/**
* Filters search results to pick out only the ones that match the query.
* @param array $results Array of results from internal_query
* @param int $desired Number of desired results
* @return object ->results containing actual results and ->dbnext
* containing database position of next set of results.
* @throws coding_exception If the results contain unsupported plugin types
*/
private function internal_filter($results, $desired)
{
global $CFG;
$required = array();
$accepted = array();
$count = 0;
$return = new StdClass();
$return->dbnext = 0;
foreach ($results as $result) {
$return->dbnext++;
if (substr($result->plugin, 0, 4) === 'mod_') {
// Module plugins.
$module = substr($result->plugin, 4);
$function = $module . '_ousearch_get_document';
if (!array_key_exists($module, $required)) {
require_once $CFG->dirroot . '/mod/' . $module . '/lib.php';
$required[$module] = true;
if (!function_exists($function)) {
throw new coding_exception('Missing module search support ' . $function, 'Module is not searchable. Needs function ' . $function . '. See local/ousearch/doc/usage.html.');
}
}
} else {
if (substr($result->plugin, 0, 5) === 'test_') {
// Testing code, assumed to already be included.
$function = substr($result->plugin, 5) . '_ousearch_get_document';
} else {
// Nothing else supported yet.
throw new coding_exception('Unsupported search plugin type ' . $result->plugin, 'OU search only currently works for modules');
}
}
// Let's request the document. Note that the 'document' fields of
// $result are those used by this function to find the right one.
$page = $function($result);
// Ignore if we can't find the document.
if (!$page) {
// Output debug warning.
debugging('Module ' . $result->plugin . ' can\'t find search document, removing from results');
$searchdoc = new local_ousearch_document();
$searchdoc->wipe_document($result->id);
continue;
}
// Page option can request that this result is not included.
if (!empty($page->hide)) {
continue;
}
// Strip XHTML from content (need this before phrase scan).
$textcontent = local_ousearch_document::strip_xhtml($page->content);
// Add extra strings to the content after a special don't-show-this
// marker and with another special marker between each (to prevent
// phrases).
if (isset($page->extrastrings) && count($page->extrastrings) > 0) {
$evilmarker = rand();
// This means people can't do it on purpose.
$textcontent .= ' xxrealcontentends' . $evilmarker;
foreach ($page->extrastrings as $string) {
$textcontent .= ' ' . $string . ' xxsplit' . $evilmarker;
}
}
// Do quick phrase scan that doesn't deal with Unicode,
// or word-splitting but just discards results that
// don't have the phrase words next to each other without
// ASCII letters in between. This is intended to discard
// results that (fairly) definitely don't have the phrase.
// The further check below will make sure they really do
// have it according to our standard (slow) word-splitting.
$quickcheckcontent = $page->title . ' ' . $textcontent;
$ok = true;
foreach ($this->terms as $term) {
if (count($term->words) < 2) {
continue;
}
$gap = '[^A-Za-z0-9]+';
$pattern = '/(^|' . $gap . ')';
$first = true;
foreach ($term->words as $word) {
if ($first) {
$first = false;
} else {
$pattern .= $gap;
}
$pattern .= $word;
}
$pattern .= '($|' . $gap . ')/i';
if (!preg_match($pattern, $quickcheckcontent)) {
$ok = false;
break;
}
}
if (!$ok) {
continue;
}
// OK, obtain document as linear text.
list($contentwords, $contentpositions) = local_ousearch_document::split_words($textcontent, false, true);
list($titlewords, $titlepositions) = local_ousearch_document::split_words($page->title, false, true);
$allwords = array_merge($titlewords, $contentwords);
// Check it for phrases.
$positivewords = array();
$ok = true;
$dnifound = -1;
foreach ($this->terms as $term) {
foreach ($term->words as $word) {
$positivewords[$word] = true;
}
if (count($term->words) < 2) {
continue;
}
$pos = 0;
$found = false;
foreach ($allwords as $word) {
if ($word === $term->words[$pos]) {
$pos++;
if ($pos === count($term->words)) {
$found = true;
break;
}
} else {
$pos = 0;
}
}
if (!$found) {
$ok = false;
break;
}
}
foreach ($this->negativeterms as $term) {
if (count($term->words) < 2) {
continue;
}
$pos = 0;
$found = false;
foreach ($allwords as $word) {
if ($word === $term->words[$pos]) {
$pos++;
if ($pos === count($term->words)) {
$found = true;
break;
}
} else {
$pos = 0;
}
}
if ($found) {
$ok = false;
break;
}
}
if (!$ok) {
continue;
}
// Result passes! Make structure holding it...
// We now have list of all positive words, let's mark these
// in title and summary.
$result->title = self::internal_highlight_words($page->title, $titlewords, $titlepositions, $positivewords);
// Strip searchable-but-not-displayable content for summary.
if (isset($evilmarker)) {
$strippedwords = array();
foreach ($contentwords as $word) {
// Do not include extra strings in summary.
if ($word === 'xxrealcontentends' . $evilmarker) {
break;
}
$strippedwords[] = $word;
}
$contentwords = $strippedwords;
}
// Pick a section to include in the summary. This algorithm works as follows:
// * Compute the 'score' (number of highlight words in the previous 20 words
// up to and including this one) at each position in the text
// * Observe where the maximum score is reached and where it is lost.
// * A nice range that contains the most highlight words in the middle of the
// range will end at ($maxstart + $maxlength/2).
$highlights = array();
$pos = 0;
$currentscore = 0;
$maxscore = -1;
$maxstart = 0;
$maxlength = 0;
$run = true;
foreach ($contentwords as $word) {
if (array_key_exists($pos - self::SUMMARY_LENGTH, $highlights)) {
unset($highlights[$pos - self::SUMMARY_LENGTH]);
$currentscore--;
}
if (array_key_exists($word, $positivewords)) {
$highlights[$pos] = true;
$currentscore++;
}
if ($currentscore > $maxscore) {
$maxscore = $currentscore;
$maxstart = $pos;
$maxlength = 1;
$run = true;
} else {
if ($currentscore === $maxscore && $run) {
$maxlength++;
} else {
$run = false;
}
}
$pos++;
}
$start = $maxstart + $maxlength / 2 - self::SUMMARY_LENGTH;
if ($start < 0) {
$start = 0;
}
$end = $start + self::SUMMARY_LENGTH;
if ($end > count($contentwords)) {
$end = count($contentwords);
}
// The $contentpositions is in characters.
$result->summary = core_text::substr($textcontent, $contentpositions[$start], $contentpositions[$end] - $contentpositions[$start]) . ($end < count($contentwords) ? '...' : '');
$offset = -$contentpositions[$start];
$result->summary = self::internal_highlight_words($result->summary, $contentwords, $contentpositions, $positivewords, $offset, $start, $end);
if ($start !== 0) {
$result->summary = '...' . $result->summary;
}
$result->summary = trim($result->summary);
$result->activityname = $page->activityname;
$result->activityurl = $page->activityurl;
$result->url = $page->url;
if (isset($page->data)) {
$result->data = $page->data;
}
// Do user-specified filter if set.
if ($this->filter) {
$filter = $this->filter;
if (!$filter($result)) {
continue;
}
}
$accepted[] = $result;
$count++;
if ($count == $desired) {
break;
}
}
$return->results = $accepted;
return $return;
}
