Add a --dev flag to forward requests to node server

static.go

@@ -1,17 +1,49 @@
 package main
 
 import (
+	"io"
 	"net/http"
+	"net/url"
+	"path"
 
 	"github.com/julienschmidt/httprouter"
 )
 
+var DevProxy string
+
 func serveOrReverse(forced_url string) func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
 	return func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
-		if forced_url != "" {
-			r.URL.Path = forced_url
+		if DevProxy != "" {
+			if u, err := url.Parse(DevProxy); err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+			} else {
+				if forced_url != "" {
+					u.Path = path.Join(u.Path, forced_url)
+				} else {
+					u.Path = path.Join(u.Path, r.URL.Path)
+				}
+
+				if r, err := http.NewRequest(r.Method, u.String(), r.Body); err != nil {
+					http.Error(w, err.Error(), http.StatusInternalServerError)
+				} else if resp, err := http.DefaultClient.Do(r); err != nil {
+					http.Error(w, err.Error(), http.StatusBadGateway)
+				} else {
+					defer resp.Body.Close()
+
+					for key := range resp.Header {
+						w.Header().Add(key, resp.Header.Get(key))
+					}
+					w.WriteHeader(resp.StatusCode)
+
+					io.Copy(w, resp.Body)
+				}
+			}
+		} else {
+			if forced_url != "" {
+				r.URL.Path = forced_url
+			}
+			http.FileServer(Assets).ServeHTTP(w, r)
 		}
-		http.FileServer(Assets).ServeHTTP(w, r)
 	}
 }