From e47cb5f0e462c200834cada0b6e258bb88f5c4f4 Mon Sep 17 00:00:00 2001
From: khlieng <kk_998@hotmail.com>
Date: Sat, 16 May 2015 01:18:52 +0200
Subject: [PATCH] Implement Last-Modified caching

---
 server/serve_files.go | 89 +++++++++++++++++++++++++++++++++++++++++++
 server/server.go      | 51 -------------------------
 2 files changed, 89 insertions(+), 51 deletions(-)
 create mode 100644 server/serve_files.go

diff --git a/server/serve_files.go b/server/serve_files.go
new file mode 100644
index 00000000..29d41666
--- /dev/null
+++ b/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
+}
diff --git a/server/server.go b/server/server.go
index 5079e9b3..1735ad49 100644
--- a/server/server.go
+++ b/server/server.go
@@ -1,13 +1,9 @@
 package server
 
 import (
-	"bytes"
-	"compress/gzip"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"strconv"
-	"strings"
 	"sync"
 
 	"github.com/khlieng/name_pending/Godeps/_workspace/src/github.com/gorilla/websocket"
@@ -21,15 +17,6 @@ var (
 	sessions     map[string]*Session
 	sessionLock  sync.Mutex
 
-	files = []File{
-		File{"bundle.js", "text/javascript"},
-		File{"bundle.css", "text/css"},
-		File{"font/fontello.eot", "application/vnd.ms-fontobject"},
-		File{"font/fontello.svg", "image/svg+xml"},
-		File{"font/fontello.ttf", "application/x-font-ttf"},
-		File{"font/fontello.woff", "application/font-woff"},
-	}
-
 	upgrader = websocket.Upgrader{
 		ReadBufferSize:  1024,
 		WriteBufferSize: 1024,
@@ -39,11 +26,6 @@ var (
 	}
 )
 
-type File struct {
-	Path        string
-	ContentType string
-}
-
 func Run(port int) {
 	defer storage.Close()
 
@@ -71,39 +53,6 @@ func upgradeWS(w http.ResponseWriter, r *http.Request) {
 	handleWS(conn)
 }
 
-func serveFiles(w http.ResponseWriter, r *http.Request) {
-	if r.URL.Path == "/" {
-		serveFile("index.html.gz", "text/html", w, r)
-		return
-	}
-
-	for _, file := range files {
-		if strings.HasSuffix(r.URL.Path, file.Path) {
-			serveFile(file.Path+".gz", file.ContentType, w, r)
-			return
-		}
-	}
-
-	serveFile("index.html.gz", "text/html", w, r)
-}
-
-func serveFile(path, contentType string, w http.ResponseWriter, r *http.Request) {
-	data, _ := Asset(path)
-
-	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, _ := gzip.NewReader(bytes.NewReader(data))
-		buf, _ := ioutil.ReadAll(gzr)
-		w.Header().Set("Content-Length", strconv.Itoa(len(buf)))
-		w.Write(buf)
-	}
-}
-
 func reconnect() {
 	for _, user := range storage.LoadUsers() {
 		session := NewSession()