/*
 *  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.ByteArrayOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Method;
import java.net.URL;
import javax.jnlp.BasicService;
import javax.jnlp.FileContents;
import javax.jnlp.PersistenceService;
import javax.jnlp.ServiceManager;

public class JnlpCache implements ResCache {
	private PersistenceService back;
	private URL base;

	private JnlpCache(PersistenceService back, URL base) {
		this.back = back;
		this.base = base;
	}

	public static JnlpCache create() {
		try {
			Class<? extends ServiceManager> cl = Class.forName("javax.jnlp.ServiceManager").asSubclass(ServiceManager.class);
			Method m = cl.getMethod("lookup", String.class);
			BasicService basic = (BasicService) m.invoke(null, "javax.jnlp.BasicService");
			PersistenceService prs = (PersistenceService) m.invoke(null, "javax.jnlp.PersistenceService");
			return (new JnlpCache(prs, basic.getCodeBase()));
		} catch (Exception e) {
			return (null);
		}
	}

	private static String mangle(String nm) {
		StringBuilder buf = new StringBuilder();
		for (int i = 0; i < nm.length(); i++) {
			char c = nm.charAt(i);
			if (c == '/')
				buf.append("_");
			else
				buf.append(c);
		}
		return (buf.toString());
	}

	private void realput(URL loc, byte[] data) {
		FileContents file;
		try {
			try {
				file = back.get(loc);
			} catch (FileNotFoundException e) {
				back.create(loc, data.length);
				file = back.get(loc);
			}
			if (file.getMaxLength() < data.length) {
				if (file.setMaxLength(data.length) < data.length) {
					back.delete(loc);
					return;
				}
			}
			OutputStream s = file.getOutputStream(true);
			try {
				s.write(data);
			} finally {
				s.close();
			}
		} catch (IOException e) {
			return;
		} catch (Exception e) {
			/* There seems to be a strange bug in NetX. */
			return;
		}
	}

	private void put(final URL loc, final byte[] data) {
		/*
		 * Interestingly enough, it seems that the JNLP persistence cache, at
		 * least in Sun's implementation, is REALLY SLOW. "Really slow" meaning
		 * that it takes like 1 second to save each muffin. How they managed to
		 * do this, I have no clue, but to counter it, so as to not take up
		 * precious resource/minimap loader time, the actual storage is
		 * deferred.
		 * 
		 * Sucks? You don't say.
		 */
		Utils.defer(new Runnable() {
			public void run() {
				realput(loc, data);
			}
		});
	}

	private InputStream get(URL loc) throws IOException {
		FileContents file = back.get(loc);
		return (file.getInputStream());
	}

	public OutputStream store(final String name) throws IOException {
		/*
		 * The persistence service actually yields a real OutputStream, but
		 * since it needs to know the final size of the data before that, it
		 * isn't actually possible to use it as an OutputStream in any
		 * reasonable manner. Thus, all data is first "pre-cached" in a
		 * ByteArrayOutputStream, and then written to the persistence store.
		 * 
		 * Oh God, it's so stupid.
		 */
		OutputStream ret = new ByteArrayOutputStream() {
			public void close() {
				byte[] res = toByteArray();
				try {
					put(new URL(base, mangle(name)), res);
				} catch (java.net.MalformedURLException e) {
					throw (new RuntimeException(e));
				}
			}
		};
		return (ret);
	}

	public InputStream fetch(String name) throws IOException {
		try {
			URL loc = new URL(base, mangle(name));
			return (get(loc));
		} catch (IOException e) {
			throw (e);
		} catch (Exception e) {
			/* There seems to be a weird bug in NetX */
			throw ((IOException) (new IOException("Virtual NetX IO exception").initCause(e)));
		}
	}
}