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main.go
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main.go
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package main
import (
"bytes"
"flag"
"fmt"
"io/ioutil"
"log"
"net/http"
"os"
"path"
"path/filepath"
"strings"
"time"
"github.com/fsnotify/fsnotify"
)
var folderToWatch, indexPage string
var port int
var messageChannels = make(map[chan []byte]bool)
var quit = make(chan bool)
var isRoutineOpen = false
const jsFile = "35b96a650c2fbb93d23dd81116b561b8.js"
func main() {
flag.IntVar(&port, "p", 8003, "port to serve")
flag.StringVar(&indexPage, "i", "index.html", "index page to render on /")
flag.StringVar(&folderToWatch, "f", ".", "folder to watch (default: current)")
flag.Parse()
var err error
err = serve()
if err != nil {
log.Println(err)
}
}
func serve() (err error) {
go watchFileSystem()
fmt.Println("listening on :", port)
http.HandleFunc("/", handler)
http.HandleFunc("/sse", handleSSE)
return http.ListenAndServe(fmt.Sprintf(":%d", port), nil)
}
func handler(w http.ResponseWriter, r *http.Request) {
if r.URL.Path == "/"+jsFile {
w.Write([]byte(js))
return
}
if r.URL.Path == "/" {
r.URL.Path = "/" + indexPage
}
ext := filepath.Ext(r.URL.Path)
var b []byte
b, err := ioutil.ReadFile(path.Join(folderToWatch, path.Clean(r.URL.Path[1:])))
if err != nil {
log.Println("could not find file")
return
}
if ext == ".css" {
w.Header().Set("Content-Type", "text/css")
}
if ext == ".html" {
b = bytes.Replace(b,
[]byte("</body>"),
[]byte(fmt.Sprintf(`<script src="/%s"></script></body>`, jsFile)),
1,
)
}
w.Write(b)
}
func watchFileSystem() (err error) {
watcher, err := fsnotify.NewWatcher()
if err != nil {
return err
}
defer watcher.Close()
lastEvent := time.Now()
done := make(chan bool)
go func() {
for {
select {
case event, ok := <-watcher.Events:
if !ok {
return
}
_, fname := filepath.Split(event.Name)
if time.Since(lastEvent).Nanoseconds() > (50*time.Millisecond).Nanoseconds() && !strings.HasPrefix(fname, ".") && !strings.HasSuffix(fname, "~") {
lastEvent = time.Now()
go func() {
for messageChannel := range messageChannels {
messageChannel <- []byte("")
}
}()
}
}
}
}()
filepath.Walk(folderToWatch, func(path string, fi os.FileInfo, err error) error {
if fi.Mode().IsDir() {
return watcher.Add(path)
}
return nil
})
<-done
return
}
func handleSSE(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Connection", "keep-alive")
w.Header().Set("Content-Type", "text/event-stream")
w.Header().Set("Access-Control-Allow-Origin", "*")
_messageChannel := make(chan []byte)
messageChannels[_messageChannel] = true
if isRoutineOpen {
quit <- true
isRoutineOpen = false
}
for {
select {
case <-_messageChannel:
w.Write([]byte("data: change\n\n"))
w.(http.Flusher).Flush()
case <-r.Context().Done():
delete(messageChannels, _messageChannel)
if len(messageChannels) == 0 {
go checkIdle()
isRoutineOpen = true
}
return
}
}
}
func checkIdle() {
select {
case <-quit:
return
case <-time.Tick(time.Second * 3):
os.Exit(3)
}
}
const js = `// scroll saving
var cookieName = "page_scroll";
var expdays = 365;
// An adaptation of Dorcht's cookie functions.
function setCookie(name, value, expires, path, domain, secure) {
if (!expires) expires = new Date();
document.cookie = name + "=" + escape(value) +
((expires == null) ? "" : "; expires=" + expires.toGMTString()) +
((path == null) ? "" : "; path=" + path) +
((domain == null) ? "" : "; domain=" + domain) +
((secure == null) ? "" : "; secure");
}
function getCookie(name) {
var arg = name + "=";
var alen = arg.length;
var clen = document.cookie.length;
var i = 0;
while (i < clen) {
var j = i + alen;
if (document.cookie.substring(i, j) == arg) {
return getCookieVal(j);
}
i = document.cookie.indexOf(" ", i) + 1;
if (i == 0) break;
}
return null;
}
function getCookieVal(offset) {
var endstr = document.cookie.indexOf(";", offset);
if (endstr == -1) endstr = document.cookie.length;
return unescape(document.cookie.substring(offset, endstr));
}
function deleteCookie(name, path, domain) {
document.cookie = name + "=" +
((path == null) ? "" : "; path=" + path) +
((domain == null) ? "" : "; domain=" + domain) +
"; expires=Thu, 01-Jan-00 00:00:01 GMT";
}
function saveScroll() {
var expdate = new Date();
expdate.setTime(expdate.getTime() + (expdays*24*60*60*1000)); // expiry date
var x = document.pageXOffset || document.body.scrollLeft || window.scrollX;
var y = document.pageYOffset || document.body.scrollTop || window.scrollY;
var data = x + "_" + y;
setCookie(cookieName, data, expdate);
}
function loadScroll() {
var inf = getCookie(cookieName);
if (!inf) { return; }
var ar = inf.split("_");
if (ar.length == 2) {
window.scrollTo(parseInt(ar[0]), parseInt(ar[1]));
}
}
document.addEventListener("DOMContentLoaded", function() {
loadScroll();
});
window.addEventListener("beforeunload", function (event) {
saveScroll();
});
// sse
var eventListener = new EventSource(window.origin + '/sse')
eventListener.onmessage = (event) => {
location.reload();
}
`