Provide abi encoded exit event in hex format from `bridge_generateExi…

…tProof` JSON RPC (#1929)

* Provide abi encoded exit event in hex format

* Simplify EventAbi.Encode function in bindings

command/bridge/exit/exit.go

@@ -2,7 +2,7 @@ package exit
 
 import (
 	"bytes"
-	"encoding/json"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"math/big"
@@ -16,7 +16,6 @@ import (
 	"github.com/0xPolygon/polygon-edge/command/bridge/common"
 	cmdHelper "github.com/0xPolygon/polygon-edge/command/helper"
 	"github.com/0xPolygon/polygon-edge/command/rootchain/helper"
-	"github.com/0xPolygon/polygon-edge/consensus/polybft"
 	"github.com/0xPolygon/polygon-edge/consensus/polybft/contractsapi"
 	"github.com/0xPolygon/polygon-edge/txrelayer"
 	"github.com/0xPolygon/polygon-edge/types"
@@ -168,37 +167,31 @@ func run(cmd *cobra.Command, _ []string) {
 }
 
 // createExitTxn encodes parameters for exit function on root chain ExitHelper contract
-func createExitTxn(sender ethgo.Address, proof types.Proof) (*ethgo.Transaction, *polybft.ExitEvent, error) {
-	exitEventMap, ok := proof.Metadata["ExitEvent"].(map[string]interface{})
+func createExitTxn(sender ethgo.Address, proof types.Proof) (*ethgo.Transaction,
+	*contractsapi.L2StateSyncedEvent, error) {
+	leafIndex, ok := proof.Metadata["LeafIndex"].(float64)
 	if !ok {
-		return nil, nil, errors.New("could not get exit event from proof")
+		return nil, nil, errors.New("failed to convert proof leaf index")
 	}
 
-	raw, err := json.Marshal(exitEventMap)
-	if err != nil {
-		return nil, nil, fmt.Errorf("failed to marshal exit event map to JSON. Error: %w", err)
+	checkpointBlock, ok := proof.Metadata["CheckpointBlock"].(float64)
+	if !ok {
+		return nil, nil, errors.New("failed to convert proof checkpoint block")
 	}
 
-	var exitEvent *polybft.ExitEvent
-	if err = json.Unmarshal(raw, &exitEvent); err != nil {
-		return nil, nil, fmt.Errorf("failed to unmarshal exit event from JSON. Error: %w", err)
+	exitEventHex, ok := proof.Metadata["ExitEvent"].(string)
+	if !ok {
+		return nil, nil, errors.New("failed to convert exit event")
 	}
 
-	var exitEventAPI contractsapi.L2StateSyncedEvent
-
-	exitEventEncoded, err := exitEventAPI.Encode(exitEvent.L2StateSyncedEvent)
+	exitEventEncoded, err := hex.DecodeString(exitEventHex)
 	if err != nil {
-		return nil, nil, fmt.Errorf("failed to encode exit event: %w", err)
+		return nil, nil, fmt.Errorf("failed to decode hex-encoded exit event '%s': %w", exitEventHex, err)
 	}
 
-	leafIndex, ok := proof.Metadata["LeafIndex"].(float64)
-	if !ok {
-		return nil, nil, errors.New("failed to convert proof leaf index")
-	}
-
-	checkpointBlock, ok := proof.Metadata["CheckpointBlock"].(float64)
-	if !ok {
-		return nil, nil, errors.New("failed to convert proof checkpoint block")
+	exitEvent := new(contractsapi.L2StateSyncedEvent)
+	if err := exitEvent.Decode(exitEventEncoded); err != nil {
+		return nil, nil, fmt.Errorf("failed to decode exit event: %w", err)
 	}
 
 	exitFn := &contractsapi.ExitExitHelperFn{

consensus/polybft/checkpoint_manager.go

@@ -405,9 +405,7 @@ func (c *checkpointManager) GenerateExitProof(exitID uint64) (types.Proof, error
 		return types.Proof{}, fmt.Errorf("checkpoint block not found for exit ID %d", exitID)
 	}
 
-	var exitEventAPI contractsapi.L2StateSyncedEvent
-
-	e, err := exitEventAPI.Encode(exitEvent.L2StateSyncedEvent)
+	exitEventEncoded, err := exitEvent.L2StateSyncedEvent.Encode()
 	if err != nil {
 		return types.Proof{}, err
 	}
@@ -422,23 +420,25 @@ func (c *checkpointManager) GenerateExitProof(exitID uint64) (types.Proof, error
 		return types.Proof{}, err
 	}
 
-	leafIndex, err := tree.LeafIndex(e)
+	leafIndex, err := tree.LeafIndex(exitEventEncoded)
 	if err != nil {
 		return types.Proof{}, err
 	}
 
-	proof, err := tree.GenerateProof(e)
+	proof, err := tree.GenerateProof(exitEventEncoded)
 	if err != nil {
 		return types.Proof{}, err
 	}
 
 	c.logger.Debug("Generated proof for exit", "exitID", exitID, "leafIndex", leafIndex, "proofLen", len(proof))
 
+	exitEventHex := hex.EncodeToString(exitEventEncoded)
+
 	return types.Proof{
 		Data: proof,
 		Metadata: map[string]interface{}{
 			"LeafIndex":       leafIndex,
-			"ExitEvent":       exitEvent,
+			"ExitEvent":       exitEventHex,
 			"CheckpointBlock": checkpointBlock,
 		},
 	}, nil
@@ -449,9 +449,8 @@ func createExitTree(exitEvents []*ExitEvent) (*merkle.MerkleTree, error) {
 	numOfEvents := len(exitEvents)
 	data := make([][]byte, numOfEvents)
 
-	var exitEventAPI contractsapi.L2StateSyncedEvent
 	for i := 0; i < numOfEvents; i++ {
-		b, err := exitEventAPI.Encode(exitEvents[i].L2StateSyncedEvent)
+		b, err := exitEvents[i].L2StateSyncedEvent.Encode()
 		if err != nil {
 			return nil, err
 		}

consensus/polybft/consensus_runtime_test.go

@@ -11,7 +11,6 @@ import (
 	"github.com/0xPolygon/go-ibft/messages/proto"
 	"github.com/0xPolygon/polygon-edge/consensus"
 	"github.com/0xPolygon/polygon-edge/consensus/polybft/bitmap"
-	"github.com/0xPolygon/polygon-edge/consensus/polybft/contractsapi"
 	bls "github.com/0xPolygon/polygon-edge/consensus/polybft/signer"
 	"github.com/0xPolygon/polygon-edge/consensus/polybft/validator"
 	"github.com/0xPolygon/polygon-edge/consensus/polybft/wallet"
@@ -1078,9 +1077,8 @@ func encodeExitEvents(t *testing.T, exitEvents []*ExitEvent) [][]byte {
 
 	encodedEvents := make([][]byte, len(exitEvents))
 
-	var exitEventAPI contractsapi.L2StateSyncedEvent
 	for i, e := range exitEvents {
-		encodedEvent, err := exitEventAPI.Encode(e.L2StateSyncedEvent)
+		encodedEvent, err := e.L2StateSyncedEvent.Encode()
 		require.NoError(t, err)
 
 		encodedEvents[i] = encodedEvent

consensus/polybft/contractsapi/bindings-gen/main.go

@@ -649,8 +649,8 @@ func (*{{.TName}}) Sig() ethgo.Hash {
 	return {{.ContractName}}.Abi.Events["{{.Name}}"].ID()
 }
 
-func (*{{.TName}}) Encode(inputs interface{}) ([]byte, error) {
-	return {{.ContractName}}.Abi.Events["{{.Name}}"].Inputs.Encode(inputs)
+func ({{.Sig}} *{{.TName}}) Encode() ([]byte, error) {
+	return {{.ContractName}}.Abi.Events["{{.Name}}"].Inputs.Encode({{.Sig}})
 }
 
 func ({{.Sig}} *{{.TName}}) ParseLog(log *ethgo.Log) (bool, error) {
@@ -659,7 +659,12 @@ func ({{.Sig}} *{{.TName}}) ParseLog(log *ethgo.Log) (bool, error) {
 	}
 
 	return true, decodeEvent({{.ContractName}}.Abi.Events["{{.Name}}"], log, {{.Sig}})
-}`
+}
+
+func ({{.Sig}} *{{.TName}}) Decode(input []byte) error {
+	return {{.ContractName}}.Abi.Events["{{.Name}}"].Inputs.DecodeStruct(input, &{{.Sig}})
+}
+`
 
 	inputs := map[string]interface{}{
 		"Structs":      res,