package registry

// DeleteIfUnchanged deletes listed.Host's route only while the stored row
// still has the identity the caller listed it with: its kind, account and
// app (the owner), whether a record provisioned it, its import gate and
// seed column, and its creation time. It reports whether a row was
// deleted.
//
// It is for a pass that decides from a route list read earlier and
// deletes by host. Between the list and the delete, another writer can
// put a different row at the host: an import's rollback restoring the
// original route, owned by someone else, is the case it was written for.
// A plain Delete would remove that row, and the operator grants it
// carries. Here the check and the delete are one statement, so a row that
// changed identity is never removed on the strength of the old one.
func (r *Registry) DeleteIfUnchanged(listed Route) (bool, error) {
	if r.remote != nil {
		return false, errRemoteMethod
	}
	res, err := r.sql.Exec(`DELETE FROM routes WHERE host = ? AND kind = ? AND account = ? AND app = ?
  AND provisioned = ? AND import_gate = ? AND seed_source = ? AND created_at = ?`,
		listed.Host, listed.Kind, listed.Account, listed.App, b2iDB(listed.Provisioned),
		listed.ImportGate, listed.SeedSource, listed.CreatedAt)
	if err != nil {
		return false, err
	}
	n, err := res.RowsAffected()
	return n > 0, err
}