content: package act.plugin;
  
  /*-
   * #%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.app.ActionContext;
  import act.controller.meta.ControllerClassMetaInfo;
  import org.osgl.$;
  import org.osgl.exception.NotAppliedException;
  import org.osgl.http.H;
  import org.osgl.mvc.result.Result;
  import org.osgl.util.C;
  
  import java.lang.annotation.Annotation;
  import java.lang.reflect.Method;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  
  /**
   * allows plugin different controller annotations framework, e.g. JAX-RS
   */
  public abstract class ControllerPlugin implements Plugin {
  
      public static final class PathAnnotationSpec {
          private final Class<? extends Annotation> annoType;
          private final boolean supportAbsolutePath;
          private final boolean supportInheritance;
  
          public PathAnnotationSpec(Class<? extends Annotation> annoType, boolean supportAbsolutePath, boolean supportInheritance) {
              this.annoType = annoType;
              this.supportAbsolutePath = supportAbsolutePath;
              this.supportInheritance = supportInheritance;
          }
  
          public Class<? extends Annotation> annoType() {
              return annoType;
          }
  
          public boolean supportAbsolutePath() {
              return supportAbsolutePath;
          }
  
          public boolean supportInheritance() {
              return supportInheritance;
          }
      }
  
      protected abstract Map<Class<? extends Annotation>, H.Method> annotationMethodLookup();
  
      protected abstract PathAnnotationSpec urlContextAnnotation();
  
      protected abstract boolean noDefaultPath();
  
      /**
       * Returns function that takes {@link ActionContext} as parameter and returns a {@link Result}. If
       * a non-null result is returned, then it will by pass the ActFramework handling process and return
       * directly, in which case the plugin literally hijack the ActFramework handling process.
       * <p>
       * The plugin might also do some changes to `ActionContext` and return `null` value in which case
       * ActFramework normal handling process still happens.
       *
       * @param controllerClass the controller class
       * @param actionMethod    the action method
       * @return a logic to be injected before ActFramework handling request
       */
      public $.Function<ActionContext, Result> beforeHandler(Class<?> controllerClass, Method actionMethod) {
          return $.f1();
      }
  
      private static final $.Func2<Result, ActionContext, Result> DUMB_AFTER_HANDLER = new $.F2<Result, ActionContext, Result>() {
          @Override
          public Result apply(Result result, ActionContext context) throws NotAppliedException, $.Break {
              return result;
          }
      };
  
      /**
       * Returns function that takes {@link Result} and {@link ActionContext} as parameter
       * and returns a {@link Result}. This function is called after ActFramework's processing
       * has finished.
       * <p>
       * The afterHandler allows plugin to inject logic to further process the returned result
       * or do some updates to `ActionContext` for example to change the response content type
       * etc.
       * <p>
       * The afterHandler shall always returns a result even if there is nothing to do with
       * it, it must return the result passed in.
       *
       * @param controllerClass the controller class
       * @param actionMethod    the action method
       * @return a logic to be injected before ActFramework handling request
       */
      public $.Func2<Result, ActionContext, Result> afterHandler(Class<?> controllerClass, Method actionMethod) {
          return DUMB_AFTER_HANDLER;
      }
  
      @Override
      public void register() {
          ControllerClassMetaInfo.registerMethodLookups(annotationMethodLookup(), noDefaultPath());
          ControllerClassMetaInfo.registerUrlContextAnnotation(urlContextAnnotation());
          Manager.INST.controllerPlugins.add(this);
      }
  
      public static class Manager extends ControllerPlugin {
  
          public static final Manager INST = new Manager();
  
          private List<ControllerPlugin> controllerPlugins = new ArrayList<>();
  
          @Override
          public $.Function<ActionContext, Result> beforeHandler(final Class<?> controllerClass, final Method actionMethod) {
              int size = controllerPlugins.size();
              switch (size) {
                  case 0:
                      return super.beforeHandler(controllerClass, actionMethod);
                  case 1:
                      return controllerPlugins.get(0).beforeHandler(controllerClass, actionMethod);
                  default:
                      return new $.Function<ActionContext, Result>() {
                          @Override
                          public Result apply(ActionContext context) throws NotAppliedException, $.Break {
                              for (ControllerPlugin plugin: controllerPlugins) {
                                  Result result = plugin.beforeHandler(controllerClass, actionMethod).apply(context);
                                  if (null != result) {
                                      return result;
                                  }
                              }
                              return null;
                          }
                      };
              }
          }
  
          @Override
          public $.Func2<Result, ActionContext, Result> afterHandler(final Class<?> controllerClass, final Method actionMethod) {
              int size = controllerPlugins.size();
              switch (size) {
                  case 0:
                      return super.afterHandler(controllerClass, actionMethod);
                  case 1:
                      return controllerPlugins.get(0).afterHandler(controllerClass, actionMethod);
                  default:
                      return new $.Func2<Result, ActionContext, Result>() {
                          @Override
                          public Result apply(Result result, ActionContext context) throws NotAppliedException, $.Break {
                              for (ControllerPlugin plugin: controllerPlugins) {
                                  result = plugin.afterHandler(controllerClass, actionMethod).apply(result, context);
                              }
                              return result;
                          }
                      };
              }
          }
  
          @Override
          protected Map<Class<? extends Annotation>, H.Method> annotationMethodLookup() {
              return C.Map();
          }
  
          @Override
          protected PathAnnotationSpec urlContextAnnotation() {
              return null;
          }
  
          @Override
          protected boolean noDefaultPath() {
              return false;
          }
  
          @Override
          public void register() {
          }
      }
  
  }
  