if(window.checkLinksToCitations === undefined)
    window.checkLinksToCitations = true;

mw.hook( 'wikipage.content' ).add( function( $content ) {
    // first check: do links in Harvard citations point to a valid citation?
    var href,
    	links = $content.find( 'a[href^="#CITEREF"]' );

    links.each( function (i, elem) {
    	href = elem.getAttribute( 'href' ).substring(1); //skip the #
    	// IDs can contain characters like . that have meaning in selectors
    	// use $.escapeSelector to make sure they are escaped
        if ( $content.find( '#' + $.escapeSelector(href) ).length < 1 && elem && elem.parentNode)
            elem.parentNode.innerHTML +=
                " <strong class=error>Harv error: link from " +
                href +
                " doesn't point to any citation.</strong>";
    } );

    // second check: do CITEREF IDs have Harvard citations pointing to them?
    if(window.checkLinksToCitations) {
        var cites = $content.find('.citation');
        for(var i=0; i < cites.length; i++) {
            var id = cites[i].getAttribute('id');
            // we only need to check citations with a
            if(!id || id.indexOf('CITEREF') !== 0)
                continue;
            // don't do cites that are inside a ref
            var parentid = cites[i].parentNode.parentNode.getAttribute('id');
            if(parentid && parentid.indexOf('cite_note') === 0)
                continue;
            // check for links to this citation
            var query = 'a[href|="#' + $.escapeSelector(id) + '"]';
            if($content.find(query).length === 0) {
                cites[i].innerHTML +=
                    " <strong class=warning>Harv warning: There is no link pointing to this citation. The anchor is named " + id + ".</strong>";
            }
        }
    }
});