Add VersionedAssets middleware (#9)

httph.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"html/template"
 	"net/http"
+	"regexp"
 	"strings"
 
 	"github.com/mitchellh/mapstructure"
@@ -221,3 +222,19 @@ func GoGet(opts GoGetOptions) Middleware {
 		})
 	}
 }
+
+// versionedAssetMatcher matches versioned assets like "app.abc123.js".
+// See https://regex101.com/r/bGfflm/latest
+var versionedAssetMatcher = regexp.MustCompile(`^(?P<name>[^.]+)\.[a-z0-9]+(?P<extension>\.[a-z0-9]+)$`)
+
+// VersionedAssets is Middleware to help serve versioned assets without the version.
+// It basically strips the version from the asset path and forwards the request, probably to a static file handler.
+func VersionedAssets(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if versionedAssetMatcher.MatchString(r.URL.Path) {
+			r.URL.Path = versionedAssetMatcher.ReplaceAllString(r.URL.Path, `$1$2`)
+		}
+
+		next.ServeHTTP(w, r)
+	})
+}

httph_test.go

@@ -211,3 +211,27 @@ func TestGoGet(t *testing.T) {
 		is.True(t, !called)
 	})
 }
+
+func TestVersionedAssets(t *testing.T) {
+	t.Run("removes version from asset path", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "/script.123456.js", nil)
+		res := httptest.NewRecorder()
+
+		h := httph.VersionedAssets(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+		h.ServeHTTP(res, req)
+
+		is.Equal(t, http.StatusOK, res.Result().StatusCode)
+		is.Equal(t, "/script.js", req.URL.Path)
+	})
+
+	t.Run("does not modify path without version", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "/script.js", nil)
+		res := httptest.NewRecorder()
+
+		h := httph.VersionedAssets(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+		h.ServeHTTP(res, req)
+
+		is.Equal(t, http.StatusOK, res.Result().StatusCode)
+		is.Equal(t, "/script.js", req.URL.Path)
+	})
+}