/*

 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package jdk.tools.jlink.internal;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import java.util.Objects;

import java.util.ServiceLoader;

import jdk.tools.jlink.plugin.Plugin;

import jdk.tools.jlink.plugin.PluginException;

/**

 *

 * Plugin Providers repository. Plugin Providers are

 * retrieved thanks to the ServiceLoader mechanism.

 */

public final class PluginRepository {

    private PluginRepository() {

    }

    private static final Map<String, Plugin> registeredPlugins = new HashMap<>();

    /**

     * Retrieves the plugin associated to the passed name. If multiple providers

     * exist for the same name,

     * then an exception is thrown.

     * @param name The plugin provider name.

     * @param pluginsLayer

     * @return A provider or null if not found.

     */

    public static Plugin getPlugin(String name,

            ModuleLayer pluginsLayer) {

        return getPlugin(Plugin.class, name, pluginsLayer);

    }

    /**

     * Build plugin for the passed name.

     *

     * @param config Optional config.

     * @param name Non null name.

     * @param pluginsLayer

     * @return A plugin or null if no plugin found.

     */

    public static Plugin newPlugin(Map<String, String> config, String name,

            ModuleLayer pluginsLayer) {

        Objects.requireNonNull(name);

        Objects.requireNonNull(pluginsLayer);

        Plugin plugin = getPlugin(name, pluginsLayer);

        if (plugin != null) {

            try {

                plugin.configure(config);

            } catch (IllegalArgumentException e) {

                if (JlinkTask.DEBUG) {

                    System.err.println("Plugin " + plugin.getName() + " threw exception with config: " + config);

                    e.printStackTrace();

                }

                throw e;

            }

        }

        return plugin;

    }

    /**

     * Explicit registration of a plugin in the repository. Used by unit tests

     * @param plugin The plugin to register.

     */

    public synchronized static void registerPlugin(Plugin plugin) {

        Objects.requireNonNull(plugin);

        registeredPlugins.put(plugin.getName(), plugin);

    }

    /**

     * Explicit unregistration of a plugin in the repository. Used by unit

     * tests

     *

     * @param name Plugin name

     */

    public synchronized static void unregisterPlugin(String name) {

        Objects.requireNonNull(name);

        registeredPlugins.remove(name);

    }

    public static List<Plugin> getPlugins(ModuleLayer pluginsLayer) {

        return getPlugins(Plugin.class, pluginsLayer);

    }

    private static <T extends Plugin> T getPlugin(Class<T> clazz, String name,

            ModuleLayer pluginsLayer) {

        Objects.requireNonNull(name);

        Objects.requireNonNull(pluginsLayer);

        @SuppressWarnings("unchecked")

        T provider = null;

        List<T> javaProviders = getPlugins(clazz, pluginsLayer);

        for(T factory : javaProviders) {

            if (factory.getName().equals(name)) {

                if (provider != null) {

                    throw new PluginException("Multiple plugin "

                            + "for the name " + name);

                }

                provider = factory;

            }

        }

        return provider;

    }

    /**

     * The plugins accessible in the current context.

     *

     * @param pluginsLayer

     * @return The list of plugins.

     */

    private static <T extends Plugin> List<T> getPlugins(Class<T> clazz, ModuleLayer pluginsLayer) {

        Objects.requireNonNull(pluginsLayer);

        List<T> factories = new ArrayList<>();

        try {

            Iterator<T> providers

                    = ServiceLoader.load(pluginsLayer, clazz).iterator();

            while (providers.hasNext()) {

                factories.add(providers.next());

            }

            registeredPlugins.values().stream().forEach((fact) -> {

                if (clazz.isInstance(fact)) {

                    @SuppressWarnings("unchecked")

                    T trans = (T) fact;

                    factories.add(trans);

                }

            });

            return factories;

        } catch (Exception ex) {

            throw new PluginException(ex);

        }

    }

}