Update server.go: Replace plugins in INITIAL_DATA

Since recently the /config/server/info data is not requested later,
but already inlined in the host page. So the proxy script has to be
adapted to that.

Change-Id: Iba60afbfc0adb1ec6a574219601b64a059153bad

polygerrit-ui/server.go

@@ -103,7 +103,7 @@ func resourceBasePath() (string, error) {
 func handleIndex(writer http.ResponseWriter, originalRequest *http.Request) {
 	fakeRequest := &http.Request{
 		URL: &url.URL{
-			Path: "/",
+			Path:     "/",
 			RawQuery: originalRequest.URL.RawQuery,
 		},
 	}
@@ -170,7 +170,7 @@ func setJsonPropByPath(json map[string]interface{}, path []string, value interfa
 func patchResponse(req *http.Request, res *http.Response) io.Reader {
 	switch req.URL.EscapedPath() {
 	case "/":
-		return replaceCdn(res.Body)
+		return rewriteHostPage(res.Body)
 	case "/config/server/info":
 		return injectLocalPlugins(res.Body)
 	default:
@@ -178,13 +178,39 @@ func patchResponse(req *http.Request, res *http.Response) io.Reader {
 	}
 }
 
-func replaceCdn(reader io.Reader) io.Reader {
+func rewriteHostPage(reader io.Reader) io.Reader {
 	buf := new(bytes.Buffer)
 	buf.ReadFrom(reader)
 	original := buf.String()
 
+	// Simply remove all CDN references, so files are loaded from the local file system  or the proxy
+	// server instead.
 	replaced := cdnPattern.ReplaceAllString(original, "")
 
+	// Modify window.INITIAL_DATA so that it has the same effect as injectLocalPlugins. To achieve
+	// this let's add JavaScript lines at the end of the <script>...</script> snippet that also
+	// contains window.INITIAL_DATA=...
+	// Here we rely on the fact that the <script> snippet that we want to append to is the first one.
+	if len(*plugins) > 0 {
+		insertionPoint := strings.Index(replaced, "</script>")
+		builder := new(strings.Builder)
+		builder.WriteString(
+			"window.INITIAL_DATA['/config/server/info'].plugin.html_resource_paths = []; ")
+		builder.WriteString(
+			"window.INITIAL_DATA['/config/server/info'].plugin.js_resource_paths = []; ")
+		for _, p := range strings.Split(*plugins, ",") {
+			if filepath.Ext(p) == ".html" {
+				builder.WriteString(
+					"window.INITIAL_DATA['/config/server/info'].plugin.html_resource_paths.push('" + p + "'); ")
+			}
+			if filepath.Ext(p) == ".js" {
+				builder.WriteString(
+					"window.INITIAL_DATA['/config/server/info'].plugin.js_resource_paths.push('" + p + "'); ")
+			}
+		}
+		replaced = replaced[:insertionPoint] + builder.String() + replaced[insertionPoint:]
+	}
+
 	return strings.NewReader(replaced)
 }
 
@@ -209,11 +235,11 @@ func injectLocalPlugins(reader io.Reader) io.Reader {
 	jsResources := getJsonPropByPath(response, jsPluginsPath).([]interface{})
 
 	for _, p := range strings.Split(*plugins, ",") {
-		if strings.HasSuffix(p, ".html") {
+		if filepath.Ext(p) == ".html" {
 			htmlResources = append(htmlResources, p)
 		}
 
-		if strings.HasSuffix(p, ".js") {
+		if filepath.Ext(p) == ".js" {
 			jsResources = append(jsResources, p)
 		}
 	}