<? /* Verify running session (and return to login page if not logged in). */
include 'session.php';
if (isset($_SESSION['uid']))
	$uid=$_SESSION['uid'];
else
	header('location:index.php');
?>
<? /* A bunch of helper functions needed in various scripts. */

/* Convert board coordinate [a-h][1-8] to 1dim index [0..63] */
function bc2i($coord)
{
	switch ($coord[0]) {
		case 'a': $x=0; break;
		case 'b': $x=1; break;
		case 'c': $x=2; break;
		case 'd': $x=3; break;
		case 'e': $x=4; break;
		case 'f': $x=5; break;
		case 'g': $x=6; break;
		case 'h': $x=7; break;
		default: return 64; /* error code */
	}
	$y=$coord[1]-1; 
	if ($y<0 || $y>7 )
		return 64; /* error code */
	$index=$y*8+$x;
	return $index;
}

/* Convert index [0..63] to board coordinate [a-h][1-8] */
function i2bc($index)
{
	if ($index<0 || $index>63)
		return '';
	$y=floor($index/8)+1;
	$x=chr(($index%8)+97);
	$coord=$x.$y;
	return $coord;
}

/* Get full name of chessman from chessman identifier. */
function getCMName($short)
{
	$name='empty';
	switch ($short) {
		case 'P': $name='Pawn'; break;
		case 'R': $name='Rook'; break;
		case 'N': $name='Knight'; break;
		case 'B': $name='Bishop'; break;
		case 'K': $name='King'; break;
		case 'Q': $name='Queen'; break;
	}
	return $name;
}

/* Get difference in chessmen for each class (pawn=0,queen=5).
 * Positive value = White has more, Negative value = Black has more. */
function getCMDiff($board)
{
	$diff = array(0,0,0,0,0);
	for ($i=0;$i<64;$i++) {
		switch ($board[$i]) {
			case 'wP': $diff[0]++; break;
			case 'wN': $diff[1]++; break;
			case 'wB': $diff[2]++; break;
			case 'wR': $diff[3]++; break;
			case 'wQ': $diff[4]++; break;
			case 'bP': $diff[0]--; break;
			case 'bN': $diff[1]--; break;
			case 'bB': $diff[2]--; break;
			case 'bR': $diff[3]--; break;
			case 'bQ': $diff[4]--; break;
		}
	}
	for ($i=0;$i<5;$i++)
		if ($diff[$i] != 0)
			return $diff;
	return null;
}

/** Return URL to game with id $gid. */
function getGameURL( $gid )
{
	/* XXX access $_SERVER; otherwise $GLOBALS seems to be empty; 
	 * maybe a bug in PHP? */
	$temp = $_SERVER['SERVER_NAME']; // dummy access
	$prot=($GLOBALS['_SERVER']['HTTPS']=='on')?'https':'http';
	$script=$GLOBALS['_SERVER']['SCRIPT_NAME'];
	/* $script is the script calling this function but we want to redirect
	 * to board.php so we have to replace the name (can't use board.php 
	 * directly since we don't know path to script on server). */
	$script = dirname($script)."/board.php";
	return $prot.'://'.$GLOBALS['_SERVER']['HTTP_HOST'].$script.'?gid='.$gid;
}

?>
<?
/* Input/output functions to access backend data. */

/* XXX Abstraction is not too good right now. E.g., the p_* variables are
 * not loaded but set by interpreting game data related to user id. Same 
 * with timestamp in saving. If finally a database should be allowed as
 * backend separation must be more accurate, e.g., via raw_io_* functions
 * that really just convert backend data to abstract format without 
 * interpreting anything. */

include_once 'misc.php';

/* Data locations */
$res_users='occ-data/users';
$res_games='occ-data/games';
$res_archive='occ-data/archive';

/* E-Mail header for notifications */
$mail_header="From: noreply-occ@yourdomain.org\n".
	"Return-Path: noreply-occ@yourdomain.org\n".
	"Content-Type: text/plain; charset=utf-8\n".
	"Content-Transfer-Encoding: 8bit\n";

/* Lock/unlock IO access via locking file. Locking is tried for two seconds
 * then the locking file is replaced. This is to prevent deadlocks through
 * broken sessions and should be safe since no action will take that long. 
 * Locking will only be done for write access. Thus there is an infinitesimal
 * chance that a read will result corrupted data (when coincidending with a
 * write access). */
$ioref=0; /* Reset IO lock reference counter on page reload. */
function ioLock()
{
	global $ioref;

	if ($ioref++==0) {
		$attempts=0;
		while (($hfile=fopen('tmp/iolock','x'))===false) {
			usleep(100000);
			if (++$attempts==20)
				break;
		}
		if ($hfile)
			fclose($hfile);
	}
}
function ioUnlock()
{
	global $ioref;

	if ($ioref==0)
		return;
	if (--$ioref==0)
		unlink('tmp/iolock');
}

/* Load a game (try active games first, then archived games) and set various
 * user-based variables, too. Return game as array or NULL on error.
 * Static (loaded) entries:
 * archived: resides in archive
 * ts_start: timestamp of starting date (secs)
 * ts_last: timestamp of last move (secs)
 * white: name of white player
 * black: name of black player
 * curmove: number of current move (start at 0)
 * curplyr: color of current player (w or b)
 * curstate: state of game (w/b=white/black won,-=draw,D=draw offered,?=open)
 * wcs: white may castle short
 * wcl: white may castle long
 * bcs, bcl: dito for black
 * w2spm: 2-step pawn move of white (x or a-h)
 * b2spm: dito for black
 * lastmove: last move in full notation (e.g. Pd2-d4 or x)
 * lastkill: chessman captured in last move with board index (e.g. wP08 or x)
 * oscf: old short castling flag (only set by king/rook move)
 * olcf: dito for long castling
 * board: chess board array (0=a1,63=h8) with e.g. 'bP', 'wQ' or ''
 * mhistory: move history list (w1,b1,w2,b2,...)
 * chatter: list of chatter lines (first is newest)
 * Dynamic (based on user id) entries:
 * p_maymove: whether it's player's turn (always 0 if user is not playing)
 * p_mayundo: player may undo last move
 * p_mayabort: player may abort game (first move or opponent took too long) 
 * p_mayarchive: player may move game to archive
 * p_color: player color (w=white,b=black or empty if not playing)
 * p_opponent: name of opponent (based on player color, empty if not playing)
 */
function ioLoadGame($gid,$uid)
{
	global $res_games,$res_archive;

	$game=array();

	/* Load raw game data */
	if (file_exists("$res_games/$gid")) {
		$raw=file("$res_games/$gid");
		$game['archived']=0;
	} else if (file_exists("$res_archive/$gid")) {
		$raw=file("$res_archive/$gid");
		$game['archived']=1;
	} else 
		return null;

	/* Build time stamps */
	$aux=explode(' ',trim($raw[0]));
	$game['ts_start']=mktime($aux[3],$aux[4],0,$aux[1],$aux[2],$aux[0]);
	$game['ts_last']=mktime($aux[8],$aux[9],0,$aux[6],$aux[7],$aux[5]);

	/* Parse header */
	$hdr=explode(' ',trim($raw[1]));
	$game['white']=$hdr[0];
	$game['black']=$hdr[1];
	$game['curmove']=$hdr[2];
	$game['curplyr']=$hdr[3];
	$game['curstate']=$hdr[4];
	$game['wcs']=$hdr[5];
	$game['wcl']=$hdr[6];
	$game['bcs']=$hdr[7];
	$game['bcl']=$hdr[8];
	$game['w2spm']=$hdr[9];
	$game['b2spm']=$hdr[10];
	$game['lastmove']=$hdr[11];
	$game['lastkill']=$hdr[12];
	$game['oscf']=$hdr[13];
	$game['olcf']=$hdr[14];

	/* Fill chess board */
	$game['board']=array(
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '');
	$wcm=explode(' ',trim($raw[2]));
	foreach ($wcm as $cm)
		$game['board'][bc2i($cm[1].$cm[2])]='w'.$cm[0];
	$bcm=explode(' ',trim($raw[3]));
	foreach ($bcm as $cm)
		$game['board'][bc2i($cm[1].$cm[2])]='b'.$cm[0];

	/* Get move history */
	$list=array();
	for ($i=1,$j=0;$i<=$game['curmove'];$i++,$j+=2)
	{
		$moves=explode(' ',trim($raw[3+$i]));
		if (count($moves)>1)
			$list[$j]=$moves[1];
		else
			$list[$j]='???';
		if (count($moves)>2)
			$list[1+$j]=$moves[2];
		else if ($i<$game['curmove'])
			$list[1+$j]='???';
		/* Note: Possibly missing move of black in current move
		 * is not set '' or something to easily allow undo of move
		 * via unset(). '' or even null would be counted as existing
		 * list item. */
	}
	$game['mhistory']=$list;

	/* Get chatter */
	$game['chatter']=array();
	for ($i=4+$game['curmove'],$j=0;$i<count($raw);$i++,$j++)
		$game['chatter'][$j]=trim($raw[$i]);

	/* Determine color and opponent */
	if ($uid==$game['black']) {
		$game['p_color']='b';
		$game['p_opponent']=$game['white'];
	} else if ($uid==$game['white']) {
		$game['p_color']='w';
		$game['p_opponent']=$game['black'];
	} else {
		$game['p_color']='';
		$game['p_opponent']='';
	}

	/* Check whether player may move/archive */
	$game['p_maymove']=0;
	$game['p_mayarchive']=0;
	if (($game['curplyr']=='w' && $uid==$game['white']) ||
			($game['curplyr']=='b' && $uid==$game['black'])) {
		if ($game['curstate']=='?' || $game['curstate']=='D')
			$game['p_maymove']=1;
		else if ($game['archived']==0)
			$game['p_mayarchive']=1;
	}

	/* Check whether player may abort */
	$game['p_mayabort']=0;
	if (!empty($game['p_color']) && $game['p_maymove']==0 &&
			($game['curstate']=='D' || $game['curstate']=='?') &&
			time()-$game['ts_last']>2419200/*four weeks*/ &&
			$game['archived']==0)
		$game['p_mayabort']=1;
	else if (!empty($game['p_color']) && $game['archived']==0 &&
			$game['p_maymove']==1 && 
			(($game['p_color']=='w' && $game['curmove']==0)||
			($game['p_color']=='b' && $game['curmove']==1)))
		$game['p_mayabort']=1;

	/* Check whether player may undo (only possible if game not finished) */
	if ($game['lastmove']!='x' && $game['archived']==0 &&
			(($game['curplyr']=='b' && $game['white']==$uid) ||
			 ($game['curplyr']=='w' && $game['black']==$uid)) &&
			($game['curstate']=='D' || $game['curstate']=='?') &&
			time()-$game['ts_last']<1200)
		$game['p_mayundo']=1;
	else
		$game['p_mayundo']=0;

	return $game;
}

/* Load game info and return it as array. If $location is not null it is either
 * 'opengames' or 'archive'. If set only that one location is checked. Return 
 * null if error occured.
 * archived: resides in archive
 * ts_start: timestamp of starting date (secs)
 * ts_last: timestamp of last move (secs)
 * white: name of white player
 * black: name of black player
 * curmove: number of current move (start at 0)
 * curplyr: color of current player (w or b)
 * curstate: state of game (w/b=white/black won,-=draw,D=draw offered,?=open) */
function ioLoadGameInfo($location,$gid)
{
	global $res_games,$res_archive;

	$game=array();

	/* Load raw game data */
	if (($location==null || $location=='opengames') &&
						file_exists("$res_games/$gid")) {
		$raw=file("$res_games/$gid");
		$game['archived']=0;
	} else if (($location==null || $location=='archive') && 
					file_exists("$res_archive/$gid")) {
		$raw=file("$res_archive/$gid");
		$game['archived']=1;
	} else 
		return null;
	/* NB: this is required since usort in loadInfos will destroy the index
	 * key. Therefore each entry needs to know the game id. */
	$game['gid']=$gid;

	/* Build time stamps */
	$aux=explode(' ',trim($raw[0]));
	$game['ts_start']=mktime($aux[3],$aux[4],0,$aux[1],$aux[2],$aux[0]);
	$game['ts_last']=mktime($aux[8],$aux[9],0,$aux[6],$aux[7],$aux[5]);

	/* Parse header */
	$hdr=explode(' ',trim($raw[1]));
	$game['white']=$hdr[0];
	$game['black']=$hdr[1];
	$game['curmove']=$hdr[2];
	$game['curplyr']=$hdr[3];
	$game['curstate']=$hdr[4];

	return $game;
}

/* Load array of game infos according to the given filter criteria. null for a
 * criteria means any value. $location must be set either 'opengames' or 
 * 'archive'.
 * Always returns an array but it may be empty if no matching games were found 
 * and entries are sorted most recent first. */
function compareTimestamp($a,$b)
{
	if ($a['ts_last']==$b['ts_last'])
		return 0;
	else if ($a['ts_last']<$b['ts_last'])
		return 1;
	else
		return -1;
}
function ioLoadGameInfoList($location,$player,$pcolor,$opponent)
{
	global $res_games,$res_archive;
	
	if ($location=='archive')
		$dirname=$res_archive;
	else
		$dirname=$res_games;
	$infos=array();

	$hdir=opendir($dirname);
	while ($entry=readdir($hdir)) {
		if ($entry=='.' || $entry=='..')
			continue;
		if ($player!=null || $opponent!=null) {
			if ($opponent!=null && 
					strpos($entry,'-'.$opponent.'-')===false)
				continue;
			if ($player!=null) {
				if (strpos($entry,'-'.$player.'-')===false)
					continue;
				if ($pcolor!=null) {
					$fields=explode('-',$entry);
					if ($pcolor=='w' && $fields[1]!=$player)
						continue;
					else if ($pcolor=='b' && $fields[2]!=$player)
						continue;
				}
			}
		}
		$infos[$entry]=ioLoadGameInfo($location,$entry);
	}
	closedir($hdir);
	/* NB: sort will destroy index key, therefore $infos['gid'] is used
	 * later instead. */
	if (count($infos)>0)
		usort($infos,'compareTimestamp');
	return $infos;
}

/* Save an open game and update last move time stamp to current time. Chatter
 * must have been updated already (newest is first in list). */
function ioSaveGame($game,$gid)
{
	global $res_games;

	$hfile=fopen("$res_games/$gid",'w');

	fwrite($hfile,date('Y m d H i ',$game['ts_start']));
	fwrite($hfile,date('Y m d H i',time()));
	fwrite($hfile,"\n");

	fwrite($hfile,$game['white'].' '.$game['black'].' ');
	fwrite($hfile,$game['curmove'].' '.$game['curplyr'].' ');
	fwrite($hfile,$game['curstate'].' '.$game['wcs'].' '.$game['wcl'].' ');
	fwrite($hfile,$game['bcs'].' '.$game['bcl'].' '.$game['w2spm'].' ');
	fwrite($hfile,$game['b2spm'].' '.$game['lastmove'].' ');
	fwrite($hfile,$game['lastkill'].' '.$game['oscf'].' ');
	fwrite($hfile,$game['olcf']."\n");

	for ($i=0;$i<64;$i++)
		if ($game['board'][$i]!='' && $game['board'][$i][0]=='w') {
			$c=i2bc($i);
			fwrite($hfile,$game['board'][$i][1].$c.' ');
		}
	fwrite($hfile,"\n");
	for ($i=0;$i<64;$i++)
		if ($game['board'][$i]!='' && $game['board'][$i][0]=='b') {
			$c=i2bc($i);
			fwrite($hfile,$game['board'][$i][1].$c.' ');
		}
	fwrite($hfile,"\n");

	for ($i=0,$j=1;$i<count($game['mhistory']);$i+=2,$j++)
		fwrite($hfile,$j.' '.$game['mhistory'][$i].' '.$game['mhistory'][$i+1]."\n");

	foreach ($game['chatter'] as $line)
		fwrite($hfile,$line."\n");

	fclose($hfile);
}

/* Archive game if user is allowed to and return a status message.
 * XXX no locking since only one user may archive and won't do it twice
 * the same time... */
function ioArchiveGame($gid,$uid)
{
	global $res_games,$res_archive;

	$game=ioLoadGame($gid,$uid);
	if ($game==null)
		return 'ERROR: Game not found!';
	if (!$game['p_mayarchive'])
		return 'ERROR: You cannot archive the game!';
	rename("$res_games/$gid","$res_archive/$gid");
	clearstatcache();
	return 'Game has been archived.';
}

/* Abort an open game. This is only possible if your opponent did not move
 * at all yet or did not move for more than four weeks. Aborting a game will
 * have NO influence on the game statistics. Return a status message. */
function ioAbortGame($gid,$uid)
{
	global $res_games;
	
	ioLock();

	$game=ioLoadGame($gid,$uid);
	if ($game==null)
		return 'ERROR: Game "'.$gid.'" does not exist!';
	if (!$game['p_mayabort'])
		return 'ERROR: You cannot abort the game!';
	unlink("$res_games/$gid");

	ioUnlock();

	return 'Game "'.$gid.'" deleted.';
}

/* Create a new game. If $bcomment is not empty it is black's initial comment.
 * Return name of game. */
function ioCreateGame($white,$black,$bcomment)
{
	/* Build new game context */ 
	$game=array();
	$game['ts_start']=time();
	$game['white']=$white;
	$game['black']=$black;
	$game['curmove']=0;
	$game['curplyr']='w';
	$game['curstate']='?';
	$game['wcs']=1;
	$game['wcl']=1;
	$game['bcs']=1;
	$game['bcl']=1;
	$game['w2spm']='x';
	$game['b2spm']='x';
	$game['lastmove']='x';
	$game['lastkill']='x';
	$game['oscf']='x';
	$game['olcf']='x';
	$game['board']=array(
		'wR', 'wN', 'wB', 'wQ', 'wK', 'wB', 'wN', 'wR',
		'wP', 'wP', 'wP', 'wP', 'wP', 'wP', 'wP', 'wP',
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '',
		'', '', '', '', '', '', '', '',
		'bP', 'bP', 'bP', 'bP', 'bP', 'bP', 'bP', 'bP',
		'bR', 'bN', 'bB', 'bQ', 'bK', 'bB', 'bN', 'bR');
	if (empty($bcomment))
		$bcomment='(silence)';
	else {
		$bcomment=str_replace("\\",'',strip_tags($bcomment));
		$bcomment=str_replace("\n",'<br>',$bcomment);
	}
	$bcomment='<u>'.$black.'</u>: '.$bcomment;
	$game['chatter']=array($bcomment);
		
	/* Save game to file */
	$gfname=sprintf('%s-%s-%s-',date('YmdHi',$game['ts_start']),$white,$black);
	ioSaveGame($game,$gfname);
	return $gfname;
}

/* Update login history of user (add new new timestamp).
 * XXX no access locking since user won't log in twice the same time... */
function ioUpdateLoginHistory($uid)
{
	global $res_users;
	if (!file_exists("$res_users/lhistory/$uid")) {
		/* Create default values (login every 48 hours) */
		$hfile=fopen("$res_users/lhistory/$uid",'w');
		$ts=time();
		for ($i=0;$i<14;$i++) {
			fwrite($hfile,$ts."\n");
			$ts-=172800;
		}
		fclose($hfile);
		return;
	}
	$list=file("$res_users/lhistory/$uid");
	$hfile=fopen("$res_users/lhistory/$uid",'w');
	$ts=time();
	fwrite($hfile,$ts."\n");
	for ($i=0;$i<13;$i++)
		fwrite($hfile,$list[$i]);
	fclose($hfile);
}

/* Compute activity from login history: A time stamp in last week (compared to
 * current time) scores four points. For every week more one point is 
 * substraced. Timestamps older than four weeks are ignored. The final score
 * is doubled. Fresher logins count more than older ones. */
function ioGetUserActivity($uid)
{
	global $res_users;

	if (!file_exists("$res_users/lhistory/$uid"))
		return 0;

	$list=file("$res_users/lhistory/$uid");
	$score=0;
	$cur=time();
	for ($i=0;$i<14;$i++) {
		if ($cur - $list[$i] <= 604800)
			$score += 4;
		else if ($cur - $list[$i] <= 2*604800)
			$score += 3;
		else if ($cur - $list[$i] <= 3*604800)
			$score += 2;
		else if ($cur - $list[$i] <= 4*604800)
			$score += 1;
	}
	if ($score<0) 
		$score=0;
	if ($score>50)
		$score=50;
	return $score*2;
}

/* Load list of all users as name=>name. */
function ioLoadUserList()
{
	global $res_users;

	include($res_users.'/accounts.php');

	$list=array();
	foreach ($passwords as $usr=>$pwd)
		$list[$usr]=$usr;
	return $list;
}

/* Load user password or return null if not found. */
function ioLoadUserPassword($uid)
{
	global $res_users;

	include($res_users.'/accounts.php');

	if (isset($passwords[$uid]))
		return $passwords[$uid];
	return null;
}

/* Get email address of user. Return null if not present. */
function ioLoadUserEmailAddress($uid)
{
	global $res_users;

	include($res_users.'/accounts.php');

	if (isset($mail_addresses[$uid]))
		return $mail_addresses[$uid];
	return null;
}

/* Load user theme. */
function ioLoadUserTheme($uid)
{
	return 'default'; /* XXX always default for now */
}

/* Load stats of user. Always return array but values are all zero if not found.
 * wins: number of wins
 * draws: number of draws
 * losses: number of losses
 * rating: current ELO rating
 * rgames: number of rating change games (update every 5 games)
 * rchange: base value of next rating modification
 */
function ioLoadUserStats($uid)
{
	global $res_users;

	$usr=array();
	$usr['wins']=0;
	$usr['draws']=0;
	$usr['losses']=0;
	$usr['rating']=0;
	$usr['rgames']=0;
	$usr['rchange']=0;
	$uf=file($res_users.'/stats');
	foreach ($uf as $entry)
		if (strncmp($entry,$uid.':',strlen($uid)+1)==0) {
  			/* name:wins:draws:losses:rating:rgames:rmod */
			$info=explode(':',$entry);
			$usr['wins']=$info[1];
			$usr['draws']=$info[2];
			$usr['losses']=$info[3];
			/* XXX backward compatibility: Always assume average 
			 * opponent strength of 1200. If less than 5 games
			 * store sum of opponent strength in 'rchange' (to get
			 * initial strength later, see rating system) otherwise
			 * compute initial strength by considering all game
			 * results (not only first five since these can't be 
			 * figured out anymore - gives better initial rating 
			 * anyway). */
			if (count($info)<5) {
				$num=$info[1]+$info[2]+$info[3];
				if ($num<5) {
					$usr['rgames']=$num;
					$usr['rchange']=$num*1200;
				} else {
					$rating=getInitRating($info[1],$info[2],
								$info[3],1200);
					$usr['rating']=floor($rating);
				}
			} else {
				$usr['rating']=$info[4];
				$usr['rgames']=$info[5];
				$usr['rchange']=$info[6];
			}
			break;
		}
	return $usr;
}

/* Save user stats to file: replace if entry exists or append if it is new. */
function ioSaveUserStats($uid,$stats)
{
	global $res_users;

	$statstr=sprintf('%s:%s:%s:%s:%s:%s:%s',$uid,
					$stats['wins'],$stats['draws'],
					$stats['losses'],$stats['rating'],
					$stats['rgames'],$stats['rchange']);
	$new=1;

	/* Load and possible replace */
	$uf=file($res_users.'/stats');
	foreach ($uf as $key=>$entry)
		if (strncmp($entry,$uid.':',strlen($uid)+1)==0) {
			$new=0;
			$uf[$key]=$statstr."\n";
		}

	/* Save and possibly append */
	$hfile=fopen($res_users.'/stats','w');
	foreach ($uf as $entry)
		fwrite($hfile,$entry);
	if ($new)
		fwrite($hfile,$statstr."\n");
	fclose($hfile);
}

/* Load (and decrypt) private notes of user related to opponent. */
function _decrypt($notes,$key)
{
	if (strlen($key)==0) 
		return $notes;
	$aux=explode(' ',$notes); 
	$high=$aux[1]; 
	$low=$aux[2];
	for ($i=0,$j=0;$i<strlen($high);$i++) {
		$high[$i]=chr((ord($high[$i])-97)*26+(ord($low[$i])-97)-
								ord($key[$j]));
		$j++; 
		if ($j==strlen($key)) 
			$j=0;
	}
	return $high;
}
function ioLoadPrivateNotes($uid,$oid)
{
	global $res_users;

	if (!file_exists($res_users.'/notes/'.$uid.'.php'))
		return '';
	include $res_users.'/notes/'.$uid.'.php';
	return str_replace("\\",'',_decrypt($user_notes[$oid],
						$_SESSION['noteskey']));
}

/* Save (and encrypt) private notes of user related to opponent.
 * XXX no locking since user won't change notes twice the same time... */
function _encrypt($notes,$key)
{
	if (strlen($key)==0) 
		return $notes;
	$high=$notes; 
	$j=0;
	for ($i=0;$i<strlen($notes);$i++) {
		$val=ord($notes[$i])+ord($key[$j]);
		$high[$i]=chr(97+floor($val/26));
		$notes[$i]=chr(97+$val%26);
		$j++; 
		if ($j==strlen($key)) 
			$j=0;
	}
	return ' '.$high.' '.$notes;
}
function ioSavePrivateNotes($uid,$oid,$note)
{
	global $res_users;

	if (!file_exists($res_users.'/notes/'.$uid.'.php')) {
		if (empty($note)) 
			return;
		$user_notes=array();
		$user_notes[$oid]=_encrypt($note,$_SESSION['noteskey']);
	} else {
		include $res_users.'/notes/'.$uid.'.php';
		if (!isset($user_notes[$oid]) && empty($note))
			return;
		if (empty($note))
			unset($user_notes[$oid]);
		else
			$user_notes[$oid]=_encrypt($note,$_SESSION['noteskey']);
	}
	$hfile=fopen($res_users.'/notes/'.$uid.'.php','w');
	fwrite($hfile,'<? $user_notes=array('."\n");
	$n=count($user_notes); 
	$i=0;
	foreach($user_notes as $opp=>$note) {
		fwrite($hfile,"'".$opp."'=>'".$note."'"); 
		if ($i+1<$n) 
			fwrite($hfile,',');
		fwrite($hfile,"\n");
		$i++;
	}
	fwrite($hfile,'); ?>');
	fclose($hfile);
}

?>