Getting a dynamic sidebar nav for categories

At the moment I have created a very neat page navigation. The function manages the sidebar page navigation, here what its does briefly explained:

• It checks if a page has children, if it does not have children. Do nothing.
• If the page has children. Display only those children in the navigation. Not the top parent.
• It manages both child and grandchild relations, even on a grandchild page the navigation outputs depends on what the top parent is.
• The top parent name should always be displayed as a headline, but only if the top parent has children
• This works amazingly well with a top navigation that only shows the top depth.

At the moment, this only works with pages. I want the exact functionality for categories. I have tried, but without success.

Here is the code for my sidebar page navigation:

if (!is_front_page()) {
			if(!$post->post_parent){
				$parent_title = get_the_title($post->post_parent);
				$children = wp_list_pages("title_li=<h2>" . $parent_title . "</h2>&child_of=".$post->ID."&echo=0");
			}else{
				$parent_title = get_the_title($post->post_parent);
				$children = wp_list_pages("title_li=<h2>" . $parent_title . "</h2>&child_of=".$post->post_parent."&echo=0");

				if($post->ancestors) {
					$parent_title = get_the_title($post->post_parent);
					$ancestors = end($post->ancestors);
					$children = wp_list_pages("title_li=<h2>" . $parent_title . "</h2>&child_of=".$ancestors."&echo=0");
				}
			}
		}
		?>
		<?php if($children){ ?>
		<div id="primary" class="aside main-aside">
			<ul class="xoxo sidebar-item">
				<?php echo $children; ?>
			</ul>
	</div><!-- #primary .aside -->
<?php } ?>

I tried using get_category() function but without any good results. Anyone got any tips, ideas for usable functions? I want to make it as dynamic as possible! Any tips appreciated.