001/*
002 * Copyright (C) 2012 eXo Platform SAS.
003 *
004 * This is free software; you can redistribute it and/or modify it
005 * under the terms of the GNU Lesser General Public License as
006 * published by the Free Software Foundation; either version 2.1 of
007 * the License, or (at your option) any later version.
008 *
009 * This software is distributed in the hope that it will be useful,
010 * but WITHOUT ANY WARRANTY; without even the implied warranty of
011 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012 * Lesser General Public License for more details.
013 *
014 * You should have received a copy of the GNU Lesser General Public
015 * License along with this software; if not, write to the Free
016 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
017 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
018 */
019package org.crsh.shell.impl.command.spi;
020
021import org.crsh.plugin.CRaSHPlugin;
022import org.crsh.plugin.PluginContext;
023
024import java.lang.reflect.Constructor;
025import java.util.HashMap;
026import java.util.Set;
027import java.util.concurrent.atomic.AtomicReference;
028
029/**
030 * A command manager that is able to load a command manager via reflection.
031 *
032 * @author Julien Viet
033 */
034public class CommandManagerProxy extends CRaSHPlugin<CommandManager> implements CommandManager {
035
036  /** . */
037  private final AtomicReference<CommandManager> real = new AtomicReference<CommandManager>();
038
039  /** . */
040  private final String name;
041
042  /** . */
043  private final String className;
044
045  /** . */
046  private final Set<String> ext;
047
048  public CommandManagerProxy(String name, String className, Set<String> ext) {
049    this.name = name;
050    this.className = className;
051    this.ext = ext;
052  }
053
054  @Override
055  public CommandManager getImplementation() {
056    return this;
057  }
058
059  @Override
060  public void init() {
061    try {
062      Class<CommandManager> mgrClass = (Class<CommandManager>)CommandManagerProxy.class.getClassLoader().loadClass(className);
063      Constructor<CommandManager> mgrCtor = mgrClass.getConstructor(PluginContext.class);
064      CommandManager mgr = mgrCtor.newInstance(getContext());
065      real.set(mgr);
066    }
067    catch (Exception e) {
068      log.info("Plugin is inactive");
069    }
070    catch (NoClassDefFoundError e) {
071      log.info("Plugin is inactive");
072    }
073  }
074
075  @Override
076  public boolean isActive() {
077    return real.get() != null;
078  }
079
080  @Override
081  public Set<String> getExtensions() {
082    return ext;
083  }
084
085  @Override
086  public CommandResolution resolveCommand(String name, byte[] source) throws CommandCreationException, NullPointerException {
087    CommandManager mgr = real.get();
088    if (mgr != null) {
089      return mgr.resolveCommand(name, source);
090    } else {
091      throw new IllegalStateException(name + " command manager is not available");
092    }
093  }
094
095  @Override
096  public void init(HashMap<String, Object> session) {
097    CommandManager mgr = real.get();
098    if (mgr != null) {
099      mgr.init(session);
100    } else {
101      throw new IllegalStateException(name + " command manager is not available");
102    }
103  }
104
105  @Override
106  public void destroy(HashMap<String, Object> session) {
107    CommandManager mgr = real.get();
108    if (mgr != null) {
109      mgr.destroy(session);
110    } else {
111      throw new IllegalStateException(name + " command manager is not available");
112    }
113  }
114
115  @Override
116  public String doCallBack(HashMap<String, Object> session, String name, String defaultValue) {
117    CommandManager mgr = real.get();
118    if (mgr != null) {
119      return mgr.doCallBack(session, name, defaultValue);
120    } else {
121      throw new IllegalStateException(name + " command manager is not available");
122    }
123  }
124}