Process .xbel files (XML Bookmark Exchange Language)

main.go

package main

import (
	"encoding/xml"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"strings"
)

const SUPPORTED_VERSION = "1.0"

const header = `<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xbel PUBLIC "+//IDN python.org//DTD XML Bookmark Exchange Language 1.0//EN//XML" "http://pyxml.sourceforge.net/topics/dtds/xbel.dtd">
`

type XBEL struct {
	XMLName xml.Name `xml:"xbel"`
	Version string   `xml:"version,attr"`
	Folders []Folder `xml:"folder"`
}

type Folder struct {
	Title     string     `xml:"title"`
	ID        int        `xml:"id,attr"`
	Folders   []Folder   `xml:"folder"`
	Bookmarks []Bookmark `xml:"bookmark"`
}

type Bookmark struct {
	Title string `xml:"title"`
	ID    int    `xml:"id,attr"`
	Href  string `xml:"href,attr"`
}

type selector func(b *Bookmark) bool

func walk(x XBEL, s selector) XBEL {
	var nf []Folder
	for _, f := range x.Folders {
		y := walkFolder(f, s)
		// Skip empty folders
		if len(y.Bookmarks) == 0 && len(y.Folders) == 0 {
			continue
		}
		nf = append(nf, y)
	}
	return XBEL{
		XMLName: x.XMLName,
		Version: SUPPORTED_VERSION,
		Folders: nf,
	}
}

// walkFolder apply s recursively to all bookmarks within
func walkFolder(x Folder, s selector) Folder {
	var nb []Bookmark
	for _, b := range x.Bookmarks {
		if s(&b) {
			nb = append(nb, b)
		}
	}
	var nf []Folder
	for _, f := range x.Folders {
		y := walkFolder(f, s)
		// Skip empty folders
		if len(y.Bookmarks) == 0 && len(y.Folders) == 0 {
			continue
		}
		nf = append(nf, y)
	}
	return Folder{
		Folders:   nf,
		Bookmarks: nb,
		Title:     x.Title,
		ID:        x.ID,
	}
}

func check(err error) {
	if err != nil {
		panic(err)
	}
}

func main() {
	xmlFile, err := os.Open("bookmarks.xbel")
	check(err)
	defer xmlFile.Close()

	byteValue, err := ioutil.ReadAll(xmlFile)
	check(err)

	var xbel XBEL
	err = xml.Unmarshal(byteValue, &xbel)
	check(err)

	if xbel.Version != SUPPORTED_VERSION {
		panic("unsupported XBEL version")
	}

	// nx := walk(xbel, func(b Bookmark) bool {
	// 	fmt.Println(b.Href)
	// 	return true
	// })

	// Remove duplicates
	hrefs := make(map[string]struct{})
	nx := walk(xbel, func(b *Bookmark) bool {
		if _, exists := hrefs[b.Href]; exists {
			// fmt.Println(b.Href)
			return false
		}

		hrefs[b.Href] = struct{}{}

		return true
	})

	// os.Exit(1)

	output, err := xml.MarshalIndent(nx, "  ", "    ")
	if err != nil {
		panic(err)
	}

	outFile, err := os.Create("out.xbel")
	check(err)
	defer outFile.Close()

	outFile.Write([]byte(header))
	outFile.Write(output)
}