1 files changed, 52 insertions, 0 deletions
diff --git a/packages/taler-wallet-core/src/common.ts b/packages/taler-wallet-core/src/common.ts
index 6d116c47e..edaba5ba4 100644
--- a/packages/taler-wallet-core/src/common.ts
+++ b/packages/taler-wallet-core/src/common.ts
@@ -21,6 +21,7 @@ import {
   AbsoluteTime,
   AmountJson,
   Amounts,
+  AsyncFlag,
   CoinRefreshRequest,
   CoinStatus,
   Duration,
@@ -35,6 +36,7 @@ import {
   TalerProtocolTimestamp,
   TombstoneIdStr,
   TransactionIdStr,
+  WalletNotification,
   assertUnreachable,
   checkDbInvariant,
   checkLogicInvariant,
@@ -769,3 +771,53 @@ export enum PendingTaskType {
 
 declare const __taskIdStr: unique symbol;
 export type TaskIdStr = string & { [__taskIdStr]: true };
+
+/**
+ * Wait until the wallet is in a particular state.
+ *
+ * Two functions must be provided:
+ * 1. checkState, which checks if the wallet is in the
+ *    desired state.
+ * 2. filterNotification, which checks whether a notification
+ *    might have lead to a state change.
+ */
+export async function genericWaitForState(
+  wex: WalletExecutionContext,
+  args: {
+    checkState: () => Promise<boolean>;
+    filterNotification: (notif: WalletNotification) => boolean;
+  },
+): Promise<void> {
+  await wex.taskScheduler.ensureRunning();
+
+  // FIXME: Clean up using the new JS "using" / Symbol.dispose syntax.
+  const flag = new AsyncFlag();
+  // Raise purchaseNotifFlag whenever we get a notification
+  // about our refresh.
+  const cancelNotif = wex.ws.addNotificationListener((notif) => {
+    if (args.filterNotification(notif)) {
+      flag.raise();
+    }
+  });
+  const unregisterOnCancelled = wex.cancellationToken.onCancelled(() => {
+    cancelNotif();
+    flag.raise();
+  });
+
+  try {
+    while (true) {
+      if (wex.cancellationToken.isCancelled) {
+        throw Error("cancelled");
+      }
+      if (await args.checkState()) {
+        return;
+      }
+      // Wait for the next transition
+      await flag.wait();
+      flag.reset();
+    }
+  } catch (e) {
+    unregisterOnCancelled();
+    cancelNotif();
+  }
+}