package welfare_activity

import (
	"context"
	"time"
)

func (s *service) ListJoinableActivitiesForUser(ctx context.Context, userID int64) ([]JoinableActivityItem, error) {
	now := time.Now()
	var activities []Activity
	if err := s.repo.GetDbR().WithContext(ctx).Where("deleted_at IS NULL AND status = ? AND start_time <= ? AND end_time > ? AND draw_time > ?", StatusActive, now, now, now).Order("draw_time ASC, id ASC").Find(&activities).Error; err != nil {
		return nil, err
	}
	if len(activities) == 0 {
		return []JoinableActivityItem{}, nil
	}

	paidByType := map[string]int64{}
	periodByType := map[string]string{}
	for _, activity := range activities {
		if _, ok := paidByType[activity.Type]; ok {
			continue
		}
		start, end, period := periodRange(activity.Type, now)
		paid, err := s.sumPaidAmount(ctx, userID, start, end)
		if err != nil {
			return nil, err
		}
		paidByType[activity.Type] = paid
		periodByType[activity.Type] = period
	}

	activityIDs := make([]int64, 0, len(activities))
	for _, activity := range activities {
		activityIDs = append(activityIDs, activity.ID)
	}
	var participants []Participant
	if err := s.repo.GetDbR().WithContext(ctx).Where("user_id = ? AND activity_id IN ?", userID, activityIDs).Find(&participants).Error; err != nil {
		return nil, err
	}
	joinedMap := map[int64]map[string]bool{}
	for _, participant := range participants {
		if _, ok := joinedMap[participant.ActivityID]; !ok {
			joinedMap[participant.ActivityID] = map[string]bool{}
		}
		joinedMap[participant.ActivityID][participant.PeriodKey] = true
	}

	items := make([]JoinableActivityItem, 0, len(activities))
	for _, activity := range activities {
		currentPaid := paidByType[activity.Type]
		periodKey := periodByType[activity.Type]
		joined := joinedMap[activity.ID][periodKey]
		canJoin := !joined && currentPaid >= activity.ThresholdAmount
		items = append(items, JoinableActivityItem{
			ActivityID:      activity.ID,
			Title:           activity.Title,
			Type:            activity.Type,
			ThresholdAmount: activity.ThresholdAmount,
			CurrentPaid:     currentPaid,
			CanJoin:         canJoin,
			Joined:          joined,
			StartTime:       activity.StartTime,
			EndTime:         activity.EndTime,
			DrawTime:        activity.DrawTime,
		})
	}
	return items, nil
}