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 */
019
020package org.crsh.shell.impl.command;
021
022import org.crsh.command.CommandCreationException;
023import org.crsh.command.ShellCommand;
024import org.crsh.plugin.PluginContext;
025import org.crsh.plugin.ResourceKind;
026import org.crsh.util.TimestampedObject;
027import org.crsh.vfs.Resource;
028
029import java.security.Principal;
030import java.util.ArrayList;
031import java.util.HashMap;
032import java.util.Map;
033import java.util.concurrent.ConcurrentHashMap;
034
035public class CRaSH {
036
037  /** . */
038  final PluginContext context;
039
040  /** . */
041  final HashMap<String, CommandManager> managers;
042
043  /** . */
044  private final Map<String, TimestampedObject<CommandResolution>> commandCache = new ConcurrentHashMap<String, TimestampedObject<CommandResolution>>();
045
046  /**
047   * Create a new CRaSH.
048   *
049   * @param context the plugin context
050   * @throws NullPointerException if the context argument is null
051   */
052  public CRaSH(PluginContext context) throws NullPointerException {
053
054    //
055    HashMap<String, CommandManager> managers = new HashMap<String, CommandManager>();
056    for (CommandManager manager : context.getPlugins(CommandManager.class)) {
057      for (String ext : manager.getExtensions()) {
058        managers.put(ext, manager);
059      }
060    }
061
062
063    this.context = context;
064    this.managers = managers;
065  }
066
067  public CRaSHSession createSession(Principal user) {
068    return new CRaSHSession(this, user);
069  }
070
071  /**
072   * Returns the plugin context.
073   *
074   * @return the plugin context
075   */
076  public PluginContext getContext() {
077    return context;
078  }
079
080  /**
081   * Attempt to obtain a command description. Null is returned when such command does not exist.
082   *
083   * @param name the command name
084   * @return a command description
085   * @throws org.crsh.command.CommandCreationException if an error occured preventing the command creation
086   * @throws NullPointerException if the name argument is null
087   */
088  public String getCommandDescription(String name) throws CommandCreationException, NullPointerException {
089    CommandResolution resolution = resolveCommand(name);
090    return resolution != null ? resolution.getDescription() : null;
091  }
092
093  /**
094   * Attempt to obtain a command instance. Null is returned when such command does not exist.
095   *
096   * @param name the command name
097   * @return a command instance
098   * @throws org.crsh.command.CommandCreationException if an error occured preventing the command creation
099   * @throws NullPointerException if the name argument is null
100   */
101  public ShellCommand getCommand(String name) throws CommandCreationException, NullPointerException {
102    CommandResolution resolution = resolveCommand(name);
103    return resolution != null ? resolution.getCommand() : null;
104  }
105
106  /**
107   * Attempt to obtain a command instance. Null is returned when such command does not exist.
108   *
109   * @param name the command name
110   * @return a command instance
111   * @throws org.crsh.command.CommandCreationException if an error occured preventing the command creation
112   * @throws NullPointerException if the name argument is null
113   */
114  public CommandResolution resolveCommand(String name) throws CommandCreationException, NullPointerException {
115    if (name == null) {
116      throw new NullPointerException("No null name accepted");
117    }
118    for (CommandManager manager : managers.values()) {
119      for (String ext : manager.getExtensions()) {
120        Iterable<Resource> resources = context.loadResources(name + "." + ext, ResourceKind.COMMAND);
121        for (Resource resource : resources) {
122          CommandResolution resolution = resolveCommand(manager, name, resource);
123          if (resolution != null) {
124            return resolution;
125          }
126        }
127      }
128    }
129    return null;
130  }
131
132  public Iterable<String> getCommandNames() {
133    ArrayList<String> names = new ArrayList<String>();
134    for (String resourceName : context.listResources(ResourceKind.COMMAND)) {
135      int index = resourceName.indexOf('.');
136      String name = resourceName.substring(0, index);
137      String ext = resourceName.substring(index + 1);
138      if (managers.containsKey(ext)) {
139        names.add(name);
140      }
141    }
142    return names;
143  }
144
145  private CommandResolution resolveCommand(CommandManager manager, String name, Resource script) throws CommandCreationException {
146    TimestampedObject<CommandResolution> ref = commandCache.get(name);
147    if (ref != null) {
148      if (script.getTimestamp() != ref.getTimestamp()) {
149        ref = null;
150      }
151    }
152    CommandResolution command;
153    if (ref == null) {
154      command = manager.resolveCommand(name, script.getContent());
155      if (command != null) {
156        commandCache.put(name, new TimestampedObject<CommandResolution>(script.getTimestamp(), command));
157      }
158    } else {
159      command = ref.getObject();
160    }
161    return command;
162  }
163}