tidy-gomod.go

package main

import (
	"bufio"
	"bytes"
	"fmt"
	"os"
	"regexp"
	"strings"
)

func main() {
	mod, err := os.Open("go.mod")
	if err != nil {
		panic(err)
	}

	var buf bytes.Buffer
	var replace bytes.Buffer
	replaceRe := regexp.MustCompile(`^replace\s+[a-zA-Z]`)

	scanner := bufio.NewScanner(mod)
	for scanner.Scan() {
		text := scanner.Text()

		if strings.HasPrefix(text, "//") {
			continue
		}

		if replaceRe.MatchString(text) {
			replace.WriteString(text[8:])
			replace.WriteRune('\n')
			continue
		}

		buf.Write(scanner.Bytes())
		buf.WriteRune('\n')
	}
	mod.Close()

	tidy, err := os.Create("go.mod")
	if err != nil {
		panic(err)
	}
	defer tidy.Close()

	replaceBytes := replace.Bytes()
	scanner = bufio.NewScanner(&replace)
	content := buf.String()
	for scanner.Scan() {
		p := strings.Split(scanner.Text(), " ")

		old := fmt.Sprintf("%s v0.0.0-00010101000000-000000000000", p[0])
		new := fmt.Sprintf("%s %s", p[0], p[3])

		content = strings.ReplaceAll(content, old, new)
	}

	tidy.WriteString("// DO NOT EDIT, auto generated by make dep\n")
	tidy.WriteString(content)
	if len(replaceBytes) > 0 {
		tidy.WriteString("replace (\n")
		tidy.Write(replaceBytes)
		tidy.WriteString(")\n")
	}
}