Added a multi-sig validator at Agora.MultiSig

src/Agora/MultiSig.hs

@@ -0,0 +1,52 @@
+{- |
+Module     : Agora.MultiSig
+Maintainer : riley_kilgore@outlook.com
+Description: A basic N of M multisignature validator.
+-}
+module Agora.MultiSig (
+  multiSigValidator,
+  MultiSig (..),
+) where
+
+import Plutarch.Api.V1 (
+  PPubKeyHash,
+  PScriptContext (..),
+ )
+import Plutarch.Monadic qualified as P
+
+--------------------------------------------------------------------------------
+
+import Agora.Utils (passert)
+
+--------------------------------------------------------------------------------
+
+import GHC.Generics qualified as GHC
+import Generics.SOP (Generic)
+import Prelude
+
+--------------------------------------------------------------------------------
+
+{- | A MultiSig represents a proof that a particular set of signatures
+     are present on a transaction.
+-}
+data MultiSig (s :: S) = MultiSig
+  { keys    :: PList PPubKeyHash s
+  -- ^ List of PubKeyHashes that must be present in the list of signatories.
+  , minSigs :: Integer
+  } deriving stock (GHC.Generic)
+    deriving anyclass (Generic)
+
+--------------------------------------------------------------------------------
+
+-- | Validator given 'MultiSig' params.
+multiSigValidator :: MultiSig s -> Term s (PData :--> PData :--> PScriptContext :--> PUnit)
+multiSigValidator params =
+  plam $ \_datum _redeemer ctx' -> P.do
+    ctx <- pletFields @'["txInfo", "purpose"] ctx'
+    let signatories = pfield @"signatories" # ctx.txInfo
+    passert "The amount of required signatures is not met."
+      ((fromInteger params.minSigs) #<= (plength #$ pfilter
+          # (plam $ \a ->
+              (pelem # pdata a # pfromData signatories))
+          # pcon params.keys))
+      (pconstant ())