go-music-player/music-player/pkg/server/clients.go

package server

import (
	"encoding/json"
	"net/http"

	"github.com/felamaslen/go-music-player/pkg/logger"
	"github.com/go-redis/redis/v7"
)

func getClientNameFromRequest(r *http.Request) string {
  return r.URL.Query().Get(CLIENT_QUERY_NAME)
}

func endSubscription(sub *redis.PubSub) error {
  if err := sub.Unsubscribe(); err != nil {
    return err
  }
  if err := sub.Close(); err != nil {
    return err
  }
  return nil
}

func (c *Client) onConnect(l *logger.Logger, rdb *redis.Client) error {
  if _, err := rdb.SAdd(KEY_CLIENT_NAMES, c.name).Result(); err != nil {
    l.Fatal("Error adding client to set: %v\n", err)
  }

  rdb.Publish(TOPIC_CLIENT_CONNECTED, c.name)

  l.Printf("subscribing to TOPIC_STATE\n")
  stateSub := rdb.Subscribe(TOPIC_STATE)

  go func() {
    for {
      select {
      case <- c.disconnected:
	endSubscription(stateSub)
	return

      case msg, ok := <- stateSub.Channel():
	l.Debug("Received message from state pubsub: %v\n", msg)
	if !ok {
	  return
	}

	var state MusicPlayer
	if err := json.Unmarshal([]byte(msg.Payload), &state); err != nil {
	  l.Error("Error parsing state from pubsub: %v\n", err)
	  return
	}
	c.conn.WriteJSON(action{
	  ActionType: ACTION_TYPE_STATE_SET,
	  Payload: state,
	})
      }
    }
  }()

  return nil
}

func (c *Client) onDisconnect(l *logger.Logger, rdb *redis.Client) error {
  close(c.disconnected)

  _, err := rdb.SRem(KEY_CLIENT_NAMES, c.name).Result()
  if err != nil {
    l.Fatal("Error removing client from set: %v\n", err)
  }

  rdb.Publish(TOPIC_CLIENT_DISCONNECTED, c.name)

  return nil
}