From dd5b1c6345824f0da4cf25df9e4cc7b7de3e3891 Mon Sep 17 00:00:00 2001
From: Wyatt Barnes <me@wyatt.email>
Date: Fri, 24 Nov 2023 22:52:49 -1000
Subject: [PATCH] Bindings and metadata overwrite warning

---
 op-bindings/bindgen/remote_handlers.go | 26 +++++++++++++++++++++++++
 op-bindings/bindgen/utils.go           | 27 ++++++++++++++++++++++++--
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/op-bindings/bindgen/remote_handlers.go b/op-bindings/bindgen/remote_handlers.go
index a182db04200ce..d0fdae6a0b14c 100644
--- a/op-bindings/bindgen/remote_handlers.go
+++ b/op-bindings/bindgen/remote_handlers.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"os"
@@ -298,6 +299,15 @@ func (generator *bindGenGeneratorRemote) writeAllOutputs(contractMetadata *remot
 
 func (generator *bindGenGeneratorRemote) writeContractMetadata(contractMetadata *remoteContractMetadata, fileTemplate *template.Template) error {
 	metadataFilePath := filepath.Join(generator.metadataOut, strings.ToLower(contractMetadata.Name)+"_more.go")
+
+	var existingOutput []byte
+	if _, err := os.Stat(metadataFilePath); err == nil {
+		existingOutput, err = os.ReadFile(metadataFilePath)
+		if err != nil {
+			generator.logger.Crit("Error reading existing metadata output file", "path", metadataFilePath, "err", err)
+		}
+	}
+
 	metadataFile, err := os.OpenFile(
 		metadataFilePath,
 		os.O_RDWR|os.O_CREATE|os.O_TRUNC,
@@ -312,6 +322,22 @@ func (generator *bindGenGeneratorRemote) writeContractMetadata(contractMetadata
 		return fmt.Errorf("error writing %s's contract metadata at %s: %w", contractMetadata.Name, metadataFilePath, err)
 	}
 
+	if len(existingOutput) != 0 {
+		var newOutput []byte
+		newOutput, err = os.ReadFile(metadataFilePath)
+		if err != nil {
+			return fmt.Errorf("error reading new file: %w", err)
+		}
+
+		if bytes.Equal(existingOutput, newOutput) {
+			generator.logger.Debug("No changes detected in the contract metadata", "contract", contractMetadata.Name)
+		} else {
+			generator.logger.Warn("Changes detected in the contract metadata, old metadata has been overwritten", "contract", contractMetadata.Name)
+		}
+	} else {
+		generator.logger.Debug("No existing contract metadata found, skipping comparison", "contract", contractMetadata.Name)
+	}
+
 	generator.logger.Debug("Successfully wrote contract metadata", "contract", contractMetadata.Name, "path", metadataFilePath)
 	return nil
 }
diff --git a/op-bindings/bindgen/utils.go b/op-bindings/bindgen/utils.go
index 8465e34af3c4e..8a0ebfad5947e 100644
--- a/op-bindings/bindgen/utils.go
+++ b/op-bindings/bindgen/utils.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"os"
@@ -119,14 +120,36 @@ func genContractBindings(logger log.Logger, abiFilePath, bytecodeFilePath, goPac
 	}
 
 	outFilePath := path.Join(cwd, goPackageName, strings.ToLower(contractName)+".go")
-	logger.Debug("Generating contract bindings", "contractName", contractName, "outFilePath", outFilePath)
 
+	var existingOutput []byte
+	if _, err := os.Stat(outFilePath); err == nil {
+		existingOutput, err = os.ReadFile(outFilePath)
+		if err != nil {
+			logger.Crit("Error reading existing bindings output file", "outFilePath", outFilePath, "err", err)
+		}
+	}
+
+	logger.Debug("Generating contract bindings", "contractName", contractName, "outFilePath", outFilePath)
 	cmd := exec.Command("abigen", "--abi", abiFilePath, "--bin", bytecodeFilePath, "--pkg", goPackageName, "--type", contractName, "--out", outFilePath)
 	cmd.Stdout = os.Stdout
-
 	if err := cmd.Run(); err != nil {
 		return fmt.Errorf("error running abigen for %s: %w", contractName, err)
 	}
 
+	if len(existingOutput) != 0 {
+		newOutput, err := os.ReadFile(outFilePath)
+		if err != nil {
+			return fmt.Errorf("error reading new file: %w", err)
+		}
+
+		if bytes.Equal(existingOutput, newOutput) {
+			logger.Debug("No changes detected in the contract bindings", "contractName", contractName)
+		} else {
+			logger.Warn("Changes detected in the contract bindings, old bindings have been overwritten", "contractName", contractName)
+		}
+	} else {
+		logger.Debug("No existing contract bindings found, skipping comparison", "contractName", contractName)
+	}
+
 	return nil
 }