package server

import (
	"context"
	"sync"
	"time"

	"forge.redroom.link/yves/meowlib"
	"github.com/go-redis/redis"
	"google.golang.org/protobuf/proto"
)

type RedisRouter struct {
	Name              string
	ServerIdentity    *Identity
	Client            *redis.Client
	InvitationTimeout int
	Context           context.Context
}

func NewRedisRouter(server *Identity, redisUrl string, password string, db int, invitationTimeout int) *RedisRouter {
	var r RedisRouter
	r.ServerIdentity = server
	r.Name = "Redis"
	r.Client = redis.NewClient(&redis.Options{
		Addr:     redisUrl,
		Password: password,
		DB:       db,
	})
	r.InvitationTimeout = invitationTimeout
	r.Context = context.Background()
	// set start for uptime
	err := r.Client.Set("statistics:start", time.Now().UTC().Format(time.RFC3339), 0).Err()
	if err != nil {
		panic(err)
	}
	return &r
}

func (r *RedisRouter) Route(msg *meowlib.ToServerMessage) (*meowlib.FromServerMessage, error) {
	var from_server *meowlib.FromServerMessage
	// update messages counter
	err := r.Client.Incr("statistics:messages:total").Err()
	if err != nil {
		panic(err)
	}
	// user message => store
	if len(msg.Messages) > 0 {
		from_server, err = r.storeMessage(msg)
		if err != nil {
			return nil, err
		}
	}
	// check for messages
	if len(msg.PullRequest) > 0 {
		from_server, err = r.checkForMessage(msg)
		if err != nil {
			return nil, err
		}
		if msg.Timeout > 0 {
			// set timeout for the lookup
			from_server, err = r.subscribe(msg, int(msg.Timeout))
			if err != nil {
				return nil, err
			}
		}
	}
	// manage Matriochka
	if msg.MatriochkaMessage != nil {
		from_server, err = r.handleMatriochka(msg)
		if err != nil {
			return nil, err
		}
	}
	// Server list exchange
	if len(msg.KnownServers) > 0 {

	}
	// Through server invitation process
	if msg.Invitation != nil {
		from_server, err = r.handleInvitation(msg)
		if err != nil {
			return nil, err
		}
	}
	/*

		case "s": // servers list
			breakmsgs

		case "m": // matriochka
			break
		case "b": // broadcast
			break
		case "a": // admin
			break
		}
	*/
	return from_server, nil
}

func (r *RedisRouter) storeMessage(msg *meowlib.ToServerMessage) (*meowlib.FromServerMessage, error) {
	var from_server meowlib.FromServerMessage
	// update messages counter
	err := r.Client.Incr("statistics:messages:usermessages").Err()
	if err != nil {
		return nil, err
	}
	for _, usrmsg := range msg.Messages {
		// serialize the message to store it as byte array into redis
		out, err := proto.Marshal(usrmsg)
		if err != nil {
			return nil, err
		}
		r.Client.ZAdd(usrmsg.Destination, redis.Z{Score: float64(time.Now().Unix()), Member: out})
		r.Client.Publish("ch:"+usrmsg.Destination, "!")
	}
	from_server.UuidAck = msg.Uuid
	return &from_server, nil
}

func (r *RedisRouter) checkForMessage(msg *meowlib.ToServerMessage) (*meowlib.FromServerMessage, error) {
	var from_server meowlib.FromServerMessage
	//dataFound := false
	// update messages counter
	err := r.Client.Incr("statistics:messages:messagelookups").Err()
	if err != nil {
		return nil, err
	}
	for _, rq := range msg.PullRequest {
		// get messages from redis
		msgcnt, err := r.Client.ZCount(rq.LookupKey, "-inf", "+inf").Result()
		if err != nil {
			return nil, err
		}
		res, err := r.Client.ZPopMin(rq.LookupKey, msgcnt).Result()
		if err != nil {
			return nil, err
		}
		// iterate over messages
		for _, redismsg := range res {
			//println(redismsg.Score)
			val := redismsg.Member
			test := val.(string)
			var usrmsg meowlib.PackedUserMessage
			err := proto.Unmarshal([]byte(test), &usrmsg)
			if err != nil {
				return nil, err
			}
			// add server timestamp
			usrmsg.ServerTimestamp = append(usrmsg.ServerTimestamp, int64(redismsg.Score))

			from_server.Chat = append(from_server.Chat, &usrmsg)
		}
		// if no messages check for invitationanswer payload
		if msgcnt == 0 {
			// get invitation answer
			var answer meowlib.Invitation
			storedAnswer, _ := r.GetAnswerToInvitation(rq.LookupKey)
			if storedAnswer != nil {
				err := proto.Unmarshal(storedAnswer, &answer)
				if err != nil {
					from_server.Invitation.Payload = []byte("invitation answer corrupted")
				}
				from_server.Invitation = &answer
				// exit loop if invitation found, cannot store several in a message
				return &from_server, nil
			}
			// add invitation answer to the response
		}

	}
	return &from_server, nil
}

func goSubscribeAndListen(client *redis.Client, key string, messages chan<- string, wg *sync.WaitGroup, done <-chan struct{}) {
	defer wg.Done()
	pubsub := client.Subscribe("ch:" + key)
	defer pubsub.Close()

	// Create a new channel for the messages from this subscription
	myMessages := make(chan *redis.Message)
	go func() {
		for {
			msg, err := pubsub.ReceiveMessage()
			if err != nil {
				close(myMessages)
				return
			}
			myMessages <- msg
		}
	}()

	// Wait for a message or for the done signal
	select {
	case msg := <-myMessages:
		messages <- msg.Payload
	case <-done:
		return
	}
}

func (r *RedisRouter) subscribe(msg *meowlib.ToServerMessage, timeout int) (*meowlib.FromServerMessage, error) {
	var from_server meowlib.FromServerMessage
	// update messages counter
	err := r.Client.Incr("statistics:messages:messagessubscription").Err()
	if err != nil {
		return nil, err
	}
	messages := make(chan string)
	var wg sync.WaitGroup
	done := make(chan struct{})
	// extract lookup keys and subscribe
	for _, rq := range msg.PullRequest {
		wg.Add(1)
		// subscribe to the lookup key
		go goSubscribeAndListen(r.Client, rq.LookupKey, messages, &wg, done)
	}
	// wait for timeout or message
	select {
	case <-messages:
		close(done)
		return r.checkForMessage(msg)
	case <-time.After(time.Duration(timeout) * time.Second): // 10 seconds timeout
		close(done)
	}
	wg.Wait()
	return &from_server, nil
}

func (r *RedisRouter) handleInvitation(msg *meowlib.ToServerMessage) (*meowlib.FromServerMessage, error) {
	var from_server meowlib.FromServerMessage
	// update messages counter
	err := r.Client.Incr("statistics:messages:invitation").Err()
	if err != nil {
		return nil, err
	}
	switch msg.Invitation.Step {
	// create invitation => provide shortcode and expiry
	case 1:
		url, expiry := r.StoreInvitation(msg.Invitation.Payload, int(msg.Invitation.Timeout), msg.Invitation.Password, r.InvitationTimeout, int(msg.Invitation.ShortcodeLen))
		from_server.Invitation = &meowlib.Invitation{}
		from_server.Invitation.Shortcode = url
		from_server.Invitation.Expiry = expiry.UTC().Unix()
	// get invitation => retrieve invitation from redis and send
	case 2:
		from_server.Invitation = &meowlib.Invitation{}
		invitation, err := r.GetInvitation(msg.Invitation.Shortcode, msg.Invitation.Password)

		if err != nil {
			if err.Error() == "auth failed" {
				from_server.Invitation.Payload = []byte("authentication failure")
			} else {
				from_server.Invitation.Payload = []byte("invitation expired")
			}
		} else {
			from_server.Invitation.Payload = invitation // protobuf invitation
		}

	// accept invitation => store accepted invitation for initiator
	case 3:
		var usermsg meowlib.PackedUserMessage
		err := proto.Unmarshal(msg.Invitation.Payload, &usermsg)
		if err != nil {
			return nil, err
		}
		data, err := proto.Marshal(msg.Invitation)
		if err != nil {
			return nil, err
		}
		expiry := r.StoreAnswerToInvitation(usermsg.Destination, int(msg.Invitation.Timeout), data, r.InvitationTimeout)
		from_server.Invitation = &meowlib.Invitation{}
		from_server.Invitation.Expiry = expiry.UTC().Unix()
	}
	return &from_server, nil
}

func (r *RedisRouter) handleMatriochka(msg *meowlib.ToServerMessage) (*meowlib.FromServerMessage, error) {
	var from_server meowlib.FromServerMessage
	// update messages counter
	err := r.Client.Incr("statistics:messages:matriochka").Err()
	if err != nil {
		return nil, err
	}
	out, err := proto.Marshal(msg)
	if err != nil {
		return nil, err
	}
	r.Client.ZAdd("mtk", redis.Z{Score: float64(time.Now().Unix()), Member: out})
	if msg.MatriochkaMessage.LookupKey != "" {
		//r.Client.ZAdd("trk:" + msg.MatriochkaMessage.Next.Uuid,{})
	}
	from_server.UuidAck = msg.Uuid
	return &from_server, nil
}