content: 
  /*
   * Copyright (C) 2012-present the original author or authors.
   * Modified by Ant Group in 2023
   * Copyright 2023 Ant Group
   *
   * 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.
   */
  
  package com.alipay.antchain.bridge.plugins.manager.pf4j.finder;
  
  import com.alipay.antchain.bridge.plugins.manager.pf4j.asm.AsmUtils;
  import com.alipay.antchain.bridge.plugins.manager.pf4j.asm.IAntChainBridgeServiceInfo;
  import org.pf4j.*;
  import org.pf4j.util.ClassUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.lang.annotation.Annotation;
  import java.util.*;
  
  public abstract class AbstractExtensionFinder implements ExtensionFinder, PluginStateListener {
  
      private static final Logger log = LoggerFactory.getLogger(AbstractExtensionFinder.class);
  
      protected PluginManager pluginManager;
      protected volatile Map<String, Set<String>> entries; // cache by pluginId
      protected volatile Map<String, IAntChainBridgeServiceInfo> extensionInfos; // cache extension infos by class name
      protected Boolean checkForExtensionDependencies = null;
  
      public AbstractExtensionFinder(PluginManager pluginManager) {
          this.pluginManager = pluginManager;
      }
  
      public abstract Map<String, Set<String>> readPluginsStorages();
  
      public abstract Map<String, Set<String>> readClasspathStorages();
  
      @Override
      @SuppressWarnings("unchecked")
      public <T> List<ExtensionWrapper<T>> find(Class<T> type) {
          log.debug("Finding extensions of extension point '{}'", type.getName());
          Map<String, Set<String>> entries = getEntries();
          List<ExtensionWrapper<T>> result = new ArrayList<>();
  
          // add extensions found in classpath and plugins
          for (String pluginId : entries.keySet()) {
              // classpath's extensions <=> pluginId = null
              List<ExtensionWrapper<T>> pluginExtensions = find(type, pluginId);
              result.addAll(pluginExtensions);
          }
  
          if (result.isEmpty()) {
              log.debug("No extensions found for extension point '{}'", type.getName());
          } else {
              log.debug("Found {} extensions for extension point '{}'", result.size(), type.getName());
          }
  
          // sort by "ordinal" property
          Collections.sort(result);
  
          return result;
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public <T> List<ExtensionWrapper<T>> find(Class<T> type, String pluginId) { // 目前类型被写死了，只能BBCServiceInfo
          log.debug("Finding extensions of extension point '{}' for plugin '{}'", type.getName(), pluginId);
          List<ExtensionWrapper<T>> result = new ArrayList<>();
  
          // classpath's extensions <=> pluginId = null
          Set<String> classNames = findClassNames(pluginId);
          if (classNames.isEmpty()) {
              return result;
          }
  
          if (pluginId != null) {
              PluginWrapper pluginWrapper = pluginManager.getPlugin(pluginId);
              if (PluginState.STARTED != pluginWrapper.getPluginState()) {
                  return result;
              }
  
              log.trace("Checking extensions from plugin '{}'", pluginId);
          } else {
              log.trace("Checking extensions from classpath");
          }
  
          ClassLoader classLoader = (pluginId != null) ? pluginManager.getPluginClassLoader(pluginId) : getClass().getClassLoader();
  
          for (String className : classNames) {
              try {
                  if (isCheckForExtensionDependencies()) {
                      // Load extension annotation without initializing the class itself.
                      //
                      // If optional dependencies are used, the class loader might not be able
                      // to load the extension class because of missing optional dependencies.
                      //
                      // Therefore we're extracting the extension annotation via asm, in order
                      // to extract the required plugins for an extension. Only if all required
                      // plugins are currently available and started, the corresponding
                      // extension is loaded through the class loader.
                      if (getExtensionInfo(className, classLoader) == null) {
                          log.error("No extension annotation was found for '{}'", className);
                          continue;
                      }
  
  //                    // Make sure, that all plugins required by this extension are available.
  //                    List<String> missingPluginIds = new ArrayList<>();
  //                    for (String requiredPluginId : extensionInfo.getProducts()) {
  //                        PluginWrapper requiredPlugin = pluginManager.getPlugin(requiredPluginId);
  //                        if (requiredPlugin == null || !PluginState.STARTED.equals(requiredPlugin.getPluginState())) {
  //                            missingPluginIds.add(requiredPluginId);
  //                        }
  //                    }
  //                    if (!missingPluginIds.isEmpty()) {
  //                        StringBuilder missing = new StringBuilder();
  //                        for (String missingPluginId : missingPluginIds) {
  //                            if (missing.length() > 0) missing.append(", ");
  //                            missing.append(missingPluginId);
  //                        }
  //                        log.trace("Extension '{}' is ignored due to missing plugins: {}", className, missing);
  //                        continue;
  //                    }
                  }
  
                  log.debug("Loading class '{}' using class loader '{}'", className, classLoader);
                  Class<?> extensionClass = classLoader.loadClass(className);
  
                  log.debug("Checking extension type '{}'", className);
                  if (type.isAssignableFrom(extensionClass)) {
                      ExtensionWrapper extensionWrapper = createExtensionWrapper(extensionClass);
                      result.add(extensionWrapper);
                      log.debug("Added extension '{}' with ordinal {}", className, extensionWrapper.getOrdinal());
                  } else {
                      log.trace("'{}' is not an extension for extension point '{}'", className, type.getName());
                      if (RuntimeMode.DEVELOPMENT.equals(pluginManager.getRuntimeMode())) {
                          checkDifferentClassLoaders(type, extensionClass);
                      }
                  }
              } catch (ClassNotFoundException | NoClassDefFoundError e) {
                  log.error(e.getMessage(), e);
              }
          }
  
          if (result.isEmpty()) {
              log.debug("No extensions found for extension point '{}'", type.getName());
          } else {
              log.debug("Found {} extensions for extension point '{}'", result.size(), type.getName());
          }
  
          // sort by "ordinal" property
          Collections.sort(result);
  
          return result;
      }
  
      @Override
      public List<ExtensionWrapper> find(String pluginId) {
          log.debug("Finding extensions from plugin '{}'", pluginId);
          List<ExtensionWrapper> result = new ArrayList<>();
  
          Set<String> classNames = findClassNames(pluginId);
          if (classNames.isEmpty()) {
              return result;
          }
  
          if (pluginId != null) {
              PluginWrapper pluginWrapper = pluginManager.getPlugin(pluginId);
              if (PluginState.STARTED != pluginWrapper.getPluginState()) {
                  return result;
              }
  
              log.trace("Checking extensions from plugin '{}'", pluginId);
          } else {
              log.trace("Checking extensions from classpath");
          }
  
          ClassLoader classLoader = (pluginId != null) ? pluginManager.getPluginClassLoader(pluginId) : getClass().getClassLoader();
  
          for (String className : classNames) {
              try {
                  log.debug("Loading class '{}' using class loader '{}'", className, classLoader);
                  Class<?> extensionClass = classLoader.loadClass(className);
  
                  ExtensionWrapper extensionWrapper = createExtensionWrapper(extensionClass);
                  result.add(extensionWrapper);
                  log.debug("Added extension '{}' with ordinal {}", className, extensionWrapper.getOrdinal());
              } catch (ClassNotFoundException | NoClassDefFoundError e) {
                  log.error(e.getMessage(), e);
              }
          }
  
          if (result.isEmpty()) {
              log.debug("No extensions found for plugin '{}'", pluginId);
          } else {
              log.debug("Found {} extensions for plugin '{}'", result.size(), pluginId);
          }
  
          // sort by "ordinal" property
          Collections.sort(result);
  
          return result;
      }
  
      @Override
      public Set<String> findClassNames(String pluginId) {
          Set<String> classNames = getEntries().get(pluginId);
          if (classNames == null) {
              return Collections.emptySet();
          }
  
          return classNames;
      }
  
      @Override
      public void pluginStateChanged(PluginStateEvent event) {
          // TODO optimize (do only for some transitions)
          // clear cache
          entries = null;
  
          // By default we're assuming, that no checks for extension dependencies are necessary.
          //
          // A plugin, that has an optional dependency to other plugins, might lead to unloadable
          // Java classes (NoClassDefFoundError) at application runtime due to possibly missing
          // dependencies. Therefore we're enabling the check for optional extensions, if the
          // started plugin contains at least one optional plugin dependency.
          if (checkForExtensionDependencies == null && PluginState.STARTED.equals(event.getPluginState())) {
              for (PluginDependency dependency : event.getPlugin().getDescriptor().getDependencies()) {
                  if (dependency.isOptional()) {
                      log.debug("Enable check for extension dependencies via ASM.");
                      checkForExtensionDependencies = true;
                      break;
                  }
              }
          }
      }
  
      /**
       * Returns true, if the extension finder checks extensions for its required plugins.
       * This feature has to be enabled, in order check the availability of
       * {@link Extension#plugins()} configured by an extension.
       * <p>
       * This feature is enabled by default, if at least one available plugin makes use of
       * optional plugin dependencies. Those optional plugins might not be available at runtime.
       * Therefore any extension is checked by default against available plugins before its
       * instantiation.
       * <p>
       * Notice: This feature requires the optional <a href="https://asm.ow2.io/">ASM library</a>
       * to be available on the applications classpath.
       *
       * @return true, if the extension finder checks extensions for its required plugins
       */
      public final boolean isCheckForExtensionDependencies() {
          return Boolean.TRUE.equals(checkForExtensionDependencies);
      }
  
      /**
       * Plugin developers may enable / disable checks for required plugins of an extension.
       * This feature has to be enabled, in order check the availability of
       * {@link Extension#plugins()} configured by an extension.
       * <p>
       * This feature is enabled by default, if at least one available plugin makes use of
       * optional plugin dependencies. Those optional plugins might not be available at runtime.
       * Therefore any extension is checked by default against available plugins before its
       * instantiation.
       * <p>
       * Notice: This feature requires the optional <a href="https://asm.ow2.io/">ASM library</a>
       * to be available on the applications classpath.
       *
       * @param checkForExtensionDependencies true to enable checks for optional extensions, otherwise false
       */
      public void setCheckForExtensionDependencies(boolean checkForExtensionDependencies) {
          this.checkForExtensionDependencies = checkForExtensionDependencies;
      }
  
      protected void debugExtensions(Set<String> extensions) {
          if (log.isDebugEnabled()) {
              if (extensions.isEmpty()) {
                  log.debug("No extensions found");
              } else {
                  log.debug("Found possible {} extensions:", extensions.size());
                  for (String extension : extensions) {
                      log.debug("   " + extension);
                  }
              }
          }
      }
  
      private Map<String, Set<String>> readStorages() {
          Map<String, Set<String>> result = new LinkedHashMap<>();
  
          result.putAll(readClasspathStorages());
          result.putAll(readPluginsStorages());
  
          return result;
      }
  
      private Map<String, Set<String>> getEntries() {
          if (entries == null) {
              entries = readStorages();
          }
  
          return entries;
      }
  
      /**
       * Returns the parameters of an {@link Extension} annotation without loading
       * the corresponding class into the class loader.
       *
       * @param className name of the class, that holds the requested {@link Extension} annotation
       * @param classLoader class loader to access the class
       * @return the contents of the {@link Extension} annotation or null, if the class does not
       * have an {@link Extension} annotation
       */
      private IAntChainBridgeServiceInfo getExtensionInfo(String className, ClassLoader classLoader) {
          if (extensionInfos == null) {
              extensionInfos = new HashMap<>();
          }
  
          if (!extensionInfos.containsKey(className)) {
              log.trace("Load annotation for '{}' using asm", className);
  
              IAntChainBridgeServiceInfo info = AsmUtils.load(className, classLoader);
              if (info == null) {
                  log.warn("No extension annotation was found for '{}'", className);
                  extensionInfos.put(className, null);
              } else {
                  extensionInfos.put(className, info);
              }
          }
  
          return extensionInfos.get(className);
      }
  
      private ExtensionWrapper createExtensionWrapper(Class<?> extensionClass) {
          Extension extensionAnnotation = findExtensionAnnotation(extensionClass);
          int ordinal = extensionAnnotation != null ? extensionAnnotation.ordinal() : 0;
          ExtensionDescriptor descriptor = new ExtensionDescriptor(ordinal, extensionClass);
  
          return new ExtensionWrapper<>(descriptor, pluginManager.getExtensionFactory());
      }
  
      public static Extension findExtensionAnnotation(Class<?> clazz) {
          if (clazz.isAnnotationPresent(Extension.class)) {
              return clazz.getAnnotation(Extension.class);
          }
  
          // search recursively through all annotations
          for (Annotation annotation : clazz.getAnnotations()) {
              Class<? extends Annotation> annotationClass = annotation.annotationType();
              if (!annotationClass.getName().startsWith("java.lang.annotation")) {
                  Extension extensionAnnotation = findExtensionAnnotation(annotationClass);
                  if (extensionAnnotation != null) {
                      return extensionAnnotation;
                  }
              }
          }
  
          return null;
      }
  
      private void checkDifferentClassLoaders(Class<?> type, Class<?> extensionClass) {
          ClassLoader typeClassLoader = type.getClassLoader(); // class loader of extension point
          ClassLoader extensionClassLoader = extensionClass.getClassLoader();
          boolean match = ClassUtils.getAllInterfacesNames(extensionClass).contains(type.getSimpleName());
          if (match && !extensionClassLoader.equals(typeClassLoader)) {
              // in this scenario the method 'isAssignableFrom' returns only FALSE
              // see http://www.coderanch.com/t/557846/java/java/FWIW-FYI-isAssignableFrom-isInstance-differing
              log.error("Different class loaders: '{}' (E) and '{}' (EP)", extensionClassLoader, typeClassLoader);
          }
      }
  
  }
  