fix: for one-time access tokens and signup tokens, pass TTLs instead of absolute expiration date (#855)

backend/internal/utils/json_util.go

@@ -0,0 +1,42 @@
+package utils
+
+import (
+	"encoding/json"
+	"errors"
+	"time"
+)
+
+// JSONDuration is a type that allows marshalling/unmarshalling a Duration
+type JSONDuration struct {
+	time.Duration
+}
+
+func (d JSONDuration) MarshalJSON() ([]byte, error) {
+	return json.Marshal(d.String())
+}
+
+func (d *JSONDuration) UnmarshalJSON(b []byte) error {
+	var v any
+	err := json.Unmarshal(b, &v)
+	if err != nil {
+		return err
+	}
+	switch value := v.(type) {
+	case float64:
+		// If the value is a number, interpret it as a number of seconds
+		d.Duration = time.Duration(value) * time.Second
+		return nil
+	case string:
+		if v == "" {
+			return nil
+		}
+		var err error
+		d.Duration, err = time.ParseDuration(value)
+		if err != nil {
+			return err
+		}
+		return nil
+	default:
+		return errors.New("invalid duration")
+	}
+}