001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.bean.hal;
018
019import java.util.*;
020
021import org.apache.juneau.marshall.*;
022import org.apache.juneau.marshall.parser.*;
023import org.apache.juneau.marshall.serializer.*;
024import org.apache.juneau.marshall.swap.spi.*;
025
026/**
027 * Per-property {@link ObjectSwap} applied to HAL {@code _links} maps so that each map entry round-trips
028 * as either a single {@link HalLink} (JSON object) or a {@link HalLinkArray} (JSON array) per the spec.
029 *
030 * <p>
031 * The swap operates on the whole {@code Map<String,Object>} bean property and walks the entries:
032 * <ul class='spaced-list'>
033 *   <li>On <b>serialize</b> ({@link #swap}): identity - values that are {@link HalLink} or
034 *     {@link HalLinkArray} already serialize as the correct JSON shape.
035 *   <li>On <b>parse</b> ({@link #unswap}): each value that came back as a parsed list is converted to
036 *     {@link HalLinkArray}; each value that came back as a parsed map is converted to {@link HalLink}.
037 *   <li>{@code null} input ⇒ {@code null} output.
038 * </ul>
039 *
040 * <p>
041 * Mirrors {@code BooleanOrSchemaSwap} in {@code juneau-bean-jsonschema} (the entry-disambiguation idea), with
042 * iteration over map entries instead of operating on a single value.
043 */
044public class HalLinkOrArraySwap extends ObjectSwap<Object,Object> {
045
046   @Override /* Overridden from ObjectSwap */
047   public Object swap(MarshallingSession session, Object o) throws SerializeException {
048      return o;
049   }
050
051   @Override /* Overridden from ObjectSwap */
052   public Object unswap(MarshallingSession session, Object o, ClassMeta<?> hint) throws ParseException {
053      if (o == null)
054         return null;
055      if (o instanceof Map<?,?> raw) {
056         var out = new LinkedHashMap<String,Object>();
057         var linkCm = session.getClassMeta(HalLink.class);
058         var arrCm = session.getClassMeta(HalLinkArray.class);
059         for (var e : raw.entrySet()) {
060            var key = String.valueOf(e.getKey());
061            var v = e.getValue();
062            if (v instanceof Collection<?>) {
063               out.put(key, session.convertToType(v, arrCm));
064            } else if (v instanceof Map<?,?>) {
065               out.put(key, session.convertToType(v, linkCm));
066            } else {
067               out.put(key, v);
068            }
069         }
070         return out;
071      }
072      return o;
073   }
074}