This approach is added like a bogie annual because it's based on in fact misinterpreted Cheap FIFA 17 Coins facts.
Actually, EA's server yield abandoned one connected from you : the accepted hour (timestamp for developers).
I haven't activated this myself but let's accept that it's true. Afresh there are at atomic two factors (there are apparently abounding added but these two are the a lot of accessible to me) that you'd accept to yield into consideration:
Your accessory can advanced abandoned one connected to EA servers but EA servers accept your accessory and annual articular (that's a must) so they can calmly use any advice they accept about you, your accessory or your annual as accession parameter. It could be implememented as a archetypal bulletin accessory arrangement for example. And if you anticipate about it a bit, they don't even allegation to use the datetime connected at all (for backpack luck, they apparently use it or accept acclimated it for something else).
You said that the beatific connected is a timestamp but you abandoned mentioned hours and annual which is in fact weird. Why? Because timestamps usually backpack advice at atomic about abnormal too (even the accepted UNIX timestamp which counts the time aback 1970 does that) and in case of aperture packs, you'd allegation even added advice (like miliseconds for example) because if I'm not mistaken, you can accessible packs on Companion app and Web app at the aforementioned time. If this accomplished affair was abandoned about hours, annual and seconds, you could accessible two packs on anniversary accessory at the aforementioned additional and get the aforementioned players.
TLDR: I don't anticipate that the actuality that you and your acquaintance arranged Mata "at the aforementioned time" agency something.
Let's attending at the backpack aperture action as artlessly as possible. The a lot of basal book could possibly (I'm not in fact a developer and I haven't done any web development aback graduation so it in fact will not be exact) attending like this:
User logs into his annual = the applicant sends a appeal to server, server does some applicant identifation (cookies or something like that), sends response, applicant sends credentials, server verifies them, maps the applicant ID to the annual and sends aback an OK response. Aback this moment, if the applicant sends accession appeal (with his ID), the server recognizes him.
User opens backpack = the applicant sends a backpack aperture appeal (with his ID + timestamp as you say), the server reads the appeal with all the advice and does some array of magic. Of course, EA can abandoned yield the datetime and abstain aggregate abroad but Fut Coins at the aforementioned time they apparently can throwaway the datetime, lookup the applicant ID in the database, get the annual info, get the bulk of FIFA credibility bought, bisect it by the player's bulk of wins in the endure 11 days, access it by the bulk of ages if the annual was created and get the dream result.
So you can accept that the abandoned advice EA use is the datetime from the applicant but:
You don't apperceive it for abiding because the server is like a atramentous box for you.
It doesn't accomplish sense. If the packs are absitively on the server, why does the server not use its own datetime?
To your additional point. I may not accept your approach altogether but from what I understand, it looks to me like a in fact poor design. Why would you even use something like "avalaible_items" field? There are added than 10000 players in the FUT database so ambience their packweight as a connected (max avalaible items) would eventually or afterwards accomplish an complete anarchy both on the bazaar and in the code. It's abundant easier and analytic to apparatus this accomplished affair abandoned with probabilites. Why would EA even ambition to accomplish the "pack luck" bigger at some specific time?