/*
    *  XNap - A P2P framework and client.
    *
    *  See the file AUTHORS for copyright information.
    *
    *  This program 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.
    *
   *  This program 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 for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; if not, write to the Free Software
   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  package org.xnap.gui.component;
  
  import java.io.File;
  import java.io.FileFilter;
  
  import javax.swing.DefaultComboBoxModel;
  
  import org.apache.log4j.Logger;
  import org.xnap.util.FileHelper;
  
  /***
   * This class provides completion for path prefixes on the local file system.
   */
  public class FileCompletionModel extends DefaultComboBoxModel 
  	implements CompletionModel
  {
  	//--- Constant(s) ---
  
  	//--- Data field(s) ---
  
  	private boolean completeOnlyDirectories = false;
  
  	private FileFilter dirFilter = new DirectoryFileFilter();
  
      private static Logger logger = Logger.getLogger(FileCompletionModel.class);
  	
  	//--- Constructor(s) ---
  
  	/***
  	 * Constructs a new file completion model.
  	 *
  	 * @param completeOnlyDirectories if true only subdirectories are
  	 * suggested as possible completions, otherwise files are taken into
  	 * account too 
  	 */
      public FileCompletionModel(boolean completeOnlyDirectories)
  	{
  		this.completeOnlyDirectories = completeOnlyDirectories;
  	}
  
  	/***
  	 * Constructs a new file completion model.
  	 *
  	 * The default setting is to complete subdirectories and files.
  	 */
  	public FileCompletionModel()
  	{
  		this(false);
  	}
  
      //--- Method(s) ---
  
  	/***
  	 * Returns true if there are files in the local file system having the
  	 * given prefix.
  	 *
  	 * First we test if the given prefix denotes a file which exists and is a
  	 * directory. If that is the case all the files contained in that
  	 * directory are added to the model.
  	 * 
  	 * Regardless of the above results the parent directory if there is one is
  	 * searched for files matching the prefix. Thus we get all possible
  	 * completions that make sense.
  	 */
  	public boolean complete(String prefix)
  	{
  		removeAllElements();
  
  		File file = new File(prefix);
  		if (file.exists() && file.isDirectory()) {
  			File[] files = file.listFiles(dirFilter);
  			for (int i = 0; files != null && i < files.length; i++) {
  				addElement(files[i].getAbsolutePath());
  			}
  		}
  		/* look for files in the parent directory having file.getName() as
             prefix.  */
  		/* else */ if (file.getParentFile() != null) {
  			File[] files = file.getParentFile().listFiles
  				(new PrefixFileFilter(file.getName()));
  			for (int i = 0; files != null && i < files.length; i++) {
 				addElement(files[i].getAbsolutePath());
 			}
 		}
 		return getSize() > 0;
 	}
 
 	/***
 	 * This method's behaviour is a matter of taste.
 	 *
 	 * It first checks if the given prefix is an existing directory. If that
 	 * is the case the commmon unique prefix of all files found in the
 	 * directory is returned.
 	 *
 	 * Only if the above fails the parent directory is searched for the common
 	 * unique prefix.
 	 */
 	public String completeUniquePrefix(String prefix)
 	{
 		File file = new File(prefix);
 		if (file.exists() && file.isDirectory()) {
 			File[] files = file.listFiles(dirFilter);
 			StringBuffer sb = new StringBuffer
 				(FileHelper.appendSeparator(file.getAbsolutePath()));
 			for (int i = 0; matches(files, i); i++) {
 				sb.append(files[0].getName().charAt(i));
 			}
 			return sb.toString();
 		}
 		else if (file.getParentFile() != null) {
 			File[] files = file.getParentFile().listFiles
 				(new PrefixFileFilter(file.getName()));
 			StringBuffer sb = new StringBuffer
 				(FileHelper.appendSeparator
 				 (file.getParentFile().getAbsolutePath()));
 			for (int i = 0; matches(files, i); i++) {
 				sb.append(files[0].getName().charAt(i));
 			}
 			return sb.toString();
 		}
 		return prefix;
 	}
 
 	/***
 	 * Returns true if all files in the given array have the same character at
 	 * position <code>index</code>.
 	 *
 	 * @param files the array of files, can be null or empty
 	 * @param index the position in the filenames that is tested for equality
 	 * @return false if the array is null or empty, true if all filenames of
 	 * the files in the array have the same character at position
 	 * <code>index</code> 
 	 */
 	private boolean matches(File[] files, int index)
 	{
 		if (files == null || files.length == 0) {
 			return false;
 		}
 		if (files.length == 1) {
 			return index < files[0].getName().length();
 		}
 		for (int i = 0; i < files.length - 1; i++) {
 			if (files[i].getName().length() == index 
 				|| files[i+1].getName().length() == index) {
 				return false;
 			}
 			else if (files[i].getName().charAt(index) 
 					 != files[i+1].getName().charAt(index)) {
 				return false;
 			}
 		}
 		return true;
 	}
 
 	/***
 	 * Does nothing, since we don't do any data keeping of our own.
 	 */
 	public void insert(Object object)
 	{
 
 	}
 
 	/***
 	 * Does nothing, since we don't do any data keeping of our own.
 	 */
 	public void remove(Object object)
 	{
 
 	}
 
 	/***
 	 * This class checks in its {@link DirectoryFileFilter#accept(File)}
 	 * method if the given file is a directory in case the constructor {@link
 	 * FileCompletionModel#FileCompletionModel(boolean)
 	 * FileCompletionModel(true)} was used.
 	 */
 	private class DirectoryFileFilter implements FileFilter
 	{
 		public boolean accept(File pathname)
 		{
 			return completeOnlyDirectories ? pathname.isDirectory() : true;
 		}
 	}
 
 	private class PrefixFileFilter extends DirectoryFileFilter
 	{
 		private String prefix;
 
 		public PrefixFileFilter(String prefix)
 		{
 			this.prefix = prefix;
 		}
 
 		public boolean accept(File pathname)
 		{
 			return super.accept(pathname)
 				&& pathname.getName().startsWith(prefix);
 		} 
 	}
 }