From dc2361edb3f401731f2099526ed93a6e963ecc45 Mon Sep 17 00:00:00 2001
From: Florian Dold <florian@dold.me>
Date: Mon, 19 Feb 2024 00:09:09 +0100
Subject: improve error message for templates with currency-only amount

---
 packages/taler-util/src/amounts.ts                 | 13 ++++++++---
 packages/taler-util/src/taleruri.ts                |  7 +++++-
 packages/taler-util/src/wallet-types.ts            |  8 +++++--
 .../src/operations/pay-merchant.ts                 | 27 +++++++++++++++-------
 4 files changed, 41 insertions(+), 14 deletions(-)

diff --git a/packages/taler-util/src/amounts.ts b/packages/taler-util/src/amounts.ts
index c3770a393..16774f376 100644
--- a/packages/taler-util/src/amounts.ts
+++ b/packages/taler-util/src/amounts.ts
@@ -22,12 +22,12 @@
  * Imports.
  */
 import {
-  buildCodecForObject,
-  codecForString,
-  codecForNumber,
   Codec,
   Context,
   DecodingError,
+  buildCodecForObject,
+  codecForNumber,
+  codecForString,
   renderContext,
 } from "./codec.js";
 import { CurrencySpecification } from "./index.js";
@@ -368,6 +368,13 @@ export class Amounts {
     return a.value === 0 && a.fraction === 0;
   }
 
+  /**
+   * Check whether a string is a valid currency for a Taler amount.
+   */
+  static isCurrency(s: string): boolean {
+    return /^[a-zA-Z]{1,11}/.test(s);
+  }
+
   /**
    * Parse an amount like 'EUR:20.5' for 20 Euros and 50 ct.
    *
diff --git a/packages/taler-util/src/taleruri.ts b/packages/taler-util/src/taleruri.ts
index 22846c7a4..db21f0ad6 100644
--- a/packages/taler-util/src/taleruri.ts
+++ b/packages/taler-util/src/taleruri.ts
@@ -75,11 +75,16 @@ export interface PayUriResult {
   noncePriv?: string;
 }
 
+export type TemplateParams = {
+  amount?: string;
+  summary?: string;
+}
+
 export interface PayTemplateUriResult {
   type: TalerUriAction.PayTemplate;
   merchantBaseUrl: string;
   templateId: string;
-  templateParams: Record<string, string>;
+  templateParams: TemplateParams;
 }
 
 export interface WithdrawUriResult {
diff --git a/packages/taler-util/src/wallet-types.ts b/packages/taler-util/src/wallet-types.ts
index e6a66ac9d..4e3e8ac30 100644
--- a/packages/taler-util/src/wallet-types.ts
+++ b/packages/taler-util/src/wallet-types.ts
@@ -46,7 +46,11 @@ import {
   codecOptional,
   renderContext,
 } from "./codec.js";
-import { CurrencySpecification, WithdrawalOperationStatus } from "./index.js";
+import {
+  CurrencySpecification,
+  TemplateParams,
+  WithdrawalOperationStatus,
+} from "./index.js";
 import { VersionMatchResult } from "./libtool-version.js";
 import { PaytoUri } from "./payto.js";
 import { AgeCommitmentProof } from "./taler-crypto.js";
@@ -1927,7 +1931,7 @@ export const codecForSharePaymentResult = (): Codec<SharePaymentResult> =>
 
 export interface PreparePayTemplateRequest {
   talerPayTemplateUri: string;
-  templateParams?: Record<string, string>;
+  templateParams?: TemplateParams;
 }
 
 export const codecForPreparePayTemplateRequest =
diff --git a/packages/taler-wallet-core/src/operations/pay-merchant.ts b/packages/taler-wallet-core/src/operations/pay-merchant.ts
index 63bef3add..1039ac95e 100644
--- a/packages/taler-wallet-core/src/operations/pay-merchant.ts
+++ b/packages/taler-wallet-core/src/operations/pay-merchant.ts
@@ -640,7 +640,8 @@ async function processDownloadProposal(
 
   if (proposal.purchaseStatus != PurchaseStatus.PendingDownloadingProposal) {
     logger.error(
-      `unexpected state ${proposal.purchaseStatus}/${PurchaseStatus[proposal.purchaseStatus]
+      `unexpected state ${proposal.purchaseStatus}/${
+        PurchaseStatus[proposal.purchaseStatus]
       } for ${ctx.transactionId} in processDownloadProposal`,
     );
     return TaskRunResult.finished();
@@ -899,7 +900,8 @@ async function createOrReusePurchase(
     oldProposal.claimToken === claimToken
   ) {
     logger.info(
-      `Found old proposal (status=${PurchaseStatus[oldProposal.purchaseStatus]
+      `Found old proposal (status=${
+        PurchaseStatus[oldProposal.purchaseStatus]
       }) for order ${orderId} at ${merchantBaseUrl}`,
     );
     if (oldProposal.purchaseStatus === PurchaseStatus.DialogShared) {
@@ -1567,12 +1569,21 @@ export async function preparePayForTemplate(
     throw Error("invalid taler-template URI");
   }
   logger.trace(`parsed URI: ${j2s(parsedUri)}`);
-  if (
-    parsedUri.templateParams.amount !== undefined &&
-    typeof parsedUri.templateParams.amount === "string"
-  ) {
-    templateDetails.amount = (req.templateParams?.amount ??
-      parsedUri.templateParams.amount) as AmountString | undefined;
+
+  const amountFromUri = parsedUri.templateParams.amount;
+  if (amountFromUri != null) {
+    const templateParamsAmount = req.templateParams?.amount;
+    if (templateParamsAmount != null) {
+      templateDetails.amount = templateParamsAmount as AmountString;
+    } else {
+      if (Amounts.isCurrency(amountFromUri)) {
+        throw Error(
+          "Amount from template URI only has a currency without value. The value must be provided in the templateParams.",
+        );
+      } else {
+        templateDetails.amount = amountFromUri as AmountString;
+      }
+    }
   }
   if (
     parsedUri.templateParams.summary !== undefined &&
-- 
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