content: package act.handler.builtin.controller;
  
  /*-
   * #%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.app.ActionContext;
  import act.plugin.Plugin;
  import act.security.CORS;
  import org.osgl.mvc.result.Result;
  import org.osgl.util.C;
  import org.osgl.util.E;
  
  import java.util.Comparator;
  import java.util.List;
  
  public abstract class ExceptionInterceptor
          extends Handler<ExceptionInterceptor>
          implements Plugin, ExceptionInterceptorInvoker, Comparable<ExceptionInterceptor> {
  
      private List<Class<? extends Exception>> exClasses;
  
      public ExceptionInterceptor() {
          this(0);
      }
  
      @SuppressWarnings("unchecked")
      public ExceptionInterceptor(Integer priority) {
          this(priority, new Class[]{});
      }
  
      public ExceptionInterceptor(Class<? extends Exception>... exClasses) {
          this(0, exClasses);
      }
  
      public ExceptionInterceptor(Integer priority, Class<? extends Exception>... exClasses) {
          super(priority);
          this.exClasses = C.listOf(exClasses).sorted(EXCEPTION_WEIGHT_COMPARATOR);
      }
  
      public ExceptionInterceptor(Integer priority, List<Class<? extends Exception>> exClasses) {
          super(priority);
          E.illegalArgumentIf(exClasses.isEmpty());
          this.exClasses = C.list(exClasses).sorted(EXCEPTION_WEIGHT_COMPARATOR);
      }
  
      @Override
      public Result handle(Exception e, ActionContext actionContext) throws Exception {
          if (exClasses.isEmpty()) {
              return internalHandle(e, actionContext);
          }
          for (Class<? extends Exception> c : exClasses) {
              if (c.isInstance(e)) {
                  return internalHandle(e, actionContext);
              }
          }
          return null;
      }
  
      @Override
      public int compareTo(ExceptionInterceptor o) {
          if (o == this) return 0;
          boolean iAmEmpty = exClasses.isEmpty(), uAreEmpty = o.exClasses.isEmpty();
          if (iAmEmpty) {
              return uAreEmpty ? 0 : 1;
          } else if (uAreEmpty) {
              return -1;
          }
          return EXCEPTION_WEIGHT_COMPARATOR.compare(o.exClasses.get(0), exClasses.get(0));
      }
  
      @Override
      public CORS.Spec corsSpec() {
          return CORS.Spec.DUMB;
      }
  
      protected abstract Result internalHandle(Exception e, ActionContext actionContext) throws Exception;
  
      @Override
      public void register() {
          RequestHandlerProxy.registerGlobalInterceptor(this);
      }
  
      public static Comparator<Class<? extends Exception>> EXCEPTION_WEIGHT_COMPARATOR = new Comparator<Class<? extends Exception>>() {
          @Override
          public int compare(Class<? extends Exception> o1, Class<? extends Exception> o2) {
              return weight(o1) - weight(o2);
          }
      };
  
      public static int weight(Class c) {
          int i = 0;
          while (c != Object.class) {
              i++;
              c = c.getSuperclass();
          }
          return i;
      }
  }
  