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gojekyll/plugins/redirect_from.go
2017-08-10 09:07:33 -04:00

126 lines
2.9 KiB
Go

package plugins
import (
"bytes"
"fmt"
"io"
"text/template"
"github.com/osteele/gojekyll/pages"
)
type jekyllRedirectFromPlugin struct{ plugin }
var redirectTemplate *template.Template
func init() {
register("jekyll-redirect-from", jekyllRedirectFromPlugin{})
tmpl, err := template.New("redirect_from").Parse(redirectFromTemplateSource)
if err != nil {
panic(err)
}
redirectTemplate = tmpl
}
func (p jekyllRedirectFromPlugin) PostRead(site Site) error {
ps := site.Pages()
newPages, err := p.processRedirectFrom(site, ps)
if err != nil {
return err
}
if err := p.processRedirectTo(site, ps); err != nil {
return err
}
for _, r := range newPages {
site.AddDocument(r, true)
}
return nil
}
func (p jekyllRedirectFromPlugin) processRedirectFrom(site Site, ps []pages.Page) ([]pages.Document, error) {
var (
cfg = site.Config()
siteurl = cfg.AbsoluteURL
baseurl = cfg.BaseURL
prefix = siteurl + baseurl
redirections = []pages.Document{}
)
addRedirectFrom := func(from string, to pages.Page) {
r := redirectionDoc{pages.PageEmbed{Path: from}, prefix + to.Permalink()}
redirections = append(redirections, &r)
}
for _, p := range ps {
sources, err := getStringArray(p, "redirect_from")
if err != nil {
return nil, err
}
for _, from := range sources {
addRedirectFrom(from, p)
}
}
return redirections, nil
}
func (p jekyllRedirectFromPlugin) processRedirectTo(site Site, ps []pages.Page) error {
for _, p := range ps {
sources, err := getStringArray(p, "redirect_to")
if err != nil {
return err
}
if len(sources) > 0 {
r := redirectionDoc{pages.PageEmbed{Path: p.Permalink()}, sources[0]}
p.SetContent(r.Content())
}
}
return nil
}
func getStringArray(p pages.Page, fieldName string) (out []string, err error) {
if value, ok := p.FrontMatter()[fieldName]; ok {
switch value := value.(type) {
case []string:
out = value
case []interface{}:
out = make([]string, len(value))
for i, item := range value {
out[i] = fmt.Sprintf("%s", item)
}
case string:
out = []string{value}
default:
err = fmt.Errorf("unimplemented redirect_from type %T", value)
}
}
return
}
type redirectionDoc struct {
pages.PageEmbed
To string
}
func (d *redirectionDoc) Content() string {
buf := new(bytes.Buffer)
if err := redirectTemplate.Execute(buf, d); err != nil {
panic(err)
}
return buf.String()
}
func (d *redirectionDoc) Write(w io.Writer) error {
return redirectTemplate.Execute(w, d)
}
// Adapted from https://github.com/jekyll/jekyll-redirect-from
const redirectFromTemplateSource = `<!DOCTYPE html>
<html lang="en-US">
<meta charset="utf-8">
<title>Redirecting…</title>
<link rel="canonical" href="{{.To}}">
<meta http-equiv="refresh" content="0; url={{.To}}">
<meta name="robots" content="noindex">
<h1>Redirecting…</h1>
<a href="{{.To}}">Click here if you are not redirected.</a>
<script>location="{{.To}}"</script>
</html>`