Discord voice bot

main.go

package main

import (
	"fmt"
	"log"
	"os"
	"os/signal"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/bwmarrin/discordgo"
)

const (
	MaxQueueSize int = 6
)

var (
	queues = make(map[string][]*PlayRequest)
	dg     *discordgo.Session
	err    error
	m      sync.Mutex
)

type PlayRequest struct {
	ChannelID string
	GuildID   string
	Sound     uint
}

func main() {
	token := os.Getenv("BOT_TOKEN")

	dg, err = discordgo.New("Bot " + token)
	if err != nil {
		panic(err)
	}

	dg.LogLevel = discordgo.LogDebug

	dg.AddHandler(messageCreate)

	err = dg.Open()
	if err != nil {
		panic(err)
	}

	fmt.Println("Airhorn is now running.  Press CTRL-C to exit.")
	sc := make(chan os.Signal, 1)
	signal.Notify(sc, syscall.SIGINT, syscall.SIGTERM, os.Interrupt, os.Kill)
	<-sc

	dg.Close()
}

func messageCreate(s *discordgo.Session, m *discordgo.MessageCreate) {

	if m.Author.ID == s.State.User.ID {
		return
	}

	if strings.HasPrefix(m.Content, "!join") {

		c, err := s.State.Channel(m.ChannelID)
		if err != nil {
			// Could not find channel.
			return
		}

		g, err := s.State.Guild(c.GuildID)
		if err != nil {
			// Could not find guild.
			return
		}

		for _, vs := range g.VoiceStates {
			if vs.UserID == m.Author.ID {
				requestPlaySound(g.ID, vs.ChannelID, 1)
				return
			}
		}
	}
}

func requestPlaySound(guildID, channelID string, soundID uint) {
	item := &PlayRequest{
		ChannelID: channelID,
		GuildID:   guildID,
		Sound:     soundID,
	}

	// If there is a queue setup there is alaso a player running, so just add it to the queue then
	m.Lock()
	if queue, ok := queues[guildID]; ok {
		if len(queue) < MaxQueueSize {
			queues[guildID] = append(queue, item)
		}
	} else {
		queues[guildID] = []*PlayRequest{item}
		go runPlayer(guildID)
	}
	m.Unlock()
}

func runPlayer(guildID string) {
	var lastChannel string
	var vc *discordgo.VoiceConnection
	for {
		m.Lock()
		var item *PlayRequest

		// Get the next item in the queue or quit life
		if queue, ok := queues[guildID]; ok && len(queue) > 0 {
			item = queue[0]
			queues[guildID] = queue[1:]
		} else {
			break
		}

		m.Unlock()
		// Should probably to changechannel but eh..
		if lastChannel != item.ChannelID && vc != nil {
			vc.Disconnect()
			vc = nil
		}

		var err error
		vc, err = playSound(vc, dg, item)
		if err != nil {
			log.Println(err)
		}
		lastChannel = item.ChannelID
	}
	if vc != nil {
		vc.Disconnect()
	}

	// When we break out, playqueuemutex is locked
	delete(queues, guildID)
	m.Unlock()
}

func playSound(vc *discordgo.VoiceConnection, session *discordgo.Session, item *PlayRequest) (*discordgo.VoiceConnection, error) {
	// Either use the passed voice connection, or create a new one
	if vc == nil || !vc.Ready {
		vc, err = session.ChannelVoiceJoin(item.GuildID, item.ChannelID, false, true)
		if err != nil {
			return nil, err
		}
		vc.Speaking(true)
	}

	// Sending voice mock
	time.Sleep(time.Second)

	return vc, nil
}