package service

import (
	"context"
	"log"
	"time"

	"with_you/internal/model"
	"with_you/internal/repository"

	"gorm.io/gorm"
)

const AccountDeletionCoolDownDays = 90

type AccountCleanupService interface {
	CleanupExpiredAccounts(ctx context.Context) (int64, error)
}

type accountCleanupServiceImpl struct {
	db         *gorm.DB
	userRepo   repository.UserRepository
	logService *LogService
}

func NewAccountCleanupService(
	db *gorm.DB,
	userRepo repository.UserRepository,
	logService *LogService,
) AccountCleanupService {
	return &accountCleanupServiceImpl{
		db:         db,
		userRepo:   userRepo,
		logService: logService,
	}
}

func (s *accountCleanupServiceImpl) CleanupExpiredAccounts(ctx context.Context) (int64, error) {
	cutoffTime := time.Now().AddDate(0, 0, -AccountDeletionCoolDownDays)

	users, err := s.userRepo.GetPendingDeletionUsers(cutoffTime)
	if err != nil {
		return 0, err
	}

	if len(users) == 0 {
		return 0, nil
	}

	var deletedCount int64
	for _, user := range users {
		if err := s.anonymizeAndDeleteUser(ctx, user); err != nil {
			log.Printf("[AccountCleanup] failed to cleanup user %s: %v", user.ID, err)
			continue
		}
		deletedCount++
	}

	log.Printf("[AccountCleanup] cleaned up %d expired accounts", deletedCount)
	return deletedCount, nil
}

func (s *accountCleanupServiceImpl) anonymizeAndDeleteUser(ctx context.Context, user *model.User) error {
	deletedUserID := "deleted_user"

	return s.db.Transaction(func(tx *gorm.DB) error {
		if err := tx.Model(&model.Post{}).Where("user_id = ?", user.ID).Update("user_id", deletedUserID).Error; err != nil {
			return err
		}

		if err := tx.Model(&model.Comment{}).Where("user_id = ?", user.ID).Update("user_id", deletedUserID).Error; err != nil {
			return err
		}

		if err := tx.Where("follower_id = ? OR following_id = ?", user.ID, user.ID).Delete(&model.Follow{}).Error; err != nil {
			return err
		}

		if err := tx.Where("user_id = ?", user.ID).Delete(&model.Favorite{}).Error; err != nil {
			return err
		}

		if err := tx.Where("user_id = ?", user.ID).Delete(&model.PostLike{}).Error; err != nil {
			return err
		}

		if err := tx.Where("user_id = ?", user.ID).Delete(&model.CommentLike{}).Error; err != nil {
			return err
		}

		if err := tx.Unscoped().Delete(&model.User{}, "id = ?", user.ID).Error; err != nil {
			return err
		}

		if s.logService != nil {
			s.logService.OperationLog.RecordOperation(&model.OperationLog{
				UserID:     user.ID,
				UserName:   user.Username,
				Operation:  "account_deleted",
				Module:     "user",
				TargetType: "user",
				TargetID:   user.ID,
				Status:     "success",
			})
		}

		return nil
	})
}