package task

import (
	"context"

	"github.com/redis/go-redis/v9"
	"go.uber.org/zap"

	"github.com/break/junhong_cmp_fiber/internal/store/postgres"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
)

// priorityIndexAbsent 判断活动优先项索引能否确认该卡该任务类型没有活动优先项。
// 索引未建立、读取失败或成员存在时返回 false，调用方照常查库。
func (b *PollingBase) priorityIndexAbsent(ctx context.Context, cardID uint, taskType string) bool {
	if b == nil || b.redis == nil {
		return false
	}
	pipe := b.redis.Pipeline()
	ready := pipe.Exists(ctx, constants.RedisPollingPriorityReadyKey)
	member := pipe.SIsMember(ctx, constants.RedisPollingPriorityActiveKey, constants.PollingPriorityIndexMember(cardID, taskType))
	if _, err := pipe.Exec(ctx); err != nil {
		return false
	}
	return ready.Val() > 0 && !member.Val()
}

// PriorityIndexRebuilder 定期按库内活动优先项重建索引（并入最近入队的项），使已终态的项退出索引。
type PriorityIndexRebuilder struct {
	store  *postgres.PollingPriorityItemStore
	redis  *redis.Client
	logger *zap.Logger
}

// NewPriorityIndexRebuilder 创建活动优先项索引重建器。
func NewPriorityIndexRebuilder(store *postgres.PollingPriorityItemStore, redisClient *redis.Client, logger *zap.Logger) *PriorityIndexRebuilder {
	if logger == nil {
		logger = zap.NewNop()
	}
	return &PriorityIndexRebuilder{store: store, redis: redisClient, logger: logger}
}

// Rebuild 重建一次索引；失败时清除就绪标记，轮询步骤回退为查库。
func (r *PriorityIndexRebuilder) Rebuild(ctx context.Context) {
	if r == nil || r.store == nil || r.redis == nil {
		return
	}
	keys, err := r.store.ListActiveKeys(ctx)
	if err != nil {
		r.logger.Warn("重建活动优先项索引失败，轮询步骤回退查库", zap.Error(err))
		r.redis.Del(ctx, constants.RedisPollingPriorityReadyKey)
		return
	}
	members := make([]any, 0, len(keys))
	for _, key := range keys {
		members = append(members, constants.PollingPriorityIndexMember(key.CardID, key.TaskType))
	}
	tmp := constants.RedisPollingPriorityRebuildKey
	pipe := r.redis.TxPipeline()
	pipe.Del(ctx, tmp)
	if len(members) > 0 {
		pipe.SAdd(ctx, tmp, members...)
	}
	pipe.SUnionStore(ctx, tmp, tmp, constants.RedisPollingPriorityRecentKey)
	pipe.Del(ctx, constants.RedisPollingPriorityActiveKey)
	pipe.SUnionStore(ctx, constants.RedisPollingPriorityActiveKey, tmp)
	pipe.Del(ctx, tmp)
	pipe.Set(ctx, constants.RedisPollingPriorityReadyKey, "1", constants.PollingPriorityIndexReadyTTL)
	if _, err := pipe.Exec(ctx); err != nil {
		r.logger.Warn("写入活动优先项索引失败，轮询步骤回退查库", zap.Error(err))
		r.redis.Del(ctx, constants.RedisPollingPriorityReadyKey)
	}
}