SearchHighlighter.php

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<?php
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Parser\Sanitizer;
use MediaWiki\Registration\ExtensionRegistry;
 
class SearchHighlighter {
    public const DEFAULT_CONTEXT_LINES = 2;
    public const DEFAULT_CONTEXT_CHARS = 75;
 
    protected $mCleanWikitext = true;
 
    public function __construct( $cleanupWikitext = true ) {
        $this->mCleanWikitext = $cleanupWikitext;
    }
 
    public function highlightText(
        $text,
        $terms,
        $contextlines = self::DEFAULT_CONTEXT_LINES,
        $contextchars = self::DEFAULT_CONTEXT_CHARS
    ) {
        $searchHighlightBoundaries = MediaWikiServices::getInstance()
            ->getMainConfig()->get( MainConfigNames::SearchHighlightBoundaries );
 
        if ( $text == '' ) {
            return '';
        }
 
        // split text into text + templates/links/tables
        $spat = "/(\\{\\{)|(\\[\\[[^\\]:]+:)|(\n\\{\\|)";
        // first capture group is for detecting nested templates/links/tables/references
        $endPatterns = [
            1 => '/(\{\{)|(\}\})/', // template
            2 => '/(\[\[)|(\]\])/', // image
            3 => "/(\n\\{\\|)|(\n\\|\\})/" ]; // table
 
        // @todo FIXME: This should prolly be a hook or something
        // instead of hardcoding the name of the Cite extension
        if ( ExtensionRegistry::getInstance()->isLoaded( 'Cite' ) ) {
            $spat .= '|(<ref>)'; // references via cite extension
            $endPatterns[4] = '/(<ref>)|(<\/ref>)/';
        }
        $spat .= '/';
        $textExt = []; // text extracts
        $otherExt = []; // other extracts
        $start = 0;
        $textLen = strlen( $text );
        $count = 0; // sequence number to maintain ordering
        while ( $start < $textLen ) {
            // find start of template/image/table
            if ( preg_match( $spat, $text, $matches, PREG_OFFSET_CAPTURE, $start ) ) {
                $epat = '';
                foreach ( $matches as $key => $val ) {
                    if ( $key > 0 && $val[1] != -1 ) {
                        if ( $key == 2 ) {
                            // see if this is an image link
                            $ns = substr( $val[0], 2, -1 );
                            if (
                                MediaWikiServices::getInstance()->getContentLanguage()->
                                getNsIndex( $ns ) !== NS_FILE
                            ) {
                                break;
                            }
 
                        }
                        $epat = $endPatterns[$key];
                        $this->splitAndAdd( $textExt, $count, substr( $text, $start, $val[1] - $start ) );
                        $start = $val[1];
                        break;
                    }
                }
                if ( $epat ) {
                    // find end (and detect any nested elements)
                    $level = 0;
                    $offset = $start + 1;
                    $found = false;
                    while ( preg_match( $epat, $text, $endMatches, PREG_OFFSET_CAPTURE, $offset ) ) {
                        if ( array_key_exists( 2, $endMatches ) ) {
                            // found end
                            if ( $level == 0 ) {
                                $len = strlen( $endMatches[2][0] );
                                $off = $endMatches[2][1];
                                $this->splitAndAdd( $otherExt, $count,
                                    substr( $text, $start, $off + $len - $start ) );
                                $start = $off + $len;
                                $found = true;
                                break;
                            } else {
                                // end of nested element
                                $level--;
                            }
                        } else {
                            // nested
                            $level++;
                        }
                        $offset = $endMatches[0][1] + strlen( $endMatches[0][0] );
                    }
                    if ( !$found ) {
                        // couldn't find appropriate closing tag, skip
                        $this->splitAndAdd( $textExt, $count, substr( $text, $start, strlen( $matches[0][0] ) ) );
                        $start += strlen( $matches[0][0] );
                    }
                    continue;
                }
            }
            // else: add as text extract
            $this->splitAndAdd( $textExt, $count, substr( $text, $start ) );
            break;
        }
        '@phan-var string[] $textExt';
 
        $all = $textExt + $otherExt; // these have disjunct key sets
 
        // prepare regexps
        foreach ( $terms as $index => $term ) {
            // manually do upper/lowercase stuff for utf-8 since PHP won't do it
            if ( preg_match( '/[\x80-\xff]/', $term ) ) {
                $terms[$index] = preg_replace_callback(
                    '/./us',
                    $this->caseCallback( ... ),
                    $terms[$index]
                );
            } else {
                $terms[$index] = $term;
            }
        }
        $anyterm = implode( '|', $terms );
        $phrase = implode( "{$searchHighlightBoundaries}+", $terms );
        // @todo FIXME: A hack to scale contextchars, a correct solution
        // would be to have contextchars actually be char and not byte
        // length, and do proper utf-8 substrings and lengths everywhere,
        // but PHP is making that very hard and unclean to implement :(
        $scale = strlen( $anyterm ) / mb_strlen( $anyterm );
        $contextchars = intval( $contextchars * $scale );
 
        $patPre = "(^|{$searchHighlightBoundaries})";
        $patPost = "({$searchHighlightBoundaries}|$)";
 
        $pat1 = "/(" . $phrase . ")/ui";
        $pat2 = "/$patPre(" . $anyterm . ")$patPost/ui";
 
        $left = $contextlines;
 
        $snippets = [];
        $offsets = [];
 
        // show beginning only if it contains all words
        $first = 0;
        $firstText = '';
        foreach ( $textExt as $index => $line ) {
            if ( $line !== '' && $line[0] != ';' && $line[0] != ':' ) {
                $firstText = $this->extract( $line, 0, $contextchars * $contextlines );
                $first = $index;
                break;
            }
        }
        if ( $firstText ) {
            $succ = true;
            // check if first text contains all terms
            foreach ( $terms as $term ) {
                if ( !preg_match( "/$patPre" . $term . "$patPost/ui", $firstText ) ) {
                    $succ = false;
                    break;
                }
            }
            if ( $succ ) {
                $snippets[$first] = $firstText;
                $offsets[$first] = 0;
            }
        }
        if ( !$snippets ) {
            // match whole query on text
            $this->process( $pat1, $textExt, $left, $contextchars, $snippets, $offsets );
            // match whole query on templates/tables/images
            $this->process( $pat1, $otherExt, $left, $contextchars, $snippets, $offsets );
            // match any words on text
            $this->process( $pat2, $textExt, $left, $contextchars, $snippets, $offsets );
            // match any words on templates/tables/images
            $this->process( $pat2, $otherExt, $left, $contextchars, $snippets, $offsets );
 
            ksort( $snippets );
        }
 
        // add extra chars to each snippet to make snippets constant size
        $extended = [];
        if ( count( $snippets ) == 0 ) {
            // couldn't find the target words, just show beginning of article
            if ( array_key_exists( $first, $all ) ) {
                $targetchars = $contextchars * $contextlines;
                $snippets[$first] = '';
                $offsets[$first] = 0;
            }
        } else {
            // if begin of the article contains the whole phrase, show only that !!
            if ( array_key_exists( $first, $snippets ) && preg_match( $pat1, $snippets[$first] )
                && $offsets[$first] < $contextchars * 2 ) {
                $snippets = [ $first => $snippets[$first] ];
            }
 
            // calc by how much to extend existing snippets
            $targetchars = intval( ( $contextchars * $contextlines ) / count( $snippets ) );
        }
 
        foreach ( $snippets as $index => $line ) {
            $extended[$index] = $line;
            $len = strlen( $line );
            // @phan-suppress-next-next-line PhanPossiblyUndeclaredVariable
            // $targetchars is set when $snippes contains anything
            if ( $len < $targetchars - 20 ) {
                // complete this line
                if ( $len < strlen( $all[$index] ) ) {
                    $extended[$index] = $this->extract(
                        $all[$index],
                        $offsets[$index],
                        // @phan-suppress-next-next-line PhanPossiblyUndeclaredVariable
                        // $targetchars is set when $snippes contains anything
                        $offsets[$index] + $targetchars,
                        $offsets[$index]
                    );
                    $len = strlen( $extended[$index] );
                }
 
                // add more lines
                $add = $index + 1;
                // @phan-suppress-next-next-line PhanPossiblyUndeclaredVariable
                // $targetchars is set when $snippes contains anything
                while ( $len < $targetchars - 20
                        && array_key_exists( $add, $all )
                        && !array_key_exists( $add, $snippets ) ) {
                    $offsets[$add] = 0;
                    // @phan-suppress-next-next-line PhanPossiblyUndeclaredVariable
                    // $targetchars is set when $snippes contains anything
                    $tt = "\n" . $this->extract( $all[$add], 0, $targetchars - $len, $offsets[$add] );
                    $extended[$add] = $tt;
                    $len += strlen( $tt );
                    $add++;
                }
            }
        }
 
        // $snippets = array_map( 'htmlspecialchars', $extended );
        $snippets = $extended;
        $last = -1;
        $extract = '';
        foreach ( $snippets as $index => $line ) {
            if ( $last == -1 ) {
                $extract .= $line; // first line
            } elseif ( $last + 1 == $index
                && $offsets[$last] + strlen( $snippets[$last] ) >= strlen( $all[$last] )
            ) {
                $extract .= " " . $line; // continuous lines
            } else {
                $extract .= '<b> ... </b>' . $line;
            }
 
            $last = $index;
        }
        if ( $extract ) {
            $extract .= '<b> ... </b>';
        }
 
        $processed = [];
        foreach ( $terms as $term ) {
            if ( !isset( $processed[$term] ) ) {
                $pat3 = "/$patPre(" . $term . ")$patPost/ui"; // highlight word
                $extract = preg_replace( $pat3,
                    "\\1<span class='searchmatch'>\\2</span>\\3", $extract );
                $processed[$term] = true;
            }
        }
 
        return $extract;
    }
 
    private function splitAndAdd( &$extracts, &$count, $text ) {
        $split = explode( "\n", $this->mCleanWikitext ? $this->removeWiki( $text ) : $text );
        foreach ( $split as $line ) {
            $tt = trim( $line );
            if ( $tt ) {
                $extracts[$count++] = $tt;
            }
        }
    }
 
    private function caseCallback( $matches ) {
        if ( strlen( $matches[0] ) > 1 ) {
            $contLang = MediaWikiServices::getInstance()->getContentLanguage();
            return '[' . $contLang->lc( $matches[0] ) .
                $contLang->uc( $matches[0] ) . ']';
        } else {
            return $matches[0];
        }
    }
 
    private function extract( $text, $start, $end, &$posStart = null, &$posEnd = null ) {
        if ( $start != 0 ) {
            $start = $this->position( $text, $start, 1 );
        }
        if ( $end >= strlen( $text ) ) {
            $end = strlen( $text );
        } else {
            $end = $this->position( $text, $end );
        }
 
        if ( $posStart !== null ) {
            $posStart = $start;
        }
        if ( $posEnd !== null ) {
            $posEnd = $end;
        }
 
        if ( $end > $start ) {
            return substr( $text, $start, $end - $start );
        } else {
            return '';
        }
    }
 
    private function position( $text, $point, $offset = 0 ) {
        $tolerance = 10;
        $s = max( 0, $point - $tolerance );
        $l = min( strlen( $text ), $point + $tolerance ) - $s;
        $m = [];
 
        if ( preg_match(
            '/[ ,.!?~!@#$%^&*\‍(\‍)+=\-\\\|\[\]"\'<>]/',
            substr( $text, $s, $l ),
            $m,
            PREG_OFFSET_CAPTURE
        ) ) {
            return $m[0][1] + $s + $offset;
        } else {
            // check if point is on a valid first UTF8 char
            $char = ord( $text[$point] );
            while ( $char >= 0x80 && $char < 0xc0 ) {
                // skip trailing bytes
                $point++;
                if ( $point >= strlen( $text ) ) {
                    return strlen( $text );
                }
                $char = ord( $text[$point] );
            }
 
            return $point;
 
        }
    }
 
    private function process( $pattern, $extracts, &$linesleft, &$contextchars, &$out, &$offsets ) {
        if ( $linesleft == 0 ) {
            return; // nothing to do
        }
        foreach ( $extracts as $index => $line ) {
            if ( array_key_exists( $index, $out ) ) {
                continue; // this line already highlighted
            }
 
            $m = [];
            if ( !preg_match( $pattern, $line, $m, PREG_OFFSET_CAPTURE ) ) {
                continue;
            }
 
            $offset = $m[0][1];
            $len = strlen( $m[0][0] );
            if ( $offset + $len < $contextchars ) {
                $begin = 0;
            } elseif ( $len > $contextchars ) {
                $begin = $offset;
            } else {
                $begin = $offset + intval( ( $len - $contextchars ) / 2 );
            }
 
            $end = $begin + $contextchars;
 
            $posBegin = $begin;
            // basic snippet from this line
            $out[$index] = $this->extract( $line, $begin, $end, $posBegin );
            $offsets[$index] = $posBegin;
            $linesleft--;
            if ( $linesleft == 0 ) {
                return;
            }
        }
    }
 
    private function removeWiki( $text ) {
        $text = preg_replace( "/\\{\\{([^|]+?)\\}\\}/", "", $text );
        $text = preg_replace( "/\\{\\{([^|]+\\|)(.*?)\\}\\}/", "\\2", $text );
        $text = preg_replace( "/\\[\\[([^|]+?)\\]\\]/", "\\1", $text );
        $text = preg_replace_callback(
            "/\\[\\[([^|]+\\|)(.*?)\\]\\]/",
            $this->linkReplace( ... ),
            $text
        );
        $text = preg_replace( "/<\/?[^>]+>/", "", $text );
        $text = preg_replace( "/'''''/", "", $text );
        $text = preg_replace( "/('''|<\/?[iIuUbB]>)/", "", $text );
        $text = preg_replace( "/''/", "", $text );
 
        // Note, the previous /<\/?[^>]+>/ is insufficient
        // for XSS safety as the HTML tag can span multiple
        // search results (T144845).
        $text = Sanitizer::escapeHtmlAllowEntities( $text );
        return $text;
    }
 
    private function linkReplace( $matches ) {
        $colon = strpos( $matches[1], ':' );
        if ( $colon === false ) {
            return $matches[2]; // replace with caption
        }
        $ns = substr( $matches[1], 0, $colon );
        $index = MediaWikiServices::getInstance()->getContentLanguage()->getNsIndex( $ns );
        if ( $index !== false && ( $index === NS_FILE || $index === NS_CATEGORY ) ) {
            return $matches[0]; // return the whole thing
        } else {
            return $matches[2];
        }
    }
 
    public function highlightSimple(
        $text,
        $terms,
        $contextlines = self::DEFAULT_CONTEXT_LINES,
        $contextchars = self::DEFAULT_CONTEXT_CHARS
    ) {
        $lines = explode( "\n", $text );
 
        $terms = implode( '|', $terms );
        $max = intval( $contextchars ) + 1;
        $pat1 = "/(.*)($terms)(.{0,$max})/ui";
 
        $extract = '';
        $contLang = MediaWikiServices::getInstance()->getContentLanguage();
        foreach ( $lines as $line ) {
            if ( $contextlines == 0 ) {
                break;
            }
            $m = [];
            if ( !preg_match( $pat1, $line, $m ) ) {
                continue;
            }
            --$contextlines;
            // truncate function changes ... to relevant i18n message.
            $pre = $contLang->truncateForVisual( $m[1], -$contextchars, '...', false );
 
            if ( count( $m ) < 3 ) {
                $post = '';
            } else {
                $post = $contLang->truncateForVisual( $m[3], $contextchars, '...', false );
            }
 
            $found = $m[2];
 
            $line = htmlspecialchars( $pre . $found . $post );
            $pat2 = '/(' . $terms . ')/ui';
            $line = preg_replace( $pat2, '<span class="searchmatch">\1</span>', $line );
 
            $extract .= "{$line}\n";
        }
 
        return $extract;
    }
 
    public function highlightNone(
        $text,
        $contextlines = self::DEFAULT_CONTEXT_LINES,
        $contextchars = self::DEFAULT_CONTEXT_CHARS
    ) {
        $match = [];
        $text = ltrim( $text ) . "\n"; // make sure the preg_match may find the last line
        $text = str_replace( "\n\n", "\n", $text ); // remove empty lines
        preg_match( "/^(.*\n){0,$contextlines}/", $text, $match );
 
        // Trim and limit to max number of chars
        $text = htmlspecialchars( substr( trim( $match[0] ), 0, $contextlines * $contextchars ) );
        return str_replace( "\n", '<br>', $text );
    }
}