package events

import (
	"context"
	"fmt"
	"log"
	"strconv"
	"time"

	"velox-bot/internal/db/services"

	"github.com/bwmarrin/discordgo"
)

// HandleVoiceStateUpdate implements the "meeting lobby" behavior:
// - When a user joins the configured lobby voice channel, create a temporary voice channel
//   with the same UserLimit and move the user into it.
// - When a temporary channel becomes empty, delete it.
func HandleVoiceStateUpdate(s *discordgo.Session, vs *discordgo.VoiceStateUpdate, svc *services.Services) {
	if svc == nil || svc.Meeting == nil {
		return
	}
	if vs == nil || vs.VoiceState == nil {
		return
	}
	if vs.GuildID == "" || vs.UserID == "" {
		return
	}

	ctx := context.Background()
	guildID64, _ := strconv.ParseInt(vs.GuildID, 10, 64)

	// Clean up the channel the user left (if any)
	if vs.BeforeUpdate != nil && vs.BeforeUpdate.ChannelID != "" {
		tryCleanupTempChannel(s, ctx, svc, vs.GuildID, guildID64, vs.BeforeUpdate.ChannelID)
	}

	// If not joining a channel (disconnect), nothing else to do.
	if vs.ChannelID == "" {
		return
	}

	lobbyID, ok, err := svc.Meeting.GetLobbyChannel(ctx, guildID64)
	if err != nil || !ok || lobbyID == 0 {
		return
	}
	if vs.ChannelID != strconv.FormatInt(lobbyID, 10) {
		return
	}

	lobbyCh, err := s.Channel(vs.ChannelID)
	if err != nil || lobbyCh == nil {
		return
	}

	// Create the new channel in the same category as the lobby, with same user limit.
	newName := fmt.Sprintf("%s • %s", lobbyCh.Name, time.Now().Format("15:04"))
	newCh, err := s.GuildChannelCreateComplex(vs.GuildID, discordgo.GuildChannelCreateData{
		Name:      newName,
		Type:      discordgo.ChannelTypeGuildVoice,
		ParentID:  lobbyCh.ParentID,
		UserLimit: lobbyCh.UserLimit,
		Bitrate:   lobbyCh.Bitrate,
	})
	if err != nil || newCh == nil {
		log.Printf("meeting: failed creating temp channel guild=%s user=%s err=%v", vs.GuildID, vs.UserID, err)
		return
	}

	newChID64, _ := strconv.ParseInt(newCh.ID, 10, 64)
	_ = svc.Meeting.AddTempChannel(ctx, guildID64, newChID64, mustParseInt64(vs.UserID))

	// Move the user into the new channel.
	targetID := newCh.ID
	if err := s.GuildMemberMove(vs.GuildID, vs.UserID, &targetID); err != nil {
		log.Printf("meeting: failed moving member guild=%s user=%s channel=%s err=%v", vs.GuildID, vs.UserID, newCh.ID, err)
		// If move fails, delete the channel to avoid junk.
		_, _ = s.ChannelDelete(newCh.ID)
		_ = svc.Meeting.RemoveTempChannel(ctx, guildID64, newChID64)
		return
	}
}

func tryCleanupTempChannel(s *discordgo.Session, ctx context.Context, svc *services.Services, guildID string, guildID64 int64, channelID string) {
	chID64, err := strconv.ParseInt(channelID, 10, 64)
	if err != nil || chID64 == 0 {
		return
	}
	isTemp, err := svc.Meeting.IsTempChannel(ctx, guildID64, chID64)
	if err != nil || !isTemp {
		return
	}

	// Check if anyone is still in the channel.
	// IMPORTANT: don't use REST `s.Guild(...)` here; it doesn't include VoiceStates.
	// Use the session state cache (requires IntentsGuildVoiceStates).
	if s == nil || s.State == nil {
		return
	}
	g, err := s.State.Guild(guildID)
	if err != nil || g == nil {
		return
	}
	for _, st := range g.VoiceStates {
		if st != nil && st.ChannelID == channelID {
			return
		}
	}

	if _, err := s.ChannelDelete(channelID); err != nil {
		// If already deleted, still remove from DB.
		log.Printf("meeting: failed deleting empty temp channel guild=%s channel=%s err=%v", guildID, channelID, err)
	}
	_ = svc.Meeting.RemoveTempChannel(ctx, guildID64, chID64)
}