Shareable Go package experiment in sdk-platform-java

internal/librariangen/languagecontainer/languagecontainer.go

@@ -0,0 +1,119 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package languagecontainer defines LanguageContainer interface and
+// the Run function to execute commands within the container.
+// TODO(b/447404382): Move this package to the https://github.com/googleapis/librarian
+// GitHub repository once the interface is finalized.
+// This package must not have any Java-specific implementation.
+package languagecontainer
+
+import (
+	"context"
+	"log/slog"
+
+	"cloud.google.com/java/internal/librariangen/message"
+)
+
+// GenerateCommandContext holds the context (the file system paths) for
+// the generate command. The createGenerateContext function creates
+// an instance of this by reading the command line flags and the
+// default values.
+type GenerateCommandContext struct {
+}
+type GenerateCommandEnv struct {
+	GenerateContext *GenerateCommandContext
+	GenerateRequest *message.GenerateRequest
+}
+
+type ConfigureCommandContext struct {
+}
+
+type ConfigureCommandEnv struct {
+	ConfigureContext *ConfigureCommandContext
+	ConfigureRequest *message.ConfigureRequest
+}
+
+// LanguageContainer defines the interface for language-specific container operations.
+type LanguageContainer interface {
+	Generate(context.Context, *GenerateCommandEnv) error
+	Configure(context.Context, *ConfigureCommandEnv) (*message.ConfigureResponse, error)
+	// Other container functions like ReleaseInit and Build would also be part of the interface.
+}
+
+// Run would accept an implementation of the LanguageContainer interface.
+func Run(args []string, container LanguageContainer) int {
+	// Logic to parse args and call the appropriate method on the container.
+	// For example, if args[1] is "generate":
+	//   request := ... // unmarshal the request from the expected location
+	//   err := container.Generate(context.Background(), request)
+	//   ...
+	if len(args) < 1 {
+		panic("args must not be empty")
+	}
+	switch args[0] {
+	case "generate":
+		env := createGenerateEnv(args[1:])
+		err := container.Generate(context.Background(), env)
+		if err != nil {
+			// TODO: Save it as a response file.
+			panic(err)
+		}
+		return 0
+	case "configure":
+		env := createConfigureEnv(args[1:])
+		resp, err := container.Configure(context.Background(), env)
+		if err != nil {
+			panic(err)
+		}
+		// TODO: Save it as a response file.
+		_ = resp
+		return 0
+	case "release-init":
+		slog.Warn("librariangen: release-init command is not yet implemented")
+		return 1
+	case "build":
+		slog.Warn("librariangen: build command is not yet implemented")
+		return 1
+	default:
+		slog.Error("librariangen: unknown command: %s (with flags %v)", args[0], args)
+		return 1
+	}
+	return 0
+}
+
+// https://github.com/googleapis/librarian/blob/main/doc/language-onboarding.md#generate
+func createGenerateEnv(args []string) *GenerateCommandEnv {
+	generateContext := createGenerateCommandContext(args)
+	return &GenerateCommandEnv{
+		GenerateContext: generateContext,
+	}
+}
+
+func createGenerateCommandContext(args []string) *GenerateCommandContext {
+	// TODO: Parse args and create the context.
+	return &GenerateCommandContext{}
+}
+
+func createConfigureCommandContext(args []string) *ConfigureCommandContext {
+	// TODO: Parse args and create the context.
+	return &ConfigureCommandContext{}
+}
+
+func createConfigureEnv(args []string) *ConfigureCommandEnv {
+	configureContext := createConfigureCommandContext(args)
+	return &ConfigureCommandEnv{
+		ConfigureContext: configureContext,
+	}
+}

internal/librariangen/main.go

@@ -16,32 +16,42 @@ package main
 
 import (
 	"context"
-	"errors"
-	"fmt"
 	"log/slog"
 	"os"
-	"strings"
+
+	"cloud.google.com/java/internal/librariangen/languagecontainer"
+	"cloud.google.com/java/internal/librariangen/message"
 )
 
 const version = "0.1.0"
 
-// main is the entrypoint for the librariangen CLI.
-func main() {
-	os.Exit(runCLI(os.Args))
+// javaContainer implements the LanguageContainer interface for Java.
+type javaContainer struct{}
+
+func (c *javaContainer) Generate(context.Context, *languagecontainer.GenerateCommandEnv) error {
+	// Java-specific implementation for the "generate" command.
+	slog.Warn("librariangen: generate command is not yet implemented")
+
+	return nil
 }
 
-func runCLI(args []string) int {
+func (c *javaContainer) Configure(ctx context.Context,
+	request *languagecontainer.ConfigureCommandEnv) (*message.ConfigureResponse, error) {
+	// Java-specific implementation for the "configure" command.
+	slog.Warn("librariangen: configure command is not yet implemented")
+	return nil, nil
+}
+
+// main is the entrypoint for the librariangen CLI.
+func main() {
 	logLevel := parseLogLevel(os.Getenv("GOOGLE_SDK_JAVA_LOGGING_LEVEL"))
 	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
 		Level: logLevel,
 	})))
+	args := os.Args
 	slog.Info("librariangen: invoked", "args", args)
-	if err := run(context.Background(), args[1:]); err != nil {
-		slog.Error("librariangen: failed", "error", err)
-		return 1
-	}
-	slog.Info("librariangen: finished successfully")
-	return 0
+	container := javaContainer{}
+	os.Exit(languagecontainer.Run(os.Args, &container))
 }
 
 func parseLogLevel(logLevelEnv string) slog.Level {
@@ -54,42 +64,3 @@ func parseLogLevel(logLevelEnv string) slog.Level {
 		return slog.LevelInfo
 	}
 }
-
-// run executes the appropriate command based on the CLI's invocation arguments.
-// The idiomatic structure is `librariangen [command] [flags]`.
-func run(ctx context.Context, args []string) error {
-	if len(args) < 1 {
-		return errors.New("librariangen: expected a command")
-	}
-
-	// The --version flag is a special case and not a command.
-	if args[0] == "--version" {
-		fmt.Println(version)
-		return nil
-	}
-
-	cmd := args[0]
-	flags := args[1:]
-
-	if strings.HasPrefix(cmd, "-") {
-		return fmt.Errorf("librariangen: command cannot be a flag: %s", cmd)
-	}
-
-	switch cmd {
-	case "generate":
-		slog.Warn("librariangen: generate command is not yet implemented")
-		return nil
-	case "release-init":
-		slog.Warn("librariangen: release-init command is not yet implemented")
-		return nil
-	case "configure":
-		slog.Warn("librariangen: configure command is not yet implemented")
-		return nil
-	case "build":
-		slog.Warn("librariangen: build command is not yet implemented")
-		return nil
-	default:
-		return fmt.Errorf("librariangen: unknown command: %s (with flags %s)", cmd, flags)
-	}
-
-}

internal/librariangen/message/message.go

@@ -0,0 +1,42 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package message defines data types which the Librarian CLI and language
+// containers exchange.
+// There shouldn't be CLI-specific data type or language container-specific
+// data types in this package.
+// TODO(b/447404382): Move this package to the https://github.com/googleapis/librarian
+// GitHub repository once the interface is finalized.
+// This package must not have any Java-specific implementation.
+package message
+
+// GenerateRequest is the JSON message sent to the language container by
+// the Librarian CLI when the "generate" command is invoked.
+type GenerateRequest struct {
+}
+
+// GenerateResponse is the JSON message sent back to the Librarian CLI
+// by the language container after processing the "generate" command.
+type GenerateResponse struct {
+}
+
+// ConfigureRequest is the JSON message sent to the language container by
+// the Librarian CLI when the "configure" command is invoked.
+type ConfigureRequest struct {
+}
+
+// ConfigureResponse is the JSON message sent back to the Librarian CLI
+// by the language container after processing the "configure" command.
+type ConfigureResponse struct {
+}