fix: using the go import path

cmd/protoc-gen-connect-go-servicestruct/main.go

@@ -27,9 +27,12 @@
 package main
 
 import (
+	"flag"
 	"fmt"
+	"go/token"
 	"os"
 	"path"
+	"path/filepath"
 	"strings"
 
 	connect "connectrpc.com/connect"
@@ -42,9 +45,11 @@ const (
 	contextPackage = protogen.GoImportPath("context")
 	connectPackage = protogen.GoImportPath("connectrpc.com/connect")
 
-	filenameSuffix    = ".servicestruct.connect.go"
-	handlerFuncSuffix = "HandlerFunc"
-	serviceSuffix     = "Struct"
+	filenameSuffix        = ".servicestruct.connect.go"
+	handlerFuncSuffix     = "HandlerFunc"
+	serviceSuffix         = "Struct"
+	defaultPackageSuffix  = "connect"
+	packageSuffixFlagName = "package_suffix"
 
 	usage = "\n\nFlags:\n  -h, --help\tPrint this help and exit.\n      --version\tPrint the version and exit."
 )
@@ -68,15 +73,21 @@ func main() {
 		}
 		os.Exit(1)
 	}
-	protogen.Options{}.Run(
+	var flagSet flag.FlagSet
+	packageSuffix := flagSet.String(
+		packageSuffixFlagName,
+		defaultPackageSuffix,
+		"Generate files into a sub-package of the package containing the base .pb.go files using the given suffix. An empty suffix denotes to generate into the same package as the base pb.go files.",
+	)
+	protogen.Options{ParamFunc: flagSet.Set}.Run(
 		func(plugin *protogen.Plugin) error {
 			plugin.SupportedFeatures = uint64(pluginpb.CodeGeneratorResponse_FEATURE_PROTO3_OPTIONAL) | uint64(pluginpb.CodeGeneratorResponse_FEATURE_SUPPORTS_EDITIONS)
 			plugin.SupportedEditionsMinimum = descriptorpb.Edition_EDITION_PROTO2
-			plugin.SupportedEditionsMaximum = descriptorpb.Edition_EDITION_2023
+			plugin.SupportedEditionsMaximum = descriptorpb.Edition_EDITION_2024
 
 			for _, file := range plugin.Files {
-				if file.Generate && len(file.Services) > 0 {
-					generateFile(plugin, file)
+				if file.Generate {
+					generateFile(plugin, file, *packageSuffix)
 				}
 			}
 
@@ -85,28 +96,42 @@ func main() {
 	)
 }
 
-func generateFile(plugin *protogen.Plugin, file *protogen.File) {
-	// Modify package name and paths to match connect plugin behavior
-	connectSuffix := "connect"
-	connectPackageName := file.GoPackageName + protogen.GoPackageName(connectSuffix)
-	dir := path.Dir(file.GeneratedFilenamePrefix)
-	base := path.Base(file.GeneratedFilenamePrefix)
-	connectDir := string(file.GoPackageName) + connectSuffix
-	filename := path.Join(dir, connectDir, base+filenameSuffix)
-	goImportPath := protogen.GoImportPath(path.Join(
-		string(file.GoImportPath),
-		connectDir,
-	))
-	generatedFile := plugin.NewGeneratedFile(filename, goImportPath)
+func generateFile(plugin *protogen.Plugin, file *protogen.File, packageSuffix string) {
+	if len(file.Services) == 0 {
+		return
+	}
 
-	// Import the base package for message types
-	generatedFile.Import(file.GoImportPath)
+	goImportPath := file.GoImportPath
+	if packageSuffix != "" {
+		if !token.IsIdentifier(packageSuffix) {
+			plugin.Error(fmt.Errorf("package_suffix %q is not a valid Go identifier", packageSuffix))
+			return
+		}
+		file.GoPackageName += protogen.GoPackageName(packageSuffix)
+		generatedFilenamePrefixToSlash := filepath.ToSlash(file.GeneratedFilenamePrefix)
+		file.GeneratedFilenamePrefix = path.Join(
+			path.Dir(generatedFilenamePrefixToSlash),
+			string(file.GoPackageName),
+			path.Base(generatedFilenamePrefixToSlash),
+		)
+		goImportPath = protogen.GoImportPath(path.Join(
+			string(file.GoImportPath),
+			string(file.GoPackageName),
+		))
+	}
+	generatedFile := plugin.NewGeneratedFile(
+		file.GeneratedFilenamePrefix+filenameSuffix,
+		goImportPath,
+	)
+	if packageSuffix != "" {
+		generatedFile.Import(file.GoImportPath)
+	}
 
 	generatedFile.P("// Code generated by protoc-gen-connect-go-servicestruct. DO NOT EDIT.")
 	generatedFile.P("//")
 	generatedFile.P("// Source: ", file.Desc.Path())
 	generatedFile.P()
-	generatedFile.P("package ", connectPackageName)
+	generatedFile.P("package ", file.GoPackageName)
 	generatedFile.P()
 
 	generateHandlerFuncTypes(generatedFile, []*protogen.File{file})

cmd/protoc-gen-connect-go-servicestruct/main_test.go

@@ -94,6 +94,7 @@ func TestGenerate(t *testing.T) {
 
 			file := rsp.File[0]
 			assert.Contains(t, file.GetName(), "example.com/test/gen/genconnect/test.servicestruct.connect.go")
+			assert.Equal(t, "example.com/test/gen/genconnect/test.servicestruct.connect.go", file.GetName())
 
 			content := file.GetContent()
 
@@ -232,6 +233,7 @@ func TestGeneratedCodeStructure(t *testing.T) {
 		assert.Equal(t, 1, len(rsp.File))
 
 		file := rsp.File[0]
+		assert.Equal(t, "example.com/test/gen/genconnect/multi_service.servicestruct.connect.go", file.GetName())
 		content := file.GetContent()
 
 		assert.Equal(t, `// Code generated by protoc-gen-connect-go-servicestruct. DO NOT EDIT.
@@ -269,6 +271,65 @@ func (s *ProductServiceStruct) Create(ctx context.Context, req *connect.Request[
 	})
 }
 
+func TestBufGoPackagePrefixPathGeneration(t *testing.T) {
+	t.Parallel()
+
+	compilerVersion := &pluginpb.Version{
+		Major:  ptr(int32(0)),
+		Minor:  ptr(int32(0)),
+		Patch:  ptr(int32(1)),
+		Suffix: ptr("test"),
+	}
+
+	t.Run("with buf go_package_prefix causing path duplication", func(t *testing.T) {
+		t.Parallel()
+
+		fileDesc := &descriptorpb.FileDescriptorProto{
+			Name:    ptr("acme/billing/v1/invoice.proto"),
+			Package: ptr("acme.billing.v1"),
+			MessageType: []*descriptorpb.DescriptorProto{
+				{Name: ptr("CreateInvoiceRequest")},
+				{Name: ptr("CreateInvoiceResponse")},
+			},
+			Service: []*descriptorpb.ServiceDescriptorProto{
+				{
+					Name: ptr("BillingService"),
+					Method: []*descriptorpb.MethodDescriptorProto{
+						{
+							Name:       ptr("CreateInvoice"),
+							InputType:  ptr(".acme.billing.v1.CreateInvoiceRequest"),
+							OutputType: ptr(".acme.billing.v1.CreateInvoiceResponse"),
+						},
+					},
+				},
+			},
+			Options: &descriptorpb.FileOptions{
+				GoPackage: ptr("github.com/acme/service/internal/grpc/pb/acme/billing/v1"),
+			},
+		}
+
+		req := &pluginpb.CodeGeneratorRequest{
+			FileToGenerate:        []string{"acme/billing/v1/invoice.proto"},
+			ProtoFile:             []*descriptorpb.FileDescriptorProto{fileDesc},
+			SourceFileDescriptors: []*descriptorpb.FileDescriptorProto{fileDesc},
+			CompilerVersion:       compilerVersion,
+		}
+
+		rsp := testGenerate(t, req)
+		assert.Nil(t, rsp.Error)
+		assert.Equal(t, 1, len(rsp.File))
+
+		file := rsp.File[0]
+		expectedPath := "github.com/acme/service/internal/grpc/pb/acme/billing/v1/v1connect/invoice.servicestruct.connect.go"
+		assert.Equal(t, expectedPath, file.GetName())
+		assert.NotContains(t, file.GetName(), "github.com/acme/service/internal/grpc/pb/github.com/acme/service/internal/grpc/pb")
+
+		content := file.GetContent()
+		assert.Contains(t, content, "package v1connect")
+		assert.Contains(t, content, "v1 \"github.com/acme/service/internal/grpc/pb/acme/billing/v1\"")
+	})
+}
+
 func testGenerate(t *testing.T, req *pluginpb.CodeGeneratorRequest) *pluginpb.CodeGeneratorResponse {
 	t.Helper()