content: /*
   * 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.apache.camel.component.jackson.transform;
  
  import java.io.InputStream;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.function.Function;
  
  import com.fasterxml.jackson.core.FormatSchema;
  import com.fasterxml.jackson.core.JsonProcessingException;
  import com.fasterxml.jackson.databind.JsonNode;
  import org.apache.camel.Exchange;
  import org.apache.camel.Processor;
  import org.apache.camel.component.jackson.SchemaHelper;
  import org.apache.camel.component.jackson.SchemaResolver;
  import org.apache.camel.component.jackson.SchemaType;
  import org.apache.camel.spi.Resource;
  import org.apache.camel.support.PluginHelper;
  import org.apache.camel.util.ObjectHelper;
  
  /**
   * Schema resolver able to read Json schema from given exchange being processed. First attempt is to retrieve the Json
   * schema reference from exchange properties. Second approach is to convert a given Json schema given as String in the
   * exchange properties to a proper schema object. Last approach it to load the Json schema as a classpath resource. The
   * following resource path is used to resolve the schema {@code classpath:schemas/json/<T>.json} where T represents the
   * content class name of the exchange body. The content class information is either set as an explicit exchange property
   * or it gets resolved from exchange body type information.
   */
  public class JsonSchemaResolver implements SchemaResolver, Processor {
      private final ConcurrentMap<String, JsonNode> schemes;
  
      private JsonNode schema;
      private String contentClass;
  
      public JsonSchemaResolver() {
          this.schemes = new ConcurrentHashMap<>();
      }
  
      public String getSchema() {
          if (this.schema != null) {
              try {
                  return Json.mapper().writeValueAsString(this.schema);
              } catch (JsonProcessingException e) {
                  throw new RuntimeException(e);
              }
          }
  
          return null;
      }
  
      public void setSchema(String schema) {
          if (ObjectHelper.isNotEmpty(schema)) {
              try {
                  this.schema = Json.mapper().readTree(schema);
              } catch (JsonProcessingException e) {
                  throw new RuntimeException(e);
              }
          } else {
              this.schema = null;
          }
      }
  
      public String getContentClass() {
          return contentClass;
      }
  
      public void setContentClass(String contentClass) {
          if (ObjectHelper.isNotEmpty(contentClass)) {
              this.contentClass = contentClass;
          } else {
              this.contentClass = null;
          }
      }
  
      @Override
      public void process(Exchange exchange) throws Exception {
          Object payload = exchange.getMessage().getBody();
          if (payload == null) {
              return;
          }
  
          JsonNode answer = computeIfAbsent(exchange);
  
          if (answer != null) {
              exchange.setProperty(SchemaHelper.CONTENT_SCHEMA, answer);
              exchange.setProperty(SchemaHelper.CONTENT_SCHEMA_TYPE, SchemaType.JSON.type());
              exchange.setProperty(SchemaHelper.CONTENT_CLASS, SchemaHelper.resolveContentClass(exchange, this.contentClass));
          }
      }
  
      private JsonNode computeIfAbsent(Exchange exchange) {
          if (this.schema != null) {
              return this.schema;
          }
  
          JsonNode answer = exchange.getProperty(SchemaHelper.CONTENT_SCHEMA, JsonNode.class);
  
          if (answer == null && exchange.getProperties().containsKey(SchemaHelper.SCHEMA)) {
              answer = tryLoadingSchema(exchange);
          }
  
          if (answer == null) {
              String contentClass = SchemaHelper.resolveContentClass(exchange, this.contentClass);
              if (contentClass != null) {
                  answer = this.schemes.computeIfAbsent(contentClass, tryLoadingSchemaFromResourceLoader(exchange));
              }
          }
  
          if (answer != null) {
              this.schema = answer;
          }
  
          return answer;
      }
  
      private static Function<String, JsonNode> tryLoadingSchemaFromResourceLoader(Exchange exchange) {
          return t -> {
              Resource res = PluginHelper.getResourceLoader(exchange.getContext())
                      .resolveResource(
                              "classpath:schemas/" + SchemaType.JSON.type() + "/" + t + "." + SchemaType.JSON.type());
  
              try {
                  if (res.exists()) {
                      try (InputStream is = res.getInputStream()) {
                          if (is != null) {
                              return Json.mapper().readTree(is);
                          }
                      }
                  }
              } catch (Exception e) {
                  throw new RuntimeException(
                          "Unable to load Json schema for type: " + t + ", resource: " + res.getLocation(), e);
              }
  
              return null;
          };
      }
  
      private static JsonNode tryLoadingSchema(Exchange exchange) {
          JsonNode answer;
          String schemaJson = exchange.getProperty(SchemaHelper.SCHEMA, String.class);
          try {
              answer = Json.mapper().readTree(schemaJson);
          } catch (JsonProcessingException e) {
              throw new RuntimeException("Unable to load Json schema", e);
          }
          return answer;
      }
  
      @Override
      public FormatSchema resolve(Exchange exchange) {
          JsonNode answer = exchange.getProperty(SchemaHelper.CONTENT_SCHEMA, JsonNode.class);
          if (answer == null) {
              answer = computeIfAbsent(exchange);
          }
  
          return new JsonFormatSchema(answer);
      }
  }
  