on-chain NFT governance module

[RadNi]

Test --quickcheck-replay=223823 fails.

[RadNi]

Close #272

[cstml]

You need to mint a token for the head when the list is initialised.

[cstml]

This token must be in the same eUTXO with the Unique Token to be able to find (on-chain) what the correct minting Policy CurrencySymbol is.

[RadNi]

The off-chain implementation is currently a bit different

    mintListHead :: NftAppInstance -> GenericContract NftAppInstance
    mintListHead appInstance = do
      let -- Unique Token
          uniqueToken = appInstance'AppAssetClass appInstance
          uniqueTokenValue = assetClassValue uniqueToken 1
          emptyTokenName = TokenName PlutusTx.Prelude.emptyByteString
      let -- Script Head Specific Information
          headDatum :: DatumNft = nftHeadInit appInstance
          headPolicy = mintPolicy appInstance
          proofTokenValue = Value.singleton (scriptCurrencySymbol headPolicy) emptyTokenName 1
          initRedeemer = asRedeemer Initialise
      let -- Gov App Head Specific information
          govHeadDatum :: GovDatum = govHeadInit
          govHeadPolicy = govMintPolicy appInstance
          govScr = govScript uniqueToken
          govProofTokenValue = Value.singleton (scriptCurrencySymbol govHeadPolicy) emptyTokenName 1
          govInitRedeemer = asRedeemer InitialiseGov

          -- NFT App Head
          (lookups, tx) =
            ( mconcat
                [ Constraints.typedValidatorLookups txPolicy
                , Constraints.mintingPolicy headPolicy
                , Constraints.mintingPolicy govHeadPolicy
                ]
            , mconcat
                [ Constraints.mustPayToTheScript headDatum (proofTokenValue <> uniqueTokenValue)
                , Constraints.mustPayToOtherScript (validatorHash govScr) (toDatum govHeadDatum) (govProofTokenValue <> uniqueTokenValue)
                , Constraints.mustMintValueWithRedeemer initRedeemer proofTokenValue
                , Constraints.mustMintValueWithRedeemer govInitRedeemer govProofTokenValue
                ]
            )
      void $ Contract.submitTxConstraintsWith @NftTrade lookups tx
      Contract.logInfo @Hask.String $ printf "Forged Script Head & Governance Head for %s" (Hask.show appInstance)
      return appInstance

Creating the list head and minting the head token are happening at the same transaction. So we are not actually spending the list head when minting the head token. Therefore, the InitialiseGov is not being used as the redeemer to the script validator.

[cstml]

If you look at

govInitRedeemer = asRedeemer InitialiseGov

The redeemer used at initialisation is the InitialiseGov redeemer. It is the only redeemer that should allow the minting of a token with Head datum.

[RadNi]

But the govInitRedeemer is only used for the minting policy here. Not for the script validator.

[cstml]

They are locking separate utxos, with separate logic.

[cstml]

#281 (comment)

Anything that gets the AppSymbol should be making use of :

plutus-use-cases/mlabs/src/Mlabs/NFT/Contract/Aux.hs

Line 111 in e532106

getNftAppSymbol :: UniqueToken -> GenericContract NftAppSymbol

This makes sure that the correct AppSymbol is retrieved through the correct path (by looking at the Head).

There are some contracts which might need to be deprecated, as they do not use this.

[cstml]

Add comment with description of behavior for each major test function.

[cstml]

Add a general test that verifies that the Minting Policy and the ListGovToken in the Head have the same CurrencySymbol. This way we know that our Minting Policy only mints for the correct List/Script.

This can be a separate issue.

[RadNi]

In MintGov and ProofAndBurn action cases we look for the head datum in the inputs.
The function that returns head datum is inputsWithHeadDatum.

    inputsWithHeadDatum :: [(GovDatum, TxOut)]
    inputsWithHeadDatum =
      filter
        ( \(datum', txO) ->
            datumIsHead (gov'list datum') && tokenPresent txO
        )
        $ getInputDatumsWithTx @GovDatum ctx

If you check it out, one of the checks that it performs is tokenPresent which itself checks the existence of our proofToken

    symbol = ownCurrencySymbol ctx
    asset tn = AssetClass (symbol, TokenName tn)
    proofToken = asset emptyByteString
    
    tokenPresent txO =
      assetClassValueOf (txOutValue txO) proofToken == 1
        && assetClassValueOf (txOutValue txO) uniqueToken >= 1

Therefore it's already checked that the head datum contains the listGov token with our own CurrencySymbol

[cstml]

Head must be present in this transaction, see previous comment about determining the correct CurrencySymbol.

[cstml]

Head must be present in this transaction,

[cstml]

Most of the changes are correct. I would have to have a conversation to validate the updated approach on Gov to be able to be sure it is all correct.

[t4ccer]

I am not sure about these two checks