From 895857595895691222b9dda3f091fd92f7193320 Mon Sep 17 00:00:00 2001
From: Manfred Touron <m@42.am>
Date: Wed, 9 Nov 2016 18:38:32 +0100
Subject: [PATCH] Add filename templating support (fix #5)

---
 encoder.go                        | 65 +++++++++++++++++++++++++------
 examples/dummy/output/export.json |  3 +-
 2 files changed, 55 insertions(+), 13 deletions(-)

diff --git a/encoder.go b/encoder.go
index 2000293..39b107a 100644
--- a/encoder.go
+++ b/encoder.go
@@ -30,6 +30,7 @@ type Ast struct {
 	PWD           string                             `json:"pwd"`
 	Debug         bool                               `json:"debug"`
 	File          *descriptor.FileDescriptorProto    `json:"file"`
+	RawFilename   string                             `json:"raw-filename"`
 	Filename      string                             `json:"filename"`
 	Service       *descriptor.ServiceDescriptorProto `json:"service"`
 }
@@ -80,14 +81,8 @@ func (e *GenericTemplateBasedEncoder) templates() ([]string, error) {
 	return filenames, nil
 }
 
-func (e *GenericTemplateBasedEncoder) buildContent(templateFilename string) (string, error) {
-	fullPath := filepath.Join(e.templateDir, templateFilename)
-
-	tmpl, err := template.New(templateFilename).Funcs(funcmap.FuncMap).ParseFiles(fullPath)
-	if err != nil {
-		return "", err
-	}
-
+func (e *GenericTemplateBasedEncoder) genAst(templateFilename string) (*Ast, error) {
+	// prepare the ast passed to the template engine
 	hostname, _ := os.Hostname()
 	pwd, _ := os.Getwd()
 	goPwd := ""
@@ -104,10 +99,34 @@ func (e *GenericTemplateBasedEncoder) buildContent(templateFilename string) (str
 		PWD:           pwd,
 		GoPWD:         goPwd,
 		File:          e.file,
-		Filename:      templateFilename,
-		Service:       e.service,
+		RawFilename:   templateFilename,
+		// Filename:      "",
+		Service: e.service,
+	}
+	return &ast, nil
+}
+
+func (e *GenericTemplateBasedEncoder) buildContent(templateFilename string) (string, error) {
+	// initialize template engine
+	fullPath := filepath.Join(e.templateDir, templateFilename)
+	templateName := filepath.Base(fullPath)
+	tmpl, err := template.New(templateName).Funcs(funcmap.FuncMap).ParseFiles(fullPath)
+	if err != nil {
+		return "", err
 	}
 
+	ast, err := e.genAst(templateFilename)
+	if err != nil {
+		return "", err
+	}
+
+	// translate the filename
+	ast.Filename, err = e.translateString(templateFilename, templateFilename)
+	if err != nil {
+		return "", err
+	}
+
+	// generate the content
 	buffer := new(bytes.Buffer)
 	if err := tmpl.Execute(buffer, ast); err != nil {
 		return "", err
@@ -116,6 +135,24 @@ func (e *GenericTemplateBasedEncoder) buildContent(templateFilename string) (str
 	return buffer.String(), nil
 }
 
+func (e *GenericTemplateBasedEncoder) translateString(input string, templateFilename string) (string, error) {
+	buffer := new(bytes.Buffer)
+	tmpl, err := template.New("").Funcs(funcmap.FuncMap).Parse(input)
+	if err != nil {
+		return "", err
+	}
+
+	ast, err := e.genAst(templateFilename)
+	if err != nil {
+		return "", err
+	}
+
+	if err := tmpl.Execute(buffer, ast); err != nil {
+		return "", err
+	}
+	return buffer.String(), nil
+}
+
 func (e *GenericTemplateBasedEncoder) Files() []*plugin_go.CodeGeneratorResponse_File {
 	files := []*plugin_go.CodeGeneratorResponse_File{}
 
@@ -125,13 +162,17 @@ func (e *GenericTemplateBasedEncoder) Files() []*plugin_go.CodeGeneratorResponse
 	}
 
 	for _, templateFilename := range templates {
-		filename := templateFilename[0 : len(templateFilename)-len(".tmpl")]
-
 		content, err := e.buildContent(templateFilename)
 		if err != nil {
 			panic(err)
 		}
 
+		translatedFilename, err := e.translateString(templateFilename, templateFilename)
+		if err != nil {
+			panic(err)
+		}
+		filename := translatedFilename[0 : len(translatedFilename)-len(".tmpl")]
+
 		files = append(files, &plugin_go.CodeGeneratorResponse_File{
 			Content: &content,
 			Name:    &filename,
diff --git a/examples/dummy/output/export.json b/examples/dummy/output/export.json
index bd2b309..2bd1687 100644
--- a/examples/dummy/output/export.json
+++ b/examples/dummy/output/export.json
@@ -1,5 +1,5 @@
 {
-  "build-date": "2016-11-07T10:27:35.986181944+01:00",
+  "build-date": "2016-11-09T18:39:15.154031816+01:00",
   "build-hostname": "moul-rose.local",
   "build-user": "moul",
   "go-pwd": "github.com/moul/protoc-gen-gotemplate/examples/dummy",
@@ -820,6 +820,7 @@
     },
     "syntax": "proto3"
   },
+  "raw-filename": "export.json.tmpl",
   "filename": "export.json.tmpl",
   "service": {
     "name": "DummyService",