FileCache.java

/*
 *  This file is part of the Haven & Hearth game client.
 *  Copyright (C) 2009 Fredrik Tolf <fredrik@dolda2000.com>, and
 *                     Björn Johannessen <johannessen.bjorn@gmail.com>
 *
 *  Redistribution and/or modification of this file is subject to the
 *  terms of the GNU Lesser General Public License, version 3, 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.
 *
 *  Other parts of this source tree adhere to other copying
 *  rights. Please see the file `COPYING' in the root directory of the
 *  source tree for details.
 *
 *  A copy the GNU Lesser General Public License is distributed along
 *  with the source tree of which this file is a part in the file
 *  `doc/LPGL-3'. If it is missing for any reason, please see the Free
 *  Software Foundation's website at <http://www.fsf.org/>, or write
 *  to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 *  Boston, MA 02111-1307 USA
 */

package haven;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class FileCache implements ResCache {
    private final File base;
    
    public FileCache(File base) {
	this.base = base;
    }
    
    public static FileCache foruser() {
	try {
	    String path = System.getProperty("user.home", null);
	    if(path == null)
		return(null);
	    File home = new File(path);
	    if(!home.exists() || !home.isDirectory() || !home.canRead() || !home.canWrite())
		return(null);
	    File base = new File(new File(home, ".haven"), "cache");
	    if(!base.exists() && !base.mkdirs())
		return(null);
	    return(new FileCache(base));
	} catch(SecurityException e) {
	    return(null);
	}
    }
    
    private File forres(String nm) {
	File res = base;
	String[] comp = nm.split("/");
	for(int i = 0; i < comp.length - 1; i++) {
	    res = new File(res, comp[i]);
	}
	return(new File(res, comp[comp.length - 1] + ".cached"));
    }

    public OutputStream store(String name) throws IOException {
	final File nm = forres(name);
	File dir = nm.getParentFile();
	final File tmp = new File(dir, nm.getName() + ".new");
	dir.mkdirs();
	tmp.delete();
	OutputStream ret = new FilterOutputStream(new FileOutputStream(tmp)) {
		public void close() throws IOException {
		    super.close();
		    if(!tmp.renameTo(nm)) {
			/* Apparently Java doesn't support atomic
			 * renames on Windows... :-/ */
			nm.delete();
			tmp.renameTo(nm);
		    }
		}
	    };
	return(ret);
    }
    
    public InputStream fetch(String name) throws IOException {
	return(new FileInputStream(forres(name)));
    }
}