From df2bbb9a24024656feb7ae8eff8b7347bae02360 Mon Sep 17 00:00:00 2001
From: Kevin McDonald <github@sudorandom.com>
Date: Sun, 13 Oct 2024 17:08:09 +0200
Subject: [PATCH] Add command to generate fake data

---
 cmd/fauxrpc/cmd_generate.go                  | 84 ++++++++++++++++++++
 cmd/fauxrpc/main.go                          |  1 +
 private/{server/grpc.go => grpc/encoding.go} |  4 +-
 private/registry/loaders.go                  |  1 +
 private/server/handler.go                    |  3 +-
 5 files changed, 90 insertions(+), 3 deletions(-)
 create mode 100644 cmd/fauxrpc/cmd_generate.go
 rename private/{server/grpc.go => grpc/encoding.go} (72%)

diff --git a/cmd/fauxrpc/cmd_generate.go b/cmd/fauxrpc/cmd_generate.go
new file mode 100644
index 0000000..07f51f8
--- /dev/null
+++ b/cmd/fauxrpc/cmd_generate.go
@@ -0,0 +1,84 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/brianvoe/gofakeit/v7"
+	"github.com/brianvoe/gofakeit/v7/source"
+	"github.com/sudorandom/fauxrpc"
+	"github.com/sudorandom/fauxrpc/private/grpc"
+	"github.com/sudorandom/fauxrpc/private/registry"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/reflect/protoreflect"
+)
+
+type GenerateCmd struct {
+	Schema []string `required:"" help:"The modules to use for the RPC schema. It can be protobuf descriptors (binpb, json, yaml), a URL for reflection or a directory of descriptors."`
+	Target string   `required:"" help:"Protobuf type" example:"'connectrpc.eliza.v1.IntroduceResponse'"`
+	Format string   `default:"json" enum:"json,proto,grpc" help:"Format to output"`
+	Seed   *uint64  `help:"Seed for random number generator"`
+}
+
+func (c *GenerateCmd) Run(globals *Globals) error {
+	theRegistry, err := registry.NewServiceRegistry()
+	if err != nil {
+		return err
+	}
+	for _, schema := range c.Schema {
+		if err := registry.AddServicesFromPath(theRegistry, schema); err != nil {
+			if strings.Contains(err.Error(), "name conflict") {
+				continue
+			}
+			return err
+		}
+	}
+
+	desc, err := theRegistry.Files().FindDescriptorByName(protoreflect.FullName(c.Target))
+	if err != nil {
+		return err
+	}
+	md, ok := desc.(protoreflect.MessageDescriptor)
+	if !ok {
+		return fmt.Errorf("unexpected type: %T", desc)
+	}
+
+	seed := uint64(0)
+	if c.Seed == nil {
+		seed = uint64(time.Now().UnixNano())
+	} else {
+		seed = *c.Seed
+	}
+	fakeSrc := source.NewJSF(seed)
+	msg := fauxrpc.NewMessage(md, fauxrpc.GenOptions{
+		Faker: gofakeit.NewFaker(fakeSrc, true),
+	})
+
+	switch c.Format {
+	case "json":
+		jsonBytes, err := protojson.Marshal(msg)
+		if err != nil {
+			return err
+		}
+		os.Stdout.Write(jsonBytes)
+	case "proto":
+		protoBytes, err := proto.Marshal(msg)
+		if err != nil {
+			return err
+		}
+		os.Stdout.Write(protoBytes)
+	case "grpc":
+		protoBytes, err := proto.Marshal(msg)
+		if err != nil {
+			return err
+		}
+		grpc.WriteGRPCMessage(os.Stdout, protoBytes)
+	default:
+		return fmt.Errorf("unexpected format: %s", c.Format)
+	}
+
+	return nil
+}
diff --git a/cmd/fauxrpc/main.go b/cmd/fauxrpc/main.go
index 6864830..a04f5ad 100644
--- a/cmd/fauxrpc/main.go
+++ b/cmd/fauxrpc/main.go
@@ -34,6 +34,7 @@ type CLI struct {
 
 	Run      RunCmd      `cmd:"" help:"Run the FauxRPC server"`
 	Stub     StubCmd     `cmd:"" help:"Contains stub commands"`
+	Generate GenerateCmd `cmd:"generate" help:"Generate fake data"`
 	Registry RegistryCmd `cmd:"" help:"Contains registry commands"`
 }
 
diff --git a/private/server/grpc.go b/private/grpc/encoding.go
similarity index 72%
rename from private/server/grpc.go
rename to private/grpc/encoding.go
index 4563aae..9aa4f65 100644
--- a/private/server/grpc.go
+++ b/private/grpc/encoding.go
@@ -1,11 +1,11 @@
-package server
+package grpc
 
 import (
 	"encoding/binary"
 	"io"
 )
 
-func writeGRPCMessage(w io.Writer, msg []byte) {
+func WriteGRPCMessage(w io.Writer, msg []byte) {
 	prefix := make([]byte, 5)
 	binary.BigEndian.PutUint32(prefix[1:], uint32(len(msg)))
 	_, _ = w.Write(prefix)
diff --git a/private/registry/loaders.go b/private/registry/loaders.go
index 9993991..3ca3bd3 100644
--- a/private/registry/loaders.go
+++ b/private/registry/loaders.go
@@ -265,6 +265,7 @@ func AddServicesFromBSR(registry ServiceRegistry, module string) error {
 // AddServicesFromGlobal adds the 'well known' types to the registry. This is typically implicitly called.
 func AddServicesFromGlobal(registry ServiceRegistry) error {
 	for _, fd := range []protoreflect.FileDescriptor{
+		descriptorpb.File_google_protobuf_descriptor_proto,
 		anypb.File_google_protobuf_any_proto,
 		apipb.File_google_protobuf_api_proto,
 		durationpb.File_google_protobuf_duration_proto,
diff --git a/private/server/handler.go b/private/server/handler.go
index e2c85d5..5144b95 100644
--- a/private/server/handler.go
+++ b/private/server/handler.go
@@ -9,6 +9,7 @@ import (
 
 	"connectrpc.com/connect"
 	"github.com/sudorandom/fauxrpc"
+	"github.com/sudorandom/fauxrpc/private/grpc"
 	"github.com/sudorandom/fauxrpc/private/stubs"
 	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/reflect/protoreflect"
@@ -57,7 +58,7 @@ func NewHandler(service protoreflect.ServiceDescriptor, db stubs.StubDatabase) h
 			w.Header().Set("Grpc-Message", err.Error())
 			return
 		}
-		writeGRPCMessage(w, b)
+		grpc.WriteGRPCMessage(w, b)
 		w.Header().Set("Grpc-Status", "0")
 		w.Header().Set("Grpc-Message", "")
 	})