Merge #2547

2547: API refactoring to move scripts into the txbody r=Jimbo4350 a=dcoutts

REMOVE: Merge #2498 after this PR has been merged

This is the first step in a refactoring that we will need for Alonzo
support. The refactoring will put the scripts within the tx body at the
sites where they are used. For Shelley era scripts we can do it either
way round, but for Alonzo it makes much more sense to place the script
at the use sites. So to break the Alonzo changes into steps we do the
refactoring for the existing Shelley-based eras first.
    
The ideas here have been co-authored with Jordan Millar and most of the
code changes here appeared first in his Alonzo branch.

- [x] Update the API tests for these API changes
- [x] Update the CLI for these API changes

There are a couple breaking changes:
- You must specify auxiliary scripts with `--auxiliary-script-file` instead of `--script-file`
- Scripts  witnessing txins, certificates, withdrawals and minting must be paired with the thing they are witnessing. 
E.g:
```
--certificate-file  $certfile --certificate-script-file $scriptfile
--tx-out $txout --minting-script-file $scriptfile
--withdrawal $withdrawal --withdrawal-script-file $scriptfile
--tx-in $txin --txin-script-file $scriptfile
```
- Scripts are no longer specified at the tx signing stage. They are specified at the txbody stage.

Co-authored-by: Duncan Coutts <duncan@well-typed.com>
Co-authored-by: Jordan Millar <jordan.millar@iohk.io>

cardano-api/src/Cardano/Api.hs

@@ -176,6 +176,11 @@ module Cardano.Api (
     TxUpdateProposal(..),
     TxMintValue(..),
 
+    -- ** Building vs viewing transactions
+    BuildTxWith(..),
+    BuildTx,
+    ViewTx,
+
     -- ** Era-dependent transaction body features
     MultiAssetSupportedInEra(..),
     OnlyAdaSupportedInEra(..),
@@ -214,13 +219,12 @@ module Cardano.Api (
 
     -- ** Incremental signing and separate witnesses
     makeSignedTransaction,
-    Witness,
+    KeyWitness,
     makeByronKeyWitness,
     makeByronTransaction,
     ShelleyWitnessSigningKey(..),
     makeShelleyKeyWitness,
     makeShelleyBootstrapWitness,
-    makeScriptWitness,
 
     -- * Fee calculation
     transactionFee,
@@ -296,6 +300,13 @@ module Cardano.Api (
     toScriptInEra,
     eraOfScriptInEra,
 
+    -- * Use of a script in an era as a witness
+    WitCtxTxIn, WitCtxMint, WitCtxStake,
+    ScriptWitness(..),
+    Witness(..),
+    KeyWitnessInCtx(..),
+    ScriptWitnessInCtx(..),
+
     -- *** Languages supported in each era
     ScriptLanguageInEra(..),
     scriptLanguageSupportedInEra,

cardano-api/src/Cardano/Api/Byron.hs

@@ -32,7 +32,7 @@ module Cardano.Api.Byron
     Tx(ByronTx),
 
     -- ** Incremental signing and separate witnesses
-    Witness (ByronKeyWitness),
+    KeyWitness (ByronKeyWitness),
     WitnessNetworkIdOrByronAddress
       ( WitnessNetworkId
       , WitnessByronAddress

cardano-api/src/Cardano/Api/Script.hs

@@ -28,6 +28,13 @@ module Cardano.Api.Script (
     toScriptInEra,
     eraOfScriptInEra,
 
+    -- * Use of a script in an era as a witness
+    WitCtxTxIn, WitCtxMint, WitCtxStake,
+    ScriptWitness(..),
+    Witness(..),
+    KeyWitnessInCtx(..),
+    ScriptWitnessInCtx(..),
+
     -- ** Languages supported in each era
     ScriptLanguageInEra(..),
     scriptLanguageSupportedInEra,
@@ -518,6 +525,95 @@ eraOfScriptInEra :: ScriptInEra era -> ShelleyBasedEra era
 eraOfScriptInEra (ScriptInEra langInEra _) = eraOfScriptLanguageInEra langInEra
 
 
+-- ----------------------------------------------------------------------------
+-- Scripts used in a transaction (in an era) to witness authorised use
+--
+
+-- | A tag type for the context in which a script is used in a transaction.
+--
+-- This type tags the context as being to witness a transaction input.
+--
+data WitCtxTxIn
+
+-- | A tag type for the context in which a script is used in a transaction.
+--
+-- This type tags the context as being to witness minting.
+--
+data WitCtxMint
+
+-- | A tag type for the context in which a script is used in a transaction.
+--
+-- This type tags the context as being to witness the use of stake addresses in
+-- both certificates and withdrawals.
+--
+data WitCtxStake
+
+-- | A /use/ of a script within a transaction body to witness that something is
+-- being used in an authorised manner. That can be
+--
+-- * spending a transaction input
+-- * minting tokens
+-- * using a certificate (stake address certs specifically)
+-- * withdrawing from a reward account
+--
+-- For simple script languages, the use of the script is the same in all
+-- contexts. For Plutus scripts, using a script involves supplying a redeemer.
+-- In addition, Plutus scripts used for spending inputs must also supply the
+-- datum value used when originally creating the TxOut that is now being spent.
+--
+data ScriptWitness witctx era where
+
+     SimpleScriptWitness :: ScriptLanguageInEra lang era
+                         -> SimpleScriptVersion lang
+                         -> SimpleScript        lang
+                         -> ScriptWitness witctx era
+
+deriving instance Show (ScriptWitness witctx era)
+
+-- The GADT in the SimpleScriptWitness constructor requires a custom instance
+instance Eq (ScriptWitness witctx era) where
+    (==) (SimpleScriptWitness langInEra  version  script)
+         (SimpleScriptWitness langInEra' version' script') =
+      case testEquality (languageOfScriptLanguageInEra langInEra)
+                        (languageOfScriptLanguageInEra langInEra') of
+        Nothing   -> False
+        Just Refl -> version == version' && script == script'
+
+
+-- ----------------------------------------------------------------------------
+-- The kind of witness to use, key (signature) or script
+--
+
+data Witness witctx era where
+
+     KeyWitness    :: KeyWitnessInCtx witctx
+                   -> Witness         witctx era
+
+     ScriptWitness :: ScriptWitnessInCtx witctx
+                   -> ScriptWitness      witctx era
+                   -> Witness            witctx era
+
+deriving instance Eq   (Witness witctx era)
+deriving instance Show (Witness witctx era)
+
+data KeyWitnessInCtx witctx where
+
+     KeyWitnessForSpending  :: KeyWitnessInCtx WitCtxTxIn
+     KeyWitnessForStakeAddr :: KeyWitnessInCtx WitCtxStake
+
+data ScriptWitnessInCtx witctx where
+
+     ScriptWitnessForSpending  :: ScriptWitnessInCtx WitCtxTxIn
+     ScriptWitnessForMinting   :: ScriptWitnessInCtx WitCtxMint
+     ScriptWitnessForStakeAddr :: ScriptWitnessInCtx WitCtxStake
+
+deriving instance Eq   (KeyWitnessInCtx witctx)
+deriving instance Show (KeyWitnessInCtx witctx)
+
+deriving instance Eq   (ScriptWitnessInCtx witctx)
+deriving instance Show (ScriptWitnessInCtx witctx)
+
+
 -- ----------------------------------------------------------------------------
 -- Script Hash
 --

cardano-api/src/Cardano/Api/Shelley.hs

@@ -59,10 +59,9 @@ module Cardano.Api.Shelley
     Tx(ShelleyTx),
 
     -- ** Incremental signing and separate witnesses
-    Witness
+    KeyWitness
       ( ShelleyBootstrapWitness
       , ShelleyKeyWitness
-      , ShelleyScriptWitness
       ),
     ShelleyWitnessSigningKey
       ( WitnessPaymentKey