// Package markdown is middleware to render markdown files as HTML
// on-the-fly.
package markdown
import (
"bytes"
"io/ioutil"
"net/http"
"path"
"strings"
"github.com/mholt/caddy/middleware"
"github.com/russross/blackfriday"
)
// New creates a new instance of Markdown middleware that
// renders markdown to HTML on-the-fly.
func New(c middleware.Controller) (middleware.Middleware, error) {
md, err := parse(c)
if err != nil {
return nil, err
}
md.Root = c.Root()
md.Renderer = blackfriday.HtmlRenderer(0, "", "")
return func(next http.HandlerFunc) http.HandlerFunc {
md.Next = next
return md.ServeHTTP
}, nil
}
// Markdown stores the configuration necessary to serve the Markdown middleware.
type Markdown struct {
// Server root
Root string
// Next HTTP handler in the chain
Next http.HandlerFunc
// Markdown renderer
Renderer blackfriday.Renderer
// Base path to match
PathScope string
// List of extensions to consider as markdown files
Extensions []string
// List of style sheets to load for each markdown file
Styles []string
// List of JavaScript files to load for each markdown file
Scripts []string
}
// ServeHTTP implements the http.Handler interface.
func (m Markdown) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if middleware.Path(r.URL.Path).Matches(m.PathScope) {
for _, ext := range m.Extensions {
if strings.HasSuffix(r.URL.Path, ext) {
fpath := m.Root + r.URL.Path
body, err := ioutil.ReadFile(fpath)
if err != nil {
panic(err) // TODO
}
content := blackfriday.Markdown(body, m.Renderer, 0)
var scripts, styles string
for _, style := range m.Styles {
styles += strings.Replace(cssTemplate, "{{url}}", style, 1) + "\r\n"
}
for _, script := range m.Scripts {
scripts += strings.Replace(jsTemplate, "{{url}}", script, 1) + "\r\n"
}
// Title is first line (length-limited), otherwise filename
title := path.Base(fpath)
newline := bytes.Index(body, []byte("\n"))
if newline > -1 {
firstline := body[:newline]
newTitle := strings.TrimSpace(string(firstline))
if len(newTitle) > 1 {
if len(newTitle) > 128 {
title = newTitle[:128]
} else {
title = newTitle
}
}
}
html := htmlTemplate
html = strings.Replace(html, "{{title}}", title, 1)
html = strings.Replace(html, "{{css}}", styles, 1)
html = strings.Replace(html, "{{js}}", scripts, 1)
html = strings.Replace(html, "{{body}}", string(content), 1)
w.Write([]byte(html))
return
}
}
}
// Didn't qualify to serve as markdown; pass-thru
m.Next(w, r)
}
// parse fills up a new instance of Markdown middleware.
func parse(c middleware.Controller) (Markdown, error) {
var md Markdown
for c.Next() {
// Get the path scope
if !c.NextArg() {
return md, c.ArgErr()
}
md.PathScope = c.Val()
// Load any other configuration parameters
for c.NextBlock() {
switch c.Val() {
case "ext":
exts := c.RemainingArgs()
if len(exts) == 0 {
return md, c.ArgErr()
}
md.Extensions = append(md.Extensions, exts...)
case "css":
if !c.NextArg() {
return md, c.ArgErr()
}
md.Styles = append(md.Styles, c.Val())
case "js":
if !c.NextArg() {
return md, c.ArgErr()
}
md.Scripts = append(md.Scripts, c.Val())
default:
return md, c.Err("Expected valid markdown configuration property")
}
}
}
return md, nil
}
const (
htmlTemplate = `
{{title}}
{{css}}
{{js}}
{{body}}
`
cssTemplate = ``
jsTemplate = ``
)