/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.eclipse.aether.spi.connector.transport.http.RFC9457;
  
  import java.lang.reflect.Type;
  import java.net.URI;
  
  import com.google.gson.Gson;
  import com.google.gson.GsonBuilder;
  import com.google.gson.JsonDeserializationContext;
  import com.google.gson.JsonDeserializer;
  import com.google.gson.JsonElement;
  import com.google.gson.JsonObject;
  import com.google.gson.JsonParseException;
  
  public class RFC9457Parser {
      private static Gson gson = new GsonBuilder()
              .registerTypeAdapter(RFC9457Payload.class, new RFC9457PayloadAdapter())
              .create();
  
      public static RFC9457Payload parse(String data) {
          return gson.fromJson(data, RFC9457Payload.class);
      }
  
      private static class RFC9457PayloadAdapter implements JsonDeserializer<RFC9457Payload> {
          @Override
          public RFC9457Payload deserialize(
                  final JsonElement json, final Type typeOfT, final JsonDeserializationContext context)
                  throws JsonParseException {
              JsonObject asJsonObject = json.getAsJsonObject();
              URI type = parseNullableURI(asJsonObject, "type", "about:blank");
              Integer status = parseStatus(asJsonObject);
              String title = parseNullableString(asJsonObject, "title");
              String detail = parseNullableString(asJsonObject, "detail");
              URI instance = parseNullableURI(asJsonObject, "instance", null);
              return new RFC9457Payload(type, status, title, detail, instance);
          }
      }
  
      private static Integer parseStatus(JsonObject jsonObject) {
          return jsonObject.get("status") == null || jsonObject.get("status").isJsonNull()
                  ? null
                  : jsonObject.get("status").getAsInt();
      }
  
      private static String parseNullableString(JsonObject jsonObject, String key) {
          return jsonObject.get(key) == null || jsonObject.get(key).isJsonNull()
                  ? null
                  : jsonObject.get(key).getAsString();
      }
  
      private static URI parseNullableURI(JsonObject jsonObject, String key, String defaultValue) {
          return !jsonObject.has(key) || jsonObject.get(key).isJsonNull()
                  ? defaultValue != null ? URI.create(defaultValue) : null
                  : URI.create(jsonObject.get(key).getAsString());
      }
  }