refactor: helper for generating script hash (#1138)

Fixes #1135

Signed-off-by: Aurora Gaffney <[email protected]>

Author: agaffney

ledger/common/script.go

@@ -17,6 +17,7 @@ package common
 import (
 	"errors"
 	"fmt"
+	"slices"
 
 	"github.com/blinklabs-io/gouroboros/cbor"
 )
@@ -28,8 +29,11 @@ const (
 	ScriptRefTypePlutusV3     = 3
 )
 
+type ScriptHash = Blake2b224
+
 type Script interface {
 	isScript()
+	Hash() ScriptHash
 }
 
 type ScriptRef struct {
@@ -82,15 +86,43 @@ type PlutusV1Script []byte
 
 func (PlutusV1Script) isScript() {}
 
+func (s PlutusV1Script) Hash() ScriptHash {
+	return Blake2b224Hash(
+		slices.Concat(
+			[]byte{ScriptRefTypePlutusV1},
+			[]byte(s),
+		),
+	)
+}
+
 type PlutusV2Script []byte
 
 func (PlutusV2Script) isScript() {}
 
+func (s PlutusV2Script) Hash() ScriptHash {
+	return Blake2b224Hash(
+		slices.Concat(
+			[]byte{ScriptRefTypePlutusV2},
+			[]byte(s),
+		),
+	)
+}
+
 type PlutusV3Script []byte
 
 func (PlutusV3Script) isScript() {}
 
+func (s PlutusV3Script) Hash() ScriptHash {
+	return Blake2b224Hash(
+		slices.Concat(
+			[]byte{ScriptRefTypePlutusV3},
+			[]byte(s),
+		),
+	)
+}
+
 type NativeScript struct {
+	cbor.DecodeStoreCbor
 	item any
 }
 
@@ -101,6 +133,7 @@ func (n *NativeScript) Item() any {
 }
 
 func (n *NativeScript) UnmarshalCBOR(data []byte) error {
+	n.SetCbor(data)
 	id, err := cbor.DecodeIdFromList(data)
 	if err != nil {
 		return err
@@ -128,6 +161,15 @@ func (n *NativeScript) UnmarshalCBOR(data []byte) error {
 	return nil
 }
 
+func (s NativeScript) Hash() ScriptHash {
+	return Blake2b224Hash(
+		slices.Concat(
+			[]byte{ScriptRefTypeNativeScript},
+			[]byte(s.Cbor()),
+		),
+	)
+}
+
 type NativeScriptPubkey struct {
 	cbor.StructAsArray
 	Type uint

ledger/common/script_test.go

@@ -40,3 +40,13 @@ func TestScriptRefDecode(t *testing.T) {
 		)
 	}
 }
+
+func TestPlutusV3ScriptHash(t *testing.T) {
+	testScriptBytes, _ := hex.DecodeString("587f01010032323232323225333002323232323253330073370e900118041baa0011323232533300a3370e900018059baa00513232533300f301100214a22c6eb8c03c004c030dd50028b18069807001180600098049baa00116300a300b0023009001300900230070013004375400229309b2b2b9a5573aaae7955cfaba157441")
+	testScript := common.PlutusV3Script(testScriptBytes)
+	expectedScriptHash := "2909c3d0441e76cd6ae1fc09664bb209868902e191c2b8c30b82d331"
+	tmpHash := testScript.Hash()
+	if tmpHash.String() != expectedScriptHash {
+		t.Errorf("did not get expected script hash, got %s, wanted %s", tmpHash.String(), expectedScriptHash)
+	}
+}