1 files changed, 22 insertions, 0 deletions
diff --git a/packages/taler-util/src/payto.ts b/packages/taler-util/src/payto.ts
index dd35b44be..2b0af4cc2 100644
--- a/packages/taler-util/src/payto.ts
+++ b/packages/taler-util/src/payto.ts
@@ -239,3 +239,25 @@ export function parsePaytoUri(s: string): PaytoUri | undefined {
     isKnown: false,
   };
 }
+
+export function talerPaytoFromExchangeReserve(
+  exchangeBaseUrl: string,
+  reservePub: string,
+): string {
+  const url = new URL(exchangeBaseUrl);
+  let proto: string;
+  if (url.protocol === "http:") {
+    proto = "taler-reserve-http";
+  } else if (url.protocol === "https:") {
+    proto = "taler-reserve";
+  } else {
+    throw Error(`unsupported exchange base URL protocol (${url.protocol})`);
+  }
+
+  let path = url.pathname;
+  if (!path.endsWith("/")) {
+    path = path + "/";
+  }
+
+  return `payto://${proto}/${url.host}${url.pathname}${reservePub}`;
+}