Centralise and use ValidateColorFilter across API, CLI, and library

Author: ashthespy

cmd/api.go

@@ -66,14 +66,9 @@ func renderHandler(w http.ResponseWriter, req *http.Request) {
 	}
 
 	// Default to "none" if color_filter is missing
-	filterType := encode.ColorFilterType(r.ColorFilter)
-	if r.ColorFilter == "" {
-		filterType = encode.ColorNone
-	} else if !filterType.IsValid() {
-		http.Error(w, fmt.Sprintf("invalid color filter: %q\nSupported filters: %s",
-			r.ColorFilter,
-			strings.Join(encode.SupportedColorFilters(), ", "),
-		), http.StatusBadRequest)
+	filterType, err := encode.ValidateColorFilter(encode.ColorFilterType(r.ColorFilter))
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}
 

cmd/render.go

@@ -172,14 +172,9 @@ func render(cmd *cobra.Command, args []string) error {
 	runtime.InitHTTP(cache)
 	runtime.InitCache(cache)
 
-	filterType := encode.ColorFilterType(colorFilter)
-	if colorFilter == "" {
-		filterType = encode.ColorNone
-	} else if !filterType.IsValid() {
-		return fmt.Errorf("invalid color filter: %q\nSupported filters: %s",
-			colorFilter,
-			strings.Join(encode.SupportedColorFilters(), ", "),
-		)
+	filterType, err := encode.ValidateColorFilter(encode.ColorFilterType(colorFilter))
+	if err != nil {
+		return err
 	}
 
 	filters := &encode.RenderFilters{

encode/filter.go

@@ -148,12 +148,23 @@ func (f *ColorFilterType) UnmarshalJSON(b []byte) error {
 		return err
 	}
 	*f = ColorFilterType(s)
-	if !f.IsValid() {
-		return fmt.Errorf("invalid color filter: %q:\nSupported filters: %s", s, strings.Join(SupportedColorFilters(), ", "))
-	}
 	return nil
 }
 
+func ValidateColorFilter(input ColorFilterType) (ColorFilterType, error) {
+	if input == "" {
+		return ColorNone, nil
+	}
+	filterType := ColorFilterType(input)
+	if !filterType.IsValid() {
+		return "", fmt.Errorf("invalid color filter: %q\nSupported filters: %s",
+			input,
+			strings.Join(SupportedColorFilters(), ", "),
+		)
+	}
+	return filterType, nil
+}
+
 func FromFilterType(f ColorFilterType) (ImageFilter, error) {
 	if f == ColorNone {
 		return nil, nil // explicit noop skip

library/library.go

@@ -60,11 +60,8 @@ func render_app(pathPtr *C.char, configPtr *C.char, width, height, magnify, maxD
 		if err := json.Unmarshal([]byte(filtersStr), &parsed); err != nil {
 			return nil, -3, nil, C.CString(fmt.Sprintf("invalid filters JSON: %v", err))
 		}
-		if parsed.ColorFilter != "" && !encode.ColorFilterType(parsed.ColorFilter).IsValid() {
-			return nil, -4, nil, C.CString(fmt.Sprintf("invalid color filter: %q\nSupported filters: %s",
-				parsed.ColorFilter,
-				strings.Join(encode.SupportedColorFilters(), ", "),
-			))
+		if _, err := encode.ValidateColorFilter(parsed.ColorFilter); err != nil {
+			return nil, -4, nil, C.CString(err.Error())
 		}
 		filters = &parsed
 	}