Add Discord client, command router and voice channel handling

internal/discord/client.go

@@ -0,0 +1,25 @@
+package discord
+
+import (
+	"log/slog"
+
+	"github.com/disgoorg/disgo"
+	"github.com/disgoorg/disgo/bot"
+	"github.com/disgoorg/disgo/cache"
+	"github.com/disgoorg/disgo/gateway"
+)
+
+func NewClient(token string, logger *slog.Logger) (*bot.Client, error) {
+	return disgo.New(token,
+		bot.WithLogger(logger),
+		bot.WithGatewayConfigOpts(
+			gateway.WithIntents(
+				gateway.IntentGuilds,
+				gateway.IntentGuildVoiceStates,
+			),
+		),
+		bot.WithCacheConfigOpts(
+			cache.WithCaches(cache.FlagVoiceStates),
+		),
+	)
+}

internal/discord/commands.go

@@ -0,0 +1,15 @@
+package discord
+
+import (
+	"fmt"
+
+	"github.com/disgoorg/disgo/bot"
+	"github.com/disgoorg/disgo/discord"
+)
+
+func RegisterCommands(client *bot.Client, definitions []discord.ApplicationCommandCreate) error {
+	if _, err := client.Rest.SetGlobalCommands(client.ApplicationID, definitions); err != nil {
+		return fmt.Errorf("registering commands: %w", err)
+	}
+	return nil
+}

internal/discord/router.go

@@ -0,0 +1,36 @@
+package discord
+
+import (
+	"context"
+	"log/slog"
+
+	"github.com/disgoorg/disgo/events"
+
+	"discord-music-bot/internal/commands"
+)
+
+type Router struct {
+	registry *commands.Registry
+	logger   *slog.Logger
+}
+
+func NewRouter(registry *commands.Registry, logger *slog.Logger) *Router {
+	return &Router{
+		registry: registry,
+		logger:   logger,
+	}
+}
+
+func (r *Router) OnApplicationCommand(event *events.ApplicationCommandInteractionCreate) {
+	name := event.SlashCommandInteractionData().CommandName()
+
+	cmd, ok := r.registry.Get(name)
+	if !ok {
+		r.logger.Warn("received unknown command", slog.String("command", name))
+		return
+	}
+
+	if err := cmd.Execute(context.Background(), event); err != nil {
+		r.logger.Error("command execution failed", slog.String("command", name), slog.Any("err", err))
+	}
+}

internal/discord/voice.go

@@ -0,0 +1,79 @@
+package discord
+
+import (
+	"context"
+	"log/slog"
+
+	"github.com/disgoorg/disgo/bot"
+	"github.com/disgoorg/disgo/events"
+	"github.com/disgoorg/disgolink/v4/disgolink"
+
+	"discord-music-bot/internal/music"
+)
+
+type VoiceForwarder struct {
+	client   *bot.Client
+	lavalink *disgolink.Client
+	music    *music.Manager
+	logger   *slog.Logger
+}
+
+func NewVoiceForwarder(client *bot.Client, lavalinkClient *disgolink.Client, musicManager *music.Manager, logger *slog.Logger) *VoiceForwarder {
+	return &VoiceForwarder{
+		client:   client,
+		lavalink: lavalinkClient,
+		music:    musicManager,
+		logger:   logger,
+	}
+}
+
+func (f *VoiceForwarder) OnVoiceStateUpdate(event *events.GuildVoiceStateUpdate) {
+	if event.VoiceState.UserID == f.client.ApplicationID {
+		f.lavalink.OnVoiceStateUpdate(context.Background(), event.VoiceState.GuildID, event.VoiceState.ChannelID, event.VoiceState.SessionID)
+		return
+	}
+
+	f.leaveIfNowAlone(event)
+}
+
+func (f *VoiceForwarder) leaveIfNowAlone(event *events.GuildVoiceStateUpdate) {
+	oldChannelID := event.OldVoiceState.ChannelID
+	if oldChannelID == nil {
+		return
+	}
+	if newChannelID := event.VoiceState.ChannelID; newChannelID != nil && *newChannelID == *oldChannelID {
+		return
+	}
+
+	guildID := event.VoiceState.GuildID
+
+	botState, ok := f.client.Caches.VoiceState(guildID, f.client.ApplicationID)
+	if !ok || botState.ChannelID == nil || *botState.ChannelID != *oldChannelID {
+		return
+	}
+
+	for state := range f.client.Caches.VoiceStates(guildID) {
+		if state.UserID != f.client.ApplicationID && state.ChannelID != nil && *state.ChannelID == *oldChannelID {
+			return
+		}
+	}
+
+	ctx := context.Background()
+	if err := f.music.Guild(guildID).Stop(ctx); err != nil {
+		f.logger.ErrorContext(ctx, "failed to stop playback after being left alone",
+			slog.String("guild_id", guildID.String()), slog.Any("err", err))
+	}
+	if err := f.client.UpdateVoiceState(ctx, guildID, nil, false, false); err != nil {
+		f.logger.ErrorContext(ctx, "failed to leave voice channel after being left alone",
+			slog.String("guild_id", guildID.String()), slog.Any("err", err))
+	}
+}
+
+func (f *VoiceForwarder) OnVoiceServerUpdate(event *events.VoiceServerUpdate) {
+	if event.Endpoint == nil {
+		f.logger.Warn("received voice server update without an endpoint", slog.String("guild_id", event.GuildID.String()))
+		return
+	}
+
+	f.lavalink.OnVoiceServerUpdate(context.Background(), event.GuildID, event.Token, *event.Endpoint)
+}