Implement Last-Modified caching

server/serve_files.go

@@ -0,0 +1,89 @@
+package server
+
+import (
+	"bytes"
+	"compress/gzip"
+	"io/ioutil"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var files = []File{
+	File{"bundle.js", "text/javascript"},
+	File{"bundle.css", "text/css"},
+	File{"font/fontello.woff", "application/font-woff"},
+	File{"font/fontello.ttf", "application/x-font-ttf"},
+	File{"font/fontello.eot", "application/vnd.ms-fontobject"},
+	File{"font/fontello.svg", "image/svg+xml"},
+}
+
+type File struct {
+	Path        string
+	ContentType string
+}
+
+func serveFiles(w http.ResponseWriter, r *http.Request) {
+	if r.URL.Path == "/" {
+		serveFile(w, r, "index.html.gz", "text/html")
+		return
+	}
+
+	for _, file := range files {
+		if strings.HasSuffix(r.URL.Path, file.Path) {
+			serveFile(w, r, file.Path+".gz", file.ContentType)
+			return
+		}
+	}
+
+	serveFile(w, r, "index.html.gz", "text/html")
+}
+
+func serveFile(w http.ResponseWriter, r *http.Request, path, contentType string) {
+	info, err := AssetInfo(path)
+	if err != nil {
+		http.Error(w, "", http.StatusInternalServerError)
+		return
+	}
+
+	if !modifiedSince(w, r, info.ModTime()) {
+		return
+	}
+
+	data, err := Asset(path)
+	if err != nil {
+		http.Error(w, "", http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("Content-Type", contentType)
+
+	if strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+		w.Header().Set("Content-Encoding", "gzip")
+		w.Header().Set("Content-Length", strconv.Itoa(len(data)))
+		w.Write(data)
+	} else {
+		gzr, err := gzip.NewReader(bytes.NewReader(data))
+		buf, err := ioutil.ReadAll(gzr)
+		if err != nil {
+			http.Error(w, "", http.StatusInternalServerError)
+			return
+		}
+
+		w.Header().Set("Content-Length", strconv.Itoa(len(buf)))
+		w.Write(buf)
+	}
+}
+
+func modifiedSince(w http.ResponseWriter, r *http.Request, modtime time.Time) bool {
+	t, err := time.Parse(http.TimeFormat, r.Header.Get("If-Modified-Since"))
+
+	if err == nil && modtime.Before(t.Add(1*time.Second)) {
+		w.WriteHeader(http.StatusNotModified)
+		return false
+	}
+
+	w.Header().Set("Last-Modified", modtime.UTC().Format(http.TimeFormat))
+	return true
+}