package dbimport (	"errors"	"farga/db/types"	"farga/lib"	"time"	"github.com/google/uuid"	"gorm.io/gorm")var ErrInvalidInvite = errors.New("invalid or already-used invite token")type NewInviteOptions struct {	UserID   uuid.UUID // optional	Length   uint	Duration time.Duration	Role     uint // user role to assign. By default, set it to normal user.}// creates a temporary new invite token.func (db *DB) NewInvite(o NewInviteOptions) (types.Invite, error) {	if o.Length == 0 {		return types.Invite{}, ErrInvalidInvite	}	if o.Duration == 0 {		return types.Invite{}, ErrInvalidInvite	}	// nil for anonymous (e.g. cli-issued admin) invites, so the FK stays unset.	var userID *uuid.UUID	if o.UserID != uuid.Nil {		userID = &o.UserID	}	var invite = types.Invite{		UserID:    userID,		Token:     lib.AlphanumericToken(o.Length),		ExpiresAt: time.Now().Add(o.Duration),		Role:      o.Role,	}	err := db.Create(&invite).Error	return invite, err}// validates a given invite token. Returns `true` if it exists and isn't expired. Otherwise false.// it will ONLY delete the invite token if it expired.func (db *DB) ValidateInviteToken(token string) (types.Invite, bool) {	if token == "" {		return types.Invite{}, false	}	var invite types.Invite	err := db.Where("token = ?", token).Find(&invite).Error	// if it doesn't exist	if err != nil || invite.ID == uuid.Nil {		return types.Invite{}, false	}	// if it expired	if time.Now().After(invite.ExpiresAt) {		db.Delete(&invite)		return types.Invite{}, false	}	return invite, true}// deletes a given invite token.func (db *DB) DeleteInviteToken(token string) error {	var invite = types.Invite{		Token: token,	}	err := db.Model(&invite).Where(&invite).Delete(&invite).Error	return err}// checks invite tokens' expiresAt and if they expired, it removes themfunc (db *DB) DeleteExpiredInviteTokens() {	db.Where("expires_at < ?", time.Now()).Delete(&types.Invite{})}// creates a new user and checks if the invite.func (db *DB) NewUserWithInvite(user *types.User, inviteToken string) error {	return db.Transaction(func(tx *gorm.DB) error {		res := tx.Model(&types.Invite{}).			Where("token = ? AND expires_at > ?", inviteToken, time.Now()).			Delete(&types.Invite{})		if res.Error != nil {			return res.Error		}		if res.RowsAffected != 1 {			return ErrInvalidInvite		}		return tx.Create(user).Error	})}