package redis

import (
	"context"
	"log"

	channelUtil "git.loafle.net/commons_go/util/channel"
	ofSubscriber "git.loafle.net/overflow/overflow_subscriber"
	"github.com/garyburd/redigo/redis"
)

type subscribeChannelAction struct {
	channelUtil.Action
	channel string
	cb      ofSubscriber.OnSubscribeFunc
}

type Subscriber interface {
	ofSubscriber.Subscriber
}

type subscriber struct {
	ctx                   context.Context
	conn                  redis.PubSubConn
	subListeners          map[string]ofSubscriber.OnSubscribeFunc
	isListenSubscriptions bool
	subCh                 chan subscribeChannelAction
}

func New(ctx context.Context, conn redis.Conn) Subscriber {
	n := &subscriber{
		ctx:                   ctx,
		subListeners:          make(map[string]ofSubscriber.OnSubscribeFunc),
		isListenSubscriptions: false,
		subCh: make(chan subscribeChannelAction),
	}
	n.conn = redis.PubSubConn{Conn: conn}

	go n.listen()

	return n
}

func (n *subscriber) listen() {
	for {
		select {
		case sa := <-n.subCh:
			switch sa.Type {
			case channelUtil.ActionTypeCreate:
				_, ok := n.subListeners[sa.channel]
				if ok {
					log.Fatalf("Subscriber: Subscription of channel[%s] is already exist", sa.channel)
				} else {
					n.subListeners[sa.channel] = sa.cb
					n.conn.Subscribe(sa.channel)
					n.listenSubscriptions()
				}
				break
			case channelUtil.ActionTypeDelete:
				_, ok := n.subListeners[sa.channel]
				if ok {
					n.conn.Unsubscribe(sa.channel)
					delete(n.subListeners, sa.channel)
				} else {
					log.Fatalf("Subscriber: Subscription of channel[%s] is not exist", sa.channel)
				}
				break
			}
		case <-n.ctx.Done():
			log.Println("redis subscriber: Context Done")
			n.conn.Close()
			return
		}
	}
}

func (n *subscriber) listenSubscriptions() {
	if n.isListenSubscriptions {
		return
	}

	go func() {
		for {
			switch v := n.conn.Receive().(type) {
			case redis.Message:
				if cb, ok := n.subListeners[v.Channel]; ok {
					cb(v.Channel, string(v.Data))
				}
			case redis.Subscription:
				log.Printf("subscription message: %s: %s %d\n", v.Channel, v.Kind, v.Count)
			case error:
				log.Println("error pub/sub, delivery has stopped")
				return
			default:
			}
		}
	}()

	n.isListenSubscriptions = true
}

func (n *subscriber) Subscribe(channel string, cb ofSubscriber.OnSubscribeFunc) {
	ca := subscribeChannelAction{
		channel: channel,
		cb:      cb,
	}
	ca.Type = channelUtil.ActionTypeCreate

	n.subCh <- ca
}

func (n *subscriber) Unsubscribe(channel string) {
	ca := subscribeChannelAction{
		channel: channel,
	}
	ca.Type = channelUtil.ActionTypeDelete

	n.subCh <- ca
}