SCB: Removing the ContractStateTransition event.

It's a confusing duplicate of `ContractStateTransition`.

plutus-scb-client/src/View/Pretty.purs

@@ -43,7 +43,6 @@ eventWithPrefix prefix content =
 
 instance prettyUserEvent :: Pretty t => Pretty (UserEvent t) where
   pretty (InstallContract contract) = span_ [ text $ "Install", nbsp, pretty contract ]
-  pretty (ContractStateTransition instanceState) = pretty instanceState
 
 instance prettyContractExe :: Pretty ContractExe where
   pretty ((ContractExe { contractPath })) = text contractPath

plutus-scb/src/Plutus/SCB/Command.hs

@@ -20,15 +20,13 @@ module Plutus.SCB.Command
     ( installCommand
     , saveBalancedTx
     , saveBalancedTxResult
-    , saveContractState
     -- * Commands related to updating the contract state
     , sendContractEvent
     ) where
 
 import           Eventful                   (Aggregate (Aggregate), aggregateCommandHandler, aggregateProjection)
 import qualified Ledger
-import           Plutus.SCB.Events          (ChainEvent (ContractEvent, UserEvent), ContractInstanceState,
-                                             UserEvent (ContractStateTransition, InstallContract))
+import           Plutus.SCB.Events          (ChainEvent (ContractEvent, UserEvent), UserEvent (InstallContract))
 import qualified Plutus.SCB.Events          as Events
 import           Plutus.SCB.Query           (nullProjection)
 
@@ -55,8 +53,5 @@ saveBalancedTx = sendEvents (return . Events.WalletEvent . Events.BalancedTx)
 saveBalancedTxResult :: forall t. Aggregate () (ChainEvent t) Ledger.Tx
 saveBalancedTxResult = sendEvents (return . Events.NodeEvent . Events.SubmittedTx)
 
-saveContractState :: forall t. Aggregate () (ChainEvent t) (ContractInstanceState t)
-saveContractState = sendEvents (return . UserEvent . ContractStateTransition)
-
 sendContractEvent :: forall t. Aggregate () (ChainEvent t) (Events.Contract.ContractEvent t)
 sendContractEvent = sendEvents (return . ContractEvent)

plutus-scb/src/Plutus/SCB/Core/ContractInstance.hs

@@ -58,7 +58,7 @@ import           Wallet.Effects                                  (ChainIndexEffe
 import           Wallet.Emulator.LogMessages                     (TxBalanceMsg)
 
 import           Plutus.SCB.Command                              (saveBalancedTx, saveBalancedTxResult,
-                                                                  saveContractState, sendContractEvent)
+                                                                  sendContractEvent)
 import           Plutus.SCB.Effects.Contract                     (ContractCommand (..), ContractEffect)
 import qualified Plutus.SCB.Effects.Contract                     as Contract
 import           Plutus.SCB.Effects.EventLog                     (EventLogEffect, runCommand, runGlobalQuery)
@@ -71,7 +71,7 @@ import           Plutus.SCB.Events.Contract                      (ContractEvent
                                                                   unContractHandlersResponse)
 import qualified Plutus.SCB.Events.Contract                      as Events.Contract
 import qualified Plutus.SCB.Query                                as Query
-import           Plutus.SCB.Types                                (SCBError (..), Source (ContractEventSource, NodeEventSource, UserEventSource, WalletEventSource))
+import           Plutus.SCB.Types                                (SCBError (..), Source (ContractEventSource, NodeEventSource, WalletEventSource))
 import           Plutus.SCB.Utils                                (tshow)
 
 import qualified Plutus.SCB.Core.Projections                     as Projections
@@ -142,7 +142,6 @@ sendContractStateMessages is = do
     void
         $ runCommand (sendContractEvent @t) ContractEventSource
         $ ContractInstanceStateUpdateEvent is
-    void $ runCommand (saveContractState @t) UserEventSource is
 
 sendContractMessage ::
     forall t effs.

plutus-scb/src/Plutus/SCB/Events/Contract.hs

@@ -15,6 +15,7 @@ module Plutus.SCB.Events.Contract(
   , ContractHandlersResponse(..)
   , ContractResponse(..)
   , PartiallyDecodedResponse(..)
+  , hasActiveRequests
   , ContractInstanceState(..)
   -- * Prisms
   -- ** ContractRequest
@@ -221,3 +222,6 @@ instance Pretty t => Pretty (ContractEvent t) where
 makePrisms ''ContractSCBRequest
 makePrisms ''ContractResponse
 makePrisms ''ContractEvent
+
+hasActiveRequests :: ContractInstanceState t -> Bool
+hasActiveRequests = not . null . hooks . csCurrentState

plutus-scb/src/Plutus/SCB/Events/User.hs

@@ -1,25 +1,22 @@
-{-# LANGUAGE DeriveAnyClass     #-}
 {-# LANGUAGE DeriveGeneric      #-}
 {-# LANGUAGE DerivingStrategies #-}
 {-# LANGUAGE LambdaCase         #-}
 {-# LANGUAGE OverloadedStrings  #-}
+{-# LANGUAGE StrictData         #-}
 
 module Plutus.SCB.Events.User where
 
-import           Data.Aeson                 (FromJSON, ToJSON)
+import           Data.Aeson                (FromJSON, ToJSON)
 import           Data.Text.Prettyprint.Doc
-import           GHC.Generics               (Generic)
-import           Plutus.SCB.Events.Contract (ContractInstanceState)
+import           GHC.Generics              (Generic)
 
 -- | Users can install contracts and transition them to a new state.
 --   Contracts are identified by values of 't'.
-data UserEvent t
-    = InstallContract !t
-    | ContractStateTransition !(ContractInstanceState t)
+newtype UserEvent t
+    = InstallContract t
     deriving (Show, Eq, Generic)
-    deriving anyclass (FromJSON, ToJSON)
+    deriving newtype (FromJSON, ToJSON)
 
 instance Pretty t => Pretty (UserEvent t) where
     pretty = \case
         InstallContract t -> "InstallContract:" <+> pretty t
-        ContractStateTransition s -> "ContractStateTransition:" <+> pretty s

plutus-scb/src/Plutus/SCB/Query.hs

@@ -54,7 +54,7 @@ import           Ledger                                  (Address, Tx, TxId, TxO
                                                           txOutRefId, txOutTxOut, txOutTxTx)
 import           Ledger.Index                            (UtxoIndex (UtxoIndex))
 import           Plutus.SCB.Events                       (ChainEvent (..), NodeEvent (SubmittedTx),
-                                                          UserEvent (ContractStateTransition, InstallContract))
+                                                          UserEvent (InstallContract), hasActiveRequests)
 import           Plutus.SCB.Events.Contract              (ContractEvent (..), ContractInstanceId,
                                                           ContractInstanceState (..), ContractResponse (..),
                                                           IterationID)
@@ -184,16 +184,17 @@ contractStates IteratedContractState{icsContractIterations=ContractIterationStat
 
 -- | IDs of active contracts by contract type
 activeContractsProjection ::
-    forall t key position. Ord t =>
-       Projection (Map t (Set ContractInstanceId)) (StreamEvent key position (ChainEvent t))
+       forall t key position. Ord t
+    => Projection (Map t (Set ContractInstanceId)) (StreamEvent key position (ChainEvent t))
 activeContractsProjection =
-    let projectionEventHandler m (StreamEvent _ _ (UserEvent (ContractStateTransition state))) =
-            Map.insertWith (<>) (csContractDefinition state) (Set.singleton (csContract state)) m
-        projectionEventHandler m _ = m
-    in Projection
-        { projectionSeed = Map.empty
-        , projectionEventHandler
-        }
+    let projectionEventHandler m = \case
+            (StreamEvent _ _ (ContractEvent (ContractInstanceStateUpdateEvent state))) ->
+                let key = csContractDefinition state
+                 in if hasActiveRequests state
+                        then Map.insertWith (<>) key (Set.singleton (csContract state)) m
+                        else Map.delete key m
+            _ -> m
+     in Projection {projectionSeed = Map.empty, projectionEventHandler}
 
 -- | Transactions submitted to the node.
 txHistoryProjection ::
@@ -212,7 +213,7 @@ activeContractHistoryProjection ::
 activeContractHistoryProjection cid =
     projectionMapMaybe contractPaths monoidProjection
     where
-    contractPaths (StreamEvent _ _ (UserEvent (ContractStateTransition state))) =
+    contractPaths (StreamEvent _ _ (ContractEvent (ContractInstanceStateUpdateEvent state))) =
         if csContract state == cid
             then Just [state]
             else Nothing