From 8e70b89593a375bb19432e6521daed618ae779f5 Mon Sep 17 00:00:00 2001
From: Florian Dold <florian@dold.me>
Date: Mon, 2 Oct 2023 23:24:06 +0200
Subject: [PATCH] wallet-core: currency hint for preset exchanges

---
 packages/taler-wallet-core/src/db.ts           |  6 ++++++
 .../taler-wallet-core/src/operations/common.ts |  2 +-
 .../src/operations/exchanges.ts                |  4 +++-
 .../taler-wallet-core/src/wallet-api-types.ts  |  7 ++++++-
 packages/taler-wallet-core/src/wallet.ts       | 18 ++++++++++++------
 5 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/packages/taler-wallet-core/src/db.ts b/packages/taler-wallet-core/src/db.ts
index 156651cc6..d59085dcc 100644
--- a/packages/taler-wallet-core/src/db.ts
+++ b/packages/taler-wallet-core/src/db.ts
@@ -620,6 +620,12 @@ export interface ExchangeEntryRecord {
    */
   baseUrl: string;
 
+  /**
+   * Currency hint for a preset exchange, relevant
+   * when we didn't contact a preset exchange yet.
+   */
+  presetCurrencyHint?: string;
+
   /**
    * When did we confirm the last withdrawal from this exchange?
    *
diff --git a/packages/taler-wallet-core/src/operations/common.ts b/packages/taler-wallet-core/src/operations/common.ts
index e8e492c08..b28a5363d 100644
--- a/packages/taler-wallet-core/src/operations/common.ts
+++ b/packages/taler-wallet-core/src/operations/common.ts
@@ -593,7 +593,7 @@ export function makeExchangeListItem(
 
   return {
     exchangeBaseUrl: r.baseUrl,
-    currency: exchangeDetails?.currency,
+    currency: exchangeDetails?.currency ?? r.presetCurrencyHint,
     exchangeUpdateStatus,
     exchangeEntryStatus,
     tosStatus: exchangeDetails
diff --git a/packages/taler-wallet-core/src/operations/exchanges.ts b/packages/taler-wallet-core/src/operations/exchanges.ts
index 5e966b719..82d7b42bf 100644
--- a/packages/taler-wallet-core/src/operations/exchanges.ts
+++ b/packages/taler-wallet-core/src/operations/exchanges.ts
@@ -309,6 +309,7 @@ export async function downloadExchangeInfo(
 export async function addPresetExchangeEntry(
   tx: WalletDbReadWriteTransaction<"exchanges">,
   exchangeBaseUrl: string,
+  currencyHint?: string,
 ): Promise<void> {
   let exchange = await tx.exchanges.get(exchangeBaseUrl);
   if (!exchange) {
@@ -316,6 +317,7 @@ export async function addPresetExchangeEntry(
       entryStatus: ExchangeEntryDbRecordStatus.Preset,
       updateStatus: ExchangeEntryDbUpdateStatus.Initial,
       baseUrl: exchangeBaseUrl,
+      presetCurrencyHint: currencyHint,
       detailsPointer: undefined,
       lastUpdate: undefined,
       lastKeysEtag: undefined,
@@ -330,7 +332,7 @@ export async function addPresetExchangeEntry(
   }
 }
 
-export async function provideExchangeRecordInTx(
+async function provideExchangeRecordInTx(
   ws: InternalWalletState,
   tx: GetReadWriteAccess<{
     exchanges: typeof WalletStoresV1.exchanges;
diff --git a/packages/taler-wallet-core/src/wallet-api-types.ts b/packages/taler-wallet-core/src/wallet-api-types.ts
index 26e86f43f..375e0a1b2 100644
--- a/packages/taler-wallet-core/src/wallet-api-types.ts
+++ b/packages/taler-wallet-core/src/wallet-api-types.ts
@@ -254,6 +254,11 @@ export type GetVersionOp = {
  */
 export type WalletConfigParameter = RecursivePartial<WalletConfig>;
 
+export interface BuiltinExchange {
+  exchangeBaseUrl: string;
+  currencyHint?: string;
+}
+
 export interface WalletConfig {
   /**
    * Initialization values useful for a complete startup.
@@ -261,7 +266,7 @@ export interface WalletConfig {
    * These are values may be overridden by different wallets
    */
   builtin: {
-    exchanges: string[];
+    exchanges: BuiltinExchange[];
   };
 
   /**
diff --git a/packages/taler-wallet-core/src/wallet.ts b/packages/taler-wallet-core/src/wallet.ts
index 44076667d..203adec0f 100644
--- a/packages/taler-wallet-core/src/wallet.ts
+++ b/packages/taler-wallet-core/src/wallet.ts
@@ -200,7 +200,6 @@ import {
   downloadTosFromAcceptedFormat,
   getExchangeDetails,
   getExchangeRequestTimeout,
-  provideExchangeRecordInTx,
   updateExchangeFromUrl,
   updateExchangeFromUrlHandler,
 } from "./operations/exchanges.js";
@@ -535,10 +534,12 @@ async function fillDefaults(ws: InternalWalletState): Promise<void> {
         logger.trace("defaults already applied");
         return;
       }
-      for (const baseUrl of ws.config.builtin.exchanges) {
-        await addPresetExchangeEntry(tx, baseUrl);
-        const now = AbsoluteTime.now();
-        provideExchangeRecordInTx(ws, tx, baseUrl, now);
+      for (const exch of ws.config.builtin.exchanges) {
+        await addPresetExchangeEntry(
+          tx,
+          exch.exchangeBaseUrl,
+          exch.currencyHint,
+        );
       }
       await tx.config.put({
         key: ConfigRecordKey.CurrencyDefaultsApplied,
@@ -1672,7 +1673,12 @@ export class Wallet {
 
   public static defaultConfig: Readonly<WalletConfig> = {
     builtin: {
-      exchanges: ["https://exchange.demo.taler.net/"],
+      exchanges: [
+        {
+          exchangeBaseUrl: "https://exchange.demo.taler.net/",
+          currencyHint: "KUDOS",
+        },
+      ],
     },
     features: {
       allowHttp: false,