function GetFingerprint($atext)
{
global $CFG;
$plagiarismsettings = (array) get_config('plagiarism');
$gram_size = $plagiarismsettings['crot_grammarsize'];
$window_size = $plagiarismsettings['crot_windowsize'];
$hashes = array();
try {
$stripped_text = StripText($atext, "");
} catch (Exception $e) {
echo "exception with stripping\n";
flush();
}
$text_len = mb_strlen($stripped_text, "utf-8") - $gram_size;
// get the original positions
$offset = 0;
$curtext = $atext;
preg_match_all('/.|\\n/u', $stripped_text, $matches);
$curstripped = $matches[0];
preg_match_all('/.|\\n/u', $atext, $matches2);
$btext = $matches2[0];
$bpos = 0;
$offset = 0;
$values = array();
for ($i = 0; $i < $text_len; $i++) {
while ($btext[$offset] != $curstripped[$i]) {
$offset++;
}
$orig_positions[$i] = $offset;
$offset++;
$values[$i] = hash('md5', mb_substr($stripped_text, $i, $gram_size, "utf-8"));
}
// compiling fingerprint
$fingers = array();
$fp = array();
$up = $text_len - $window_size + 1;
$i = 0;
$minHashPos = $window_size - 1;
while ($i < $up) {
if ($i == 0 || $minHashPos == $i - 1) {
$minHashPos = $i + $window_size - 1;
$hash = new Fingerprint();
$hash->value = $values[$minHashPos];
$hash->position = $orig_positions[$minHashPos];
$min_hash = $hash;
for ($j = $i + $window_size - 1; $j >= $i; $j--) {
if ($values[$j] < $min_hash->value) {
$hash = new Fingerprint();
$hash->value = $values[$j];
$hash->position = $orig_positions[$j];
$min_hash = $hash;
$minHashPos = $j;
}
}
$i = $minHashPos + 1;
$fingers[] = $min_hash;
} else {
if ($values[$i + $window_size - 1] < $min_hash->value) {
$minHashPos = $i + $window_size - 1;
$hash = new Fingerprint();
$hash->value = $values[$minHashPos];
$hash->position = $orig_positions[$minHashPos];
$min_hash = $hash;
$fingers[] = $min_hash;
$i = $minHashPos + 1;
}
}
}
return $fingers;
}
} else {
// TODO update
}
}
// end of comparing with local documents
}
}
// end for local search
if ($plagiarismvalues['crot_global'] == 1) {
// global search
echo "\nfile {$afile->id} is selected for global search. Starting global search\n";
// strip text
$atext = StripText($atext, " ");
// create search queries
$words = array();
$words = preg_split("/[\\s]+/", trim(StripText($atext, " ")));
$max = sizeof($words) - $query_size + 1;
$queries = array();
for ($i = 0; $i < $max; $i++) {
$query = "";
for ($j = $i; $j - $i < $query_size; $j++) {
$query = $query . " " . $words[$j];
}
$queries[] = $query;
}
// queries are ready!
// create list of URLs
srand((double) microtime() * 10000000);
// randomly select x% of queries
$rand_keys = array_rand($queries, sizeof($queries) / 100 * $globs);
$narr = array();
