content: package act.inject.param;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2018 ActFramework
   * %%
   * Licensed 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.
   * #L%
   */
  
  import act.Act;
  import act.app.App;
  import org.osgl.$;
  import org.osgl.inject.BeanSpec;
  import org.osgl.inject.ValueLoader;
  import org.osgl.inject.annotation.LoadValue;
  import org.osgl.util.S;
  
  import java.lang.annotation.Annotation;
  import java.lang.reflect.Field;
  import java.util.*;
  import javax.persistence.Transient;
  
  /**
   * Patch JSON DTO bean object in case there are
   * value loader annotation on certain field, and the
   * value of the field on the bean is null, then it
   * shall inject the value loader result into the field
   * on the bean.
   *
   * See https://github.com/actframework/actframework/issues/1016
   */
  public class JsonDtoPatch {
      private List<JsonDtoPatch> fieldsPatches = new ArrayList<>();
      private String name;
      private ValueLoader loader;
      private JsonDtoPatch(String name, BeanSpec spec, Set<BeanSpec> circularReferenceDetector) {
          this.name = S.requireNotBlank(name);
          this.loader = valueLoaderOf(spec);
          if (null == loader) {
              for (BeanSpec fieldSpec : spec.nonStaticFields()) {
                  if (circularReferenceDetector.contains(fieldSpec)) {
                      continue;
                  }
                  circularReferenceDetector.add(fieldSpec);
                  if (fieldSpec.isTransient()
                          || fieldSpec.hasAnnotation(Transient.class)
                          || fieldSpec.hasAnnotation(NoBind.class)
                  ) {
                      continue;
                  }
                  Class fieldType = fieldSpec.rawType();
                  if (App.class == fieldType || Class.class == fieldType || Object.class == fieldType
                          || Field.class == fieldType || ResourceBundle.class == fieldType
                          || Collection.class.isAssignableFrom(fieldType)
                          || Map.class.isAssignableFrom(fieldType)
                  ) {
                      continue;
                  }
                  String fieldName = fieldSpec.name();
                  JsonDtoPatch child = new JsonDtoPatch(fieldName, fieldSpec, circularReferenceDetector);
                  if (!child.isEmpty()) {
                      fieldsPatches.add(child);
                  }
                  circularReferenceDetector.remove(fieldSpec);
              }
          }
      }
  
      public String name() {
          return name;
      }
  
      @Override
      public String toString() {
          return name();
      }
  
      public void applyChildren(Object host) {
          for (JsonDtoPatch child : fieldsPatches) {
              child.apply(host);
          }
      }
  
      public void apply(Object host) {
          if (null != loader) {
              Object o = loader.get();
              $.setProperty(host, o, name);
          } else {
              Object o = $.getProperty(host, name);
              applyChildren(o);
          }
      }
  
      private boolean isEmpty() {
          return null == loader && fieldsPatches.isEmpty();
      }
  
      private ValueLoader valueLoaderOf(BeanSpec spec) {
          LoadValue loadValue = spec.getAnnotation(LoadValue.class);
          if (null == loadValue) {
              Annotation[] aa = spec.taggedAnnotations(LoadValue.class);
              if (aa.length > 0) {
                  Annotation a = aa[0];
                  loadValue = a.annotationType().getAnnotation(LoadValue.class);
              }
          }
          return null == loadValue ? null : Act.getInstance(loadValue.value());
      }
  
      public static JsonDtoPatch of(BeanSpec spec) {
          Set<BeanSpec> circularReferenceDetector = new HashSet<>();
          JsonDtoPatch patch = new JsonDtoPatch(spec.name(), spec, circularReferenceDetector);
          return patch.isEmpty() ? null : patch;
      }
  }
  