How can I make zsh show that there are Stashed revisions on a Git repo whenever I get into it

Question

This is my current prompt:

user@machine ~/Projects/git/repo (git)-[name_of_the_branch] %

I want it to show me that there are Stash revisions by appending a 'S', like this:

user@machine ~/Projects/git/repo (git)-[name_of_the_branch][S] %

And the 'S' should be green :)

An even better way would be to append the number of stashed revision.

user@machine ~/Projects/git/repo (git)-[name_of_the_branch][Number_of_stashed_revisions] %

What do I need to change in .zshrc?

This is my current .zshrc file

https://gist.github.com/801944