How to do AWS-like compute billing?

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I am looking into selling servers with hourly pricing. For example, I want to sell a server for € 0.0395 for every hour and charge another € 0.10 for every Terabyte. If the user keeps the server running for 30 days, the monthly price should be reduced to € 25, instead of 0.0395 (hourly price) * 730 (hours are 30 days) = € 28.835.

Users should top up their balance, and that balance should then be used towards the usage. If a server is only deployed for 1 minute, we should still round up to the next hour and deduct that from the balance.

I'm really struggling with this, can anyone point me in the right direction on how to implement this? I don't think the metrics provided by lotus are able to do this, at least I didn't get it to work after playing with it for several hours.