Word count (doc, docx, pdf, rtf, and txt) via php

Hi all, We are working on one project and we need assistance on feature of calculating word count for a file uploaded by user. Please note that user will be uploading doc, or docx or pdf or rtf or txt file, so your script should work for all these file types. We are using Linux hosting, please don't come up with the solution that will work on window hosting only. If any one has done this before he/she will be more likely to get this project. I would like to mention that we need this script on urgent basis, so please don't waste your and our time on this as we are already late on this project.