felhom.eu/hub/internal/store/domain_conflict.go

package store

import "strings"

// R-415 / R-138 option B (2026-10-08; operator ruling 2026-09-14, `01` §7: every customer has their OWN domain, never a
// name under felhom.eu). The hub enforced uniqueness on customer_id only, so two customers could be given the same
// domain — or one inside the other, a shared zone in all but name — silently. DomainConflict answers, for a domain about
// to be saved for customerID, which rule it breaks ("" = none):
//
//   - "felhom.eu" — the domain is felhom.eu or a name under it;
//   - "<other id>" — another customer's domain equals it, contains it, or lies under it.
//
// Matching is case-insensitive, ignores a trailing dot, and is on LABEL boundaries („notexample.hu" is not under
// „example.hu"). An empty domain conflicts with nothing. Pinned by TestR415_* (domain_conflict_test.go) and the
// handler test TestR415_CreateAndEditRefuseConflictingDomain.
func (s *Store) DomainConflict(customerID, domain string) (string, error) {
	d := normDomain(domain)
	if d == "" {
		return "", nil
	}
	if d == "felhom.eu" || strings.HasSuffix(d, ".felhom.eu") {
		return "felhom.eu", nil
	}
	rows, err := s.db.Query(`SELECT customer_id, domain FROM customer_configs WHERE customer_id != ? AND domain != ''`, customerID)
	if err != nil {
		return "", err
	}
	defer rows.Close()
	for rows.Next() {
		var id, other string
		if err := rows.Scan(&id, &other); err != nil {
			return "", err
		}
		o := normDomain(other)
		if o == "" {
			continue
		}
		if d == o || strings.HasSuffix(d, "."+o) || strings.HasSuffix(o, "."+d) {
			return id, nil
		}
	}
	return "", rows.Err()
}

func normDomain(d string) string {
	return strings.TrimSuffix(strings.ToLower(strings.TrimSpace(d)), ".")
}