package msc.gs.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.Properties;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

import msc.config.Config;

import com.thoughtworks.xstream.XStream;

public class PersistenceManager {
    private static final XStream xstream = new XStream();

    static {
	setupAliases();
    }

    public static Object load(String filename) {
	try {
	    InputStream is = new FileInputStream(new File(Config.CONF_DIR, filename));
	    if (filename.endsWith(".gz")) {
		is = new GZIPInputStream(is);
	    }
	    Object rv = xstream.fromXML(is);
	    return rv;
	} catch (IOException ioe) {
	    Logger.error(ioe);
	}
	return null;
    }

    public static void setupAliases() {
	try {
	    Properties aliases = new Properties();
	    FileInputStream fis = new FileInputStream(new File(Config.CONF_DIR, "aliases.xml"));
	    aliases.loadFromXML(fis);
	    for (Enumeration e = aliases.propertyNames(); e.hasMoreElements();) {
		String alias = (String) e.nextElement();
		Class c = Class.forName((String) aliases.get(alias));
		xstream.alias(alias, c);
	    }
	} catch (Exception ioe) {
	    Logger.error(ioe);
	}
    }

    public static void write(String filename, Object o) {
	try {
	    OutputStream os = new FileOutputStream(new File(Config.CONF_DIR, filename));
	    if (filename.endsWith(".gz")) {
		os = new GZIPOutputStream(os);
	    }
	    xstream.toXML(o, os);
	} catch (IOException ioe) {
	    Logger.error(ioe);
	}
    }
}