Input validator using XML schema

I am building a website to help businesses standardise their HTML publishing (not just WCAG stuff but also their own intranet/website business rules). As this will be customised for each customer, this version of the site only need to support the business rules for one company. Details: I need some server-side code (preferably PHP) that can do the following: - filter HTML code for anything malicious (from code pasted into a text box) - allow regular and extended expressions from multiple files to be run against this code (both to convert the code for later tests and to detect pass/fail against business rules) - allow rules from multiple XML schema documents to be run against this code (to detect pass/fail against business rules) (relevant XML schema documents to be used based on options selected on webpage) - allow extraction of results for: --- displaying fail results on the HTML results page --- displaying pass and fail results in a PDF document - displayed results are to list: --- line number (for any fail results) --- error code (as listed in the relevant XML document) --- full-text explanation of what the test was (as listed in the relevant XML document) --- full-text explanation of how to fix it (for any fail results) (as listed in the relevant XML document) The business rules will be written separately (as required) and are not part of this job.