content: package act.util;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 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.apidoc.ApiManager;
  import act.app.*;
  import act.cli.Command;
  import act.inject.util.LoadConfig;
  import act.inject.util.LoadResource;
  import act.job.JobContext;
  import act.route.RouteSource;
  import act.route.RoutedContext;
  import org.osgl.$;
  import org.osgl.inject.annotation.Configuration;
  import org.osgl.mvc.annotation.*;
  import org.osgl.util.C;
  import org.osgl.util.E;
  
  import java.lang.annotation.Annotation;
  import java.lang.annotation.Inherited;
  import java.lang.reflect.*;
  import java.util.*;
  import javax.inject.Singleton;
  
  public class ReflectedInvokerHelper {
  
      public static void classInit(App app) {
          requestHandlerMethodParamAnnotationCache = new IdentityHashMap<>();
      }
  
      /**
       * If the `invokerClass` specified is singleton, or without field or all fields are
       * stateless, then return an instance of the invoker class. Otherwise, return null
       * @param invokerClass the invoker class
       * @param app the app
       * @return an instance of the invokerClass or `null` if invoker class is stateful class
       */
      public static Object tryGetSingleton(Class<?> invokerClass, App app) {
          Object singleton = app.singleton(invokerClass);
          if (null == singleton) {
              if (isGlobalOrStateless(invokerClass, new HashSet<Class>())) {
                  singleton = app.getInstance(invokerClass);
              }
          }
          if (null != singleton) {
              app.registerSingleton(singleton);
          }
          return singleton;
      }
  
      private static Set<Class<? extends Annotation>> ACTION_ANNO_TYPES = C.set(
              Action.class, GetAction.class, PostAction.class, PutAction.class,
              DeleteAction.class, PatchAction.class, WsAction.class,
              Catch.class, Before.class, After.class, Finally.class,
              Command.class
      );
  
      private static Map<Method, Annotation[][]> requestHandlerMethodParamAnnotationCache;
  
      public static Annotation[][] requestHandlerMethodParamAnnotations(Method method) {
          if (!ApiManager.inProgress() && null == ActionContext.current()) {
              return method.getParameterAnnotations();
          }
          Annotation[][] paramAnnotations = requestHandlerMethodParamAnnotationCache.get(method);
          if (null == paramAnnotations) {
              boolean searchForOverwrittenMethod = false;
              RoutedContext ctx = RoutedContext.Current.get();
              if (null != ctx) {
                  searchForOverwrittenMethod = RouteSource.ACTION_ANNOTATION == ctx.routeSource() && !hasActionAnnotation(method);
              } else {
                  E.illegalStateIf(null == JobContext.current(), "Unable to detected current RoutedContext");
              }
              if (searchForOverwrittenMethod) {
                  Method overwrittenMethod = overwrittenMethodOf(method);
                  paramAnnotations = overwrittenMethod == method ? method.getParameterAnnotations() : requestHandlerMethodParamAnnotations(overwrittenMethod);
              } else {
                  paramAnnotations = method.getParameterAnnotations();
              }
              requestHandlerMethodParamAnnotationCache.put(method, paramAnnotations);
          }
          return paramAnnotations;
      }
  
      public static Method overwrittenMethodOf(Method method) {
          Class host = method.getDeclaringClass();
          Class base = host.getSuperclass();
          try {
              return base.getMethod(method.getName(), method.getParameterTypes());
          } catch (NoSuchMethodException e) {
              throw E.unexpected("Unable to find the overwritten method of " + method);
          }
      }
  
      private static boolean hasActionAnnotation(Method method) {
          Annotation[] aa = method.getDeclaredAnnotations();
          for (Annotation a: aa) {
              if (ACTION_ANNO_TYPES.contains(a.annotationType())) {
                  return true;
              }
          }
          return false;
      }
  
      public static boolean isGlobalOrStateless(Class type) {
          return isGlobalOrStateless(type, new HashSet<Class>());
      }
  
      public static boolean isGlobalOrStateless(Field field) {
          return isGlobalOrStateless(field, new HashSet<Class>());
      }
  
      public static <T extends Annotation> boolean isAnnotationPresent(Class<T> annotationClass, Method method) {
          return null != getAnnotation(annotationClass, method);
      }
  
      public static <T extends Annotation> T getAnnotation(Class<T> annotationClass, Method method) {
          T anno = method.getAnnotation(annotationClass);
          if (null != anno) {
              return anno;
          }
          if (!annotationClass.isAnnotationPresent(Inherited.class)) {
              return null;
          }
          Method overridenMethod = getOverridenMethod(method);
          return null == overridenMethod ? null : getAnnotation(annotationClass, overridenMethod);
      }
  
      private static Method getOverridenMethod(Method method) {
          Class<?> host = method.getDeclaringClass();
          host = host.getSuperclass();
          if (null == host || Object.class == host) {
              return null;
          }
          String name = method.getName();
          Class<?>[] params = method.getParameterTypes();
          return $.getMethod(host, name, params);
      }
  
      private static boolean isGlobalOrStateless(Class type, Set<Class> circularReferenceDetector) {
          if ($.isSimpleType(type)) {
              return false;
          }
          if (type.getAnnotation(Stateful.class) != null) {
              return false;
          }
          if (Act.app().isSingleton(type) || AppServiceBase.class.isAssignableFrom(type) || _hasGlobalOrStatelessAnnotations(type)) {
              return true;
          }
          // when type is interface or abstract class we need to infer it as stateful
          // as we can't determine the implementation class
          if ((Modifier.isAbstract(type.getModifiers()) || type.isInterface()) && !isStatelessType(type)) {
              return false;
          }
          if (circularReferenceDetector.contains(type)) {
              return false;
          }
          circularReferenceDetector.add(type);
          try {
              return _isGlobalOrStateless(type, circularReferenceDetector);
          } finally {
              circularReferenceDetector.remove(type);
          }
      }
  
  
      private static List<String> statelessTypeTraits = C.list("Logger", "CacheService");
      private static boolean isStatelessType(Class<?> intfType) {
          String typeName = intfType.getName();
          for (String s : statelessTypeTraits) {
              if (typeName.contains(s)) {
                  return true;
              }
          }
          return false;
      }
  
      private static $.Predicate<Class<?>> STATEFUL_CLASS = new $.Predicate<Class<?>>() {
          @Override
          public boolean test(Class<?> aClass) {
              return !_hasGlobalOrStatelessAnnotations(aClass);
          }
      };
  
      private static $.Predicate<Field> NON_STATIC_FIELD = new $.Predicate<Field>() {
          @Override
          public boolean test(Field field) {
              return !Modifier.isStatic(field.getModifiers());
          }
      };
  
      private static boolean _isGlobalOrStateless(Class type, Set<Class> circularReferenceDetector) {
          List<Field> fields = $.fieldsOf(type, STATEFUL_CLASS, NON_STATIC_FIELD);
          if (fields.isEmpty()) {
              return true;
          }
          for (Field field : fields) {
              if (Modifier.isFinal(field.getModifiers())) {
                  // suppose final field
                  continue;
              }
              if (!Modifier.isFinal(field.getModifiers()) && !isGlobalOrStateless(field, circularReferenceDetector)) {
                  return false;
              }
          }
          return true;
      }
  
      private static boolean isGlobalOrStateless(Field field, Set<Class> circularReferenceDetector) {
          if (_hasGlobalOrStatelessAnnotations(field)) {
              return true;
          }
          Class<?> fieldType = field.getType();
          return isGlobalOrStateless(fieldType, circularReferenceDetector);
      }
  
      private final static List<Class<? extends Annotation>> statelessMarkersForClass = C.list(
              Singleton.class, Stateless.class, InheritedStateless.class
      );
  
      private final static List<Class<? extends Annotation>> statelessMarkersForFields = C.list(
              Stateless.class, Global.class, Configuration.class,
              LoadResource.class, LoadConfig.class
      );
  
      private static boolean _hasGlobalOrStatelessAnnotations(Class<?> type) {
          return _hasAnnotations(type, statelessMarkersForClass);
      }
  
      private static boolean _hasGlobalOrStatelessAnnotations(Field field) {
          return _hasAnnotations(field, statelessMarkersForFields);
      }
  
      private static boolean _hasAnnotations(AnnotatedElement element, List<Class<? extends Annotation>> annotations) {
          for (Class<? extends Annotation> type : annotations) {
              if (null != element.getAnnotation(type)) {
                  return true;
              }
          }
          return false;
      }
  
  }
  