wikimedia/mediawiki-extensions-Wikibase

( function () {
    'use strict';

    /**
     * Escapes a string to be used in a regular expression.
     *
     * @ignore
     *
     * @param {string} value
     * @return {string}
     */
    function escapeRegex( value ) {
        return value.replace( /[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&' );
    }

    /**
     * "Highlights" matching characters in a string using HTML.
     *
     *     @example
     *     var highlighted = highlightSubstring( 'abc', 'abcdef' );
     *     // highlighted === '<span class="highlighted">abc</span>def';
     *
     * @license GNU GPL v2+
     * @author H. Snater < mediawiki@snater.com >
     *
     * @param {string} substring
     * @param {string} string
     * @param {Object} [options]
     * @param {boolean} [options.caseSensitive=false]
     * @param {boolean} [options.withinString=false]
     *        Whether to highlight characters within the string, in contrast to at the beginning only.
     * @param {string} [options.wrapperNodeName='span']
     * @param {string} [options.wrapperNodeClass='highlight']
     * @return {string}
     */
    var highlightSubstring = function ( substring, string, options ) {
        if ( substring === '' || string === '' ) {
            return string;
        }

        options = options || {};
        options.caseSensitive = !!options.caseSensitive;
        options.withinString = !!options.withinString;
        options.wrapperNodeName = options.wrapperNodeName || 'span';
        options.wrapperNodeClass = options.wrapperNodeClass || 'highlight';

        var escapedSubstring = escapeRegex( substring );

        var regExpString = options.withinString
            ? '((?:(?!' + escapedSubstring + ').)*?)(' + escapedSubstring + ')(.*)'
            : '^()(' + escapedSubstring + ')(.*)$';

        var indexOfSubstring = string.indexOf( substring );

        if ( options.caseSensitive
        && (
            !options.withinString && indexOfSubstring !== 0
            || options.withinString && indexOfSubstring === -1
        )
        ) {
            return string;
        } else if ( !options.caseSensitive ) {
            var lowerCaseString = string.toLowerCase(),
                lowerCaseSubstring = substring.toLowerCase(),
                caseInsensitiveIndexOfSubstring = lowerCaseString.indexOf( lowerCaseSubstring );

            if ( !options.withinString && caseInsensitiveIndexOfSubstring !== 0
            || options.withinString && caseInsensitiveIndexOfSubstring === -1
            ) {
                return string;
            }
        }

        var matches = string.match(
            // eslint-disable-next-line security/detect-non-literal-regexp
            new RegExp( regExpString, options.caseSensitive ? '' : 'i' )
        );

        if ( matches ) {
            var wrapped = document.createElement( options.wrapperNodeName ),
                container = document.createElement( 'div' );

            wrapped.appendChild( document.createTextNode( matches[ 2 ] ) );

            if ( options.wrapperNodeClass ) {
                wrapped.setAttribute( 'class', options.wrapperNodeClass );
            }

            container.appendChild( wrapped );

            string = matches[ 1 ] + container.innerHTML + matches[ 3 ];
        }

        return string;
    };

    module.exports = highlightSubstring;

}() );