1 files changed, 22 insertions, 1 deletions
diff --git a/packages/taler-util/src/time.ts b/packages/taler-util/src/time.ts
index c677d52ae..5702b2947 100644
--- a/packages/taler-util/src/time.ts
+++ b/packages/taler-util/src/time.ts
@@ -21,7 +21,7 @@
 /**
  * Imports.
  */
-import { Codec, renderContext, Context } from "./codec.js";
+import { Codec, Context, renderContext } from "./codec.js";
 
 declare const flavor_AbsoluteTime: unique symbol;
 declare const flavor_TalerProtocolTimestamp: unique symbol;
@@ -412,6 +412,10 @@ export namespace AbsoluteTime {
     return cmp(t, now()) <= 0;
   }
 
+  export function isNever(t: AbsoluteTime): boolean {
+    return t.t_ms === "never";
+  }
+
   export function fromProtocolTimestamp(
     t: TalerProtocolTimestamp,
   ): AbsoluteTime {
@@ -503,6 +507,23 @@ export namespace AbsoluteTime {
     return { t_ms: t1.t_ms + d.d_ms, [opaque_AbsoluteTime]: true };
   }
 
+  /**
+   * Get the remaining duration until {@param t1}.
+   *
+   * If {@param t1} already happened, the remaining duration
+   * is zero.
+   */
+  export function remaining(t1: AbsoluteTime): Duration {
+    if (t1.t_ms === "never") {
+      return Duration.getForever();
+    }
+    const stampNow = now();
+    if (stampNow.t_ms === "never") {
+      throw Error("invariant violated");
+    }
+    return Duration.fromMilliseconds(Math.max(0, t1.t_ms - stampNow.t_ms));
+  }
+
   export function subtractDuraction(
     t1: AbsoluteTime,
     d: Duration,