api/types/filters: remove deprecated ToParamWithVersion

It's only used by the client to support API versions older than v1.22.
Make it an internal utility that doesn't depend on internal fields of
`filter.Args`.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

client/utils.go

@@ -81,3 +81,41 @@ func encodePlatform(platform *ocispec.Platform) (string, error) {
 	}
 	return string(p), nil
 }
+
+// encodeLegacyFilters encodes Args in the legacy format as used in API v1.21 and older.
+// where values are a list of strings, instead of a set.
+//
+// Don't use in any new code; use [filters.ToJSON]] instead.
+func encodeLegacyFilters(currentFormat string) (string, error) {
+	// The Args.fields field is not exported, but used to marshal JSON,
+	// so we'll marshal to the new format, then unmarshal to get the
+	// fields, and marshal again.
+	//
+	// This is far from optimal, but this code is only used for deprecated
+	// API versions, so should not be hit commonly.
+	var argsFields map[string]map[string]bool
+	err := json.Unmarshal([]byte(currentFormat), &argsFields)
+	if err != nil {
+		return "", err
+	}
+
+	buf, err := json.Marshal(convertArgsToSlice(argsFields))
+	if err != nil {
+		return "", err
+	}
+	return string(buf), nil
+}
+
+func convertArgsToSlice(f map[string]map[string]bool) map[string][]string {
+	m := map[string][]string{}
+	for k, v := range f {
+		values := []string{}
+		for kk := range v {
+			if v[kk] {
+				values = append(values, kk)
+			}
+		}
+		m[k] = values
+	}
+	return m
+}