foldable wp_nav_menu with javascript

Hi there,
theres a lot of time I already spent to the challenge making the menu which comes through wp_nav_menu(); foldable, collapsible, expandable or how ever you want to call it.
The sub-menu tagged ul should roll out of the parent li item if I click on it. If I click again it should roll back and hide. When you’re on a sub-page the parent menu item should be expanded.

What do I do wrong that I’m not finding an easy solution!?! I google every day but this is a part which is too hard for me…

Is there a plugin or javascript, jequery or function I can use for this?

Regards
Scorp