Align InitObservatin further with OnInitTx

This allows us to define a backwards compatible JSON parser only using
the HeadObservation type.

Author: ch1bo

hydra-node/src/Hydra/Chain/Direct/Handlers.hs

@@ -322,14 +322,8 @@ chainSyncHandler tracer callback getTimeHandle ctx localChainState =
 convertObservation :: TimeHandle -> HeadObservation -> Maybe (OnChainTx Tx)
 convertObservation TimeHandle{slotToUTCTime} = \case
   NoHeadTx -> Nothing
-  Init InitObservation{headId, contestationPeriod, parties, seedTxIn, participants} ->
-    pure
-      OnInitTx
-        { headId
-        , headSeed = txInToHeadSeed seedTxIn
-        , headParameters = HeadParameters{contestationPeriod, parties}
-        , participants
-        }
+  Init InitObservation{headId, headSeed, headParameters, participants} ->
+    pure OnInitTx{headId, headSeed, headParameters, participants}
   Abort AbortObservation{headId} ->
     pure OnAbortTx{headId}
   Commit CommitObservation{headId, party, committed} ->

hydra-node/src/Hydra/Chain/Direct/State.hs

@@ -87,6 +87,7 @@ import Hydra.Tx (
   deriveParty,
   getSnapshot,
   headIdToPolicyId,
+  headSeedToTxIn,
   mkSimpleBlueprintTx,
   partyToChain,
   registryUTxO,
@@ -765,26 +766,21 @@ observeInit _ctx _allVerificationKeys tx = do
   let initialThreadUTxO = (mkTxIn tx 0, toCtxUTxOTxOut headOut)
   pure (toEvent observation, toState initialThreadUTxO observation)
  where
-  toEvent InitObservation{contestationPeriod, parties, headId, seedTxIn, participants} =
-    OnInitTx
-      { headId
-      , headSeed = txInToHeadSeed seedTxIn
-      , headParameters = HeadParameters{contestationPeriod, parties}
-      , participants
-      }
+  toEvent InitObservation{headParameters, headId, headSeed, participants} =
+    OnInitTx{headId, headSeed, headParameters, participants}
 
-  toState initialThreadUTxO InitObservation{parties, contestationPeriod, headId, seedTxIn} =
+  toState initialThreadUTxO InitObservation{headParameters, headId, headSeed} =
     InitialState
       { initialThreadOutput =
           InitialThreadOutput
             { initialThreadUTxO
-            , initialParties = partyToChain <$> parties
-            , initialContestationPeriod = toChain contestationPeriod
+            , initialParties = partyToChain <$> headParameters.parties
+            , initialContestationPeriod = toChain headParameters.contestationPeriod
             }
       , initialInitials = initials
       , initialCommits = mempty
       , headId
-      , seedTxIn
+      , seedTxIn = fromJust $ headSeedToTxIn headSeed
       }
 
   indexedOutputs = zip [0 ..] (txOuts' tx)

hydra-tx/src/Hydra/Tx/Init.hs

@@ -11,11 +11,11 @@ import Hydra.Contract.Initial qualified as Initial
 import Hydra.Contract.MintAction (MintAction (..))
 import Hydra.Ledger.Cardano.Builder (addTxInsSpending, mintTokens, unsafeBuildTransaction)
 import Hydra.Plutus (initialValidatorScript)
-import Hydra.Tx.ContestationPeriod (ContestationPeriod, fromChain, toChain)
-import Hydra.Tx.HeadId (HeadId, mkHeadId)
+import Hydra.Tx.ContestationPeriod (fromChain, toChain)
+import Hydra.Tx.HeadId (HeadId, HeadSeed, mkHeadId, txInToHeadSeed)
 import Hydra.Tx.HeadParameters (HeadParameters (..))
 import Hydra.Tx.OnChainId (OnChainId (..))
-import Hydra.Tx.Party (Party, partyFromChain, partyToChain)
+import Hydra.Tx.Party (partyFromChain, partyToChain)
 import Hydra.Tx.Utils (assetNameToOnChainId, findFirst, hydraHeadV1AssetName, mkHydraHeadV1TxName, onChainIdToAssetName)
 
 -- * Construction
@@ -83,14 +83,9 @@ mkInitialOutput networkId seedTxIn participant =
 -- | Data which can be observed from an `initTx`.
 data InitObservation = InitObservation
   { headId :: HeadId
-  , -- XXX: This is cardano-specific, while headId, parties and
-    -- contestationPeriod are already generic here. Check which is more
-    -- convenient and consistent!
-    seedTxIn :: TxIn
-  , contestationPeriod :: ContestationPeriod
-  , parties :: [Party]
-  , -- XXX: Improve naming
-    participants :: [OnChainId]
+  , headSeed :: HeadSeed
+  , headParameters :: HeadParameters
+  , participants :: [OnChainId]
   }
   deriving stock (Show, Eq, Generic)
   deriving anyclass (ToJSON, FromJSON)
@@ -136,9 +131,8 @@ observeInitTx tx = do
   pure $
     InitObservation
       { headId = mkHeadId pid
-      , seedTxIn
-      , contestationPeriod
-      , parties
+      , headSeed = txInToHeadSeed seedTxIn
+      , headParameters = HeadParameters{contestationPeriod, parties}
       , participants = assetNameToOnChainId <$> mintedTokenNames pid
       }
  where