Compute metadata for transaction

[akegalj]

Context

A real wallet implementation may need to store more information than we have modelled in the specification so far. For instance, users may wish to know when their pending transactions got confirmed in the blockchain (as opposed to merely that they were confirmed), or what the effect was of a particular transaction on their balance (rather than merely being able to see the current balance).

Decision

Compute and maintain metadata for every transaction tracked by the wallet (transactions send to/from the wallet).

Acceptance Criteria

1. Tx metadata must contain unique identifier (probably tx id)
2. Tx metadata must contain depth (a.k.a "number of confirmations)
3. Tx metadata must contain status: pending vs in-ledger vs invalidated
4. Tx metadata must contain total amount
5. Tx metadata must contain direction: outgoing vs incoming
6. Tx metadata must contain timestamp when transaction was created
7. Tx metadata must contain info about absolute slot & block number the transaction was inserted (from genesis)

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Development Plan

PR

Number	Base
#114	master

QA

[KtorZ]

This was done as part of #137 . This ticket is actually redundant with #90 so closing in favor of the latter.