Create a hydra-pab standalone PAB executable

This is running the PAB in Simulation mode and can be communicated with
using HTTP

cabal.project

@@ -146,7 +146,9 @@ source-repository-package
     plutus-contract
     plutus-ledger
     plutus-ledger-api
+    plutus-pab
     plutus-tx-plugin
+    plutus-use-cases
     prettyprinter-configurable
     quickcheck-dynamic
 

hydra-plutus/exe/hydra-pab/Main.hs

@@ -0,0 +1,99 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeOperators #-}
+
+module Main (main) where
+
+import Control.Monad (void)
+import Control.Monad.Freer (Eff, Member, interpret, type (~>))
+import Control.Monad.Freer.Error (Error)
+import Control.Monad.Freer.Extras.Log (LogMsg)
+import Control.Monad.IO.Class (MonadIO (..))
+import Data.Aeson (
+  FromJSON (..),
+  Options (..),
+  ToJSON (..),
+  defaultOptions,
+  genericParseJSON,
+  genericToJSON,
+ )
+import Data.Text.Prettyprint.Doc (Pretty (..), viaShow)
+import GHC.Generics (Generic)
+import Plutus.Contract (BlockchainActions, ContractError)
+import Plutus.Contracts.Game as Game
+import Plutus.PAB.Effects.Contract (ContractEffect (..))
+import Plutus.PAB.Effects.Contract.Builtin (Builtin, SomeBuiltin (..), type (.\\))
+import qualified Plutus.PAB.Effects.Contract.Builtin as Builtin
+import Plutus.PAB.Monitoring.PABLogMsg (PABMultiAgentMsg)
+import Plutus.PAB.Simulator (SimulatorEffectHandlers)
+import qualified Plutus.PAB.Simulator as Simulator
+import Plutus.PAB.Types (PABError (..))
+import qualified Plutus.PAB.Webserver.Server as PAB.Server
+import Wallet.Emulator.Types (Wallet (..))
+
+main :: IO ()
+main = void $
+  Simulator.runSimulationWith handlers $ do
+    Simulator.logString @(Builtin StarterContracts) "Starting plutus-starter PAB webserver on port 8080. Press enter to exit."
+    shutdown <- PAB.Server.startServerDebug
+
+    -- Pressing enter results in the balances being printed
+    void $ liftIO getLine
+
+    Simulator.logString @(Builtin StarterContracts) "Balances at the end of the simulation"
+    b <- Simulator.currentBalances
+    Simulator.logBalances @(Builtin StarterContracts) b
+
+    shutdown
+
+data StarterContracts
+  = HydraContract
+  deriving (Eq, Ord, Show, Generic)
+
+-- NOTE: Because 'StarterContracts' only has one constructor, corresponding to
+-- the demo 'Game' contract, we kindly ask aeson to still encode it as if it had
+-- many; this way we get to see the label of the contract in the API output!
+-- If you simple have more contracts, you can just use the anyclass deriving
+-- statement on 'StarterContracts' instead:
+--
+--    `... deriving anyclass (ToJSON, FromJSON)`
+instance ToJSON StarterContracts where
+  toJSON =
+    genericToJSON
+      defaultOptions
+        { tagSingleConstructors = True
+        }
+instance FromJSON StarterContracts where
+  parseJSON =
+    genericParseJSON
+      defaultOptions
+        { tagSingleConstructors = True
+        }
+
+instance Pretty StarterContracts where
+  pretty = viaShow
+
+handleStarterContract ::
+  ( Member (Error PABError) effs
+  , Member (LogMsg (PABMultiAgentMsg (Builtin StarterContracts))) effs
+  ) =>
+  ContractEffect (Builtin StarterContracts)
+    ~> Eff effs
+handleStarterContract = Builtin.handleBuiltin getSchema getContract
+ where
+  getSchema = \case
+    HydraContract -> Builtin.endpointsToSchemas @(Hydra.Schema .\\ BlockchainActions)
+  getContract = \case
+    HydraContract -> SomeBuiltin (Hydra.contract @ContractError)
+
+handlers :: SimulatorEffectHandlers (Builtin StarterContracts)
+handlers =
+  Simulator.mkSimulatorHandlers @(Builtin StarterContracts) [HydraContract] $
+    interpret handleStarterContract

hydra-plutus/hydra-plutus.cabal

@@ -130,3 +130,24 @@ test-suite hydra-plutus-test
       tasty-hunit,
       tasty-quickcheck,
       text
+
+executable hydra-pab
+  import: project-config
+  hs-source-dirs: exe/hydra-pab
+  main-is: Main.hs
+  build-depends:
+      aeson
+    , base
+    , cardano-prelude
+    , freer-extras
+    , freer-simple
+    , hydra-plutus
+    , optparse-applicative
+    , plutus-contract
+    , plutus-ledger
+    , plutus-pab
+    , prettyprinter
+    , text
+  ghc-options:
+    -threaded
+    -rtsopts