not found page

internal/server/api/templates/router.go

@@ -123,8 +123,7 @@ func (s *webpageRouter) serveTemplate(c *gin.Context) (response.Response, error)
 	r := c.Request
 	ctx := r.Context()
 
-	b, err := s.templater.Execute(
-		strings.Trim(r.URL.Path, "/"),
+	args := []any{
 		"Request",
 		r,
 		// add services and data here
@@ -142,24 +141,36 @@ func (s *webpageRouter) serveTemplate(c *gin.Context) (response.Response, error)
 		middleware.GetIdentity(ctx),
 		"Auth",
 		newTemplateAuthenticator(r),
-	)
+	}
+
+	b, err := s.templater.Execute(strings.Trim(r.URL.Path, "/"), args...)
 	if err != nil {
-		return s.handleTemplateError(err)
+		if isFileNotFoundError(err) || isInvalidWildcardValue(err) {
+			werr := response.NotFound().
+				Wrap(ErrTemplateNotFound{
+					err: err,
+				}).
+				Msg("resource not found")
+
+			nfb, nferr := s.templater.Execute("not-found", args...)
+			if nferr != nil {
+				s.log.Error("failed to render not-found page: %v", nferr)
+				return nil, werr
+			}
+
+			return nil, werr.
+				HTML(nfb)
+		}
+
+		return nil, err
 	}
 
 	return response.HTML(b), nil
 }
 
-func (s *webpageRouter) handleTemplateError(err error) (response.Response, error) {
-	if isFileNotFoundError(err) {
-		return nil, response.NotFound().
-			Wrap(ErrTemplateNotFound{
-				err: err,
-			}).
-			Msg("resource not found")
-	}
-
-	return nil, err
+func isInvalidWildcardValue(err error) bool {
+	var te *templater.ErrInvalidWildcardValue
+	return errors.As(err, &te)
 }
 
 func isFileNotFoundError(err error) bool {

internal/server/response/error.go

@@ -14,6 +14,7 @@ type (
 		err    error
 		msg    string
 		status int
+		html   []byte
 	}
 )
 
@@ -77,6 +78,11 @@ func (e ErrorResponse) Wrap(err error) ErrorResponse {
 	return e
 }
 
+func (e ErrorResponse) HTML(h []byte) ErrorResponse {
+	e.html = h
+	return e
+}
+
 // error implementation
 
 func (e ErrorResponse) Error() string {
@@ -130,6 +136,19 @@ func (e ErrorResponse) GetMsg() (string, bool) {
 	return "", false
 }
 
+func (e ErrorResponse) GetHTML() ([]byte, bool) {
+	if len(e.html) != 0 {
+		return e.html, true
+	}
+
+	ce, ok := GetError(e.err)
+	if ok {
+		return ce.GetHTML()
+	}
+
+	return nil, false
+}
+
 func GetError(err error) (e ErrorResponse, ok bool) {
 	ok = errors.As(err, &e)
 	return e, ok

internal/server/response/write.go

@@ -52,7 +52,14 @@ func Write(c *gin.Context, res Response) {
 }
 
 func WriteError(c *gin.Context, err error) {
-	c.String(GetStatusFromError(err), err.Error())
+	status := GetStatusFromError(err)
+	if h, ok := GetHTMLFromError(err); ok {
+		c.Status(status)
+		c.Header("Content-Type", "text/html")
+		c.Writer.Write(h)
+	} else {
+		c.String(status, err.Error())
+	}
 }
 
 func GetStatusFromError(err error) int {
@@ -66,3 +73,12 @@ func GetStatusFromError(err error) int {
 
 	return status
 }
+
+func GetHTMLFromError(err error) ([]byte, bool) {
+	e, ok := GetError(err)
+	if !ok {
+		return nil, false
+	}
+
+	return e.GetHTML()
+}