[FR] - Show slotInEpoch in cardano-cli query tip

[CarlosLopezDeLara]

Internal

Area
Other CLI

Describe the feature you'd like
Show slotInEpoch in cardano-cli query tip output so that one can easily know beforehand (and automate) if is still within the window for submitting transactions like Update proposals and MIR.

Additional context / screenshots

https://input-output-rnd.slack.com/archives/G011N23CEAE/p1652967091248049

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Acceptance Criteria

Slot in epoch is the slot number within a given epoch, as opposed to the absolute slot number.

When the user queries the tip of the chain:

• query tip returns "slotInEpoch":

{
"era": "Alonzo",
"syncProgress":
"hash":
"epoch":
"slot":
"block":
"slotInEpoch":
}

• slotinEpoch restarts properly at every epoch transition
• slotinEpoch can never be greater than EpochLength

[Jimbo4350]

So this involves changing the JSON output of the query tip to include the current slot in the current epoch. This is different to what is already reported, the absolute slot value. This will be a little tricky as the epoch size changes as we move from Byron -> Shelley:

defaultByronEpochSlots :: Word64
defaultByronEpochSlots = 21600

and in the mainnet shelley genesis file

  ...
  "networkMagic": 764824073,
  "epochLength": 432000,
  "systemStart": "2017-09-23T21:44:51Z",
  ...

We should be able to take the result of slotToEpoch and subtract one from the other SlotsInEpoch - SlotsToEpochEnd to get the current slot in epoch.