001/*
002 * SPDX-License-Identifier: Apache-2.0
003 *
004 * Copyright 2024-2026 The Enola <https://enola.dev> Authors
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License");
007 * you may not use this file except in compliance with the License.
008 * You may obtain a copy of the License at
009 *
010 *     https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package dev.enola.thing;
019
020import com.google.errorprone.annotations.Immutable;
021
022/**
023 * Link is an IRI "reference" to another {@link Thing}.
024 *
025 * <p>IRI are normally just String in Enola; this type only exists, and is required, so that it can
026 * be returned by {@link Thing#get(String)} and distinguished from a String which is not an IRI but
027 * text.
028 *
029 * @param iri the IRI (Internationalized Resource Identifier) that references another Thing
030 */
031// TODO Consider using a Datatype to indicate link? But which...
032// TODO Abandon this and just use java.net.URI in Things instead?! No, that's less efficient.
033//   Or change this record to a class and have an URI field, for 1 time conversion.
034// TODO Make it extend Thing; and voilà, it's a Property Graph!
035@Immutable
036public record Link(String iri) implements HasIRI {
037
038    public Link {
039        if (iri == null || iri.isBlank()) {
040            throw new IllegalArgumentException("IRI cannot be null or trimmed empty.");
041        }
042    }
043
044    @Override
045    public String toString() {
046        // TODO return "<" + iri + ">";
047        return iri;
048    }
049}