refactor(api): extract inline datum parsing into helper function

Eliminates ~50 lines of code duplication by extracting the repeated
inline datum parsing logic from Babbage/Conway/Dijkstra cases into a
single parseInlineDatum helper function.

The refactored helper:
- Parses both inlineDatumhash and inlineDatum fields
- Validates that the datum matches its hash
- Handles era-specific parsing differences between Babbage
  (scriptDataJsonToHashable) and Conway/Dijkstra (scriptDataFromJson)
- Maintains identical behavior with all existing tests passing

This consolidation improves maintainability by ensuring consistent
error handling and validation across all Babbage+ eras.

Author: newhoggy

cardano-api/src/Cardano/Api/Tx/Internal/Output.hs

@@ -457,77 +457,48 @@ instance IsShelleyBasedEra era => FromJSON (TxOut CtxTx era) where
       ShelleyBasedEraAlonzo -> alonzoTxOutParser AlonzoEraOnwardsAlonzo o
       ShelleyBasedEraBabbage -> do
         alonzoTxOutInBabbage <- alonzoTxOutParser AlonzoEraOnwardsBabbage o
-
-        -- We check for the existence of inline datums
-        inlineDatumHash <- o .:? "inlineDatumhash"
-        inlineDatum <- o .:? "inlineDatum"
-        mInlineDatum <-
-          case (inlineDatum, inlineDatumHash) of
-            (Just dVal, Just h) -> do
-              case scriptDataJsonToHashable ScriptDataJsonDetailedSchema dVal of
-                Left err ->
-                  fail $ "Error parsing TxOut JSON: " <> displayError err
-                Right hashableData -> do
-                  if hashScriptDataBytes hashableData /= h
-                    then fail "Inline datum not equivalent to inline datum hash"
-                    else return $ TxOutDatumInline BabbageEraOnwardsBabbage hashableData
-            (Nothing, Nothing) -> return TxOutDatumNone
-            (_, _) ->
-              fail
-                "Should not be possible to create a tx output with either an inline datum hash or an inline datum"
-
+        mInlineDatum <- parseInlineDatum BabbageEraOnwardsBabbage o
         mReferenceScript <- o .:? "referenceScript"
-
         reconcileBabbage alonzoTxOutInBabbage mInlineDatum mReferenceScript
       ShelleyBasedEraConway -> do
         alonzoTxOutInConway <- alonzoTxOutParser AlonzoEraOnwardsConway o
-
-        -- We check for the existence of inline datums
-        inlineDatumHash <- o .:? "inlineDatumhash"
-        inlineDatum <- o .:? "inlineDatum"
-        mInlineDatum <-
-          case (inlineDatum, inlineDatumHash) of
-            (Just dVal, Just h) ->
-              case scriptDataFromJson ScriptDataJsonDetailedSchema dVal of
-                Left err ->
-                  fail $ "Error parsing TxOut JSON: " <> displayError err
-                Right sData ->
-                  if hashScriptDataBytes sData /= h
-                    then fail "Inline datum not equivalent to inline datum hash"
-                    else return $ TxOutDatumInline BabbageEraOnwardsConway sData
-            (Nothing, Nothing) -> return TxOutDatumNone
-            (_, _) ->
-              fail
-                "Should not be possible to create a tx output with either an inline datum hash or an inline datum"
-
+        mInlineDatum <- parseInlineDatum BabbageEraOnwardsConway o
         mReferenceScript <- o .:? "referenceScript"
-
         reconcileConway ConwayEraOnwardsConway alonzoTxOutInConway mInlineDatum mReferenceScript
       ShelleyBasedEraDijkstra -> do
         alonzoTxOutInConway <- alonzoTxOutParser AlonzoEraOnwardsDijkstra o
-
-        -- We check for the existence of inline datums
-        inlineDatumHash <- o .:? "inlineDatumhash"
-        inlineDatum <- o .:? "inlineDatum"
-        mInlineDatum <-
-          case (inlineDatum, inlineDatumHash) of
-            (Just dVal, Just h) ->
-              case scriptDataFromJson ScriptDataJsonDetailedSchema dVal of
-                Left err ->
-                  fail $ "Error parsing TxOut JSON: " <> displayError err
-                Right sData ->
-                  if hashScriptDataBytes sData /= h
-                    then fail "Inline datum not equivalent to inline datum hash"
-                    else return $ TxOutDatumInline BabbageEraOnwardsDijkstra sData
-            (Nothing, Nothing) -> return TxOutDatumNone
-            (_, _) ->
-              fail
-                "Should not be possible to create a tx output with either an inline datum hash or an inline datum"
-
+        mInlineDatum <- parseInlineDatum BabbageEraOnwardsDijkstra o
         mReferenceScript <- o .:? "referenceScript"
-
         reconcileConway ConwayEraOnwardsDijkstra alonzoTxOutInConway mInlineDatum mReferenceScript
    where
+    -- | Parse inline datum fields from JSON object
+    -- Handles both inlineDatumhash and inlineDatum fields, validating they match
+    parseInlineDatum
+      :: BabbageEraOnwards era
+      -> Aeson.Object
+      -> Aeson.Parser (TxOutDatum CtxTx era)
+    parseInlineDatum w o = do
+      inlineDatumHash <- o .:? "inlineDatumhash"
+      inlineDatum <- o .:? "inlineDatum"
+      case (inlineDatum, inlineDatumHash) of
+        (Just dVal, Just h) -> do
+          sData <- case (convert w :: ShelleyBasedEra era) of
+            ShelleyBasedEraBabbage ->
+              case scriptDataJsonToHashable ScriptDataJsonDetailedSchema dVal of
+                Left err -> fail $ "Error parsing TxOut JSON: " <> displayError err
+                Right hashableData -> return hashableData
+            _ ->
+              case scriptDataFromJson ScriptDataJsonDetailedSchema dVal of
+                Left err -> fail $ "Error parsing TxOut JSON: " <> displayError err
+                Right scriptData -> return scriptData
+          if hashScriptDataBytes sData /= h
+            then fail "Inline datum not equivalent to inline datum hash"
+            else return $ TxOutDatumInline w sData
+        (Nothing, Nothing) -> return TxOutDatumNone
+        (_, _) ->
+          fail
+            "Should not be possible to create a tx output with either an inline datum hash or an inline datum"
+
     reconcileBabbage
       :: TxOut CtxTx BabbageEra
       -- \^ Alonzo era datum in Babbage era