tools/src/cmd/gen/common/header.go

// Copyright 2023 The Tint Authors.
//
// 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 common

import (
	"fmt"
	"regexp"
	"strconv"
	"strings"
	"time"
)

var re = regexp.MustCompile(`• Copyright (\d+) The`)

const header = `• Copyright %v The Tint Authors.
•
• 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.

‣
• File generated by 'tools/src/cmd/gen' using the template:
•   %v
•
• To regenerate run: './tools/run gen'
•
•                       Do not modify this file directly
‣
`

func Header(existing, templatePath, comment string) string {
	copyrightYear := time.Now().Year()

	// Replace comment characters with '•'
	existing = strings.ReplaceAll(existing, comment, "•")

	// Look for the existing copyright year
	if match := re.FindStringSubmatch(string(existing)); len(match) == 2 {
		if year, err := strconv.Atoi(match[1]); err == nil {
			copyrightYear = year
		}
	}

	// Replace '•' with comment characters, '‣' with a line of comment characters
	out := strings.ReplaceAll(header, "•", comment)
	out = strings.ReplaceAll(out, "‣", strings.Repeat(comment, 80/len(comment)))

	return fmt.Sprintf(out, copyrightYear, templatePath)
}