From b7c3789e3c3d27f30320db60c0e8585fd603bbfd Mon Sep 17 00:00:00 2001
From: Roy Crihfield <roy@manteia.ltd>
Date: Sat, 9 Sep 2023 18:12:12 +0800
Subject: [PATCH] utils: load config

---
 utils/utils.go | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/utils/utils.go b/utils/utils.go
index 5d22034..d6ead2e 100644
--- a/utils/utils.go
+++ b/utils/utils.go
@@ -1,9 +1,12 @@
 package utils
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 
+	"github.com/cerc-io/plugeth-statediff/utils/log"
+	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
@@ -21,3 +24,38 @@ func MustDecode[T any](buf []byte) *T {
 	}
 	return &ret
 }
+
+// LoadConfig loads chain config from json file
+func LoadConfig(chainConfigPath string) (*params.ChainConfig, error) {
+	file, err := os.Open(chainConfigPath)
+	if err != nil {
+		log.Error("Failed to read chain config file", "error", err)
+		return nil, err
+	}
+	defer file.Close()
+
+	chainConfig := new(params.ChainConfig)
+	if err := json.NewDecoder(file).Decode(chainConfig); err != nil {
+		log.Error("invalid chain config file", "error", err)
+
+		return nil, err
+	}
+
+	log.Debug(fmt.Sprintf("Using chain config from '%s'. Content: %+v", chainConfigPath, chainConfig))
+
+	return chainConfig, nil
+}
+
+// ChainConfig returns the appropriate ethereum chain config for the provided chain id
+func ChainConfig(chainID uint64) (*params.ChainConfig, error) {
+	switch chainID {
+	case 1:
+		return params.MainnetChainConfig, nil
+	case 4:
+		return params.RinkebyChainConfig, nil
+	case 5:
+		return params.GoerliChainConfig, nil
+	default:
+		return nil, fmt.Errorf("chain config for chainid %d not available", chainID)
+	}
+}