/* funkce najde div pomoci nazvu class */
function getElementsByClass(searchClass,node,tag) {
    var classElements = new Array();
    if ( node == null )
        node = document;
    if ( tag == null )
        tag = '*';
    var els = node.getElementsByTagName(tag);
    var elsLen = els.length;
    var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");
    for (i = 0, j = 0; i < elsLen; i++) {
        if ( pattern.test(els[i].className) ) {
            classElements[j] = els[i];
            j++;
        }
    }
    return classElements;
}

function galeryChangeImage(where)
{
    // ziskame aktivni object
    var active = getElementsByClass('show');

    // ziskame neaktivni objekty
    var inactive = getElementsByClass('hidden');
    
    // ziskame celkovy pocet elementu
    var maxCount = inactive.length;

    // zjistime si hodnotu dalsiho obrazku
    var newImage = active[0].id;

    if(where == "prev")
    {
         newImage = active[0].id - 1;
         if(newImage < 0) newImage = 0;
    }
    if(where == "next")
    {
         newImage = parseInt(active[0].id) + 1;
         if(newImage > maxCount) newImage = maxCount;
    }

    var prev = newImage - 1;
    if(prev >= 0) document.getElementById('left').innerHTML = '<a href="#" onclick="galeryChangeImage(\'prev\'); return false;"><img src="http://www.galerie-vankovka.cz/images/jaro/leftArrow.png" alt="slide left" /></a>';
    else document.getElementById('left').innerHTML = '<img src="http://www.galerie-vankovka.cz/images/jaro/leftArrow.png" alt="slide left" />';

    var next = newImage + 1;
    if(next >= maxCount) document.getElementById('right').innerHTML = '<img src="http://www.galerie-vankovka.cz/images/jaro/rightArrow.png" alt="slide right" />';
    else document.getElementById('right').innerHTML = '<a href="#" onclick="galeryChangeImage(\'next\'); return false;"><img src="http://www.galerie-vankovka.cz/images/jaro/rightArrow.png" alt="slide right" /></a>';

    active[0].className = 'hidden';
    document.getElementById(newImage).className = 'show';
}

function switchText(id)
{
    $('#'+id).slideToggle();
}