package gatewaylimit

import (
	"context"
	"strconv"

	"github.com/redis/go-redis/v9"
	"gorm.io/gorm"

	"github.com/break/junhong_cmp_fiber/pkg/constants"
)

// CarrierResolver 按 ICCID 解析卡所属的本系统运营商账户（tb_iot_card.carrier_id），结果缓存在 Redis。
type CarrierResolver struct {
	db    *gorm.DB
	redis *redis.Client
}

// NewCarrierResolver 创建运营商账户解析器。
func NewCarrierResolver(db *gorm.DB, redisClient *redis.Client) *CarrierResolver {
	return &CarrierResolver{db: db, redis: redisClient}
}

// Resolve 返回 ICCID 对应卡的运营商账户 ID；卡不存在时返回 0、nil，由调用方按未知账户处理。
func (r *CarrierResolver) Resolve(ctx context.Context, iccid string) (uint, error) {
	if r == nil || iccid == "" {
		return 0, nil
	}
	cacheKey := constants.RedisGatewayCardCarrierKey(iccid)
	if r.redis != nil {
		if raw, err := r.redis.Get(ctx, cacheKey).Result(); err == nil {
			if value, parseErr := strconv.ParseUint(raw, 10, 64); parseErr == nil {
				return uint(value), nil
			}
		}
	}
	if r.db == nil {
		return 0, nil
	}
	var carrierIDs []uint
	err := r.db.WithContext(ctx).Table("tb_iot_card").
		Where("iccid = ? AND deleted_at IS NULL", iccid).Limit(1).Pluck("carrier_id", &carrierIDs).Error
	if err != nil {
		return 0, err
	}
	if len(carrierIDs) == 0 {
		return 0, nil
	}
	if r.redis != nil {
		_ = r.redis.Set(ctx, cacheKey, strconv.FormatUint(uint64(carrierIDs[0]), 10), constants.GatewayCardCarrierCacheTTL).Err()
	}
	return carrierIDs[0], nil
}