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/**
 * Copyright (c) 1998-2018 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source 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, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *
 *   Free SoftwareFoundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.loader;

import com.caucho.config.ConfigException;
import com.caucho.config.Configurable;
import com.caucho.vfs.JarPath;
import com.caucho.vfs.Path;

import javax.annotation.PostConstruct;
import java.net.URL;
import java.security.CodeSource;
import java.security.cert.Certificate;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Class loader which checks for changes in class files and automatically
 * picks up new jars.
 */
@Configurable
public class SimpleLoader extends Loader {
  private static Logger _log;
  
  // The class directory
  private Path _path;
  private String _prefix;
  private String _pathPrefix;

  private CodeSource _codeSource;

  /**
   * Null constructor for the simple loader.
   */
  public SimpleLoader()
  {
  }
  
  public SimpleLoader(ClassLoader loader)
  {
    super(loader);
  }

  /**
   * Creates the simple loader with the specified path.
   *
   * @param path specifying the root of the resources
   */
  public SimpleLoader(DynamicClassLoader loader, Path path)
  {
    this(loader);
    
    setPath(path);
  }

  /**
   * Creates the simple loader with the specified path and prefix.
   *
   * @param path specifying the root of the resources
   * @param prefix the prefix that the resources must match
   */
  public SimpleLoader(DynamicClassLoader loader, Path path, String prefix)
  {
    this(loader);
    
    setPath(path);
    setPrefix(prefix);
  }

  /**
   * Create a class loader based on the SimpleLoader
   *
   * @param parent parent class loader
   * @param path traditional classpath
   * @param prefix the class prefix restriction
   *
   * @return the new ClassLoader
   */
  public static DynamicClassLoader create(ClassLoader parent,
                                          Path path,
                                          String prefix)
  {
    DynamicClassLoader loader = new DynamicClassLoader(parent, false, true);

    SimpleLoader simpleLoader = new SimpleLoader(loader, path, prefix);
    simpleLoader.init();
    
    loader.addLoader(simpleLoader);

    loader.init();

    return loader;
  }

  /**
   * Create a class loader based on the SimpleLoader
   *
   * @param parent parent class loader
   * @param path traditional classpath
   *
   * @return the new ClassLoader
   */
  public static DynamicClassLoader create(ClassLoader parent,
                                          Path path)
  {
    DynamicClassLoader loader = new DynamicClassLoader(parent, false, false);

    loader.addLoader(new SimpleLoader(loader, path));

    loader.init();
    
    return loader;
  }

  /**
   * Create a class loader based on the SimpleLoader
   *
   * @param path traditional classpath
   *
   * @return the new ClassLoader
   */
  public static DynamicClassLoader create(Path path)
  {
    ClassLoader parent = Thread.currentThread().getContextClassLoader();

    return create(parent, path);
  }

  /**
   * Sets the resource directory.
   */
  public void setPath(Path path)
  {
    if (path.getPath().endsWith(".jar")
        || path.getPath().endsWith(".zip")) {
      path = JarPath.create(path);
    }

    _path = path;
  }

  /**
   * Gets the resource path.
   */
  public Path getPath()
  {
    return _path;
  }

  /**
   * Sets the resource prefix
   */
  public void setPrefix(String prefix)
  {
    _prefix = prefix;
    
    if (prefix != null)
      _pathPrefix = prefix.replace('.', '/');
  }

  /**
   * Gets the resource prefix
   */
  public String getPrefix()
  {
    return _prefix;
  }

  /**
   * Sets the owning class loader.
   */
  @Override
  public void setLoader(DynamicClassLoader loader)
  {
    super.setLoader(loader);
  }
  
  /**
   * The simple-loader scans class directories.
   */
  @Override
  public boolean isDirectoryLoader()
  {
    return true;
  }

  /**
   * Initializes the loader.
   */
  @PostConstruct
  @Override
  public void init()
    throws ConfigException
  {
    try {
      _codeSource = new CodeSource(new URL(_path.getURL()),
                                   (Certificate []) null);
    } catch (Exception e) {
      log().log(Level.FINE, e.toString(), e);
    }
    
    super.init();

    getClassLoader().addURL(_path);
  }

  /**
   * Given a class or resource name, returns a patch to that resource.
   *
   * @param name the class or resource name.
   *
   * @return the path representing the class or resource.
   */
  @Override
  public Path getPath(String name)
  {
    if (_prefix != null && _pathPrefix == null) {
      _pathPrefix = _prefix.replace('.', '/');
    }
    
    if (_pathPrefix != null && ! name.startsWith(_pathPrefix)) {
      return null;
    }
    
    return lookupPath(_path, name);
  }

  /**
   * Returns the code source for the directory.
   */
  @Override
  protected CodeSource getCodeSource(Path path)
  {
    return _codeSource;
  }

  /**
   * Adds the class of this resource.
   */
  @Override
  protected void buildClassPath(ArrayList pathList)
  {
    String path = null;
    
    if (_path instanceof JarPath)
      path = ((JarPath) _path).getContainer().getNativePath();
    else if (_path.isDirectory())
      path = _path.getNativePath();

    if (path != null && ! pathList.contains(path))
      pathList.add(path);
  }
  
  private static Logger log()
  {
    if (_log == null) {
      _log = Logger.getLogger(SimpleLoader.class.getName());
    }
    
    return _log;
  }

  /**
   * Returns a printable representation of the loader.
   */
  @Override
  public String toString()
  {
    if (_prefix != null)
      return getClass().getSimpleName() + "[" + _path + ",prefix=" + _prefix + "]";
    else
      return getClass().getSimpleName() + "[" + _path + "]";
  }
}