// Copyright (C) 2012 The Android Open Source Project
//
// 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.google.gerrit.sshd;

import com.google.gerrit.server.plugins.Plugin;
import com.google.gerrit.server.plugins.ReloadPluginListener;
import com.google.gerrit.server.plugins.StartPluginListener;
import com.google.inject.Inject;
import com.google.inject.Key;
import com.google.inject.Provider;
import com.google.inject.Singleton;

import org.apache.sshd.server.Command;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Singleton
class SshPluginStarterCallback
    implements StartPluginListener, ReloadPluginListener {
  private static final Logger log = LoggerFactory
      .getLogger(SshPluginStarterCallback.class);

  private final DispatchCommandProvider root;

  @Inject
  SshPluginStarterCallback(
      @CommandName(Commands.ROOT) DispatchCommandProvider root) {
    this.root = root;
  }

  @Override
  public void onStartPlugin(Plugin plugin) {
    Provider<Command> cmd = load(plugin);
    if (cmd != null) {
      plugin.add(root.register(Commands.named(plugin.getName()), cmd));
    }
  }

  @Override
  public void onReloadPlugin(Plugin oldPlugin, Plugin newPlugin) {
    Provider<Command> cmd = load(newPlugin);
    if (cmd != null) {
      newPlugin.add(root.replace(Commands.named(newPlugin.getName()), cmd));
    }
  }

  private Provider<Command> load(Plugin plugin) {
    if (plugin.getSshInjector() != null) {
      Key<Command> key = Commands.key(plugin.getName());
      try {
        return plugin.getSshInjector().getProvider(key);
      } catch (RuntimeException err) {
        log.warn(String.format(
            "Plugin %s did not define its top-level command",
            plugin.getName()), err);
      }
    }
    return null;
  }
}