001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.dto.jsonschema;
014
015import static org.apache.juneau.internal.StringUtils.*;
016import java.io.*;
017import java.net.*;
018import java.util.concurrent.*;
019
020import org.apache.juneau.*;
021import org.apache.juneau.json.*;
022
023/**
024 * A container for retrieving JSON {@link Schema} objects by URI.
025 * 
026 * <p>
027 * Subclasses must implement one of the following methods to load schemas from external sources:
028 * <ul class='spaced-list'>
029 *    <li>
030 *       {@link #getReader(URI)} - If schemas should be loaded from readers and automatically parsed.
031 *    <li>
032 *       {@link #load(URI)} - If you want control over construction of {@link Schema} objects.
033 * </ul>
034 * 
035 * <h5 class='section'>See Also:</h5>
036 * <ul class='doctree'>
037 *    <li class='jp'><a class='doclink' href='package-summary.html#TOC'>org.apache.juneau.dto.jsonschema</a>
038 * </ul>
039 */
040public abstract class SchemaMap extends ConcurrentHashMap<URI,Schema> {
041
042   private static final long serialVersionUID = 1L;
043
044   /**
045    * Return the {@link Schema} object at the specified URI.
046    * 
047    * <p>
048    * If this schema object has not been loaded yet, calls {@link #load(URI)}.
049    * 
050    * <p>
051    * The value can be of any of the following types: {@link URI}, {@link URL}, {@link String}.
052    * Strings must be valid URIs.
053    * 
054    * <p>
055    * URIs defined by {@link UriResolver} can be used for values.
056    * 
057    * @param uri The URI of the schema to retrieve.
058    * @return The Schema, or <jk>null</jk> if schema was not located and could not be loaded.
059    */
060   @Override /* Map */
061   public Schema get(Object uri) {
062      URI u = toURI(uri);
063      Schema s = super.get(u);
064      if (s != null)
065         return s;
066      synchronized(this) {
067         s = load(u);
068         if (s != null) {
069            // Note:  Can't use add(Schema...) since the ID property may not be set.
070            s.setSchemaMap(this);
071            put(u, s);
072         }
073         return s;
074      }
075   }
076
077   /**
078    * Convenience method for pre-populating this map with the specified schemas.
079    * 
080    * <p>
081    * The schemas passed in through this method MUST have their ID properties set.
082    * 
083    * @param schemas The set of schemas to add to this map.
084    * @return This object (for method chaining).
085    * @throws RuntimeException If one or more schema objects did not have their ID property set.
086    */
087   public SchemaMap add(Schema...schemas) {
088      for (Schema schema : schemas) {
089         if (schema.getId() == null)
090            throw new RuntimeException("Schema with no ID passed to SchemaMap.add(Schema...)");
091         put(schema.getId(), schema);
092         schema.setSchemaMap(this);
093      }
094      return this;
095   }
096
097   /**
098    * Subclasses must implement either this method or {@link #getReader(URI)} to load the schema with the specified URI.
099    * 
100    * <p>
101    * It's up to the implementer to decide where these come from.
102    * 
103    * <p>
104    * The default implementation calls {@link #getReader(URI)} and parses the schema document.
105    * If {@link #getReader(URI)} returns <jk>null</jk>, this method returns <jk>null</jk> indicating this is an
106    * unreachable document.
107    * 
108    * @param uri The URI to load the schema from.
109    * @return The parsed schema.
110    */
111   public Schema load(URI uri) {
112      try (Reader r = getReader(uri)) {
113         if (r == null)
114            return null;
115         return JsonParser.DEFAULT.parse(r, Schema.class);
116      } catch (Exception e) {
117         throw new RuntimeException(e);
118      }
119   }
120
121   /**
122    * Subclasses must implement either this method or {@link #load(URI)} to load the schema with the specified URI.
123    * 
124    * <p>
125    * It's up to the implementer to decide where these come from.
126    * 
127    * <p>
128    * The default implementation returns <jk>null</jk>.
129    * 
130    * @param uri The URI to connect to and retrieve the contents.
131    * @return The reader from reading the specified URI.
132    */
133   public Reader getReader(URI uri) {
134      return null;
135   }
136}