package yumigiftchallenge

import (
	"context"
	"fmt"
	"time"

	"chatapp3-golang/internal/model"
)

const (
	defaultSettleDueBatch = 20
	maxSettleDueBatch     = 100
	settleDueItemTimeout  = 30 * time.Second
)

// SettleDue 是 chatapp-cron 的单轮幂等 runner：冻结到期周期，并恢复 PENDING/过租期 PROCESSING。
// 本仓库不启动 ticker；同一端点可被多个实例重复调用，数据库门闩和 delivery item 唯一键负责并发幂等。
func (s *Service) SettleDue(ctx context.Context, batch int) (*SettleDueResult, error) {
	batch = normalizeSettleDueBatch(batch)
	result := &SettleDueResult{FailedKeys: []string{}}
	var periods []model.YumiGiftChallengePeriodSettlement
	if err := s.db.WithContext(ctx).
		Where("status IN ? AND snapshot_due_time <= ?", []string{StatusNotStarted, StatusProcessing}, time.Now()).
		Order("snapshot_due_time ASC, id ASC").Limit(batch).Find(&periods).Error; err != nil {
		return nil, err
	}
	for _, period := range periods {
		if err := ctx.Err(); err != nil {
			return result, err
		}
		result.PeriodsScanned++
		request := SettlementRequest{PeriodType: period.PeriodType}
		if period.StatDate != nil {
			request.StatDate = *period.StatDate
		}
		itemCtx, cancel := context.WithTimeout(ctx, settleDueItemTimeout)
		target, err := s.resolveSettlementTarget(itemCtx, period.ActivityID, request)
		if err == nil {
			err = s.freezeSettlementTarget(itemCtx, target)
		}
		if err == nil {
			// 空榜直接完成；有获奖 parent 时保持 PROCESSING，后面的有界 delivery 恢复负责逐项发放。
			err = s.refreshPeriodStatus(itemCtx, target.activity.ID, target.period, target.periodKey)
		}
		cancel()
		if err != nil {
			result.FailedKeys = append(result.FailedKeys, fmt.Sprintf("PERIOD:%d:%s:%s", period.ActivityID, period.PeriodType, period.PeriodKey))
			continue
		}
		result.PeriodsFrozen++
	}
	if err := s.recoverTaskOwners(ctx, batch, result); err != nil {
		return result, err
	}
	if err := s.recoverSettlementOwners(ctx, batch, result); err != nil {
		return result, err
	}
	return result, nil
}

func (s *Service) recoverTaskOwners(ctx context.Context, batch int, result *SettleDueResult) error {
	var rows []model.YumiGiftChallengeUserTaskDaily
	if err := s.db.WithContext(ctx).Select("id").
		Where("delivery_status = ? OR (delivery_status = ? AND update_time <= ?)", DeliveryPending, DeliveryProcessing, s.deliveryLeaseCutoff()).
		Order("update_time ASC, id ASC").Limit(batch).Find(&rows).Error; err != nil {
		return err
	}
	for _, row := range rows {
		if err := ctx.Err(); err != nil {
			return err
		}
		result.TaskOwnersScanned++
		itemCtx, cancel := context.WithTimeout(ctx, settleDueItemTimeout)
		err := s.deliverOwnerItems(itemCtx, OwnerTask, row.ID)
		cancel()
		if err != nil {
			result.FailedKeys = append(result.FailedKeys, fmt.Sprintf("TASK:%d", row.ID))
			continue
		}
		result.OwnersProcessed++
	}
	return nil
}

func (s *Service) recoverSettlementOwners(ctx context.Context, batch int, result *SettleDueResult) error {
	var rows []model.YumiGiftChallengeSettlement
	if err := s.db.WithContext(ctx).Select("id").
		Where("delivery_status = ? OR (delivery_status = ? AND update_time <= ?)", DeliveryPending, DeliveryProcessing, s.deliveryLeaseCutoff()).
		Order("update_time ASC, id ASC").Limit(batch).Find(&rows).Error; err != nil {
		return err
	}
	for _, row := range rows {
		if err := ctx.Err(); err != nil {
			return err
		}
		result.SettlementOwnersScanned++
		itemCtx, cancel := context.WithTimeout(ctx, settleDueItemTimeout)
		err := s.ensureSettlementDeliveryItems(itemCtx, row.ID)
		if err == nil {
			err = s.deliverOwnerItems(itemCtx, OwnerSettlement, row.ID)
		}
		cancel()
		if err != nil {
			result.FailedKeys = append(result.FailedKeys, fmt.Sprintf("SETTLEMENT:%d", row.ID))
			continue
		}
		result.OwnersProcessed++
	}
	return nil
}

func normalizeSettleDueBatch(batch int) int {
	if batch <= 0 {
		return defaultSettleDueBatch
	}
	if batch > maxSettleDueBatch {
		return maxSettleDueBatch
	}
	return batch
}

func (s *Service) deliveryLeaseCutoff() time.Time {
	leaseSeconds := s.cfg.YumiGiftChallenge.DeliveryProcessingLeaseSeconds
	if leaseSeconds < 30 {
		leaseSeconds = 300
	}
	return time.Now().Add(-time.Duration(leaseSeconds) * time.Second)
}