/*
 * Created on 1 Nov 2006
 * Created by Paul Gardner
 * Copyright (C) 2006 Aelitis, All Rights Reserved.
 *
 * 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; either version 2
 * of the License, or (at your option) any later version.
 * 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.
 * 
 * AELITIS, SAS au capital de 63.529,40 euros
 * 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
 *
 */


package org.gudy.azureus2.core3.disk.impl;

import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

import org.gudy.azureus2.core3.config.COConfigurationManager;
import org.gudy.azureus2.core3.config.ParameterListener;
import org.gudy.azureus2.core3.disk.*;
import org.gudy.azureus2.core3.disk.impl.resume.RDResumeHandler;
import org.gudy.azureus2.core3.download.DownloadManager;
import org.gudy.azureus2.core3.download.DownloadManagerException;
import org.gudy.azureus2.core3.download.DownloadManagerState;
import org.gudy.azureus2.core3.internat.LocaleTorrentUtil;
import org.gudy.azureus2.core3.internat.LocaleUtilDecoder;
import org.gudy.azureus2.core3.logging.LogAlert;
import org.gudy.azureus2.core3.logging.LogEvent;
import org.gudy.azureus2.core3.logging.LogIDs;
import org.gudy.azureus2.core3.logging.Logger;
import org.gudy.azureus2.core3.torrent.TOTorrent;
import org.gudy.azureus2.core3.torrent.TOTorrentFile;
import org.gudy.azureus2.core3.util.*;

import com.aelitis.azureus.core.diskmanager.cache.CacheFile;
import com.aelitis.azureus.core.diskmanager.cache.CacheFileManagerFactory;
import com.aelitis.azureus.core.diskmanager.cache.CacheFileOwner;
import com.aelitis.azureus.core.diskmanager.file.FMFileManagerFactory;

public class 
DiskManagerUtil 
{
    private static final LogIDs LOGID = LogIDs.DISK;

	protected static int        max_read_block_size;

	static{

		ParameterListener param_listener = new ParameterListener() {
			public void
			parameterChanged(
					String  str )
			{
				max_read_block_size = COConfigurationManager.getIntParameter( "BT Request Max Block Size" );
			}
		};

		COConfigurationManager.addAndFireParameterListener( "BT Request Max Block Size", param_listener);
	}

	public static boolean
	checkBlockConsistencyForHint(
		DiskManager	dm,
		String		originator,
		int 		pieceNumber,
		int 		offset,
		int 		length)
	{
		if (length <= 0 ) {
			if (Logger.isEnabled())
				Logger.log(new LogEvent(dm, LOGID, LogEvent.LT_ERROR,
						"Hint invalid: " + originator + " length=" + length + " <= 0"));
			return false;
		}
		if (pieceNumber < 0) {
			if (Logger.isEnabled())
				Logger.log(new LogEvent(dm, LOGID, LogEvent.LT_ERROR,
						"Hint invalid: " + originator + " pieceNumber=" + pieceNumber + " < 0"));
			return false;
		}
		if (pieceNumber >= dm.getNbPieces()) {
			if (Logger.isEnabled())
				Logger.log(new LogEvent(dm, LOGID, LogEvent.LT_ERROR,
						"Hint invalid: " + originator + " pieceNumber=" + pieceNumber + " >= this.nbPieces="
						+ dm.getNbPieces()));
			return false;
		}
		int pLength = dm.getPieceLength(pieceNumber);

		if (offset < 0) {
			if (Logger.isEnabled())
				Logger.log(new LogEvent(dm, LOGID, LogEvent.LT_ERROR,
						"Hint invalid: " + originator + " offset=" + offset + " < 0"));
			return false;
		}
		if (offset > pLength) {
			if (Logger.isEnabled())
				Logger.log(new LogEvent(dm, LOGID, LogEvent.LT_ERROR,
						"Hint invalid: " + originator + " offset=" + offset + " > pLength=" + pLength));
			return false;
		}
		if (offset + length > pLength) {
			if (Logger.isEnabled())
				Logger.log(new LogEvent(dm, LOGID, LogEvent.LT_ERROR,
						"Hint invalid: " + originator + " offset=" + offset + " + length=" + length
						+ " > pLength=" + pLength));
			return false;
		}

		return true;
	}
	
	public static boolean
	checkBlockConsistencyForRead(
		DiskManager	dm,
		String		originator,
		boolean		peer_request,
		int 		pieceNumber,
		int 		offset,
		int 		length)
	{
		if ( !checkBlockConsistencyForHint( dm, originator, pieceNumber, offset, length )){
			
			return( false );
		}
		
		if (length > max_read_block_size && peer_request) {
			if (Logger.isEnabled())
				Logger.log(new LogEvent(dm, LOGID, LogEvent.LT_ERROR,
						"Read invalid: " + originator + " length=" + length + " > " + max_read_block_size));
			return false;
		}

		if(!dm.getPiece(pieceNumber).isDone()) {
			Logger.log(new LogEvent(dm, LOGID, LogEvent.LT_ERROR,
					"Read invalid: " + originator + " piece #" + pieceNumber + " not done"));
			return false;
		}
		
		return true;
	}
	
	public static void doFileExistenceChecks(DiskManagerFileInfoSet fileSet, boolean[] toCheck, DownloadManager dm, boolean allowAlloction)
	{
		DiskManagerFileInfo[] files = fileSet.getFiles();
		
		int lastPieceScanned = -1;
		int windowStart = -1;
		int windowEnd = -1;
		
		String[] types = DiskManagerImpl.getStorageTypes(dm);
		
		// sweep over all files to see if adjacent files of changed files can be deleted or need allocation
		for(int i = 0; i< files.length;i++)
		{
			int firstPiece = files[i].getFirstPieceNumber();
			int lastPiece = files[i].getLastPieceNumber();
			
			if(toCheck[i])
			{ // found a file that changed, scan adjacent files
				if(lastPieceScanned < firstPiece)
				{ // haven't checked the preceding files, slide backwards
					windowStart = firstPiece;
					while(i > 0 && files[i-1].getLastPieceNumber() >= windowStart)
						i--;
				}
					
				if(windowEnd < lastPiece)
					windowEnd = lastPiece;
			}
			
			if((windowStart <= firstPiece && firstPiece <= windowEnd) || (windowStart <= lastPiece && lastPiece <= windowEnd))
			{ // file falls in current scanning window, check it
				File currentFile = files[i].getFile(true);
				if(!RDResumeHandler.fileMustExist(dm, files[i]))
				{
					int	st = convertDMStorageTypeFromString( types[i] );
					if( st == DiskManagerFileInfo.ST_COMPACT || st == DiskManagerFileInfo.ST_REORDER_COMPACT ){
						currentFile.delete();
					}
				} else if(allowAlloction && !currentFile.exists())	{
					/*
					 * file must exist, does not exist and we probably just changed to linear
					 * mode, assume that (re)allocation of adjacent files is necessary
					 */
					dm.setDataAlreadyAllocated(false);
				}
				lastPieceScanned = lastPiece;
			}


		}
	}

	private static AEMonitor    cache_read_mon  = new AEMonitor( "DiskManager:cacheRead" );

	private static boolean
	setFileLink(
	    DownloadManager         download_manager,
	    DiskManagerFileInfo[]   info,
	    DiskManagerFileInfo     file_info,
	    File                    from_file,
	    File                    to_link )
	{
	        // existing link is that for the TO_LINK and will come back as TO_LINK if no link is defined
	
	    File    existing_link = FMFileManagerFactory.getSingleton().getFileLink( download_manager.getTorrent(), to_link );
	
	    if ( !existing_link.equals( to_link )){
	
	            // where we're mapping to is already linked somewhere else. Only case we support
	            // is where this is a remapping of the same file back to where it came from
	
	        if ( !from_file.equals( to_link )){
	
	            Logger.log(new LogAlert(download_manager, LogAlert.REPEATABLE, LogAlert.AT_ERROR,
	                            "Attempt to link to existing link '" + existing_link.toString()
	                                    + "'"));
	
	            return( false );
	        }
	    }
	
	    File    existing_file = file_info.getFile( true );
	
	    if ( to_link.equals( existing_file )){
	
	            // already pointing to the right place
	
	        return( true );
	    }
	
	    for (int i=0;i<info.length;i++){
	
	        if ( to_link.equals( info[i].getFile( true ))){
	
	            Logger.log(new LogAlert(download_manager, LogAlert.REPEATABLE, LogAlert.AT_ERROR,
	                            "Attempt to link to existing file '" + info[i].getFile(true)
	                                    + "'"));
	
	            return( false );
	        }
	    }
	
	    if ( to_link.exists()){
	
	        if ( !existing_file.exists()){
	
	                // using a new file, make sure we recheck
	
	            download_manager.recheckFile( file_info );
	
	        }else{
	
                if ( FileUtil.deleteWithRecycle( 
            		existing_file,
            		download_manager.getDownloadState().getFlag( DownloadManagerState.FLAG_LOW_NOISE ))){
	
	                    // new file, recheck
	
	                download_manager.recheckFile( file_info );
	
	            }else{
	
	                Logger.log(new LogAlert(download_manager, LogAlert.REPEATABLE, LogAlert.AT_ERROR,
	                        "Failed to delete '" + existing_file.toString() + "'"));
	
	                return( false );
	            }
	        }
	    }else{
	
	        if ( existing_file.exists()){
	
	            if ( !FileUtil.renameFile( existing_file, to_link )){
	
	                Logger.log(new LogAlert(download_manager, LogAlert.REPEATABLE, LogAlert.AT_ERROR,
	                    "Failed to rename '" + existing_file.toString() + "'" ));
	
	                return( false );
	            }
	        }
	    }
	
	    DownloadManagerState    state = download_manager.getDownloadState();
	
	    state.setFileLink( from_file, to_link );
	
	    state.save();
	
	    return( true );
	}

	static abstract class FileSkeleton implements DiskManagerFileInfoHelper {
	    protected int     priority;
	    protected boolean skipped;
		protected long    downloaded;
	}

	public static DiskManagerFileInfoSet
	getFileInfoSkeleton(
	    final DownloadManager       download_manager,
	    final DiskManagerListener   listener )
	{
	    TOTorrent   torrent = download_manager.getTorrent();
	
	    if ( torrent == null ){
	
	        return( new DiskManagerFileInfoSetImpl(new DiskManagerFileInfoImpl[0],null) );
	    }
	
	    String  tempRootDir = download_manager.getAbsoluteSaveLocation().getParent();
	    
	    if(tempRootDir == null) // in case we alraedy are at the root
	    	tempRootDir = download_manager.getAbsoluteSaveLocation().getPath();
	    
	
	    if ( !torrent.isSimpleTorrent()){
	    	tempRootDir += File.separator + download_manager.getAbsoluteSaveLocation().getName();
	    }
	
	    tempRootDir    += File.separator;
	    
	    final String root_dir = StringInterner.intern(tempRootDir) ;
	
	    try{
	        final LocaleUtilDecoder locale_decoder = LocaleTorrentUtil.getTorrentEncoding( torrent );
	
	        TOTorrentFile[] torrent_files = torrent.getFiles();
	
	        final FileSkeleton[]   res = new FileSkeleton[ torrent_files.length ];
	        
			final String incomplete_suffix = download_manager.getDownloadState().getAttribute( DownloadManagerState.AT_INCOMP_FILE_SUFFIX );

	        final DiskManagerFileInfoSet fileSetSkeleton = new DiskManagerFileInfoSet() {
	
				public DiskManagerFileInfo[] getFiles() {
					return res;
				}
	
				public int nbFiles() {
					return res.length;
				}
	
				public void setPriority(int[] toChange) {
					if(toChange.length != res.length)
						throw new IllegalArgumentException("array length mismatches the number of files");
					
					for(int i=0;i<res.length;i++)
						res[i].priority = toChange[i];
					
					DiskManagerImpl.storeFilePriorities( download_manager, res);
					
					
					
					for(int i=0;i<res.length;i++)
						if(toChange[i] != 0 )
							listener.filePriorityChanged(res[i]);
				}
	
				public void setSkipped(boolean[] toChange, boolean setSkipped) {
					if(toChange.length != res.length)
						throw new IllegalArgumentException("array length mismatches the number of files");
					
	        		if (!setSkipped ){
	    				String[] types = DiskManagerImpl.getStorageTypes(download_manager);

	    				boolean[]	toLinear 	= new boolean[toChange.length];
	    				boolean[]	toReorder 	= new boolean[toChange.length];
	    				
	    				int	num_linear 	= 0;
	    				int num_reorder	= 0;
	    				
	    				for ( int i=0;i<toChange.length;i++){
	    					
	    					if ( toChange[i] ){
	    						
	    						int old_type = DiskManagerUtil.convertDMStorageTypeFromString( types[i] );
	    						
	    						if ( old_type == DiskManagerFileInfo.ST_COMPACT ){
	    							
	    							toLinear[i] = true;
	    							
	    							num_linear++;
	    							
	    						}else if ( old_type == DiskManagerFileInfo.ST_REORDER_COMPACT ){
	    							
	    							toReorder[i] = true;
	    							
	    							num_reorder++;
	    						}
	    					}	
	    				}
	    				
	    				if ( num_linear > 0 ){
	    					
	    					if (!Arrays.equals(toLinear, setStorageTypes(toLinear, DiskManagerFileInfo.ST_LINEAR))){
	    						
	    						return;
	    					}
	    				}
	    			
	    				if ( num_reorder > 0 ){
	    					
	    					if (!Arrays.equals(toReorder, setStorageTypes(toReorder, DiskManagerFileInfo.ST_REORDER ))){
	    						
	    						return;
	    					}
	    				}
	        		}
	        		
					for(int i=0;i<res.length;i++)
						if(toChange[i])
							res[i].skipped = setSkipped;
					
					if(!setSkipped)
						doFileExistenceChecks(this, toChange, download_manager, true);
					
					DiskManagerImpl.storeFilePriorities( download_manager, res);
					
					for(int i=0;i<res.length;i++)
						if(toChange[i])
							listener.filePriorityChanged(res[i]);
				}
	
				public boolean[] setStorageTypes(boolean[] toChange, int newStorageType) {
					if(toChange.length != res.length)
						throw new IllegalArgumentException("array length mismatches the number of files");
					
					String[] types = DiskManagerImpl.getStorageTypes(download_manager);
					boolean[] modified = new boolean[res.length];
					boolean[] toSkip = new boolean[res.length];
					int toSkipCount = 0;
					DownloadManagerState dmState = download_manager.getDownloadState();
					
					try {
						dmState.suppressStateSave(true);
	
						for(int i=0;i<res.length;i++)
						{
							if(!toChange[i])
								continue;
	
	
							final int idx = i;
	
							int old_type = DiskManagerUtil.convertDMStorageTypeFromString( types[i] );
	
							//System.out.println(old_type + " <> " + newStroageType);
	
							if ( newStorageType == old_type )
							{
								modified[i] = true;
								continue;
							}
	
							try{
								File    target_file = res[i].getFile( true );
	
								// if the file doesn't exist then this is the start-of-day, most likely
								// being called from the torrent-opener, so we don't need to do any
								// file fiddling (in fact, if we do, we end up leaving zero length
								// files for dnd files which then force a recheck when the download
								// starts for the first time)
	
								if ( target_file.exists()){
	
									CacheFile cache_file =
										CacheFileManagerFactory.getSingleton().createFile(
											new CacheFileOwner()
											{
												public String
												getCacheFileOwnerName()
												{
													return( download_manager.getInternalName());
												}
	
												public TOTorrentFile
												getCacheFileTorrentFile()
												{
													return( res[idx].getTorrentFile() );
												}
	
												public File
												getCacheFileControlFileDir()
												{
													return( download_manager.getDownloadState().getStateFile( ));
												}
												public int
												getCacheMode()
												{
													return( CacheFileOwner.CACHE_MODE_NORMAL );
												}
											},
											target_file,
											DiskManagerUtil.convertDMStorageTypeToCache( newStorageType ));
	
									cache_file.close();
	
									toSkip[i] = ( newStorageType == FileSkeleton.ST_COMPACT || newStorageType == FileSkeleton.ST_REORDER_COMPACT )&& !res[i].isSkipped();
									if(toSkip[i])
										toSkipCount++;
								}
	
	
								modified[i] = true;
	
							}catch( Throwable e ){
	
								Debug.printStackTrace(e);
	
								Logger.log(
									new LogAlert(download_manager,
										LogAlert.REPEATABLE,
										LogAlert.AT_ERROR,
										"Failed to change storage type for '" + res[i].getFile(true) +"': " + Debug.getNestedExceptionMessage(e)));
	
								// download's not running - tag for recheck
	
								RDResumeHandler.recheckFile( download_manager, res[i] );
	
							}
	
							types[i] = DiskManagerUtil.convertDMStorageTypeToString( newStorageType );
						}
						
						/*
						 * set storage type and skipped before we do piece clearing and file
						 * clearing checks as those checks work better when skipped/stype is set
						 * properly
						 */
						dmState.setListAttribute( DownloadManagerState.AT_FILE_STORE_TYPES, types);
						if(toSkipCount > 0)
							setSkipped(toSkip, true);
						
						
						for(int i=0;i<res.length;i++)
						{
							if(!toChange[i])
								continue;
							
							// download's not running, update resume data as necessary
	
							int cleared = RDResumeHandler.storageTypeChanged( download_manager, res[i] );
	
							// try and maintain reasonable figures for downloaded. Note that because
							// we don't screw with the first and last pieces of the file during
							// storage type changes we don't have the problem of dealing with
							// the last piece being smaller than torrent piece size
	
							if (cleared > 0)
							{
								res[i].downloaded = res[i].downloaded - cleared * res[i].getTorrentFile().getTorrent().getPieceLength();
								if (res[i].downloaded < 0) res[i].downloaded = 0;
							}
						}
	
						DiskManagerImpl.storeFileDownloaded( download_manager, res, true );
	
						doFileExistenceChecks(this, toChange, download_manager, newStorageType == FileSkeleton.ST_LINEAR || newStorageType == FileSkeleton.ST_REORDER );
	
					} finally {
						dmState.suppressStateSave(false);
						dmState.save();
					}
					
					return modified;
				}
	        };
	
	        for (int i=0;i<res.length;i++){
	
	            final TOTorrentFile torrent_file    = torrent_files[i];
	
	            final int file_index = i;
	
	            FileSkeleton info = new FileSkeleton() {
	
	            	private CacheFile   read_cache_file;
	            	// do not access this field directly, use lazyGetFile() instead 
	            	private WeakReference dataFile = new WeakReference(null);
	
	            	public void
	            	setPriority(int b)
	            	{
	            		priority    = b;
	
	            		DiskManagerImpl.storeFilePriorities( download_manager, res );
	
	            		listener.filePriorityChanged( this );
	            	}
	
	            	public void
	            	setSkipped(boolean _skipped)
	            	{
	            		if ( !_skipped && getStorageType() == ST_COMPACT ){
	            			if ( !setStorageType( ST_LINEAR )){
	            				return;
	            			}
	            		}
	
	            		if ( !_skipped && getStorageType() == ST_REORDER_COMPACT ){
	            			if ( !setStorageType( ST_REORDER )){
	            				return;
	            			}
	            		}

	            		skipped = _skipped;
	
	            		DiskManagerImpl.storeFilePriorities( download_manager, res );
	            		
	            		if(!_skipped)
	            		{
	            			boolean[] toCheck = new boolean[fileSetSkeleton.nbFiles()];
	            			toCheck[file_index] = true;
	            			doFileExistenceChecks(fileSetSkeleton, toCheck, download_manager, true);                			
	            		}
	            		
	
	            		listener.filePriorityChanged( this );
	            	}
	
	            	public int
	            	getAccessMode()
	            	{
	            		return( READ );
	            	}
	
	            	public long
	            	getDownloaded()
	            	{
	            		return( downloaded );
	            	}
	
	            	public void
	            	setDownloaded(
	            		long    l )
	            	{
	            		downloaded  = l;
	            	}
	
	            	public String
	            	getExtension()
	            	{
	            		String    ext   = lazyGetFile().getName();
	            		
	                    if ( incomplete_suffix != null && ext.endsWith( incomplete_suffix )){
	                    	
	                    	ext = ext.substring( 0, ext.length() - incomplete_suffix.length());
	                    }

	            		int separator = ext.lastIndexOf(".");
	            		if (separator == -1)
	            			separator = 0;
	            		return ext.substring(separator);
	            	}
	
	            	public int
	            	getFirstPieceNumber()
	            	{
	            		return( torrent_file.getFirstPieceNumber());
	            	}
	
	            	public int
	            	getLastPieceNumber()
	            	{
	            		return( torrent_file.getLastPieceNumber());
	            	}
	
	            	public long
	            	getLength()
	            	{
	            		return( torrent_file.getLength());
	            	}
	
	            	public int
	            	getIndex()
	            	{
	            		return( file_index );
	            	}
	
	            	public int
	            	getNbPieces()
	            	{
	            		return( torrent_file.getNumberOfPieces());
	            	}
	
	            	public int
	            	getPriority()
	            	{
	            		return( priority );
	            	}
	
	            	public boolean
	            	isSkipped()
	            	{
	            		return( skipped );
	            	}
	
	            	public DiskManager
	            	getDiskManager()
	            	{
	            		return( null );
	            	}
	
	            	public DownloadManager
	            	getDownloadManager()
	            	{
	            		return( download_manager );
	            	}
	
	            	public File
	            	getFile(
	            		boolean follow_link )
	            	{
	            		if ( follow_link ){
	
	            			File link = getLink();
	
	            			if ( link != null ){
	
	            				return( link );
	            			}
	            		}
	            		return lazyGetFile();
	            	}
	
	            	private File lazyGetFile()
	            	{
	            		File toReturn = (File)dataFile.get();
	            		if(toReturn != null)
	            			return toReturn;
	
	            		TOTorrent tor = download_manager.getTorrent();
	
	            		String  path_str = root_dir;
	            		File simpleFile = null;
	
	            		// for a simple torrent the target file can be changed
	
	            		if ( tor.isSimpleTorrent()){
	
	            			simpleFile = download_manager.getAbsoluteSaveLocation();
	
	            		}else{
	            			byte[][]path_comps = torrent_file.getPathComponents();
	
	            			for (int j=0;j<path_comps.length;j++){
	
	            				String comp;
	            				try
	            				{
	            					comp = locale_decoder.decodeString( path_comps[j] );
	            				} catch (UnsupportedEncodingException e)
	            				{
	            					Debug.printStackTrace(e);
	            					comp = "undecodableFileName"+file_index;
	            				}
	
	            				comp = FileUtil.convertOSSpecificChars( comp,  j != path_comps.length-1 );
	
	            				path_str += (j==0?"":File.separator) + comp;
	            			}
	            		}
	
	            		dataFile = new WeakReference(toReturn = simpleFile != null ? simpleFile : new File( path_str ));
	
	            		//System.out.println("new file:"+toReturn);
	            		return toReturn;
	            	}
	
	            	public TOTorrentFile
	            	getTorrentFile()
	            	{
	            		return( torrent_file );
	            	}
	            	
                	public boolean
                	setLink(
                		File    link_destination )
                	{
                		/**
                		 * If we a simple torrent, then we'll redirect the call to the download and move the
                		 * data files that way - that'll keep everything in sync.
                		 */  
                		if (download_manager.getTorrent().isSimpleTorrent()) {
                			try {
                				download_manager.moveDataFiles(link_destination.getParentFile(), link_destination.getName());
                				return true;
                			}
                			catch (DownloadManagerException e) {
                				// What should we do with the error?
                				return false;
                			}
                		}
                		return setLinkAtomic(link_destination);
                	}

                	public boolean
                	setLinkAtomic(
                		File    link_destination )
                	{
                		return( setFileLink( download_manager, res, this, lazyGetFile(), link_destination ));
                	}

                	public File
                	getLink()
                	{
                		return( download_manager.getDownloadState().getFileLink( lazyGetFile() ));
                	}

                	public boolean setStorageType(int type) {
                		boolean[] change = new boolean[res.length];
                		change[file_index] = true;
                		return fileSetSkeleton.setStorageTypes(change, type)[file_index];
                	}

                	public int
                	getStorageType()
                	{
                		return( DiskManagerUtil.convertDMStorageTypeFromString( DiskManagerImpl.getStorageType(download_manager, file_index)));
                	}

                	public void
                	flushCache()
                	{
                	}

                	public DirectByteBuffer
                	read(
                		long    offset,
                		int     length )

                		throws IOException
                	{
                		CacheFile temp;;
                		
                		try{
                			cache_read_mon.enter();

                			if ( read_cache_file == null ){

                				try{
                					int type = convertDMStorageTypeFromString( DiskManagerImpl.getStorageType(download_manager, file_index));

                					read_cache_file =
                						CacheFileManagerFactory.getSingleton().createFile(
                							new CacheFileOwner()
                							{
                								public String
                								getCacheFileOwnerName()
                								{
                									return( download_manager.getInternalName());
                								}

                								public TOTorrentFile
                								getCacheFileTorrentFile()
                								{
                									return( torrent_file );
                								}

                								public File
                								getCacheFileControlFileDir()
                								{
                									return( download_manager.getDownloadState().getStateFile( ));
                								}
                								public int
                								getCacheMode()
                								{
                									return( CacheFileOwner.CACHE_MODE_NORMAL );
                								}
                							},
                							getFile( true ),
                							convertDMStorageTypeToCache( type ));

                				}catch( Throwable e ){

                					Debug.printStackTrace(e);

                					throw( new IOException( e.getMessage()));
                				}
                			}
                			
                			temp = read_cache_file;
                			
                		}finally{

                			cache_read_mon.exit();
                		}

                		DirectByteBuffer    buffer =
                			DirectByteBufferPool.getBuffer( DirectByteBuffer.AL_DM_READ, length );

                		try{
                			temp.read( buffer, offset, CacheFile.CP_READ_CACHE );

                		}catch( Throwable e ){

                			buffer.returnToPool();

                			Debug.printStackTrace(e);

                			throw( new IOException( e.getMessage()));
                		}

                		return( buffer );
                	}

                	public void
                	close()
                	{
                		CacheFile temp;
                	
                   		try{
                			cache_read_mon.enter();

                			temp = read_cache_file;
                			
                			read_cache_file = null;
                			
                   		}finally{
                   			
                   			cache_read_mon.exit();
                   		}
                   		
                		if ( temp != null ){

                			try{
                				temp.close();

                			}catch( Throwable e ){

                				Debug.printStackTrace(e);
                			}
                		}
                	}
	
	            	public void
	            	addListener(
	            		DiskManagerFileInfoListener listener )
	            	{
	            		if ( getDownloaded() == getLength()){
	
	            			try{
	            				listener.dataWritten( 0, getLength());
	
	            				listener.dataChecked( 0, getLength());
	
	            			}catch( Throwable e ){
	
	            				Debug.printStackTrace(e);
	            			}
	            		}
	            	}
	
	            	public void
	            	removeListener(
	            		DiskManagerFileInfoListener listener )
	            	{
	            	}
	            };
	
	            res[i]  = info;
	        }
	
	        loadFilePriorities( download_manager, fileSetSkeleton);
	
	        loadFileDownloaded( download_manager, res );
	
	        return( fileSetSkeleton );
	
	    }catch( Throwable e ){
	
	        Debug.printStackTrace(e);
	
	        return( new DiskManagerFileInfoSetImpl(new DiskManagerFileInfoImpl[0],null) );
	
	    }
	}

	public static int
	convertDMStorageTypeFromString(
		String		str )
	{
		char c = str.charAt(0);
		
		switch( c ){
			case 'L':{
				return( DiskManagerFileInfo.ST_LINEAR );
			}
			case 'C':{
				return( DiskManagerFileInfo.ST_COMPACT );
			}
			case 'R':{
				return( DiskManagerFileInfo.ST_REORDER );
			}
			case 'X':{
				return( DiskManagerFileInfo.ST_REORDER_COMPACT );
			}
		}
		
		Debug.out( "eh?" );
		
		return( DiskManagerFileInfo.ST_LINEAR );
	}
	
	public static String
	convertDMStorageTypeToString(
		int		dm_type )
	{
		switch( dm_type ){
			case DiskManagerFileInfo.ST_LINEAR:{
				return( "L" );
			}
			case DiskManagerFileInfo.ST_COMPACT:{
				return( "C" );
			}
			case DiskManagerFileInfo.ST_REORDER:{
				return( "R" );
			}
			case DiskManagerFileInfo.ST_REORDER_COMPACT:{
				return( "X" );
			}
		}
		
		Debug.out( "eh?" );
		
		return( "?" );
	}
	
	public static String
	convertCacheStorageTypeToString(
		int		cache_type )
	{
		switch( cache_type ){
			case CacheFile.CT_LINEAR:{
				return( "L" );
			}
			case CacheFile.CT_COMPACT:{
				return( "C" );
			}
			case CacheFile.CT_PIECE_REORDER:{
				return( "R" );
			}
			case CacheFile.CT_PIECE_REORDER_COMPACT:{
				return( "X" );
			}
		}
		
		Debug.out( "eh?" );
		
		return( "?" );
	}
	public static int
	convertDMStorageTypeToCache(
		int	dm_type )
	{
		switch( dm_type ){
			case DiskManagerFileInfo.ST_LINEAR:{
				return( CacheFile.CT_LINEAR );
			}
			case DiskManagerFileInfo.ST_COMPACT:{
				return( CacheFile.CT_COMPACT );
			}
			case DiskManagerFileInfo.ST_REORDER:{
				return( CacheFile.CT_PIECE_REORDER );
			}
			case DiskManagerFileInfo.ST_REORDER_COMPACT:{
				return( CacheFile.CT_PIECE_REORDER_COMPACT );
			}
		}
		
		Debug.out( "eh?" );
		
		return( CacheFile.CT_LINEAR );
	}
	
	protected static void
	storeFilePriorities(
		DownloadManager         download_manager,
		DiskManagerFileInfo[]   files )
	{
		if ( files == null ) return;
		// bit confusing this: priorities are stored as
		// >= 1   : priority, 1 = high, 2 = higher etc
		// 0      : skipped
		// -1     : normal priority
		// <= -2  : negative priority , so -2 -> priority -1, -3 -> priority -2 etc

		List file_priorities = new ArrayList(files.length);
		for (int i=0; i < files.length; i++) {
			DiskManagerFileInfo file = files[i];
			if (file == null) return;
			boolean skipped = file.isSkipped();
			int priority = file.getPriority();
			int value;
			if ( skipped ){
				value = 0;
			}else if ( priority > 0 ){
				value = priority;
			}else{
				value = priority - 1;
				if ( value > 0 ){
					value = Integer.MIN_VALUE;
				}
			}
			file_priorities.add( i, Long.valueOf(value));
		}
		
	   download_manager.setData( "file_priorities", file_priorities );
	}
	  
	static void
	loadFilePriorities(
		DownloadManager         download_manager,
		DiskManagerFileInfoSet   fileSet )
	{
		//  TODO: remove this try/catch.  should only be needed for those upgrading from previous snapshot
		try {
			DiskManagerFileInfo[] files = fileSet.getFiles();

			if ( files == null ) return;
			List file_priorities = (List)download_manager.getData( "file_priorities" );
			if ( file_priorities == null ) return;

			boolean[] toSkip = new boolean[files.length];
			int[] prio = new int[files.length];

			for (int i=0; i < files.length; i++) {
				DiskManagerFileInfo file = files[i];
				if (file == null) return;
				int priority = ((Long)file_priorities.get( i )).intValue();
				if ( priority == 0 ){
					toSkip[i] = true;
				}else{
					if ( priority < 0 ){
						priority++;
					}
					prio[i] = priority;
				}
			}

			fileSet.setPriority(prio);
			fileSet.setSkipped(toSkip, true);

		}
		catch (Throwable t) {Debug.printStackTrace( t );}
	}

	protected static void
	  loadFileDownloaded(
	    DownloadManager             download_manager,
	    DiskManagerFileInfoHelper[] files )
	  {
	      DownloadManagerState  state = download_manager.getDownloadState();
	
	      Map   details = state.getMapAttribute( DownloadManagerState.AT_FILE_DOWNLOADED );
	
	      if ( details == null ){
	
	          return;
	      }
	
	      List  downloaded = (List)details.get( "downloaded" );
	
	      if ( downloaded == null ){
	
	          return;
	      }
	
	      try{
	          for (int i=0;i<files.length;i++){
	
	              files[i].setDownloaded(((Long)downloaded.get(i)).longValue());
	          }
	     }catch( Throwable e ){
	
	         Debug.printStackTrace(e);
	     }
	
	  }


}
