PHP unique visitor tracking script (img or iframe)

This should be an easy PHP script to build, but please read the instructions carefully to avoid misunderstandings. In a nut-shell: I have a site A and I want to insert into its pages a tracker that will be hosted on site B. These are located on different servers. Site B (where the tracking script will be) runs on PHP 7+/nginX. I want to run this as a very simple affiliate system, where the users get rewarded for the visitors they send to site A's pages. On site A, I want to have a small javascript code that will check if the visited URL has the tracking query (for example [login to view URL], where ID is a unique tracking ID). If this exists, the javascript should insert (innerHTML is fine) an img or iframe with the tracking page located on B site, parsing the query from the A URL to the B img src (example <img src=[login to view URL] Theoretically, this should work. So basically I don't want to load the tracking script from B site, unless there is the tracking query in the A visited URL. I guess the main idea is to make everything as light and fast as possible, especially site A which is the main site. To stop spammers and wrong analytics, [login to view URL] should probably die if a query is not present, without registering any hits. I do not need to load [login to view URL], only [login to view URL] Ideally, [login to view URL] will also have some detector before loading and/or logging the hit, to make sure that it is inserted in a [login to view URL] page. I know an iframe detector is easy to make, I'm not sure this is possible if the [login to view URL] page will be inserted as an img src (ideas?). Overall, the script should have no more than 4-5 pages: - [login to view URL] - this will contain a login and a registration form - to register users should need an email, an URL from site [login to view URL] and the script should autogenerate for them a tracking ID (all these 3 must be stored in the db. - to login, users will need the email and the tracking ID - both the above forms must have some spamming protection (equation captcha should be fine) - [login to view URL] - this will load when a user logs in or registers, and will display only the users hits/earnings and their tracking URL ([login to view URL]). - There no need for a logout option, just make it stay logged in per browser session or 1 day (ie short time) - [login to view URL] - this is the script that will track the visitors based on their IP/cookies (I'm thinking this is the best way to ensure the visitors are unique, but other ideas are welcome) - it will be inserted on site's A pages as SRC of an IMG (ideally) or an IFRAME - either the IMG or IFRAME must be javascript generated, only if site's A URL contains the string 'ID=', which will then be passed to the inserted IMG/IFRAME SRC such as [login to view URL] - it will probably need to log into db the visitors' IP, date of visit, hits (of course) - it should load/do nothing if loaded in the URL, not having an ID string or not inserted in the [login to view URL] site - [login to view URL] - this should contain db login details, also a constant numeric value that will allow conversion of hits into earnings. For example, in case I DO NOT want to display the real hits from the database, but the result of a division between these hits and these constant. Obviously, if I do want the hits as they are in the db, this constant will have to be 1. It should also have a numerical constant for days, used below: - [login to view URL] - when opened, this script should clean [1] the hits older than the days constant above, the users that had 0 hits for the last (constant) days. This should ensure the db is cleaned periodically. As an affiliate/user of site B, I want to be able to register, get a tracking ID and check my stats; that's all. As an admin, I don't need any control panel. I trust my explanation is clear, but feel free to ask if something is not