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epub.go
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package main
import (
"archive/zip"
"bytes"
"crypto/sha256"
"encoding/hex"
"errors"
"flag"
"fmt"
"html/template"
"io"
"log"
"net/http"
"net/url"
"os"
"path"
"runtime"
"regexp"
"strings"
"syscall"
"time"
"github.com/bmizerany/pat"
"github.com/jbowtie/gokogiri"
"github.com/jbowtie/gokogiri/css"
"github.com/jbowtie/gokogiri/xml"
)
type Item struct {
Id string
Href string
Type string
Spine bool
}
type Image struct {
Filename string
Mimetype string
Content []byte
}
type Epub struct {
Zip *zip.Writer
Identifier string
Title string
Subject string
Date string
Cover string
Creator string
Contributors []string
Items []Item
Images []string
ChanImages chan *Image
}
const (
// The maximal size for an image is 5MiB
maxSize = 5 * (1 << 20)
ContentType = "application/epub+zip"
XmlDeclaration = `<?xml version="1.0" encoding="utf-8"?>`
Container = XmlDeclaration + `
<container xmlns="urn:oasis:names:tc:opendocument:xmlns:container" version="1.0">
<rootfiles>
<rootfile full-path="EPUB/package.opf" media-type="application/oebps-package+xml"/>
</rootfiles>
</container>`
Nav = XmlDeclaration + `
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" lang="fr" xml:lang="fr">
<head>
<title>LinuxFr.org</title>
<meta charset="utf-8" />
</head>
<body>
<section class="frontmatter TableOfContents" epub:type="frontmatter toc">
<h1>Sommaire</h1>
<nav xmlns:epub="http://www.idpf.org/2007/ops" epub:type="toc" id="toc">
<ol>
<li><a href="content.xhtml">Aller au contenu</a></li>
</ol>
</nav>
</section>
</body>
</html>`
Stylesheet = `
body { font-family: sans-serif; }
img { display: block; margin: 0 auto; max-width: 100%; border: none; }
blockquote { border-left: 3px solid #4C575F; padding-left: 5px; margin: 10px 0 10px 10px; }
code { white-space: pre-wrap; border: 1px solid #E9E6E4; border-radius: 4px; padding: 1px 4px; }
pre code { display: block; border-width: 0 0 0 3px; border-color: #4C575F; }
article, ul.threads > li.comment {
display: block;
padding: 10px;
border-radius: 6px;
border: 1px solid #93877B;
min-height: 70px;
line-height: 1.4em;
text-align: justify; }
header .topic:after { content: " :"; }
article .image { float: left; margin: 10px; }
article h1 {
border-left: solid 6px #4C575F;
padding-left: 13px;
font-size: 1.5em;
margin-top: 7px;
margin-bottom: 8px; }
article h1 a { color: inherit; text-decoration: none; }
.meta { color: #93877B; }
.meta a { color: inherit; font-weight: bold; text-decoration: none; }
.tags ul { display: inline; }
.tags ul li { display: inline; padding: 0; list-style: none; }
.tags ul li:after { content: ", "; }
.tags ul li:last-child:after { content: ""; }
ul.poll .result { background: #F1ABC5; font-size: x-small; border-top: 1px solid #4C575F; border-bottom: 1px solid #4C575F; }
ul.threads li { list-style: none; }
li.comment > h2 { background: #E9E6E4; clear: right; }
li.comment > h2 a { color: inherit; text-decoration: none; margin-bottom: 0; }
li.comment .meta { margin-top: 5px; }
li.comment .avatar { float: right; margin: 0 5px 5px 10px; }
li.comment .content { border-left: 1px solid #93877B; padding-left: 5px; }
.deleted { border-left: 3px solid red; font-style: italic; }
.signature { color: #999; font-size: 11px; }
.signature:before { white-space: pre; content: "-- \a"; }
`
HeaderHtml = XmlDeclaration + `
<html xmlns="http://www.w3.org/1999/xhtml" lang="fr" xml:lang="fr">
<head>
<title>LinuxFr.org</title>
<meta charset="utf-8" />
<link rel="stylesheet" type="text/css" href="RonRonnement.css" />
</head>
<body>`
FooterHtml = "</body></html>"
)
var PackageTemplate = template.Must(template.New("package").Parse(`
<package xmlns="http://www.idpf.org/2007/opf" unique-identifier="pub-identifier" xml:lang="fr" version="3.0">
<metadata xmlns:dc="http://purl.org/dc/elements/1.1/">
<dc:language id="pub-language">fr</dc:language>
<dc:identifier id="pub-identifier">{{.Identifier}}</dc:identifier>
<dc:date>{{.Date}}</dc:date>
<meta property="dcterms:modified">{{.Date}}</meta>
{{if .Title}}<dc:title id="pub-title">{{.Title}}</dc:title>{{end}}
{{if .Creator}}<dc:creator id="pub-creator">{{.Creator}}</dc:creator>{{end}}
{{range .Contributors}}<dc:contributor>{{.}}</dc:contributor>
{{end}}
<meta name="cover" content="cover"/>
</metadata>
<manifest>
<item id="nav" href="nav.xhtml" media-type="application/xhtml+xml" properties="nav"/>
<item id="css" href="RonRonnement.css" media-type="text/css"/>
<item id="cover" href="{{.Cover}}" media-type="image/png"/>
{{range .Items}}<item id="{{.Id}}" href="{{.Href}}" media-type="{{.Type}}"/>
{{end}}
</manifest>
<spine>
{{range .Items}}{{if .Spine}}<itemref idref="{{.Id}}"/>{{end}}
{{end}}
</spine>
</package>`))
var Host string
var selector2xpath map[string]string
func Css2xpath(selector string) string {
xpath, ok := selector2xpath[selector]
if !ok {
xpath = css.Convert(selector, css.LOCAL)
selector2xpath[selector] = xpath
}
return xpath
}
func NewEpub(w io.Writer, id string) (epub *Epub) {
epub = &Epub{
Zip: zip.NewWriter(w),
Identifier: id,
ChanImages: make(chan *Image),
Items: []Item{},
Images: []string{},
}
err := epub.AddMimetype()
if (err != nil) {
log.Print("Error: ", err)
}
err = epub.AddDir("META-INF")
if (err != nil) {
log.Print("Error: ", err)
}
err = epub.AddFile("META-INF/container.xml", []byte(Container))
if (err != nil) {
log.Print("Error: ", err)
}
err = epub.AddDir("EPUB")
if (err != nil) {
log.Print("Error: ", err)
}
err = epub.AddFile("EPUB/nav.xhtml", []byte(Nav))
if (err != nil) {
log.Print("Error: ", err)
}
err = epub.AddFile("EPUB/RonRonnement.css", []byte(Stylesheet))
if (err != nil) {
log.Print("Error: ", err)
}
return
}
func (epub *Epub) importImage(uri *url.URL, filename string) {
if uri.Scheme == "data" {
epub.ChanImages <- nil
return
}
if uri.Host == "" {
uri.Host = Host
}
if uri.Scheme == "" {
uri.Scheme = "https"
}
resp, err := http.Get(uri.String())
if err != nil {
log.Print("Error: ", err)
epub.ChanImages <- nil
return
}
defer resp.Body.Close()
if resp.StatusCode != 200 {
log.Printf("Status code of %s is: %d\n", uri, resp.StatusCode)
epub.ChanImages <- nil
return
}
if resp.ContentLength > maxSize {
log.Printf("Exceeded max size for %s: %d\n", uri, resp.ContentLength)
epub.ChanImages <- nil
return
}
body, err := io.ReadAll(resp.Body)
if err != nil {
log.Print("Error: ", err)
epub.ChanImages <- nil
return
}
mimetype := resp.Header.Get("Content-Type")
img := &Image{filename, mimetype, body}
select {
case epub.ChanImages <- img:
// OK
case <-time.After(30 * time.Second):
log.Printf("Timeout for %s", filename)
}
}
func (epub *Epub) toHtml(node xml.Node) string {
// Remove some actions buttons/links
xpath := Css2xpath(".actions, a.close, a.anchor, a.parent, .datePourCss, figure.score, meta")
actions, err := node.Search(xpath)
if err == nil {
for _, action := range actions {
action.Remove()
}
}
// Remove itemprop attributes
itemtype := node.Attribute("itemtype")
if itemtype != nil {
itemtype.Remove()
}
itemscope := node.Attribute("itemscope")
if itemscope != nil {
itemscope.Remove()
}
xpath = Css2xpath("[itemprop]")
props, err := node.Search(xpath)
if err == nil {
for _, prop := range props {
attr := prop.Attribute("itemprop")
if attr != nil {
attr.Remove()
}
}
}
// Fix relative links
xpath = Css2xpath("a")
links, err := node.Search(xpath)
if err == nil {
for _, link := range links {
href := link.Attr("href")
if len(href) > 2 && href[0] == '/' {
if href[1] == '/' {
link.SetAttr("href", "https:"+href)
} else {
link.SetAttr("href", "https://"+Host+href)
}
}
}
}
// Import images
xpath = Css2xpath("img")
imgs, err := node.Search(xpath)
if err == nil {
for _, img := range imgs {
uri, err := url.Parse(img.Attr("src"))
if uri.Scheme == "data" {
continue
}
if err == nil {
found := false
for _, s := range epub.Images {
if s == uri.Path {
found = true
}
}
filename := strings.Replace(uri.Path, "/", "", -1)
if len(filename) > 64 {
hashpart := sha256.Sum224([]byte(uri.String()))
filename = hex.EncodeToString(hashpart[:]) + path.Ext(filename)
}
if !found {
go epub.importImage(uri, filename)
epub.Images = append(epub.Images, uri.Path)
}
img.SetAttr("src", filename)
}
}
}
flags := xml.XML_SAVE_AS_HTML | xml.XML_SAVE_FORMAT | xml.XML_SAVE_XHTML
b, size := node.SerializeWithFormat(flags, nil, nil)
if b == nil {
return ""
}
return string(b[:size])
}
func (epub *Epub) AddContent(article xml.Node) {
html := HeaderHtml +
epub.toHtml(article) +
FooterHtml
filename := "content.xhtml"
epub.Items = append(epub.Items, Item{"item-content", filename, "application/xhtml+xml", true})
err := epub.AddFile("EPUB/"+filename, []byte(html))
if (err != nil) {
log.Print("Error: ", err)
}
}
func (epub *Epub) AddComments(article xml.Node) {
list := article.NextSibling()
xpath := Css2xpath(".threads>li")
threads, err := list.Search(xpath)
if err != nil {
return
}
for _, thread := range threads {
html := HeaderHtml +
`<ul class="threads">` +
epub.toHtml(thread) +
`</ul>` +
FooterHtml
id := thread.Attr("id")
filename := id + ".html"
epub.Items = append(epub.Items, Item{id, filename, "application/xhtml+xml", true})
err := epub.AddFile("EPUB/"+filename, []byte(html))
if (err != nil) {
log.Print("Error: ", err)
}
}
}
func (epub *Epub) FindMeta(article xml.Node, selector string) string {
xpath := Css2xpath(selector)
nodes, err := article.Search(xpath)
if err != nil || len(nodes) == 0 {
return ""
}
return nodes[0].Content()
}
func (epub *Epub) FindMetas(article xml.Node, selector string) []string {
xpath := Css2xpath(selector)
nodes, err := article.Search(xpath)
if err != nil {
return nil
}
metas := make([]string, len(nodes))
for i, node := range nodes {
metas[i] = node.Content()
}
return metas
}
func (epub *Epub) FindCover(article xml.Node) string {
root := article.MyDocument().Root()
xpath := "//style"
nodes, err := root.Search(xpath)
if err != nil || len(nodes) == 0 {
return ""
}
var re = regexp.MustCompile(`^.*url\((.*)\).*$`)
imgpath := re.ReplaceAllString(nodes[0].Content(), `$1`)
filename := strings.Replace(imgpath, "/", "", -1)
go epub.importImage(&url.URL{Host: Host, Path: imgpath}, filename)
epub.Images = append(epub.Images, imgpath)
return filename
}
func (epub *Epub) FillMeta(article xml.Node) {
epub.Title = epub.FindMeta(article, "header h1 a:last-child")
epub.Subject = epub.FindMeta(article, "header h1 a.topic")
meta := epub.FindMeta(article, "header time.updated")
loc, _ := time.LoadLocation("Europe/Paris")
date, err := time.ParseInLocation("le 02/01/06 à 15:04", meta, loc)
if err != nil {
date = time.Now()
}
epub.Date = date.Format("2006-01-02T15:04:05Z")
epub.Cover = epub.FindCover(article)
epub.Creator = epub.FindMeta(article, "header .meta a[rel=\"author\"]")
epub.Contributors = epub.FindMetas(article, "header .meta .edited_by a")
}
func (epub *Epub) AddMimetype() (err error) {
header := &zip.FileHeader{Name: "mimetype", Method: zip.Store}
f, err := epub.Zip.CreateHeader(header)
if err != nil {
log.Print("Zip error: ", err)
return
}
_, err = f.Write([]byte(ContentType))
if err != nil {
log.Print("Zip error: ", err)
return
}
return
}
func (epub *Epub) AddDir(dirname string) error {
_, err := epub.Zip.Create(dirname + "/")
if err != nil {
log.Print("Zip error: ", err)
}
return err
}
func (epub *Epub) AddFile(filename string, content []byte) (err error) {
f, err := epub.Zip.Create(filename)
if err != nil {
log.Print("Zip error: ", err)
return
}
_, err = f.Write(content)
if err != nil {
log.Print("Zip error: ", err)
return
}
return
}
func (epub *Epub) Close() {
for i := 0; i < len(epub.Images); i++ {
image := <-epub.ChanImages
if image != nil {
err := epub.AddFile("EPUB/"+image.Filename, image.Content)
if (err != nil) {
log.Print("Error: ", err)
} else if image.Filename != epub.Cover {
id := fmt.Sprintf("img-%d", i)
item := Item{id, image.Filename, image.Mimetype, false}
epub.Items = append(epub.Items, item)
}
}
}
var opf bytes.Buffer
err := PackageTemplate.Execute(&opf, epub)
if err != nil {
log.Print("Template error: ", err)
return
}
err = epub.AddFile("EPUB/package.opf", []byte(XmlDeclaration+opf.String()))
if (err != nil) {
log.Print("Error: ", err)
}
err = epub.Zip.Close()
if err != nil {
log.Print("Error on closing zip: ", err)
}
epub.Zip = nil
}
func FetchArticle(uri string) (article xml.Node, err error) {
log.Printf("Fetch %s", uri)
resp, err := http.Get(uri)
if err != nil {
return
}
body, err := io.ReadAll(resp.Body)
resp.Body.Close()
if err != nil {
log.Printf("Error on io.ReadAll for %s: %s\n", uri, err)
return
}
doc, err := gokogiri.ParseHtml(body)
if err != nil {
log.Printf("Gokogiri error: %s\n", err)
return
}
if doc.Root() == nil {
log.Printf("No root found in the page\n")
return
}
xpath := Css2xpath("#contents article")
articles, err := doc.Root().Search(xpath)
if err != nil {
log.Printf("Gokogiri error: %s\n", err)
return
}
if len(articles) == 0 {
err = errors.New("No article found in the page")
return
}
article = articles[0]
return
}
func Content(w http.ResponseWriter, r *http.Request) {
uri := "https://" + Host + strings.Replace(r.URL.Path, ".epub", "", 1)
if strings.HasPrefix(r.URL.Path, "/sondages") {
uri += "?results=1"
}
article, err := FetchArticle(uri)
if err != nil || article == nil {
http.NotFound(w, r)
return
}
w.Header().Add("Content-Type", ContentType)
w.Header().Add("Link", fmt.Sprintf("<%s>; rel=\"canonical\"", uri))
epub := NewEpub(w, r.URL.Path)
epub.FillMeta(article)
epub.AddContent(article)
epub.AddComments(article)
epub.Close()
article.MyDocument().Free()
}
// Returns 200 OK if the server is running (for monitoring)
func Status(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "OK")
}
func main() {
runtime.GOMAXPROCS(runtime.NumCPU())
runtime.MemProfileRate = 1
selector2xpath = make(map[string]string)
// Parse the command-line
var addr string
var logs string
flag.StringVar(&addr, "a", "127.0.0.1:9000", "Bind to this address:port")
flag.StringVar(&logs, "l", "-", "Use this file for logs")
flag.StringVar(&Host, "H", "linuxfr.org", "Use this host to fetch pages")
flag.Parse()
// Logging
if logs != "-" {
f, err := os.OpenFile(logs, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0644)
if err != nil {
log.Fatal("OpenFile: ", err)
}
err = syscall.Dup2(int(f.Fd()), int(os.Stdout.Fd()))
if err != nil {
log.Fatal("Dup2 (stdout): ", err)
}
err = syscall.Dup2(int(f.Fd()), int(os.Stderr.Fd()))
if err != nil {
log.Fatal("Dup2 (stderr): ", err)
}
}
// Routing
m := pat.New()
m.Get("/status", http.HandlerFunc(Status))
m.Get("/news/:slug.epub", http.HandlerFunc(Content))
m.Get("/users/:user/journaux/:slug.epub", http.HandlerFunc(Content))
m.Get("/forums/:forum/posts/:slug.epub", http.HandlerFunc(Content))
m.Get("/sondages/:slug.epub", http.HandlerFunc(Content))
m.Get("/suivi/:slug.epub", http.HandlerFunc(Content))
m.Get("/wiki/:slug.epub", http.HandlerFunc(Content))
http.Handle("/", m)
// Start the HTTP server
log.Printf("Listening on http://%s/\n", addr)
server := &http.Server{
Addr: addr,
ReadTimeout: 30 * time.Second,
WriteTimeout: 30 * time.Second,
}
err := server.ListenAndServe()
if err != nil {
log.Fatal("ListenAndServe: ", err)
}
}