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main.go
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main.go
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package main
import (
"flag"
"io/ioutil"
"log"
"net/http"
"os"
"path/filepath"
"sync"
"github.com/fsnotify/fsnotify"
"github.com/pkg/errors"
"github.com/russross/blackfriday/v2"
)
func usage() {
log.Print("usage: mdindicator [markdownfile]")
log.Print("If given no argument, then README.md, if any, is used as a target.")
log.Print()
flag.PrintDefaults()
}
var header = []byte(`<!DOCTYPE html>
<meta charset="utf-8">
<title>mdindicator</title>
<style>
body {
font-family: -apple-system, BlinkMacSystemFont, sans-serif;
font-size: 1rem;
line-height: 1.5;
margin: auto;
width: 80%;
}
pre {
background-color: #f7f7f7;
border-radius: 4px;
padding: 1rem;
}
pre > code {
font-size: 0.66rem;
}
code {
font-family: menlo, monospace;
font-size: 0.9rem;
}
</style>
`)
func main() {
var httpAddr = flag.String("http", ":9999", "HTTP service address")
var verbose = flag.Bool("verbose", false, "set verbose")
log.SetFlags(0)
flag.Usage = usage
flag.Parse()
filename := "README.md"
if n := flag.NArg(); n == 1 {
filename = flag.Arg(0)
} else if n > 1 {
flag.Usage()
os.Exit(1)
} else {
_, err := os.Stat(filename)
if err != nil {
flag.Usage()
os.Exit(1)
}
}
log.Printf("filename: %s", filename)
log.Printf("http://localhost%s", *httpAddr)
if err := serve(*httpAddr, filepath.Clean(filename), *verbose); err != nil {
log.Print(err)
os.Exit(1)
}
}
func serve(addr, name string, verbose bool) error {
if verbose {
log.Printf("starting with %s", name)
}
p := &provider{name: name}
if err := p.convert(); err != nil {
return err
}
errch := make(chan error)
go func() {
err := p.watch(verbose)
if err != nil {
errch <- err
}
}()
http.Handle("/", p)
go func() {
err := http.ListenAndServe(addr, nil)
if err != nil {
errch <- err
}
}()
return <-errch
}
type provider struct {
name string
mu sync.Mutex
html []byte
}
func (p *provider) ServeHTTP(w http.ResponseWriter, r *http.Request) {
w.Write(header)
p.mu.Lock()
w.Write(p.html)
p.mu.Unlock()
}
func (p *provider) convert() error {
input, err := ioutil.ReadFile(p.name)
if err != nil {
return err
}
html := blackfriday.Run(input)
p.mu.Lock()
p.html = html
p.mu.Unlock()
return nil
}
func (p *provider) watch(verbose bool) error {
watcher, err := fsnotify.NewWatcher()
if err != nil {
return err
}
if verbose {
log.Printf("watching %s", filepath.Dir(p.name))
}
if err := watcher.Add(filepath.Dir(p.name)); err != nil {
return err
}
for {
select {
case event := <-watcher.Events:
if filepath.Clean(event.Name) == p.name && event.Op != fsnotify.Rename {
if verbose {
log.Printf("caught event (%s): %v", p.name, event.Op)
}
if err := p.convert(); err != nil {
return err
}
}
case err := <-watcher.Errors:
return errors.Wrap(err, "watcher")
}
}
}