Lay of the Land
I have been tasked with rewriting a website, (I'm new to the ways of PHP). This website is a way for users to transfer files, usually between 10 MB - 1 GB using HTTPS; which includes a coupling to a broad single-sign on service. Half the files are in PHP the other half use mod_perl and CGI (PERL was the primary part of the site during its inception in 99). The site has been untouched since 2008, the original developer left. Towards the end he did primarily everything in PHP but kept building on the perl since he didn't have a chance to rewrite it all before he left. I have little documentation that he left, but one of the few pieces I had was a very general/braod to-do list. And it looked like he was transferring most the PERL-cgi stuff to strictly PHP... Also there is no database with this program, it usees an XML log file. Any files on the server over X days are deleted.
Problem
My problem is there are over 100 perl files. Everything I have done in the past has been ground up or just added functionality to a site. The minor things that I have changed thus far have all been javascript and php. But the meat of the code is in perl and I'm not sure if I should read through and catalogue the code which would include learning perl... Or should I write the everything in PHP. There are many different directions I could go. I am competent in PHP, python, c++, java, but not PERL x.x
Questions
1. IS there anything that PHP can't do that the perl stuff is doing?
2. How would you suggest I approach this problem from a methodology standpoint. -What approaches can I take to tackle this problem?
3. Any reference material that I should use?