Programming :: Expandable File Tree For Uploads?

I am working on a PHP enabled webpage that will allow a user to select multiple files and directories to upload from a local machine to an ftp server. I am comfortable with uploading the files from the machine to the server. The problem is making it easy to select all the desired files. What I would like to do is create an expandable file tree that lists all the directories and files on the local filesystem. From there, the user should be able to select directories and files using checkboxes. Upon clicking submit, all of the selected files should be fed into an array of files that can be sequentially uploaded to the ftp server.