feat: TX voting procedures attribute support

This adds support for decoding and retrieving Conway voting procedures
from a TX

Fixes #343

ledger/allegra.go

@@ -178,6 +178,10 @@ func (t AllegraTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t AllegraTransaction) VotingProcedures() VotingProcedures {
+	return t.Body.VotingProcedures()
+}
+
 func (t AllegraTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/alonzo.go

@@ -288,6 +288,10 @@ func (t AlonzoTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t AlonzoTransaction) VotingProcedures() VotingProcedures {
+	return t.Body.VotingProcedures()
+}
+
 func (t AlonzoTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/babbage.go

@@ -464,6 +464,10 @@ func (t BabbageTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t BabbageTransaction) VotingProcedures() VotingProcedures {
+	return t.Body.VotingProcedures()
+}
+
 func (t BabbageTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/byron.go

@@ -200,6 +200,11 @@ func (t *ByronTransaction) Withdrawals() map[*Address]uint64 {
 	return nil
 }
 
+func (t *ByronTransaction) VotingProcedures() VotingProcedures {
+	// No voting procedures in Byron
+	return nil
+}
+
 func (t *ByronTransaction) Metadata() *cbor.Value {
 	return t.Attributes
 }

ledger/conway.go

@@ -121,16 +121,61 @@ func (h *ConwayBlockHeader) Era() Era {
 
 type ConwayTransactionBody struct {
 	BabbageTransactionBody
-	VotingProcedures     *cbor.Value `cbor:"19,keyasint,omitempty"`
-	ProposalProcedures   *cbor.Value `cbor:"20,keyasint,omitempty"`
-	CurrentTreasuryValue int64       `cbor:"21,keyasint,omitempty"`
-	Donation             uint64      `cbor:"22,keyasint,omitempty"`
+	TxVotingProcedures   VotingProcedures `cbor:"19,keyasint,omitempty"`
+	ProposalProcedures   *cbor.Value      `cbor:"20,keyasint,omitempty"`
+	CurrentTreasuryValue int64            `cbor:"21,keyasint,omitempty"`
+	Donation             uint64           `cbor:"22,keyasint,omitempty"`
 }
 
 func (b *ConwayTransactionBody) UnmarshalCBOR(cborData []byte) error {
 	return b.UnmarshalCbor(cborData, b)
 }
 
+func (b *ConwayTransactionBody) VotingProcedures() VotingProcedures {
+	return b.TxVotingProcedures
+}
+
+// VotingProcedures is a convenience type to avoid needing to duplicate the full type definition everywhere
+type VotingProcedures map[*Voter]map[*GovActionId]VotingProcedure
+
+const (
+	VoterTypeConstitutionalCommitteeHotKeyHash    uint8 = 0
+	VoterTypeConstitutionalCommitteeHotScriptHash       = 1
+	VoterTypeDRepKeyHash                                = 2
+	VoterTypeDRepScriptHash                             = 3
+	VoterTypeStakingPoolKeyHash                         = 4
+)
+
+type Voter struct {
+	cbor.StructAsArray
+	Type uint8
+	Hash [28]byte
+}
+
+const (
+	GovVoteNo      uint8 = 0
+	GovVoteYes           = 1
+	GovVoteAbstain       = 2
+)
+
+type VotingProcedure struct {
+	cbor.StructAsArray
+	Vote   uint8
+	Anchor *GovAnchor
+}
+
+type GovAnchor struct {
+	cbor.StructAsArray
+	Url      string
+	DataHash [32]byte
+}
+
+type GovActionId struct {
+	cbor.StructAsArray
+	TransactionId [32]byte
+	GovActionIdx  uint32
+}
+
 type ConwayTransaction struct {
 	cbor.StructAsArray
 	cbor.DecodeStoreCbor
@@ -184,6 +229,10 @@ func (t ConwayTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t ConwayTransaction) VotingProcedures() VotingProcedures {
+	return t.Body.VotingProcedures()
+}
+
 func (t ConwayTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/mary.go

@@ -195,6 +195,10 @@ func (t MaryTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t MaryTransaction) VotingProcedures() VotingProcedures {
+	return t.Body.VotingProcedures()
+}
+
 func (t MaryTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/shelley.go

@@ -244,6 +244,11 @@ func (b *ShelleyTransactionBody) Withdrawals() map[*Address]uint64 {
 	return b.TxWithdrawals
 }
 
+func (t *ShelleyTransactionBody) VotingProcedures() VotingProcedures {
+	// No voting procedures in Shelley
+	return nil
+}
+
 func (b *ShelleyTransactionBody) Utxorpc() *utxorpc.Tx {
 	var txi []*utxorpc.TxInput
 	var txo []*utxorpc.TxOutput
@@ -402,6 +407,10 @@ func (t ShelleyTransaction) Withdrawals() map[*Address]uint64 {
 	return t.Body.Withdrawals()
 }
 
+func (t ShelleyTransaction) VotingProcedures() VotingProcedures {
+	return t.Body.VotingProcedures()
+}
+
 func (t ShelleyTransaction) Metadata() *cbor.Value {
 	return t.TxMetadata
 }

ledger/tx.go

@@ -46,6 +46,7 @@ type TransactionBody interface {
 	TotalCollateral() uint64
 	Certificates() []Certificate
 	Withdrawals() map[*Address]uint64
+	VotingProcedures() VotingProcedures
 	Utxorpc() *utxorpc.Tx
 }