var current_li;

function nextByTag(parent,current,name){
    var next = false;
    var next_element;
    for( var i=0; i<parent.childNodes.length; i++ ){
        if( parent.childNodes[i]==current ){
            next = true;
            continue;
        }
        if( next && parent.childNodes[i].nodeName == name ){
            next_element = parent.childNodes[i];
            break;
        }
    }
    return next_element;
}

function prevByTag(parent,current,name){
    var next = false;
    var prev_element;
    for( var i=parent.childNodes.length-1; i>=0; i-- ){
        if( parent.childNodes[i]==current ){
            next = true;
            continue;
        }
        if( next && parent.childNodes[i].nodeName == name ){
            next_element = parent.childNodes[i];
            break;
        }
    }
    return next_element;
}

function prevImg(){
    var parent = current_li.parentNode;
    var prev_li = prevByTag(parent,current_li,"LI");
    if( !prev_li ){
        return;
    }
    var img = prev_li.getElementsByTagName("img")[0];
    var div = document.getElementById("gallery_container");
    var oldimg = div.getElementsByTagName("img"); 
    if( oldimg ){
        for( var i=0; i<oldimg.length; i++){
            if( oldimg[i].parentNode == div ){
                oldimg[i].src = img.src;
            }
        }
    }
    current_li = prev_li;
}

function nextImg(){
    var parent = current_li.parentNode;
    var next_li = nextByTag(parent,current_li,"LI");
    if( !next_li ){
        return;
    }
    var img = next_li.getElementsByTagName("img")[0];
    var div = document.getElementById("gallery_container");
    var oldimg = div.getElementsByTagName("img"); 
    if( oldimg ){
        for( var i=0; i<oldimg.length; i++){
            if( oldimg[i].parentNode == div ){
                oldimg[i].src = img.src;
            }
        }
    }
    current_li = next_li;
}

function loadImg(src,target){
    var body = document.getElementsByTagName("body")[0];
    var div = document.getElementById("gallery_container");
    current_li = target.parentNode;

    if( !div ) {
        div = document.createElement('div');
        div.setAttribute('id', 'gallery_container');    
        body.appendChild(div);  

        var anch = document.createElement('a');
        anch.setAttribute('href', '#'); 
        div.appendChild(anch);
        
        var close = new Image();
        close.src = "_img/close.png"
        close.id = "gallery_close";
        close.onclick = function(){
            div.style.visibility='hidden';
            return false;
        }
        anch.appendChild(close);
        
        anch = document.createElement('a');
        anch.setAttribute('href', '#'); 
        var prev = new Image();
        anch.appendChild(prev);
        div.appendChild(anch);
        prev.src = "_img/prev.png";
        prev.id = "gallery_prev";
        prev.onclick = prevImg;
        
        var img = new Image()
        div.appendChild(img);
        img.src = src;
        img.id = "gallery_img"
        
        anch = document.createElement('a');
        anch.setAttribute('href', '#'); 
        var next = new Image();
        anch.appendChild(next);
        div.appendChild(anch);
        next.src = "_img/next.png";
        next.id = "gallery_next";
        next.onclick = nextImg;
    }else{
        var oldimg = div.getElementsByTagName("img"); 
        if( oldimg ){
            for( var i=0; i<oldimg.length; i++){
                if( oldimg[i].parentNode == div ){
                    oldimg[i].src = src;
                }
            }
        }
        div.style.visibility='visible';
    }

}