
			sfu.initInterPeerStream(streamID, peer.NodeID)
		} else {
			http.Error(w, "Stream not found", http.StatusNotFound)
			return
		}
	}

	// ... (rest of WHEP subscribe logic)
}

// findStreamPeer finds the peer that has the origin of a stream
func (sfu *DistributedSFU) findStreamPeer(streamID string) *PeerInfo {
	sfu.mu.RLock()
	defer sfu.mu.RUnlock()

	for _, peer := range sfu.peers {
		if isOrigin, exists := peer.Streams[streamID]; exists && isOrigin {
			return peer
		}
	}
	return nil
}

func main() {
	// Initialize the distributed SFU
	sfu, err := NewDistributedSFU(
		"sfu-1",
		"us-east",
		"203.0.113.1",
		"10.0.0.1",
		[]string{"203.0.113.2:7946", "203.0.113.3:7946"},
	)
	if err != nil {
		panic(err)
	}

	router := mux.NewRouter()

	// Regular WHIP/WHEP endpoints
	router.HandleFunc("/whip/{streamID}", sfu.HandleWHIPPublish).Methods("POST")
	router.HandleFunc("/whep/{streamID}/{subscriberID}", sfu.HandleWHEPSubscribe).Methods("POST")

	// Inter-peer communication endpoint
	router.HandleFunc("/peer/{peerID}/stream/{streamID}", sfu.HandlePeerSignaling).Methods("POST")

	server := &http.Server{
		Addr:         ":8080",
		Handler:      router,
		ReadTimeout:  10 * time.Second,
		WriteTimeout: 10 * time.Second,
	}

	server.ListenAndServe()
}