/*
    * 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.commons.weaver.privilizer;
  
  import java.io.InputStream;
  import java.lang.annotation.ElementType;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.weaver.model.ScanRequest;
  import org.apache.commons.weaver.model.Scanner;
  import org.apache.commons.weaver.model.WeavableClass;
  import org.apache.commons.weaver.model.WeaveEnvironment;
  import org.apache.commons.weaver.model.WeaveInterest;
  import org.apache.commons.weaver.spi.Cleaner;
  import org.objectweb.asm.ClassReader;
  import org.objectweb.asm.ClassVisitor;
  
  /**
   * Removes classes privilized with a different policy.
   */
  public class PrivilizerCleaner implements Cleaner {
  
      @Override
      public boolean clean(final WeaveEnvironment environment, final Scanner scanner) {
          final Privilizer privilizer = new Privilizer(environment);
  
          final List<String> toDelete = new ArrayList<>();
  
          final ScanRequest scanRequest = new ScanRequest().add(WeaveInterest.of(Privilized.class, ElementType.TYPE));
  
          environment.debug("Cleaning classes privilized with policy other than %s", privilizer.policy);
          for (final WeavableClass<?> weavableClass : scanner.scan(scanRequest).getClasses().with(Privilized.class)) {
              final Policy privilizedPolicy = Policy.valueOf(weavableClass.getAnnotation(Privilized.class).value());
              if (privilizedPolicy == privilizer.policy) {
                  continue;
              }
              final String className = weavableClass.getTarget().getName();
              environment.debug("Class %s privilized with %s; deleting.", className, privilizedPolicy);
  
              try (InputStream bytecode = privilizer.env.getClassfile(className).getInputStream()) {
                  final ClassReader classReader = new ClassReader(bytecode);
                  classReader.accept(new ClassVisitor(Privilizer.ASM_VERSION) {
                      @Override
                      @SuppressWarnings("PMD.UseVarargs") // overridden method
                      public void visit(final int version, final int access, final String name, final String signature,
                          final String superName, final String[] interfaces) {
                          toDelete.add(name);
                      }
  
                      @Override
                      public void visitInnerClass(final String name, final String outerName, final String innerName,
                          final int access) {
                          if (toDelete.contains(outerName)) {
                              toDelete.add(name);
                          }
                      }
                  }, ClassReader.SKIP_CODE + ClassReader.SKIP_DEBUG + ClassReader.SKIP_FRAMES);
              } catch (final Exception e) {
                  throw new IllegalStateException(e);
              }
          }
          boolean result = false;
          for (final String className : toDelete) {
              final String resourcePath = toResourcePath(className);
              final boolean success = environment.deleteResource(resourcePath);
              environment.debug("Deletion of resource %s was %ssuccessful.", resourcePath, success ? "" : "un");
              result |= success;
          }
          return result;
      }
  
      private static String toResourcePath(final String className) {
          return className.replace('.', '/') + ".class";
      }
  
  }