mambax7 / chess

game.php

<?php

use XoopsModules\Chess;

//  ------------------------------------------------------------------------ //
//                XOOPS - PHP Content Management System                      //
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//  You may not change or alter any portion of this comment or credits       //
//  of supporting developers from this source code or any supporting         //
//  source code which is considered copyrighted (c) material of the          //
//  original comment or credit authors.                                      //
//                                                                           //
//  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.                             //
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//  You should have received a copy of the GNU General Public License        //
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/**
 * Handle an individual chess game.
 *
 * The array $gamedata used throughout this file contains the columns of the
 * database row for the current game.
 * @see        ChessGame
 *
 * @package    chess
 * @subpackage game
 */

/**#@+
 */
require_once dirname(__DIR__, 2) . '/mainfile.php';
require_once XOOPS_ROOT_PATH . '/class/xoopsformloader.php';

$GLOBALS['xoopsOption']['template_main']                  = 'chess_game_main.tpl';
$xoopsConfig['module_cache'][$xoopsModule->getVar('mid')] = 0; // disable caching
require_once XOOPS_ROOT_PATH . '/header.php';
require_once XOOPS_ROOT_PATH . '/modules/chess/include/constants.inc.php';
require_once XOOPS_ROOT_PATH . '/modules/chess/include/functions.php';

chess_game();

require_once XOOPS_ROOT_PATH . '/include/comment_view.php';
require_once XOOPS_ROOT_PATH . '/footer.php';
/**#@-*/

/**
 * Handle an individual chess game.
 *
 * processing:
 *  - fetch game data from database
 *  - handle user request
 *  - update game data in database
 *  - display board
 */
function chess_game()
{
    // user input

    $game_id = (int)@$_GET['game_id'];

    $submit_move = isset($_POST['submit_move']);

    $submit_refresh = isset($_POST['submit_refresh']);

    $move = chess_sanitize(trim(@$_POST['chessmove']), 'A-Za-z0-9=-');

    $movetype = chess_sanitize(@$_POST['movetype']);

    $confirm = isset($_POST['confirm']) ? 1 : 0;

    $move_explain = chess_sanitize(trim(@$_POST['move_explain']), 'A-Za-z0-9 .,;:=()[]*?!-');

    $arbiter_explain = chess_sanitize(trim(@$_POST['arbiter_explain']), 'A-Za-z0-9 .,;:=()[]*?!-');

    $orientation = chess_sanitize(@$_POST['orientation']);

    $show_arbiter_ctrl = isset($_POST['show_arbiter_ctrl']);

    $submit_arbitrate = isset($_POST['submit_arbitrate']);

    $arbiter_action = chess_sanitize(@$_POST['arbiter_action']);

    // If form-submit, check security token.

    if (($submit_move || $submit_refresh || $submit_arbitrate || $show_arbiter_ctrl) && is_object($GLOBALS['xoopsSecurity']) && !$GLOBALS['xoopsSecurity']->check()) {
        redirect_header(
            XOOPS_URL . '/modules/chess/',
            _CHESS_REDIRECT_DELAY_FAILURE,
            _MD_CHESS_TOKEN_ERROR . '<br>' . implode('<br>', $GLOBALS['xoopsSecurity']->getErrors())
        );
    }

    // Fetch the game data from the database.

    $gamedata = chess_get_game($game_id);

    if (false === $gamedata) {

The condition false === $gamedata is always false.

        redirect_header(XOOPS_URL . '/modules/chess/', _CHESS_REDIRECT_DELAY_FAILURE, _MD_CHESS_GAME_NOT_FOUND);
    }

    $gamedata_updated = false;

    $move_performed        = false; // status result from move-handler
    $move_result_text      = '';    // text result from move-handler
    $draw_claim_error_text = '';    // text describing invalid draw-claim
    $notify                = '';    // text description of action for notification
    $delete_game           = false;

    global $xoopsUser;

    $uid = $xoopsUser ? $xoopsUser->getVar('uid') : 0;

    $selfplay = $gamedata['white_uid'] == $gamedata['black_uid'];

    if ($selfplay) {
        if ($uid == $gamedata['white_uid']) {
            $user_color = $gamedata['fen_active_color']; // current user is either player, so consider him active player
        } else {
            $user_color = '';                            // current user is not a player
        }
        // not self-play
    } else {
        if ($uid == $gamedata['white_uid']) {
            $user_color = 'w'; // current user is white
        } elseif ($uid == $gamedata['black_uid']) {
            $user_color = 'b'; // current user is black
        } else {
            $user_color = '';  // current user is not a player
        }
    }

    // Determine whether current user is a player in the current game, and whether it's his move.

    $user_is_player = 'w' == $user_color || 'b' == $user_color;

    $user_is_player_to_move = $user_color == $gamedata['fen_active_color'];

    $user_color_name = 'w' == $user_color ? _MD_CHESS_WHITE : _MD_CHESS_BLACK;

    if ($submit_move && !$gamedata['suspended']) {
        // If the player has changed his confirm-move preference, it needs to be updated in the database.

        // For a self-play game, the white and black confirm-move preferences are kept the same, to avoid confusion.

        if ($user_is_player) {
            if ('w' == $user_color && $gamedata['white_confirm'] != $confirm) {
                $gamedata['white_confirm'] = $confirm;

                if ($selfplay) {
                    $gamedata['black_confirm'] = $confirm;
                }

                $gamedata_updated = true;
            } elseif ('b' == $user_color && $gamedata['black_confirm'] != $confirm) {
                $gamedata['black_confirm'] = $confirm;

                if ($selfplay) {
                    $gamedata['white_confirm'] = $confirm;
                }

                $gamedata_updated = true;
            }
        }

        switch ($movetype) {
            default:
            case _CHESS_MOVETYPE_NORMAL:
                if ($user_is_player_to_move && $gamedata['offer_draw'] != $user_color) {
                    [$move_performed, $move_result_text] = chess_move($gamedata, $move);

                    if ($move_performed) {
                        if ($selfplay) { // If self-play, the current user's color switches.
                            $user_color = $gamedata['fen_active_color'];
                        }

                        $gamedata['offer_draw'] = '';

                        $gamedata_updated = true;

                        $notify = "$user_color_name: $move";
                    }
                }
                break;
            case _CHESS_MOVETYPE_CLAIM_DRAW_3:
            case _CHESS_MOVETYPE_CLAIM_DRAW_50:
                if ($user_is_player_to_move && $gamedata['offer_draw'] != $user_color) {
                    if (!empty($move)) {
                        [$move_performed, $move_result_text] = chess_move($gamedata, $move);

                        #var_dump('chess_game', $move_performed, $move_result_text);#*#DEBUG#

                        if ($move_performed) {
                            if ($selfplay) { // If self-play, the current user's color switches.
                                $user_color = $gamedata['fen_active_color'];
                            }

                            $gamedata['offer_draw'] = '';

                            $gamedata_updated = true;

                            $notify = "$user_color_name: $move";
                        } else {
                            break; // move invalid, so don't bother checking draw-claim
                        }
                    }

                    [$draw_claim_valid, $draw_claim_text] = _CHESS_MOVETYPE_CLAIM_DRAW_3 == $movetype ? chess_is_draw_threefold_repetition($gamedata) : chess_is_draw_50_move_rule($gamedata);

                    #var_dump('chess_game', $draw_claim_valid, $draw_claim_text);#*#DEBUG#

                    if ($draw_claim_valid) {
                        $gamedata['offer_draw'] = '';

                        $gamedata['pgn_result'] = '1/2-1/2';

                        $comment = '{' . $draw_claim_text . '}';

                        $gamedata['pgn_movetext'] = str_replace('*', "{$gamedata['pgn_result']} $comment", $gamedata['pgn_movetext']);

                        $gamedata_updated = true;

                        $notify = !empty($move) ? "$user_color_name: $move: $draw_claim_text" : "$user_color_name: $draw_claim_text";
                    } else {
                        $draw_claim_error_text = $draw_claim_text;
                    }
                }
                break;
            case _CHESS_MOVETYPE_RESIGN:
                if ($user_is_player) {
                    $gamedata['offer_draw'] = '';

                    $gamedata['pgn_result'] = 'w' == $user_color ? '0-1' : '1-0';

                    $comment = '{' . $user_color_name . ' ' . _MD_CHESS_RESIGNED . '}';

                    $gamedata['pgn_movetext'] = str_replace('*', "{$gamedata['pgn_result']} $comment", $gamedata['pgn_movetext']);

                    $gamedata_updated = true;

                    $notify = "$user_color_name " . _MD_CHESS_RESIGNED;
                }
                break;
            case _CHESS_MOVETYPE_OFFER_DRAW:
                if ($user_is_player && empty($gamedata['offer_draw']) && !$selfplay) {
                    $gamedata['offer_draw'] = $user_color;

                    $gamedata_updated = true;

                    $notify = "$user_color_name " . _MD_CHESS_OFFERED_DRAW;
                }
                break;
            case _CHESS_MOVETYPE_ACCEPT_DRAW:
                if ($user_is_player && !empty($gamedata['offer_draw']) && $gamedata['offer_draw'] != $user_color && !$selfplay) {
                    $gamedata['offer_draw'] = '';

                    $gamedata['pgn_result'] = '1/2-1/2';

                    $comment = '{' . _MD_CHESS_DRAW_BY_AGREEMENT . '}';

                    $gamedata['pgn_movetext'] = str_replace('*', "{$gamedata['pgn_result']} $comment", $gamedata['pgn_movetext']);

                    $gamedata_updated = true;

                    $notify = "$user_color_name " . _MD_CHESS_ACCEPTED_DRAW;
                }

            // no break
            case _CHESS_MOVETYPE_REJECT_DRAW:
                if ($user_is_player && !empty($gamedata['offer_draw']) && $gamedata['offer_draw'] != $user_color && !$selfplay) {
                    $gamedata['offer_draw'] = '';

                    $gamedata_updated = true;

                    $notify = "$user_color_name " . _MD_CHESS_REJECTED_DRAW;
                }
                break;
            case _CHESS_MOVETYPE_RESTART:
                if ($user_is_player && $selfplay) {
                    // instantiate a ChessGame to get a "fresh" gamestate

                    $chessgame = new Chess\ChessGame($gamedata['pgn_fen']);

The type XoopsModules\Chess\ChessGame was not found. Maybe you did not declare it correctly or list all dependencies?

                    $new_gamestate = $chessgame->gamestate();

                    // update the game data

                    $gamedata['fen_piece_placement'] = $new_gamestate['fen_piece_placement'];

                    $gamedata['fen_active_color'] = $new_gamestate['fen_active_color'];

                    $gamedata['fen_castling_availability'] = $new_gamestate['fen_castling_availability'];

                    $gamedata['fen_en_passant_target_square'] = $new_gamestate['fen_en_passant_target_square'];

                    $gamedata['fen_halfmove_clock'] = $new_gamestate['fen_halfmove_clock'];

                    $gamedata['fen_fullmove_number'] = $new_gamestate['fen_fullmove_number'];

                    $gamedata['pgn_fen'] = $new_gamestate['pgn_fen'];

                    $gamedata['pgn_result'] = $new_gamestate['pgn_result'];

                    $gamedata['pgn_movetext'] = $new_gamestate['pgn_movetext'];

                    // update user color

                    $user_color = $gamedata['fen_active_color'];

                    $gamedata_updated = true;
                }
                break;
            case _CHESS_MOVETYPE_DELETE:
                if ($user_is_player && ($selfplay || chess_can_delete())) {
                    $delete_game = true; // must defer actual deletion until after notifications are sent
                    $notify      = eval('return \'' . _MD_CHESS_DELETED_GAME . '\';'); // eval references $username

The use of eval() is discouraged.

                }
                break;
            case _CHESS_MOVETYPE_WANT_ARBITRATION:
                if ($user_is_player) {
                    // Ensure that $move_explain does not contain separator $sep.

                    $sep = '|';

                    $move_explain = str_replace($sep, '_', $move_explain);

                    $gamedata['suspended'] = implode($sep, [date('Y-m-d H:i:s'), $uid, _CHESS_MOVETYPE_WANT_ARBITRATION, $move_explain]);

                    $gamedata_updated = true;

                    $notify = "$user_color_name " . _MD_CHESS_RQSTED_ARBT . ' ' . _MD_CHESS_BEEN_SUSPENDED;
                }
                break;
        }
    }

    // If board orientation setting uninitialized or invalid, set it to the appropriate default.

    if (!in_array($orientation, [_CHESS_ORIENTATION_ACTIVE, _CHESS_ORIENTATION_WHITE, _CHESS_ORIENTATION_BLACK])) {
        if ($user_is_player && 'b' == $user_color) {
            $orientation = _CHESS_ORIENTATION_BLACK;
        } else {
            $orientation = _CHESS_ORIENTATION_WHITE;
        }
    }

    // Determine if user is a valid arbiter.

    global $xoopsModule;

    $is_arbiter = is_object($xoopsUser) && $xoopsUser->isAdmin($xoopsModule->getVar('mid'));

    // If arbiter action was submitted, and user is a valid arbiter, process the action.

    if ($submit_arbitrate && $is_arbiter) {
        $username = $xoopsUser ? $xoopsUser->getVar('uname') : '*unknown*';

$xoopsUser is of type object, thus it always evaluated to true.

The assignment to $username is dead and can be removed.

        switch ($arbiter_action) {
            case _CHESS_ARBITER_RESUME:
                if ($gamedata['suspended'] && '*' == $gamedata['pgn_result']) {
                    $gamedata['suspended'] = '';

                    $gamedata_updated = true;

                    $notify = eval('return \'' . _MD_CHESS_RESUMED_PLAY . '\';'); // eval references $username

The use of eval() is discouraged.

                }
                break;
            case _CHESS_ARBITER_DRAW:
                if ($gamedata['suspended'] && '*' == $gamedata['pgn_result']) {
                    $gamedata['offer_draw'] = '';

                    $gamedata['pgn_result'] = '1/2-1/2';

                    $arbiter_explain = str_replace('{', '(', $arbiter_explain);

                    $arbiter_explain = str_replace('}', ')', $arbiter_explain);

                    $comment = '{' . sprintf(_MD_CHESS_DRAW_DECLARED, $arbiter_explain) . '}';

                    $gamedata['pgn_movetext'] = str_replace('*', "{$gamedata['pgn_result']} $comment", $gamedata['pgn_movetext']);

                    $gamedata['suspended'] = '';

                    $gamedata_updated = true;

                    $notify = eval('return \'' . _MD_CHESS_DECLARED_DRAW . '\';'); // eval references $username

The use of eval() is discouraged.

                }
                break;
            case _CHESS_ARBITER_DELETE:
                if ($gamedata['suspended']) {
                    $delete_game = true; // must defer actual deletion until after notifications are sent
                    $notify      = eval('return \'' . _MD_CHESS_DELETED_GAME . '\';'); // eval references $username

The use of eval() is discouraged.

                }
                break;
            case _CHESS_ARBITER_SUSPEND:
                if (!$gamedata['suspended'] && '*' == $gamedata['pgn_result']) {
                    // Ensure that $arbiter_explain does not contain separator $sep.

                    $sep = '|';

                    $arbiter_explain = str_replace($sep, '_', $arbiter_explain);

                    $gamedata['suspended'] = implode('|', [date('Y-m-d H:i:s'), $uid, _CHESS_MOVETYPE_ARBITER_SUSPEND, $arbiter_explain]);

                    $gamedata_updated = true;

                    $notify = eval('return \'' . _MD_CHESS_SUSPENDED_PLAY . '\';'); // eval references $username

The use of eval() is discouraged.

                }
                break;
            default:
                break;
        }
    }

    // Store the updated game data in the database.

    if ($gamedata_updated) {
        chess_put_game($game_id, $gamedata);
    }

    // Display the (possibly updated) board.

    if (!$delete_game) {
        chess_show_board($gamedata, $orientation, $user_color, $move_performed, $move_result_text, $draw_claim_error_text, $show_arbiter_ctrl && $is_arbiter);
    }

    // If a move (or other action) was made, notify any subscribers.

    if (!empty($notify)) {
        $notificationHandler = xoops_getHandler('notification');

        $notificationHandler->triggerEvent('game', $game_id, 'notify_game_move', ['CHESS_ACTION' => $notify]);

The method triggerEvent() does not exist on XoopsObjectHandler. It seems like you code against a sub-type of XoopsObjectHandler such as XoopsNotificationHandler or XoopsPersistableObjectHandler.

        // admin notifications

        if (_CHESS_MOVETYPE_WANT_ARBITRATION == $movetype) {
            $event = 'notify_request_arbitration';

            $username = $xoopsUser ? $xoopsUser->getVar('uname') : '(' . _MD_CHESS_UNKNOWN . ')';

            $extra_tags = ['CHESS_REQUESTOR' => $username, 'CHESS_GAME_ID' => $game_id, 'CHESS_EXPLAIN' => $move_explain];

            $notificationHandler->triggerEvent('global', 0, $event, $extra_tags);
        }
    }

    // Handle delete-game action.

    if ($delete_game) {
        chess_delete_game($game_id);

        redirect_header(XOOPS_URL . '/modules/chess/', _CHESS_REDIRECT_DELAY_SUCCESS, _MD_CHESS_GAME_DELETED);
    }
}

/**
 * Fetch game data from database.
 *
 * @param int $game_id Game ID
 * @return array  Game data
 */
function chess_get_game($game_id)
{
    global $xoopsDB;

    $games_table = $xoopsDB->prefix('chess_games');

    $result = $xoopsDB->query("SELECT * FROM $games_table WHERE game_id = '$game_id'");

    $gamedata = $xoopsDB->fetchArray($result);

    #var_dump('chess_get_game, gamedata', $gamedata);#*#DEBUG#

    $xoopsDB->freeRecordSet($result);

    return $gamedata;
}

/**
 * Store game data in database.
 *
 * @param int   $game_id  Game ID
 * @param array $gamedata Game data
 */
function chess_put_game($game_id, $gamedata)
{
    global $xoopsDB;

    $myts = MyTextSanitizer::getInstance();

    $suspended_q = $myts->addSlashes($gamedata['suspended']);

    $movetext_q = $myts->addSlashes($gamedata['pgn_movetext']);

    $table = $xoopsDB->prefix('chess_games');

    #echo "updating database table $table<br>\n";#*#DEBUG#

    $xoopsDB->query(
        trim(
            "
        UPDATE $table
        SET
            start_date                   = '{$gamedata['start_date']}',
            last_date                    = '{$gamedata['last_date']}',
            fen_piece_placement          = '{$gamedata['fen_piece_placement']}',
            fen_active_color             = '{$gamedata['fen_active_color']}',
            fen_castling_availability    = '{$gamedata['fen_castling_availability']}',
            fen_en_passant_target_square = '{$gamedata['fen_en_passant_target_square']}',
            fen_halfmove_clock           = '{$gamedata['fen_halfmove_clock']}',
            fen_fullmove_number          = '{$gamedata['fen_fullmove_number']}',
            pgn_result                   = '{$gamedata['pgn_result']}',
            pgn_movetext                 = '$movetext_q',
            offer_draw                   = '{$gamedata['offer_draw']}',
            suspended                    = '$suspended_q',
            white_confirm                = '{$gamedata['white_confirm']}',
            black_confirm                = '{$gamedata['black_confirm']}'
        WHERE  game_id = '$game_id'
    "
        )
    );

    if ($xoopsDB->errno()) {
        trigger_error($xoopsDB->errno() . ':' . $xoopsDB->error(), E_USER_ERROR);
    }

    if ('*' != $gamedata['pgn_result'] && '1' == $gamedata['is_rated']) {
        require_once XOOPS_ROOT_PATH . '/modules/chess/include/ratings.php';

        chess_ratings_adj($game_id);
    }
}

/**
 * Delete game from database.
 *
 * @param int $game_id Game ID
 */
function chess_delete_game($game_id)
{
    global $xoopsModule, $xoopsDB;

    // delete notifications associated with this game

    xoops_notification_deletebyitem($xoopsModule->getVar('mid'), 'game', $game_id);

    $table = $xoopsDB->prefix('chess_games');

    $xoopsDB->query("DELETE FROM $table WHERE game_id='$game_id'");

    if ($xoopsDB->errno()) {
        trigger_error($xoopsDB->errno() . ':' . $xoopsDB->error(), E_USER_ERROR);
    }
}

/**
 * Handle a move.
 *
 * @param array  $gamedata Game data (input/output)
 * @param string $move     The move
 * @return array A two-element array:
 *                         - $move_performed: true if the move was performed and the game state has been updated, false otherwise
 *                         - $move_result_text: text message
 */
function chess_move(&$gamedata, $move)
{
    $gamestate = [
        'fen_piece_placement'          => $gamedata['fen_piece_placement'],
        'fen_active_color'             => $gamedata['fen_active_color'],
        'fen_castling_availability'    => $gamedata['fen_castling_availability'],
        'fen_en_passant_target_square' => $gamedata['fen_en_passant_target_square'],
        'fen_halfmove_clock'           => $gamedata['fen_halfmove_clock'],
        'fen_fullmove_number'          => $gamedata['fen_fullmove_number'],
        'pgn_fen'                      => $gamedata['pgn_fen'],
        'pgn_result'                   => $gamedata['pgn_result'],
        'pgn_movetext'                 => $gamedata['pgn_movetext'],
    ];

    $chessgame = new Chess\ChessGame($gamestate);

    #echo "Performing move: '$move'<br>\n";#*#DEBUG#

    [$move_performed, $move_result_text] = $chessgame->move($move);

    #echo "Move result: '$move_result_text'<br>\n";#*#DEBUG#

    if ($move_performed) {
        // The move was valid - update the game data.

        $new_gamestate = $chessgame->gamestate();

        #var_dump('new_gamestate', $new_gamestate);#*#DEBUG#

        #*#DEBUG# - start

        #if ($new_gamestate['fen_castling_availability'] != $gamedata['fen_castling_availability']) {

        #    echo "*** castling_availability changed from '{$gamedata['fen_castling_availability']}' to '{$new_gamestate['fen_castling_availability']}' ***<br>\n";

        #}

        #*#DEBUG# - end

        $gamedata['fen_piece_placement'] = $new_gamestate['fen_piece_placement'];

        $gamedata['fen_active_color'] = $new_gamestate['fen_active_color'];

        $gamedata['fen_castling_availability'] = $new_gamestate['fen_castling_availability'];

        $gamedata['fen_en_passant_target_square'] = $new_gamestate['fen_en_passant_target_square'];

        $gamedata['fen_halfmove_clock'] = $new_gamestate['fen_halfmove_clock'];

        $gamedata['fen_fullmove_number'] = $new_gamestate['fen_fullmove_number'];

        $gamedata['pgn_fen'] = $new_gamestate['pgn_fen'];

        $gamedata['pgn_result'] = $new_gamestate['pgn_result'];

        $gamedata['pgn_movetext'] = $new_gamestate['pgn_movetext'];

        $gamedata['last_date'] = date('Y-m-d H:i:s');

        // if start_date undefined (first move), initialize it

        if ('0000-00-00 00:00:00' == $gamedata['start_date']) {
            $gamedata['start_date'] = $gamedata['last_date'];
        }
    }

    return [$move_performed, $move_result_text];
}

/**
 * Verify a draw-claim under the 50-move rule.
 *
 * @param array $gamedata Game data
 * @return array  A two-element array:
 *                        - $draw_claim_valid: True if draw-claim is valid, otherwise false
 *                        - $draw_claim_text: Describes draw-claim result
 */
function chess_is_draw_50_move_rule($gamedata)
{
    #var_dump('gamedata', $gamedata);#*#DEBUG#

    if ($gamedata['fen_halfmove_clock'] >= 100) {
        $draw_claim_valid = true;

        $draw_claim_text = _MD_CHESS_DRAW_50;
    } else {
        $draw_claim_valid = false;

        $draw_claim_text = _MD_CHESS_NO_DRAW_50;
    }

    return [$draw_claim_valid, $draw_claim_text];
}

/**
 * Verify a draw-claim under the threefold-repetition rule.
 *
 * Board positions are compared using the first four fields of the FEN data:
 * fen_piece_placement, fen_active_color, fen_castling_availability and fen_en_passant_target_square.
 *
 * @param array $gamedata Game data
 * @return array  A two-element array:
 *                        - $draw_claim_valid: True if draw-claim is valid, otherwise false
 *                        - $draw_claim_text: Describes draw-claim result
 */
function chess_is_draw_threefold_repetition($gamedata)
{
    #var_dump('gamedata', $gamedata);#*#DEBUG#

    // Define this constant as true to output a log file containing a move analysis.

    define('CHESS_LOG_3FOLD', false);

    if (CHESS_LOG_3FOLD) {
        $log = [];
    }

    $chessgame = new Chess\ChessGame($gamedata);

The assignment to $chessgame is dead and can be removed.

    // board position against which to check for repetitions

    $last_board_state = "{$gamedata['fen_piece_placement']} {$gamedata['fen_active_color']} {$gamedata['fen_castling_availability']} {$gamedata['fen_en_passant_target_square']}";

    $last_move_number = $gamedata['fen_fullmove_number'];

    #echo "last_board_state='$last_board_state'<br>\n";#*#DEBUG#

    if (CHESS_LOG_3FOLD) {
        $log[] = sprintf('%08x %03d%1s %s', crc32($last_board_state), $gamedata['fen_fullmove_number'], $gamedata['fen_active_color'], $last_board_state);
    }

    $chessgame = new Chess\ChessGame($gamedata['pgn_fen']);

    empty($chessgame->error) or trigger_error('chessgame invalid', E_USER_ERROR);

    $tmp_gamedata = $chessgame->gamestate();

    is_array($tmp_gamedata) or trigger_error('gamestate invalid', E_USER_ERROR);

    #*#DEBUG# - start

    /***
     * if (function_exists('posix_times')) {
     * $posix_times = posix_times();
     * var_dump('posix_times', $posix_times);
     * }
     * if (function_exists('getrusage')) {
     * $rusage = getrusage();
     * var_dump('rusage', $rusage);
     * }
     ***/

    #*#DEBUG# - end

    // $repeats is the list of moves for which the board positions are identical.

    // For example, '6w' would represent the board position immediately before white's sixth move.

    // The current position is included, since that's the position against which the other positions will be compared.

    $repeats[] = $gamedata['fen_fullmove_number'] . $gamedata['fen_active_color'];

$repeats was never initialized. Although not strictly required by PHP, it is generally a good practice to add $repeats = array(); before regardless.

    // Compare initial board position with last board position, unless the move number is the same, meaning that there haven't been any moves.

    #echo "FEN: '{$tmp_gamedata['fen_piece_placement']} {$tmp_gamedata['fen_active_color']} {$tmp_gamedata['fen_castling_availability']} {$tmp_gamedata['fen_en_passant_target_square']} {$tmp_gamedata['fen_halfmove_clock']} {$tmp_gamedata['fen_fullmove_number']}'<br>\n";#*#DEBUG#

    $board_state = "{$tmp_gamedata['fen_piece_placement']} {$tmp_gamedata['fen_active_color']} {$tmp_gamedata['fen_castling_availability']} {$tmp_gamedata['fen_en_passant_target_square']}";

    if ($tmp_gamedata['fen_fullmove_number'] != $last_move_number && $board_state == $last_board_state) {
        $repeats[] = $tmp_gamedata['fen_fullmove_number'] . $tmp_gamedata['fen_active_color'];

        if (CHESS_LOG_3FOLD) {
            $log[] = sprintf('%08x %03d%1s %s', crc32($board_state), $tmp_gamedata['fen_fullmove_number'], $tmp_gamedata['fen_active_color'], $board_state);
        }

        #*#DEBUG# - start
        /***
         * if (count($repeats) >= 3) {
         * echo "*** Three repetitions! {$repeats[1]},{$repeats[2]},{$repeats[0]} ***<br>\n";
         * } elseif (count($repeats) >= 2) {
         * echo "*** Two repetitions!  {$repeats[1]},{$repeats[0]} ***<br>\n";
         * }
         ***/

        #*#DEBUG# - end
    }

    // Convert pgn_movetext into Nx3 array $movelist.

    $movelist = chess_make_movelist($gamedata['pgn_movetext']);

    #var_dump('movelist', $movelist);#*#DEBUG#

    // Compare board positions after each move with last board position.

    foreach ($movelist as $fullmove) {
        #echo "'{$fullmove[0]}' '{$fullmove[1]}' '{$fullmove[2]}'<br>\n";#*#DEBUG#

        if (CHESS_LOG_3FOLD) {
            #$log[] = "'{$fullmove[0]}' '{$fullmove[1]}' '{$fullmove[2]}'";#*#LOG_3FOLD# #*#DEBUG#
        }

        for ($i = 1; $i <= 2; ++$i) {
            if (!empty($fullmove[$i])) {
                $move = $fullmove[$i];
            } else {
                continue; // $fullmove[$i] can be empty if last move was white's, or if game was setup with black to move first.
            }

            // Remove check/checkmate annotation, if present.

            $move = str_replace('+', '', $move);

            $move = str_replace('#', '', $move);

            #echo "Performing move: '$move'<br>\n";#*#DEBUG#

            [$tmp_move_performed, $tmp_move_result_text] = $chessgame->move($move);

            #echo "Move result: '$tmp_move_result_text'<br>\n";#*#DEBUG#

            $tmp_move_performed or trigger_error("Failed to perform move $move: $tmp_move_result_text", E_USER_ERROR);

            $tmp_gamedata = $chessgame->gamestate();

            #echo "FEN: '{$tmp_gamedata['fen_piece_placement']} {$tmp_gamedata['fen_active_color']} {$tmp_gamedata['fen_castling_availability']} {$tmp_gamedata['fen_en_passant_target_square']} {$tmp_gamedata['fen_halfmove_clock']} {$tmp_gamedata['fen_fullmove_number']}'<br>\n";#*#DEBUG#

            $board_state = "{$tmp_gamedata['fen_piece_placement']} {$tmp_gamedata['fen_active_color']} {$tmp_gamedata['fen_castling_availability']} {$tmp_gamedata['fen_en_passant_target_square']}";

            if (CHESS_LOG_3FOLD) {
                $log[] = sprintf('%08x %03d%1s %s', crc32($board_state), $tmp_gamedata['fen_fullmove_number'], $tmp_gamedata['fen_active_color'], $board_state);
            }

            if ($tmp_gamedata['fen_fullmove_number'] != $last_move_number && $board_state == $last_board_state) {
                $repeats[] = $tmp_gamedata['fen_fullmove_number'] . $tmp_gamedata['fen_active_color'];

                #*#DEBUG# - start

                /***
                 * if (count($repeats) >= 3) {
                 * echo "*** Three repetitions! {$repeats[1]},{$repeats[2]},{$repeats[0]} ***<br>\n";
                 * } elseif (count($repeats) >= 2) {
                 * echo "*** Two repetitions!  {$repeats[1]},{$repeats[0]} ***<br>\n";
                 * }
                 ***/

                #*#DEBUG# - end

                if (count($repeats) >= 3) {
                    break 2;
                }
            }
        }
    }

    #*#DEBUG# - start

    /***
     * if (function_exists('posix_times')) {
     * $posix_times = posix_times();
     * var_dump('posix_times', $posix_times);
     * }
     * if (function_exists('getrusage')) {
     * $rusage = getrusage();
     * var_dump('rusage', $rusage);
     * }
     ***/

    #*#DEBUG# - end

    if (count($repeats) >= 3) {
        $draw_claim_valid = true;

        $draw_claim_text = sprintf(_MD_CHESS_DRAW_3, "{$repeats[1]},{$repeats[2]},{$repeats[0]}");
    } else {
        $draw_claim_valid = false;

        $draw_claim_text = _MD_CHESS_NO_DRAW_3;
    }

    if (CHESS_LOG_3FOLD) {
        $logfile = XOOPS_ROOT_PATH . '/cache/' . date('Ymd_His') . '_3fold.log';

        sort($log);

        error_log(implode("\n", $log), 3, $logfile);
    }

    return [$draw_claim_valid, $draw_claim_text];
}

/**
 * Convert pgn_movetext into Nx3 array.
 *
 * @param array $movetext pgn_movetext
 * @return array Nx3 array
 */
function chess_make_movelist($movetext)
{
    $movelist = [];

    $move_tokens = explode(' ', preg_replace('/\{.*\}/', '', $movetext));

preg_replace('/\{.*\}/', '', $movetext) of type string[] is incompatible with the type string expected by parameter $string of explode().

    $index = -1;

    while ($move_tokens) {

The expression $move_tokens of type string[] is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

        $move_token = array_shift($move_tokens);

        if (in_array($move_token, ['1-0', '0-1', '1/2-1/2', '*'])) {
            break;
        } elseif (preg_match('/^\d+(\.|\.\.\.)$/', $move_token, $matches)) {
            ++$index;

            $movelist[$index][] = $move_token;

            if ('...' == $matches[1]) { // setup-game with initial black move - add padding for white's move
                $movelist[$index][] = '';
            }
        } else {
            $movelist[$index][] = $move_token;
        }
    }

    return $movelist;
}

/**
 * Display chess board.
 *
 * @param array  $gamedata              Game data
 * @param string $orientation           _CHESS_ORIENTATION_ACTIVE, _CHESS_ORIENTATION_WHITE or _CHESS_ORIENTATION_BLACK
 * @param string $user_color            'w', 'b' or '' (empty string indicates that current user is not a player in this game)
 * @param bool   $move_performed        True if move was performed
 * @param string $move_result_text      Text describing move
 * @param string $draw_claim_error_text Non-empty if draw claim invalid
 * @param bool   $show_arbiter_ctrl     True if arbiter controls are to be displayed
 */
function chess_show_board($gamedata, $orientation, $user_color, $move_performed, $move_result_text = '', $draw_claim_error_text = '', $show_arbiter_ctrl = false)
{
    global $xoopsTpl;

    $xoopsTpl->assign(
        'xoops_module_header',
        '
        <link rel="stylesheet" type="text/css" media="screen" href="' . XOOPS_URL . '/modules/chess/assets/css/style.css">
    '
    );

    $memberHandler = xoops_getHandler('member');

    $white_user = $memberHandler->getUser($gamedata['white_uid']);

The method getUser() does not exist on XoopsObjectHandler. It seems like you code against a sub-type of XoopsObjectHandler such as XoopsAvatarHandler or XoopsPersistableObjectHandler.

    $white_username = is_object($white_user) ? $white_user->getVar('uname') : '?';

    $black_user = $memberHandler->getUser($gamedata['black_uid']);

    $black_username = is_object($black_user) ? $black_user->getVar('uname') : '?';

    // Determine whether board is flipped (black at bottom) or "normal" (white at bottom).

    switch ($orientation) {
        default:
        case _CHESS_ORIENTATION_ACTIVE:
            $flip = 'b' == $gamedata['fen_active_color'];
            break;
        case _CHESS_ORIENTATION_WHITE:
            $flip = false;
            break;
        case _CHESS_ORIENTATION_BLACK:
            $flip = true;
            break;
    }

    // Convert fen_piece_placement string into 8x8-array $tiles.

    $tiles = [];

    $ranks = explode('/', $gamedata['fen_piece_placement']);

    if ($flip) {
        $ranks = array_reverse($ranks);
    }

    foreach ($ranks as $rank) {
        $expanded_row = preg_replace_callback(
            '/(\d)/',

            static function ($matches) {
                return str_repeat('x', $matches[1]);
            },
            $rank
        );

        $rank_tiles = preg_split('//', $expanded_row, -1, PREG_SPLIT_NO_EMPTY);

        $tiles[] = $flip ? array_reverse($rank_tiles) : $rank_tiles;

It seems like $rank_tiles can also be of type false; however, parameter $array of array_reverse() does only seem to accept array, maybe add an additional type check?

    }

    #var_dump('tiles', $tiles);#*#DEBUG#

    // Convert pgn_movetext into Nx3 array $movelist.

    $movelist = chess_make_movelist($gamedata['pgn_movetext']);

    static $file_labels = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];

    if ($flip) {
        $file_labels = array_reverse($file_labels);
    }

    $xoopsTpl->assign('chess_gamedata', $gamedata);

    // comment at end of movetext

    if (preg_match('/\{(.*?)\}\s*$/', $gamedata['pgn_movetext'], $matches)) {
        $xoopsTpl->assign('chess_result_comment', $matches[1]);
    } else {
        $xoopsTpl->assign('chess_result_comment', '');
    }

    $xoopsTpl->assign('chess_create_date', '0000-00-00 00:00:00' != $gamedata['create_date'] ? strtotime($gamedata['create_date']) : 0);

    $xoopsTpl->assign('chess_start_date', '0000-00-00 00:00:00' != $gamedata['start_date'] ? strtotime($gamedata['start_date']) : 0);

    $xoopsTpl->assign('chess_last_date', '0000-00-00 00:00:00' != $gamedata['last_date'] ? strtotime($gamedata['last_date']) : 0);

    $xoopsTpl->assign('chess_white_user', $white_username);

    $xoopsTpl->assign('chess_black_user', $black_username);

    $xoopsTpl->assign('chess_tiles', $tiles);

    $xoopsTpl->assign('chess_file_labels', $file_labels);

    $xoopsTpl->assign(
        'chess_pgn_string',
        chess_to_pgn_string(
            [
                'event'    => '?',
                'site'     => $_SERVER['SERVER_NAME'],
                'datetime' => $gamedata['start_date'],
                'round'    => '?',
                'white'    => $white_username,
                'black'    => $black_username,
                'result'   => $gamedata['pgn_result'],
                'setup'    => !empty($gamedata['pgn_fen']) ? 1 : 0,
                'fen'      => $gamedata['pgn_fen'],
                'movetext' => $gamedata['pgn_movetext'],
            ]
        )
    );

    $xoopsTpl->assign('chess_movelist', $movelist);

    $xoopsTpl->assign('chess_date_format', _MEDIUMDATESTRING);

    #if (empty($move_result_text)) {$move_result_text = 'test';}#*#DEBUG#

    $xoopsTpl->assign('chess_move_performed', $move_performed);

    $xoopsTpl->assign('chess_move_result', $move_result_text);

    $xoopsTpl->assign('chess_draw_claim_error_text', $draw_claim_error_text);

    $xoopsTpl->assign('chess_user_color', $user_color);

    $xoopsTpl->assign('chess_confirm', $gamedata['w' == $user_color ? 'white_confirm' : 'black_confirm']);

    $xoopsTpl->assign('chess_orientation', $orientation);

    $xoopsTpl->assign('chess_rank_start', $flip ? 1 : 8);

    $xoopsTpl->assign('chess_rank_direction', $flip ? 'up' : 'down');

    $xoopsTpl->assign('chess_file_start', $flip ? 8 : 1);

    $xoopsTpl->assign('chess_file_direction', $flip ? 'down' : 'up');

    static $pieces = [
        'K' => ['color' => 'w', 'name' => 'wking', 'alt' => _MD_CHESS_ALT_WKING],
        'Q' => ['color' => 'w', 'name' => 'wqueen', 'alt' => _MD_CHESS_ALT_WQUEEN],
        'R' => ['color' => 'w', 'name' => 'wrook', 'alt' => _MD_CHESS_ALT_WROOK],
        'B' => ['color' => 'w', 'name' => 'wbishop', 'alt' => _MD_CHESS_ALT_WBISHOP],
        'N' => ['color' => 'w', 'name' => 'wknight', 'alt' => _MD_CHESS_ALT_WKNIGHT],
        'P' => ['color' => 'w', 'name' => 'wpawn', 'alt' => _MD_CHESS_ALT_WPAWN],
        'k' => ['color' => 'b', 'name' => 'bking', 'alt' => _MD_CHESS_ALT_BKING],
        'q' => ['color' => 'b', 'name' => 'bqueen', 'alt' => _MD_CHESS_ALT_BQUEEN],
        'r' => ['color' => 'b', 'name' => 'brook', 'alt' => _MD_CHESS_ALT_BROOK],
        'b' => ['color' => 'b', 'name' => 'bbishop', 'alt' => _MD_CHESS_ALT_BBISHOP],
        'n' => ['color' => 'b', 'name' => 'bknight', 'alt' => _MD_CHESS_ALT_BKNIGHT],
        'p' => ['color' => 'b', 'name' => 'bpawn', 'alt' => _MD_CHESS_ALT_BPAWN],
        'x' => ['color' => 'x', 'name' => 'empty', 'alt' => _MD_CHESS_ALT_EMPTY],
    ];

    $xoopsTpl->assign('chess_pieces', $pieces);

    $xoopsTpl->assign('chess_show_arbitration_controls', $show_arbiter_ctrl);

    if ($show_arbiter_ctrl && $gamedata['suspended']) {
        [$susp_date, $susp_uid, $susp_type, $susp_explain] = explode('|', $gamedata['suspended']);

        switch ($susp_type) {
            case 'arbiter_suspend':
                $susp_type_display = _MD_CHESS_SUSP_TYPE_ARBITER;
                break;
            case 'want_arbitration':
                $susp_type_display = _MD_CHESS_SUSP_TYPE_PLAYER;
                break;
            default:
                $susp_type_display = _MD_CHESS_LABEL_ERROR;
                break;
        }

        $susp_user = $memberHandler->getUser($susp_uid);

        $susp_username = is_object($susp_user) ? $susp_user->getVar('uname') : _MD_CHESS_UNKNOWN;

        $suspend_info = [
            'date'   => strtotime($susp_date),
            'user'   => $susp_username,
            'type'   => $susp_type_display,
            'reason' => $susp_explain,
        ];

        $xoopsTpl->assign('chess_suspend_info', $suspend_info);
    }

    // Initialize $captured_pieces_all to indicate all pieces captured, then subtract off the pieces remaining on the board.

    $captured_pieces_all = [
        'Q' => 1,
        'R' => 2,
        'B' => 2,
        'N' => 2,
        'P' => 8,
        'q' => 1,
        'r' => 2,
        'b' => 2,
        'n' => 2,
        'p' => 8,
    ];

    for ($i = 0, $iMax = mb_strlen($gamedata['fen_piece_placement']); $i < $iMax; ++$i) {
        $piece = $gamedata['fen_piece_placement'][$i];

        if (!empty($captured_pieces_all[$piece])) {
            --$captured_pieces_all[$piece];
        }
    }

    // Construct lists of white's and black's captured pieces.

    $captured_pieces = ['white' => [], 'black' => []];

    foreach ($captured_pieces_all as $piece => $count) {
        if ($count > 0) {
            if (ctype_upper($piece)) {
                $captured_pieces['white'] = array_merge($captured_pieces['white'], array_pad([], $count, $piece));
            } elseif (ctype_lower($piece)) {
                $captured_pieces['black'] = array_merge($captured_pieces['black'], array_pad([], $count, $piece));
            }
        }
    }

    #var_dump('captured_pieces_all', $captured_pieces_all);#*#DEBUG#

    #var_dump('captured_pieces', $captured_pieces);#*#DEBUG#

    $xoopsTpl->assign('chess_captured_pieces', $captured_pieces);

    $xoopsTpl->assign('chess_pawn_promote_choices', 'w' == $gamedata['fen_active_color'] ? ['Q', 'R', 'B', 'N'] : ['q', 'r', 'b', 'n']);

    $xoopsTpl->assign('chess_allow_delete', chess_can_delete());

    // popup window contents for selecting piece to which pawn is promoted

    // (Note that template is compiled here by fetch(), so any template variables it uses must already be defined.)

    $xoopsTpl->assign('chess_pawn_promote_popup', $user_color ? $xoopsTpl->fetch('db:chess_game_promote_popup.tpl') : '');

    $xoopsTpl->assign('chess_ratings_enabled', 'none' != chess_moduleConfig('rating_system'));

    // security token

    $xoopsTpl->assign('chess_xoops_request_token', is_object($GLOBALS['xoopsSecurity']) ? $GLOBALS['xoopsSecurity']->getTokenHTML() : '');
}

?>

It is not recommended to use PHP's closing tag ?> in files other than templates.