548367 PHP script for managing files through web interface

We need a simple PHP script, which will allow to manage a files in a set of folders through web interface. We have about 1000 files in up to 10 different folders on your web server. Sometimes we need to allow to someone (3rd party contractor) to edit one or more of them. When the editation is complete, we want to lock the file again, so further editation is not possible. This script will - list all the files in defined directories to our administrator. Administrator will have an oportunity to easily lock/unlock files he selects. - than we will provide some URL to the third party contractor. He will see only the files which has been unlocked for him. He will be able to download those files, and upload them (after they has been modified) back, everything through simple wWW interface. Remember that there can be more than one contractor at the same time, everyone hes his own set of files - and can NOT see or edit other files. - when the work is complete, our administrator will lock the files again. Contractor will not be able to see or modify them afterwards. When the same file or files will be (later) unlocked to other contractor, the first contractor must NOT be able to see them. Other requirements - PHP5. - No database use - Simple integration - just one PHP file which does everything - no need of modification of other files, like .htaccess - the only setup will be list of folders, which will be managed by this script. The setup can be done in PHP code, like modifying some array or so.