package voiceroomredpacket

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"time"

	"chatapp3-golang/internal/config"
	"chatapp3-golang/internal/model"

	"gorm.io/gorm"
)

// Heartbeat 记录用户当前语音房在线态，供 Go 侧红包广播和房间校验使用。
func (s *Service) Heartbeat(ctx context.Context, user AuthUser, req PresenceRequest) (*PresenceResponse, error) {
	roomID := req.RoomID.Int64()
	if roomID <= 0 {
		return nil, NewAppError(http.StatusBadRequest, "missing_room_id", "roomId is required")
	}
	sysOrigin := normalizeSysOrigin(user.SysOrigin)
	regionCode, err := s.resolveUserRegion(ctx, sysOrigin, user.UserID)
	if err != nil {
		return nil, err
	}
	ttl := presenceTTL(s.cfg)
	roomKey := onlineRoomKey(sysOrigin, roomID)
	if err := s.redis.SAdd(ctx, roomKey, user.UserID).Err(); err != nil {
		return nil, NewAppError(http.StatusServiceUnavailable, "voice_room_presence_failed", err.Error())
	}
	if err := s.redis.Expire(ctx, roomKey, ttl).Err(); err != nil {
		return nil, NewAppError(http.StatusServiceUnavailable, "voice_room_presence_failed", err.Error())
	}
	if err := s.redis.Set(ctx, userRoomKey(sysOrigin, user.UserID), strconv.FormatInt(roomID, 10), ttl).Err(); err != nil {
		return nil, NewAppError(http.StatusServiceUnavailable, "voice_room_presence_failed", err.Error())
	}
	if err := s.redis.Set(ctx, userRegionKey(sysOrigin, user.UserID), regionCode, ttl).Err(); err != nil {
		return nil, NewAppError(http.StatusServiceUnavailable, "voice_room_presence_failed", err.Error())
	}
	if err := s.redis.Set(ctx, userSeenKey(sysOrigin, user.UserID), strconv.FormatInt(time.Now().UnixMilli(), 10), ttl).Err(); err != nil {
		return nil, NewAppError(http.StatusServiceUnavailable, "voice_room_presence_failed", err.Error())
	}
	return &PresenceResponse{
		UserID:     user.UserID,
		SysOrigin:  sysOrigin,
		RoomID:     roomID,
		RegionCode: regionCode,
		TTLSeconds: int(ttl / time.Second),
	}, nil
}

// Leave 清理用户当前房间在线态。
func (s *Service) Leave(ctx context.Context, user AuthUser, req PresenceRequest) (*PresenceResponse, error) {
	roomID := req.RoomID.Int64()
	if roomID <= 0 {
		return nil, NewAppError(http.StatusBadRequest, "missing_room_id", "roomId is required")
	}
	sysOrigin := normalizeSysOrigin(user.SysOrigin)
	regionCode, _ := s.resolveCachedUserRegion(ctx, sysOrigin, user.UserID)
	if err := s.redis.SRem(ctx, onlineRoomKey(sysOrigin, roomID), user.UserID).Err(); err != nil {
		return nil, NewAppError(http.StatusServiceUnavailable, "voice_room_presence_failed", err.Error())
	}
	if err := s.redis.Del(ctx, userRoomKey(sysOrigin, user.UserID), userSeenKey(sysOrigin, user.UserID)).Err(); err != nil {
		return nil, NewAppError(http.StatusServiceUnavailable, "voice_room_presence_failed", err.Error())
	}
	return &PresenceResponse{
		UserID:     user.UserID,
		SysOrigin:  sysOrigin,
		RoomID:     roomID,
		RegionCode: regionCode,
		TTLSeconds: int(presenceTTL(s.cfg) / time.Second),
	}, nil
}

func (s *Service) ensureUserInRoom(ctx context.Context, sysOrigin string, userID, roomID int64) error {
	online, err := s.redis.SIsMember(ctx, onlineRoomKey(sysOrigin, roomID), userID).Result()
	if err != nil {
		return NewAppError(http.StatusServiceUnavailable, "voice_room_presence_failed", err.Error())
	}
	if !online {
		return NewAppError(http.StatusBadRequest, "voice_room_red_packet_room_presence_required", "user is not online in this room")
	}
	return nil
}

func (s *Service) resolveCachedUserRegion(ctx context.Context, sysOrigin string, userID int64) (string, error) {
	region, err := s.redis.Get(ctx, userRegionKey(sysOrigin, userID)).Result()
	if err == nil && strings.TrimSpace(region) != "" {
		return strings.ToUpper(strings.TrimSpace(region)), nil
	}
	return s.resolveUserRegion(ctx, sysOrigin, userID)
}

func (s *Service) resolveUserRegion(ctx context.Context, sysOrigin string, userID int64) (string, error) {
	var user model.UserBaseInfo
	err := s.db.WithContext(ctx).Where("id = ?", userID).First(&user).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return "", NewAppError(http.StatusBadRequest, "voice_room_region_missing", "user region is missing")
	}
	if err != nil {
		return "", err
	}
	countryCode := strings.ToUpper(strings.TrimSpace(user.CountryCode))
	if countryCode == "" {
		return "", NewAppError(http.StatusBadRequest, "voice_room_region_missing", "user country code is missing")
	}

	if s != nil && s.regionResolver != nil {
		regionCode, err := s.regionResolver.ResolveRegionCodeByCountryCode(ctx, sysOrigin, countryCode)
		if err == nil {
			if normalized := strings.ToUpper(strings.TrimSpace(regionCode)); normalized != "" {
				return normalized, nil
			}
		}
	}

	var mapping model.VoiceRoomRegionCountry
	err = s.db.WithContext(ctx).
		Where("sys_origin = ? AND country_code = ? AND enabled = ?", sysOrigin, countryCode, true).
		First(&mapping).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return countryCode, nil
	}
	if err != nil {
		return "", err
	}
	regionCode := strings.ToUpper(strings.TrimSpace(mapping.RegionCode))
	if regionCode == "" {
		return countryCode, nil
	}
	return regionCode, nil
}

func onlineRoomKey(sysOrigin string, roomID int64) string {
	return fmt.Sprintf("voice_room:online:%s:%d", normalizeSysOrigin(sysOrigin), roomID)
}

func userRoomKey(sysOrigin string, userID int64) string {
	return fmt.Sprintf("voice_room:user_room:%s:%d", normalizeSysOrigin(sysOrigin), userID)
}

func userRegionKey(sysOrigin string, userID int64) string {
	return fmt.Sprintf("voice_room:user_region:%s:%d", normalizeSysOrigin(sysOrigin), userID)
}

func userSeenKey(sysOrigin string, userID int64) string {
	return fmt.Sprintf("voice_room:user_seen:%s:%d", normalizeSysOrigin(sysOrigin), userID)
}

func presenceTTL(cfg config.Config) time.Duration {
	seconds := cfg.VoiceRoomRedPacket.PresenceTTLSeconds
	if seconds <= 0 {
		seconds = defaultPresenceTTLSeconds
	}
	return time.Duration(seconds) * time.Second
}