var current_tab_id = '0';

function Tabs() {
    for (var i=1; i<=4; i++) {
        el = document.getElementById('tabstop'+i);

        if (el.className.indexOf('hiddenTab') == -1) {

            current_tab_id = i.toString();
            break;

        }
    }
}

var current_article_tab_id = '1';

function switch_tab(id) {
    var current = document.getElementById('tabstop' + current_tab_id);
    var new_el = document.getElementById('tabstop' + id);
    index = new_el.className.indexOf(' hiddenTab');
    if (index != -1) {
        current.className += ' hiddenTab';
        new_el.className = new_el.className.substring(0, index);
        
        current = document.getElementById('tab' + current_tab_id);
        new_el = document.getElementById('tab' + id)
        index = current.className.indexOf('selected');

        if (index != -1) {
            current.className = current.className.substring(0, index);
            new_el.className = new_el.className.replace(/\s+$/g, "" ) + ' selected';
        }
        current_tab_id = id;
    }
}

function switch_article_tab(id) {

    var current = document.getElementById('article_tab' + current_article_tab_id);
    var new_el = document.getElementById('article_tab' + id);
    index = new_el.className.indexOf(' hiddenTab');
    if (index != -1) {
        current.className += ' hiddenTab';
        new_el.className = new_el.className.substring(0, index);
        current = document.getElementById('articletab' + current_article_tab_id);
        
        current = document.getElementById('articletab' + current_article_tab_id)
        new_el = document.getElementById('articletab' + id)
        index = current.className.indexOf('selected');
        
        if (index != -1) {
            current.className = current.className.substring(0, index);
            new_el.className = new_el.className.replace(/\s+$/g, "" ) + ' selected';
        }
        current_article_tab_id = id;
    }

}