TimeKeeper/questionGenerators/english/anagrams.php

<?php

/**
 * Anagram question generator.
 *
 * Changes from the original:
 *  - word selection used `year >= difficulty`, i.e. beginners got every word
 *    and strong players only the hardest; now `year <= difficulty` (same
 *    direction as spelling2, and consistent with the min(...) caps below)
 *  - falls back to any word when nothing exists at the user's level, and shows
 *    a message instead of crashing when the word list is empty
 *  - the scramble is never the original word (up to 10 reshuffles)
 *  - multibyte-safe letter splitting, escaped output
 *  - user escaped in SQL; hard-coded `e107.` database name replaced by MPREFIX
 *  - only the data the checker needs is stored (server-side via TkAnswerStore)
 *  - previous tkLastQuestion row removed before inserting the new one
 */
class anagrams {

    private $user;

    /**
     * @param string $user User to supply the question for.
     */
    public function __construct($user) {
        $this->user = $user;
    }

    public function getanagram() {
        $year = max(1, (int) ceil($this->difficulty()));

        $question = $this->pickWord($year);
        if ($question === null) {
            $question = $this->pickWord(13); // nothing at this level: fall back to any word
        }
        if ($question === null) {
            e107::getRender()->tablerender('Anagrams', 'No anagram words are available yet.');
            return;
        }

        $questionHtml = $this->anagramsHtml($question['word']);

        $db = e107::getDb();
        $db->delete('tkLastQuestion', "user = '" . $db->escape($this->user) . "'");
        $db->insert('tkLastQuestion', ['user' => $this->user, 'LastQuestionHtml' => base64_encode($questionHtml)]);

        e107::getRender()->tablerender('Anagrams', $questionHtml);
    }

    /**
     * Pick a word at or below $year, preferring words this user has answered
     * least in the last month.
     *
     * @return array|null Row with `word`, or null when none found.
     */
    private function pickWord($year) {
        $db = e107::getDb();
        $row = $db->retrieve(
                "SELECT `word`, IFNULL(`cnt`, 0) AS Ncnt FROM
                (SELECT `word` FROM `" . MPREFIX . "tk_wordList`
                 WHERE `year` <= " . (int) $year . " AND `usage` != '' AND CHAR_LENGTH(`word`) > 3) AS wList
             LEFT JOIN
                (SELECT `answer`, COUNT(`answer`) AS `cnt` FROM `" . MPREFIX . "tkReport`
                 WHERE `answereddatestamp` > UNIX_TIMESTAMP(NOW() - INTERVAL 1 MONTH)
                 AND `username` = '" . $db->escape($this->user) . "'
                 AND `subject` = 'anagrams' GROUP BY `answer`) AS Ans
             ON wList.`word` = Ans.`answer`
             ORDER BY IFNULL(`cnt`, 0), RAND() LIMIT 1"
        );

        return (is_array($row) && !empty($row['word'])) ? $row : null;
    }

    /**
     * Build the anagram form for $word. The expected answer is stored
     * server-side; the form only carries a token.
     */
    private function anagramsHtml($word) {
        $letters = preg_split('//u', $word, -1, PREG_SPLIT_NO_EMPTY);
        $shuffled = $letters;
        for ($i = 0; $i < 10; $i++) {
            shuffle($shuffled);
            if ($shuffled !== $letters) {
                break;
            }
        }

        $token = TkAnswerStore::issue($this->user, ['answer1' => $word, 'question' => $shuffled, 'type' => 'anagrams']);

        $frm = e107::getForm();

        $fString = $frm->open('questionForm', 'post', '', ['autocomplete' => 'off', 'class' => 'formclass']);
        $fString .= $frm->label('<h4>Anagrams</h4>') . "</br>\n";
        $fString .= $frm->label('Unjumble the letters to find the word.') . "\n";
        $fString .= '</br>';

        foreach ($shuffled as $letter) {
            $fString .= $frm->label(htmlspecialchars($letter) . " &nbsp; ") . "\n";
        }

        $fString .= '</br></br>';
        $fString .= $frm->text('a1', '', 80, ['placeholder' => 'Write answer here!', 'autocomplete' => "off", 'spellcheck' => "false"]) . "\n";
        $fString .= $frm->hidden('checkerData', $token, ['id' => 'checkerData']);
        $fString .= $frm->hidden('subject', 'anagrams', ['id' => 'subject']);
        $fString .= '</br>' . "\n";
        $fString .= $frm->button('Answer', 'Check answer') . "\n";
        $fString .= $frm->close();
        $fString .= '</br></br>';

        return $fString;
    }

    /**
     * Difficulty (word year level 1-13) from the last month of answers.
     * Capped while the user has few answers.
     *
     * @return float
     */
    private function difficulty() {
        $db = e107::getDb();
        $stats = $db->retrieve(
                "SELECT (SUM(correct)/COUNT(correct)*13) AS percent, COUNT(correct) AS count
             FROM `" . MPREFIX . "tkReport`
             WHERE answereddatestamp >= UNIX_TIMESTAMP(NOW() - INTERVAL 1 MONTH)
             AND `username` = '" . $db->escape($this->user) . "' AND `subject` = 'anagrams'"
        );

        if (!is_array($stats)) {
            return 1;
        }

        $count = (int) $stats['count'];
        $percent = (float) $stats['percent'];

        if ($count >= 30) {
            return $percent;
        } elseif ($count >= 25) {
            return min($percent, 7);
        } elseif ($count >= 20) {
            return min($percent, 5);
        } elseif ($count >= 10) {
            return min($percent, 3);
        }
        return 1;
    }
}