Refactor amounts calculation

[pskl]

Here be dragons 💀

Time to clean the way we calculate amounts, mere mortal

• Kill PfmpAmountCalculator concern (-> PfmpManager) 🎯
• Add new API for updating day_count 🎯
• Kill after_save callback for Amount recalculation 🎯
• Add validation on amount not being negative (😮)
• Remove state transition on after save too
• Add lock on Amounts calculation (prevent possible race)
• Encapsulate calculation methods as private methods on the Manager object

About the removal of after_save callback check

Why remove it? Because it sucks, amounts ceilings can be exceeded by spamming requests, rebalancing could happily trigger other rebalancing (the fact that it doesnt currently is pure fluke), highway to Callback Hell 👿 and also just to simplify the mental model around this unnecessarily complex process.

Replaced by what? A new method on the PfmpManager called update -> PfmpManager.new(pfmp).update(day_count: X) with no side effects other than the one we want which is rebalancing of other pfmps for that same mef.

Retrocompatibility issues

What are the entry points of those callbacks? -> AFAIK:

• Pfmp controller update -> replace with new API
• Specs trying to check something -> replace with new API
• In case of Pfmp destruction -> maybe change condition

Risks

• Not enough tests?
• Potential side effects with callbacks of callbacks that might go unnoticed?
• Potential negative amounts Pfmps: I reset the ones in the db to 0 (77 records)

[tnicolas1]

La fonction 'create' et 'update' n'avaient pas la même condition initialement, mais maintenant elles vérifient toutes les 2 'PfmpManager.new(@PFMP).update(pfmp_params)', est-ce normal ?

[pskl]

Oui normalement c'est équivalent parce que #update et #save retournent true quand les validations sont passées et false quand ca n'est pas le cas. Et ici on veut juste déclencher explicitement le recalcul.