content: /*
   *  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.causeway.core.codegen.bytebuddy.services;
  
  import java.lang.invoke.MethodHandle;
  import java.lang.invoke.MethodHandles;
  import java.lang.reflect.Method;
  
  import org.apache.causeway.commons.internal.exceptions._Exceptions;
  
  import org.jspecify.annotations.NonNull;
  import lombok.SneakyThrows;
  import net.bytebuddy.dynamic.loading.ClassInjector;
  import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
  
  /**
   * package private utility to advise on the ClassLoadingStrategy, dependent on the JVM version we are running on
   *
   * see <a href="https://mydailyjava.blogspot.com/2018/04/jdk-11-and-proxies-in-world-past.html">byte-buddy blog</a>
   */
  record ClassLoadingStrategyAdvisor(MethodHandle privateLookupMethodHandle) {
  
      ClassLoadingStrategyAdvisor() {
          this(createPrivateLookupMethodHandle());
      }
  
      public ClassLoadingStrategy<ClassLoader> getSuitableStrategy(final Class<?> targetClass) {
          try {
              final Object privateLookup = invokeLookup(privateLookupMethodHandle, targetClass);
              return ClassLoadingStrategy.UsingLookup.of(privateLookup);
          } catch (Throwable e) {
              throw _Exceptions.illegalState(e,
                      "Failed to utilize code generation strategy on class '%s'",
                      targetClass.getName());
          }
      }
  
      // -- HELPER
  
      @SneakyThrows
      private static Object invokeLookup(final @NonNull MethodHandle mh, final Class<?> targetClass) {
          return mh.invoke(reads(targetClass), MethodHandles.lookup());
      }
  
      private static MethodHandle createPrivateLookupMethodHandle() {
          // JDK 9+ required
          if (!ClassInjector.UsingLookup.isAvailable()) {
              throw new IllegalStateException("No code generation strategy available");
          }
          try {
              final Method privateLookupIn = java.lang.invoke.MethodHandles.class
                      .getMethod("privateLookupIn",
                          Class.class,
                          java.lang.invoke.MethodHandles.Lookup.class);
              return MethodHandles.publicLookup().unreflect(privateLookupIn);
          } catch (Throwable e) {
              throw _Exceptions.illegalState(e,
                      "MethodHandles.privateLookupIn(...) is not available");
          }
      }
  
      private static Class<?> reads(final Class<?> cls) {
          final Class<?> otherClass = cls.isArray() ? cls.getComponentType() : cls;
          final Module otherModule = otherClass.getModule();
          //no need for unnamed and java.base types
          if (!otherModule.isNamed()
                  || "java.base".equals(otherModule.getName())) {
              return cls;
          }
          thisModule().addReads(otherModule);
          return cls;
      }
  
      private static Module thisModule() {
          return ClassLoadingStrategyAdvisor.class.getModule();
      }
  
  }
  