From ad1127d33ea11879422afa4106a9dec9cccc1a7d Mon Sep 17 00:00:00 2001
From: David Pena <david.pena@coinbase.com>
Date: Wed, 19 Jul 2023 14:11:22 -0400
Subject: [PATCH] Make an optional resolver.gotpl ResolverTemplate to implement
 a custom resolver

---
 codegen/config/resolver.go     |  1 +
 plugin/resolvergen/resolver.go | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/codegen/config/resolver.go b/codegen/config/resolver.go
index a3ec38f8e20..cb5fb72b36a 100644
--- a/codegen/config/resolver.go
+++ b/codegen/config/resolver.go
@@ -17,6 +17,7 @@ type ResolverConfig struct {
 	Layout              ResolverLayout `yaml:"layout,omitempty"`
 	DirName             string         `yaml:"dir"`
 	OmitTemplateComment bool           `yaml:"omit_template_comment,omitempty"`
+	ResolverTemplate    string         `yaml:"resolver_template,omitempty"`
 }
 
 type ResolverLayout string
diff --git a/plugin/resolvergen/resolver.go b/plugin/resolvergen/resolver.go
index 09cfbab63bb..215bc469df3 100644
--- a/plugin/resolvergen/resolver.go
+++ b/plugin/resolvergen/resolver.go
@@ -81,6 +81,10 @@ func (m *Plugin) generateSingleFile(data *codegen.Data) error {
 		OmitTemplateComment: data.Config.Resolver.OmitTemplateComment,
 	}
 
+	if data.Config.Resolver.ResolverTemplate != "" {
+		resolverTemplate = readResolverTemplate(data.Config.Resolver.ResolverTemplate)
+	}
+
 	return templates.Render(templates.Options{
 		PackageName: data.Config.Resolver.Package,
 		FileNotice:  `// THIS CODE IS A STARTING POINT ONLY. IT WILL NOT BE UPDATED WITH SCHEMA CHANGES.`,
@@ -159,6 +163,10 @@ func (m *Plugin) generatePerSchema(data *codegen.Data) error {
 		file.RemainingSource = rewriter.RemainingSource(filename)
 	}
 
+	if data.Config.Resolver.ResolverTemplate != "" {
+		resolverTemplate = readResolverTemplate(data.Config.Resolver.ResolverTemplate)
+	}
+
 	for filename, file := range files {
 		resolverBuild := &ResolverBuild{
 			File:                file,
@@ -257,3 +265,11 @@ func gqlToResolverName(base string, gqlname, filenameTmpl string) string {
 	filename := strings.ReplaceAll(filenameTmpl, "{name}", strings.TrimSuffix(gqlname, ext))
 	return filepath.Join(base, filename)
 }
+
+func readResolverTemplate(customResolverTemplate string) string {
+	contentBytes, err := os.ReadFile(customResolverTemplate)
+	if err != nil {
+		panic(err)
+	}
+	return string(contentBytes)
+}