From f5b4e4dc942134bcf26a174e79bdfa418444828d Mon Sep 17 00:00:00 2001
From: i-norden <iansnorden@gmail.com>
Date: Wed, 1 Nov 2023 14:56:14 -0500
Subject: [PATCH] ToMessage method for transaction_arguments

---
 pkg/eth/transaction_arguments.go | 88 ++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)

diff --git a/pkg/eth/transaction_arguments.go b/pkg/eth/transaction_arguments.go
index f837c500..3b974215 100644
--- a/pkg/eth/transaction_arguments.go
+++ b/pkg/eth/transaction_arguments.go
@@ -1,9 +1,15 @@
 package eth
 
 import (
+	"errors"
+	"math/big"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/common/math"
+	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/sirupsen/logrus"
 )
 
 // TransactionArgs represents the arguments to construct a new transaction
@@ -47,3 +53,85 @@ func (args *TransactionArgs) data() []byte {
 	}
 	return nil
 }
+
+// ToMessage converts the transaction arguments to the Message type used by the
+// core evm. This method is used in calls and traces that do not require a real
+// live transaction.
+func (args *TransactionArgs) ToMessage(globalGasCap uint64, baseFee *big.Int) (*core.Message, error) {
+	// Reject invalid combinations of pre- and post-1559 fee styles
+	if args.GasPrice != nil && (args.MaxFeePerGas != nil || args.MaxPriorityFeePerGas != nil) {
+		return nil, errors.New("both gasPrice and (maxFeePerGas or maxPriorityFeePerGas) specified")
+	}
+	// Set sender address or use zero address if none specified.
+	addr := args.from()
+
+	// Set default gas & gas price if none were set
+	gas := globalGasCap
+	if gas == 0 {
+		gas = uint64(math.MaxUint64 / 2)
+	}
+	if args.Gas != nil {
+		gas = uint64(*args.Gas)
+	}
+	if globalGasCap != 0 && globalGasCap < gas {
+		logrus.Warn("Caller gas above allowance, capping", "requested", gas, "cap", globalGasCap)
+		gas = globalGasCap
+	}
+	var (
+		gasPrice  *big.Int
+		gasFeeCap *big.Int
+		gasTipCap *big.Int
+	)
+	if baseFee == nil {
+		// If there's no basefee, then it must be a non-1559 execution
+		gasPrice = new(big.Int)
+		if args.GasPrice != nil {
+			gasPrice = args.GasPrice.ToInt()
+		}
+		gasFeeCap, gasTipCap = gasPrice, gasPrice
+	} else {
+		// A basefee is provided, necessitating 1559-type execution
+		if args.GasPrice != nil {
+			// User specified the legacy gas field, convert to 1559 gas typing
+			gasPrice = args.GasPrice.ToInt()
+			gasFeeCap, gasTipCap = gasPrice, gasPrice
+		} else {
+			// User specified 1559 gas fields (or none), use those
+			gasFeeCap = new(big.Int)
+			if args.MaxFeePerGas != nil {
+				gasFeeCap = args.MaxFeePerGas.ToInt()
+			}
+			gasTipCap = new(big.Int)
+			if args.MaxPriorityFeePerGas != nil {
+				gasTipCap = args.MaxPriorityFeePerGas.ToInt()
+			}
+			// Backfill the legacy gasPrice for EVM execution, unless we're all zeroes
+			gasPrice = new(big.Int)
+			if gasFeeCap.BitLen() > 0 || gasTipCap.BitLen() > 0 {
+				gasPrice = math.BigMin(new(big.Int).Add(gasTipCap, baseFee), gasFeeCap)
+			}
+		}
+	}
+	value := new(big.Int)
+	if args.Value != nil {
+		value = args.Value.ToInt()
+	}
+	data := args.data()
+	var accessList types.AccessList
+	if args.AccessList != nil {
+		accessList = *args.AccessList
+	}
+	msg := &core.Message{
+		From:              addr,
+		To:                args.To,
+		Value:             value,
+		GasLimit:          gas,
+		GasPrice:          gasPrice,
+		GasFeeCap:         gasFeeCap,
+		GasTipCap:         gasTipCap,
+		Data:              data,
+		AccessList:        accessList,
+		SkipAccountChecks: true,
+	}
+	return msg, nil
+}