//   3/26/06

import	java.util.*;
import	javax.microedition.rms.*;

/**
* This class manages a set of user preferences, and stores them in a RecordStore. A
* single Preferences object is maintained by this class, and can be obtained using
* the static getinstance() method. Preferences are stored as key/value pairs
* (of Strings). A value may be requested as a String using the,
*
*	public String getpreference (String key)
*
* method, or as an int using the.
*
*	public int getintpreference (String key)
*
* method. These methods are available:
*
*	getinstance()			obtain the singleton Preferences object.
*
*	getpreference (String key)	obtain the corresponding value as a String.
*
*	getintpreference (String key)	obtain the corresponding value as an int.
*
*	removepreference (String key)	remove the Preferences key and its value.
*
*	save()				store the preferences in the Record Store.
*
*	setdefaults (String[][])	the parameter is a 2xN array of Strings,
*					where each row of the array is a key/value
*					pair. For each key in the array that is NOT
*					already a Preference, the key/value pair
*					will be added as a Preference.
*
*	setpreference (String key,	add (overwrite) the key/value pair.
*		String value)
*
*	setpreference (String key,	add (overwrite) the key/value pair, after
*		int value)		converting the int to a String.
*/

public class Preferences
{
	static private final int	BUFSIZE = 100,

					KEY = 0,
					VALUE = 1,

					ERROR = -1;

	static private String		STORENAME = "PREFS";

	static private Preferences	instance_;

	private boolean		exists_,
				haschanged_;

	private Hashtable	table_;



	static public Preferences
	getinstance()
	{
		if (instance_ == null) {
			instance_ = new Preferences();
		}
		return  instance_;
	}


	static public boolean
	ispref (String field, String value)
	{
		Preferences	prefs;


		prefs = getinstance();
		return  prefs.getpreference (field).equals (value);
	}


	private
	Preferences()
	{
		byte			buf[];

		RecordEnumeration	records;

		RecordStore		recstore;

		String			strings[];



		table_ = new Hashtable();
		exists_ = false;

		recstore = null;
		records = null;
			try {
		//////////////////////////////////////////////////////////////////
		// Try to open the RecordStore. It may or may not exist.	//
		// If it doesn't exist a RecordStoreNotFoundException results	//
		//////////////////////////////////////////////////////////////////
		recstore = RecordStore.openRecordStore (STORENAME, false);
		exists_ = true;

		//////////////////////////////////////////////////////////
		// Obtain an enumeration of the records in the store	//
		// No filter, no comparer, don't keep updated.		//
		//////////////////////////////////////////////////////////
		records = recstore.enumerateRecords (null, null, false);
		strings = new String[2];

		while (records.hasNextElement()) {
			buf = records.nextRecord();
			makestrings (buf, strings);

			table_.put (strings[KEY], strings[VALUE]);
		}
			}
			catch (RecordStoreException e) {
			}
			finally {
		if (records != null) {
			records.destroy();
		}
		if (recstore != null) {
				try {
			recstore.closeRecordStore();
				}
				catch (RecordStoreException e) {
				}
		}
			}

	}


	public int
	getintpreference (String key)
	{
		int		pref;

		String		value;


		value = (String) table_.get (key);
		if (value != null) {
			pref = Integer.parseInt (value);
		}
		else {
			pref = ERROR;
		}

		return  pref;
	}


	public String
	getpreference (String key)
	{
		return  (String) table_.get (key);
	}


	private int
	makebuffer (String key, String value, byte buf[])
	{
		int		len;


		len = stringintobuf (buf, key, 0);
		len = stringintobuf (buf, value, len);

		return  len;
	}


	private void
	makestrings (byte buf[], String strings[])
	{
		int		len,
				offset;


		len = buf[0];
		strings[KEY] = new String (buf, 1, len);

		offset = len + 1;
		len = buf[offset++];
		strings[VALUE] = new String (buf, offset, len);
	}


	public void
	removepreference (String key)
	{
		table_.remove (key);
		haschanged_ = true;
	}


	public void
	save()
		throws RecordStoreException
	{
		byte			buf[];

		int			len;

		Enumeration		keys;

		RecordStore		recstore;

		String			key,
					value;


		if (haschanged_) {
			recstore = null;
				try {
			if (exists_) {
				RecordStore.deleteRecordStore (STORENAME);
			}

			recstore = RecordStore.openRecordStore (STORENAME, true);

			buf = new byte[BUFSIZE];

			keys = table_.keys();
			while (keys.hasMoreElements()) {
				key = (String) keys.nextElement();
				value = (String) table_.get (key);

				len = makebuffer (key, value, buf);
				recstore.addRecord (buf, 0, len);
			}

			haschanged_ = false;
			exists_ = true;
				}
				catch (RecordStoreException e) {
					throw e;
				}
				finally {
			if (recstore != null) {
				recstore.closeRecordStore();
			}
				}
		}
	}


	public void
	setdefaults (String table[][])
	{
		int		len,
				pos;

		String		key;


		len = table.length;

		for (pos = 0; pos < len; pos++) {
			key = table[pos][KEY];
			
			if (!table_.containsKey (key)) {
				table_.put (key, table[pos][VALUE]);
				haschanged_ = true;
			}
		}
	}


	public void
	setpreference (String key, int value)
	{
		setpreference (key, value + "");
	}


	public void
	setpreference (String key, String value)
	{
		instance_ = getinstance();
		table_.put (key, value);
		haschanged_ = true;
	}


	private int
	stringintobuf (byte buf[], String text, int offset)
	{
		byte		bytes[];

		int		len;


		len = text.length();
		bytes = text.getBytes();
		buf[offset] = (byte) len;
		System.arraycopy (bytes, 0, buf, offset + 1, len);

		return  offset + len + 1;
	}
}