scrapbox.ioのエクスポートJSONをプレーンテキスト(UTF8)に展開するやつ （１ページ１ファイルにする時は-dオプションでディレクトリを指定する）

scrapbox.go

package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
	"time"
)

var optionOutputDir = flag.String("d", "", "directory where files output")

type ScrapboxPage struct {
	Title   string   `json:"title"`
	Created int64    `json:"created"`
	Updated int64    `json:"updated"`
	Lines   []string `json:"lines"`
}

type ScrapboxJson struct {
	Name        string          `json:"name"`
	DisplayName string          `json:"displayName"`
	Exported    int64           `json:"exported"`
	Pages       []*ScrapboxPage `json:"pages"`
}

func (this *ScrapboxJson) Read(r io.Reader) error {
	bin, err := ioutil.ReadAll(r)
	if err != nil {
		return err
	}
	err = json.Unmarshal(bin, this)
	if err != nil {
		return err
	}
	return nil
}

func (this *ScrapboxJson) Load(fname string) error {
	fd, err := os.Open(fname)
	if err != nil {
		return err
	}
	defer fd.Close()

	err = this.Read(fd)
	if err != nil {
		return err
	}
	return nil
}

func (page *ScrapboxPage) WriteTo(w io.Writer) (int64, error) {
	n, _ := fmt.Fprintf(w, "Subject: %s\n", page.Title)
	n1, _ := fmt.Fprintf(w, "Created: %s\n", time.Unix(page.Created, 0).Format(time.ANSIC))
	n += n1
	n1, _ = fmt.Fprintf(w, "Updated: %s\n", time.Unix(page.Updated, 0).Format(time.ANSIC))
	n += n1
	n1, _ = fmt.Fprintln(w)
	n += n1
	for _, line := range page.Lines {
		n1, _ = fmt.Fprintln(w, line)
		n += n1
	}
	return int64(n), nil
}

var forbiddens = strings.NewReplacer(
	`\`, `￥`,
	`/`, `／`,
	`:`, `：`,
	`*`, `＊`,
	`?`, `？`,
	`"`, `”`,
	`<`, `＜`,
	`>`, `＞`,
	`|`, `｜`)

func safeFileName(name string) string {
	return forbiddens.Replace(name)
}

func main1(fname string) error {
	var sbox ScrapboxJson
	if err := sbox.Load(fname); err != nil {
		return fmt.Errorf("%s: %w", fname, err)
	}

	if *optionOutputDir != "" {
		for _, page := range sbox.Pages {
			ofname := filepath.Join(
				*optionOutputDir, safeFileName(page.Title)+".txt")
			fd, err := os.Create(ofname)
			if err != nil {
				return fmt.Errorf("%s: Create: %w", ofname, err)
			}
			if _, err := page.WriteTo(fd); err != nil {
				fd.Close()
				return fmt.Errorf("%s: %w", ofname, err)
			}
			if err := fd.Close(); err != nil {
				return fmt.Errorf("%s: Close: %w", ofname, err)
			}
		}
		return nil
	}
	for i, page := range sbox.Pages {
		if i > 0 {
			fmt.Println("\f")
		}
		page.WriteTo(os.Stdout)
	}
	return nil
}

func mains(args []string) error {
	for _, fname := range args {
		if err := main1(fname); err != nil {
			return fmt.Errorf("%s: %w", fname, err)
		}
	}
	return nil
}

func main() {
	flag.Parse()
	if err := mains(flag.Args()); err != nil {
		fmt.Fprintln(os.Stderr, err.Error())
		os.Exit(1)
	}
}