Implement deposit validators and off-chain code

[noonio]

Why

Given the new deposit workflow of #199, we would like to implement the fairly independent steps of depositing and canceling independent of the hydra-node. Such that this work can be tested and merged independently.

TODO: Why doing this separate to #1522?

What

• Can create Hydra deposit transactions from command line

  • Supports only one version of the scripts, that is the hydra-plutus version that is compiled into it
  • Input:
    • UTxO to deposit
    • HeadId?
    • Deadline?
  • Result: Transaction envelope on disk and the TxIn of the created deposit on stdout
  • i.e. hydra-tx deposit <utxo> <headid> <deadline>

• Can create Hydra recover transactions from command line

  • Input:
    • Transaction input of the deposit to recover
    • Transaction output of the deposit to recover (at least the datum and value)
    • Current time as a slot (used for lower validity bound)
  • i.e. hydra-tx recover <utxo> <txin> <slot>

TBD: Out of scope?

• TBD: Are transactions produced by hydra-tx balanced (fees paid)?

• TBD: hydra-tx does NOT do any communication whatsoever.

• TBD: Too big? Move all hydra protocol transaction creation, into a package with command line interface, and also include mutation and end-to-end tests

  • Blackbox testing of hydra-tx
  • hydra-node uses hydra-tx library for building transactions

How

• TODO: Does the architecture change by doing this? Do we want do do this in this item?

• How to use it with cardano-cli roughly:

  cardano-cli query utxo --address "addr_..." > utxo.json
  hydra-tx deposit --utxo utxo.json \
    --deposit-txin "b7765b081a1ac48a3751346cfd0758116ec170c63a9de31380556ba311e73faa#0" \
    --head-id "1231241" \
    --deadline $(($(date --date "2 hours" +"%s"))) \
    --out-file tx.json
  
  # TBD: Does not exist. Contribute? Similar functionality in cardano-api?
  cardano-cli transaction balance \
    --protocol-parameters ... \ # Can change every epoch
    --system-start ... \        # Never change for network
    --epoch-info ... \          # May change in between hard-forks
    --unbalanced-tx tx.json \
    --cardano-signing-key fuel.sk \
    --out-file tx.json
  cardano-cli transaction submit --tx-file tx.json

[v0d1ch]

Question: What about the fees? The fees are not mentioned for the deposit/recover transactions. Since the user is responsible for submitting we also need to take into account setting the fees since we are constructing the transaction. User could be able to import the tx cbor into their wallet but idea here was that we provide some compatibility with cardano-cli. Perhaps we could set minimum fees and/or provide argument to the hydra-tx executable to set the desired fee (this looks more feasible than importing the tx into wallet)