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/*
 * 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.eventmesh.spi.loader;

import org.apache.eventmesh.spi.EventMeshSPI;
import org.apache.eventmesh.spi.ExtensionException;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;

import com.google.common.base.Joiner;
import com.google.common.collect.Lists;

import lombok.extern.slf4j.Slf4j;

/**
 * Load extension from '${eventMeshPluginDir}', the default loading directory is './plugin'
 */
@Slf4j
public class JarExtensionClassLoader implements ExtensionClassLoader {

    private static final String EVENT_MESH_PLUGIN_DIR = "eventMeshPluginDir";

    private static final String EVENTMESH_EXTENSION_PLUGIN_DIR = System.getProperty(EVENT_MESH_PLUGIN_DIR,
        Joiner.on(File.separator).join(Lists.newArrayList(".", "plugin")));

    private static final JarExtensionClassLoader INSTANCE = new JarExtensionClassLoader();

    private final ConcurrentHashMap, Map>> extensionClassCache = new ConcurrentHashMap<>(16);

    private JarExtensionClassLoader() {

    }

    public static JarExtensionClassLoader getInstance() {
        return INSTANCE;
    }

    @Override
    public  Map> loadExtensionClass(Class extensionType, String extensionInstanceName) {
        return extensionClassCache.computeIfAbsent(extensionType, this::doLoadExtensionClass);
    }

    private  Map> doLoadExtensionClass(Class extensionType) {
        Map> extensionMap = new HashMap<>(16);
        EventMeshSPI eventMeshSpiAnnotation = extensionType.getAnnotation(EventMeshSPI.class);

        String pluginDir = Paths.get(EVENTMESH_EXTENSION_PLUGIN_DIR, eventMeshSpiAnnotation.eventMeshExtensionType().getExtensionTypeName())
            .toString();

        String extensionFileName = EventMeshExtensionConstant.EVENTMESH_EXTENSION_META_DIR + extensionType.getName();
        EventMeshUrlClassLoader urlClassLoader = EventMeshUrlClassLoader.getInstance();
        urlClassLoader.addUrls(loadJarPathFromResource(pluginDir));
        try {
            Enumeration extensionUrls = urlClassLoader.getResources(extensionFileName);
            if (extensionUrls != null) {
                while (extensionUrls.hasMoreElements()) {
                    URL url = extensionUrls.nextElement();
                    extensionMap.putAll(loadResources(urlClassLoader, url, extensionType));
                }
            }
        } catch (IOException e) {
            throw new ExtensionException("load extension class error", e);
        }
        return extensionMap;
    }

    private List loadJarPathFromResource(String pluginPath) {
        File plugin = new File(pluginPath);
        if (!plugin.exists()) {
            log.warn("plugin dir:{} is not exist", pluginPath);
            return Lists.newArrayList();
        }
        if (plugin.isFile() && plugin.getName().endsWith(".jar")) {
            try {
                return Lists.newArrayList(plugin.toURI().toURL());
            } catch (Exception e) {
                throw new ExtensionException(e);
            }
        }
        File[] files = plugin.listFiles();
        List pluginUrls = new ArrayList<>();
        if (files != null) {
            for (File file : files) {
                pluginUrls.addAll(loadJarPathFromResource(file.getPath()));
            }
        }
        // Sort the path here just to guarantee load the ConsumeMessageConcurrentlyService
        // defined in EventMesh rather than defined in rocketmq
        pluginUrls.sort(Comparator.comparing(URL::getPath));
        return pluginUrls;
    }

    private  Map> loadResources(URLClassLoader urlClassLoader, URL url, Class extensionType) throws IOException {
        Map> extensionMap = new HashMap<>();
        try (InputStream inputStream = url.openStream()) {
            Properties properties = new Properties();
            properties.load(inputStream);
            properties.forEach((extensionName, extensionClass) -> {
                String extensionNameStr = (String) extensionName;
                String extensionClassStr = (String) extensionClass;
                try {
                    Class targetClass = urlClassLoader.loadClass(extensionClassStr);
                    log.info("load extension class success, extensionType: {}, extensionClass: {}", extensionType, targetClass);
                    if (!extensionType.isAssignableFrom(targetClass)) {
                        throw new ExtensionException(
                            String.format("class: %s is not subClass of %s", targetClass, extensionType));
                    }
                    extensionMap.put(extensionNameStr, targetClass);
                } catch (ClassNotFoundException e) {
                    throw new ExtensionException("load extension class error", e);
                }
            });
        }
        return extensionMap;
    }
}