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)
}