package service

import (
	"context"
	_ "embed"
	"fmt"

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

	"github.com/topfans/backend/pkg/logger"
	"github.com/topfans/backend/pkg/models"
	"github.com/topfans/backend/services/moderationService/config"
	"github.com/topfans/backend/services/moderationService/repository"
)

//go:embed lua/auto_hide.lua
var autoHideLuaScript string

type AutoHideService struct {
	repo  *repository.ModerationRepository
	redis *redis.Client
	tx    *TxHelper
	cfg   config.ModerationConfig
}

func NewAutoHideService(
	repo *repository.ModerationRepository,
	rdb *redis.Client,
	tx *TxHelper,
	cfg config.ModerationConfig,
) *AutoHideService {
	return &AutoHideService{repo: repo, redis: rdb, tx: tx, cfg: cfg}
}

// TryTrigger - 提交举报后调用（spec §6.1 step 6）
// 返回值：(triggered bool, counter int64)
func (s *AutoHideService) TryTrigger(
	ctx context.Context, targetType string, targetID int64, reporterID int64,
) (bool, int64, error) {
	// 应用层短锁（spec §6.4：5s 锁覆盖整个 auto-hide 流程）
	lockKey := fmt.Sprintf("%s:lock:%s:%d", s.cfg.RedisKeyPrefix, targetType, targetID)
	ok, err := s.redis.SetNX(ctx, lockKey, "1", s.cfg.LockTTL).Result()
	if err != nil {
		return false, 0, err
	}
	if !ok {
		return false, 0, nil // 5s 内已有并发请求在跑
	}
	defer func() {
		if err := s.redis.Del(ctx, lockKey).Err(); err != nil {
			logger.Sugar.Warnw("failed to release auto-hide lock", "key", lockKey, "err", err)
		}
	}()

	counterKey := fmt.Sprintf("%s:counter:%s:%d", s.cfg.RedisKeyPrefix, targetType, targetID)
	userMarkerKey := fmt.Sprintf("%s:user:%s:%d:%d", s.cfg.RedisKeyPrefix, targetType, targetID, reporterID)

	result, err := s.redis.Eval(ctx, autoHideLuaScript,
		[]string{counterKey, userMarkerKey},
		s.cfg.AutoHideThreshold,
		int(s.cfg.CounterTTL.Seconds()),
		int(s.cfg.UserMarkerTTL.Seconds()),
	).Result()
	if err != nil {
		return false, 0, err
	}

	arr := result.([]interface{})
	triggered := arr[0].(int64) == 1
	counter := arr[1].(int64)
	return triggered, counter, nil
}

// ExecuteAutoHide - 触发自动隐藏（事务内：业务表软删除 + reports UPDATE + mts UPSERT + 流水）
func (s *AutoHideService) ExecuteAutoHide(
	ctx context.Context, targetType string, targetID int64, triggerReportID int64,
) error {
	now := repository.Now()

	return s.tx.WithTx(ctx, func(tx *gorm.DB) error {
		var affected int64
		var err error

		// ① 业务表软删除（按 target_type 路由）
		switch targetType {
		case "asset":
			affected, err = s.repo.SoftDeleteAsset(ctx, targetID, now)
		case "user_profile":
			affected, err = s.repo.SoftDeleteUser(ctx, targetID, now)
		default:
			return fmt.Errorf("unsupported target_type: %s", targetType)
		}
		if err != nil {
			return err
		}

		// ② reports UPDATE pending → auto_hidden
		if _, err := s.repo.UpgradePendingToAutoHidden(ctx, targetType, targetID, triggerReportID, now); err != nil {
			return err
		}

		// ③ mts UPSERT
		mts := &models.ModerationTargetStatus{
			TargetType:     targetType,
			TargetID:       targetID,
			LastActionType: "autohide",
			Source:         "auto",
			SourceReportID: &triggerReportID,
			CreatedAt:      now,
			UpdatedAt:      now,
		}
		if err := s.repo.UpsertTargetStatus(ctx, mts); err != nil {
			return err
		}

		// ③.5 写 moderation_actions 流水（v2.4 V7 conditional）
		actionType := "takedown"
		note := "auto-hide threshold reached"
		if affected == 0 {
			actionType = "autohide_noop"
			note = "auto-hide no-op: target already is_active=false"
		}
		reportID := triggerReportID
		tt := targetType
		tid := targetID
		action := &models.ModerationAction{
			ReportID:   &reportID,
			AdminID:    0, // 系统自动 sentinel (v2.2 B4)
			ActionType: actionType,
			TargetType: &tt,
			TargetID:   &tid,
			Note:       &note,
			Success:    true,
			CreatedAt:  now,
		}
		return s.repo.CreateAction(ctx, action)
	})
}

// ResetCounter - spec §6.2 path C: admin 判定误报，重置 Redis 计数
func (s *AutoHideService) ResetCounter(ctx context.Context, targetType string, targetID int64) error {
	counterKey := fmt.Sprintf("%s:counter:%s:%d", s.cfg.RedisKeyPrefix, targetType, targetID)
	lockKey := fmt.Sprintf("%s:lock:%s:%d", s.cfg.RedisKeyPrefix, targetType, targetID)
	userMarkerPattern := fmt.Sprintf("%s:user:%s:%d:*", s.cfg.RedisKeyPrefix, targetType, targetID)

	// DEL counter + lock
	if err := s.redis.Del(ctx, counterKey, lockKey).Err(); err != nil {
		return err
	}

	// SCAN MATCH user_marker 逐个 DEL（spec §6.4 v2.2 B1：DEL 不支持通配）
	iter := s.redis.Scan(ctx, 0, userMarkerPattern, 100).Iterator()
	var keys []string
	for iter.Next(ctx) {
		keys = append(keys, iter.Val())
	}
	if err := iter.Err(); err != nil {
		return err
	}
	if len(keys) > 0 {
		if err := s.redis.Del(ctx, keys...).Err(); err != nil {
			return err
		}
	}
	return nil
}