refactor: consolidate license generation in internal/sidekick/license and internal/yaml/copyright (#3715)

Consolidate license generation into a shared internal package by merging
duplicated logic between `internal/sidekick/license` and
`internal/yaml/copyright`.

Key changes:
- Moved `internal/sidekick/license` to `internal/license`.
- Removed `internal/yaml/copyright.go` and updated `internal/yaml` to
use the new `internal/license` package for generating license headers.

This is part of a larger refactoring effort to delete
`internal/sidekick/sidekick` the CLI and associated configs

Fixes #3716

---------

Signed-off-by: James Wu <jameslynnwu@users.noreply.github.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: jameslynnwu

internal/sidekick/license/license.go internal/license/license.gointernal/sidekick/license/license.go renamed to internal/license/license.go

@@ -22,7 +22,7 @@ import (
 	"os"
 	"path"
 
-	"github.com/googleapis/librarian/internal/sidekick/license"
+	"github.com/googleapis/librarian/internal/license"
 	"github.com/pelletier/go-toml/v2"
 )
 

internal/sidekick/license/license_test.go internal/license/license_test.gointernal/sidekick/license/license_test.go renamed to internal/license/license_test.go

@@ -23,9 +23,9 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/googleapis/librarian/internal/license"
 	"github.com/googleapis/librarian/internal/sidekick/api"
 	"github.com/googleapis/librarian/internal/sidekick/language"
-	"github.com/googleapis/librarian/internal/sidekick/license"
 	"github.com/iancoleman/strcase"
 )
 

internal/sidekick/config/config.go

@@ -21,9 +21,9 @@ import (
 	"slices"
 	"strings"
 
+	"github.com/googleapis/librarian/internal/license"
 	"github.com/googleapis/librarian/internal/sidekick/api"
 	"github.com/googleapis/librarian/internal/sidekick/language"
-	"github.com/googleapis/librarian/internal/sidekick/license"
 	"github.com/iancoleman/strcase"
 )
 

internal/sidekick/dart/annotate.go

@@ -18,9 +18,9 @@ package rust_prost
 import (
 	"strings"
 
+	"github.com/googleapis/librarian/internal/license"
 	"github.com/googleapis/librarian/internal/sidekick/api"
 	"github.com/googleapis/librarian/internal/sidekick/config"
-	"github.com/googleapis/librarian/internal/sidekick/license"
 	"github.com/googleapis/librarian/internal/sidekick/protobuf"
 	"github.com/googleapis/librarian/internal/sidekick/rust"
 )

internal/sidekick/rust/annotate.go

@@ -18,8 +18,12 @@ package yaml
 import (
 	"bytes"
 	"os"
+	"strconv"
+	"strings"
+	"time"
 
 	"github.com/google/yamlfmt/formatters/basic"
+	"github.com/googleapis/librarian/internal/license"
 	"gopkg.in/yaml.v3"
 )
 
@@ -79,7 +83,19 @@ func Write(path string, v any) error {
 	if err != nil {
 		return err
 	}
-	data = append([]byte(copyright), data...)
+
+	// Add # comment prefix to each line of the license header.
+	var b strings.Builder
+	year := time.Now().Year()
+	for _, line := range license.LicenseHeader(strconv.Itoa(year)) {
+		b.WriteString("#")
+		b.WriteString(line)
+		b.WriteString("\n")
+	}
+	b.WriteString("\n")
+	header := b.String()
+
+	data = append([]byte(header), data...)
 	return os.WriteFile(path, data, 0644)
 }
 

internal/sidekick/rust_prost/annotate.go

@@ -15,9 +15,12 @@
 package yaml
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
+	"strconv"
 	"testing"
+	"time"
 
 	"github.com/google/go-cmp/cmp"
 )
@@ -75,8 +78,26 @@ func TestReadWrite(t *testing.T) {
 	}
 }
 
+const copyright = `# Copyright %s 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
+#
+#     https://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.
+
+`
+
 func TestWrite(t *testing.T) {
-	want := copyright + `name: test
+	// Construct expected header
+	header := fmt.Sprintf(copyright, strconv.Itoa(time.Now().Year()))
+	want := header + `name: test
 version: v1.0.0
 `
 	path := filepath.Join(t.TempDir(), "test.yaml")