dndmusicbot/ws.go

package main

import (
	"context"
	"encoding/json"
	"log"
	"sync"
	"time"

	"github.com/gorilla/websocket"
	"github.com/grafov/bcast"
	"github.com/kataras/go-events"
)

type Websocket struct {
	sync.Mutex

	clients *bcast.Group
}

var ws *Websocket

func init() {
	log.Println("ws.go loading..")
	ws = new(Websocket)

	ws.clients = bcast.NewGroup()

	go ws.clients.Broadcast(0)

	log.Println("ws.go done.")
}

type WSmsg struct {
	Event   string
	Payload json.RawMessage
}

type Event struct {
	Event   string `json:"event"`
	Payload any    `json:"payload,omitempty"`
}

func (ws *Websocket) SendEvent(e Event) {
	ws.Lock()
	ws.clients.Send(e)
	ws.Unlock()
}

func (ws *Websocket) join(c *websocket.Conn) error {
	memb := ws.clients.Join()
	defer memb.Close()

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	go func() {
		ticker := time.NewTicker(30 * time.Second)

		for {
			select {
			case <-ctx.Done():
				return
			case <-ticker.C:
				c.WriteControl(websocket.PingMessage, []byte{}, time.Now().Add(10*time.Second))
			case msg := <-memb.Read:
				c.SetWriteDeadline(time.Now().Add(10 * time.Second))
				c.WriteJSON(msg)
			}
		}
	}()

	c.SetPongHandler(func(d string) error {
		return nil
	})

	msg, err := app.songInfoEvent("song_info")
	if err != nil {
		return err
	}

	vol := Event{"volume", map[string]float64{
		"playlist": VolumeToPercent(pl_volume.Volume),
		"ambiance": VolumeToPercent(amb_volume.Volume),
	}}

	c.SetWriteDeadline(time.Now().Add(10 * time.Second))
	c.WriteJSON(msg)
	c.WriteJSON(vol)

	if app.ambiance.Len() > 0 {
		msg := Event{"ambiance_play", map[string]string{
			"id": app.curamb.Id,
		}}
		c.WriteJSON(msg)
	} else {
		msg := Event{"ambiance_stop", nil}
		c.WriteJSON(msg)
	}

	for {
		var msg WSmsg
		err := c.ReadJSON(&msg)
		if err != nil {
			return err
		}

		app.events.Emit(events.EventName(msg.Event), msg.Payload, memb)
	}
}