Dropdowns for multiple attributes + items in stock

Hi! I'm an experienced developer, but new to Zen Cart. We have products having two attributes (size and color), but some combinations are not available. Let's say for example, that shoes of size 36 are only available in black. All other sizes are available in black and white. In my frontend, I allways see black and white in the color dropdown, even if I select size 36. I want the color dropdown to be udated based on the size selection. The next step would be, to also display the number of items in stock for a given combination.

From my experience with software development, this should not be too hard. The required data should be small enought to be calculated in advance so it can be transfered to the page. Updating the dropdowns should just be matter of a few jQuery event handlers. I thought that probably somebody had done this before and searched for plugins/extensions, but only found solutions for older ZC versions.

Any hint how to solve my problem? I would prefer an existing solution, but writing code is fine too. In the later case, some starting hints would be very appreciated.

cheers,
Achim

I want the color dropdown to be udated based on the size selection
What you are asking for are dependent attributes and ZenCart has no support for them

Of course, being open source, one can write the code to do so