Add SmartRedirectSlashes to http/middleware

http/middleware/chi.go

@@ -0,0 +1,59 @@
+package middleware
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+)
+
+// SmartRedirectSlashes is a middleware that matches the request path with
+// patterns added to the router and redirects it.
+//
+// If a pattern is added to the router with a trailing slash, any matches on
+// that pattern without a trailing slash will be redirected to the version with
+// the slash. If a pattern does not have a trailing slash, matches on that
+// pattern with a trailing slash will be redirected to the version without.
+//
+// This middleware depends on chi, so it needs to be mounted on chi's router.
+// It make the router behavior similar to httptreemux.
+func SmartRedirectSlashes(next http.Handler) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		rctx := chi.RouteContext(r.Context())
+		if rctx != nil {
+			var path string
+			if rctx.RoutePath != "" {
+				path = rctx.RoutePath
+			} else {
+				path = r.URL.Path
+			}
+			var method string
+			if rctx.RouteMethod != "" {
+				method = rctx.RouteMethod
+			} else {
+				method = r.Method
+			}
+			if len(path) > 1 {
+				if rctx.Routes != nil {
+					if !rctx.Routes.Match(chi.NewRouteContext(), method, path) {
+						if path[len(path)-1] == '/' {
+							path = path[:len(path)-1]
+						} else {
+							path += "/"
+						}
+						if rctx.Routes.Match(chi.NewRouteContext(), method, path) {
+							if r.URL.RawQuery != "" {
+								path = fmt.Sprintf("%s?%s", path, r.URL.RawQuery)
+							}
+							redirectURL := fmt.Sprintf("//%s%s", r.Host, path)
+							http.Redirect(w, r, redirectURL, http.StatusMovedPermanently)
+							return
+						}
+					}
+				}
+			}
+		}
+		next.ServeHTTP(w, r)
+	}
+	return http.HandlerFunc(fn)
+}

http/middleware/chi_test.go

@@ -0,0 +1,58 @@
+package middleware
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	goahttp "goa.design/goa/v3/http"
+)
+
+func TestSmartRedirectSlashes(t *testing.T) {
+	cases := []struct {
+		Pattern  string
+		URL      string
+		Status   int
+		Location string
+	}{
+		{"/users", "/users", http.StatusOK, ""},
+		{"/users", "/users/", http.StatusMovedPermanently, "/users"},
+		{"/users/", "/users/", http.StatusOK, ""},
+		{"/users/", "/users", http.StatusMovedPermanently, "/users/"},
+		{"/users/{id}", "/users/123", http.StatusOK, ""},
+		{"/users/{id}", "/users/123/", http.StatusMovedPermanently, "/users/123"},
+		{"/users/{id}/", "/users/123/", http.StatusOK, ""},
+		{"/users/{id}/", "/users/123", http.StatusMovedPermanently, "/users/123/"},
+		{"/users/{id}/posts/{post_id}", "/users/123/posts/456", http.StatusOK, ""},
+		{"/users/{id}/posts/{post_id}", "/users/123/posts/456/", http.StatusMovedPermanently, "/users/123/posts/456"},
+		{"/users/{id}/posts/{post_id}/", "/users/123/posts/456/", http.StatusOK, ""},
+		{"/users/{id}/posts/{post_id}/", "/users/123/posts/456", http.StatusMovedPermanently, "/users/123/posts/456/"},
+		{"/users/{id}/posts/{*post_id}", "/users/123/posts/456/789", http.StatusOK, ""},
+		{"/users/{id}/posts/{*post_id}", "/users/123/posts/456/789/", http.StatusOK, ""},
+		{"/users", "/users?name=foo", http.StatusOK, ""},
+		{"/users", "/users/?name=foo", http.StatusMovedPermanently, "/users?name=foo"},
+		{"/users/", "/users/?name=foo", http.StatusOK, ""},
+		{"/users/", "/users?name=foo", http.StatusMovedPermanently, "/users/?name=foo"},
+	}
+
+	for _, c := range cases {
+		t.Run(c.Pattern, func(t *testing.T) {
+			var called bool
+			mux := goahttp.NewMuxer()
+			mux.Use(SmartRedirectSlashes)
+			handler := http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
+				called = true
+			})
+			mux.Handle("GET", c.Pattern, handler)
+			req, _ := http.NewRequest("GET", c.URL, nil)
+			w := httptest.NewRecorder()
+			mux.ServeHTTP(w, req)
+			assert.Equal(t, c.Status, w.Code)
+			assert.Equal(t, w.Code == http.StatusOK, called)
+			if w.Code == http.StatusMovedPermanently {
+				assert.Equal(t, c.Location, w.Header().Get("Location"))
+			}
+		})
+	}
+}