From 0d69feb8057b6b812879ff38f1b3b85712817d94 Mon Sep 17 00:00:00 2001
From: Florian Dold <florian@dold.me>
Date: Mon, 25 Mar 2024 20:53:58 +0100
Subject: wallet-core: re-denomination of refresh groups

---
 packages/taler-wallet-core/src/refresh.ts  | 73 +++++++++++++++++++++++++++---
 packages/taler-wallet-core/src/withdraw.ts |  2 +-
 2 files changed, 68 insertions(+), 7 deletions(-)

diff --git a/packages/taler-wallet-core/src/refresh.ts b/packages/taler-wallet-core/src/refresh.ts
index 7bf231870..a92b3baf1 100644
--- a/packages/taler-wallet-core/src/refresh.ts
+++ b/packages/taler-wallet-core/src/refresh.ts
@@ -60,7 +60,9 @@ import {
 } from "@gnu-taler/taler-util";
 import {
   readSuccessResponseJsonOrThrow,
+  readTalerErrorResponse,
   readUnexpectedResponseDetails,
+  throwUnexpectedRequestError,
 } from "@gnu-taler/taler-util/http";
 import {
   constructTaskIdentifier,
@@ -103,7 +105,10 @@ import {
   getDenomInfo,
   WalletExecutionContext,
 } from "./wallet.js";
-import { getCandidateWithdrawalDenomsTx } from "./withdraw.js";
+import {
+  getCandidateWithdrawalDenomsTx,
+  updateWithdrawalDenoms,
+} from "./withdraw.js";
 
 const logger = new Logger("refresh.ts");
 
@@ -499,6 +504,8 @@ async function refreshMelt(
   refreshGroupId: string,
   coinIndex: number,
 ): Promise<void> {
+  const ctx = new RefreshTransactionContext(wex, refreshGroupId);
+  const transactionId = ctx.transactionId;
   const d = await wex.db.runReadWriteTx(
     ["refreshGroups", "refreshSessions", "coins", "denominations"],
     async (tx) => {
@@ -618,11 +625,6 @@ async function refreshMelt(
     },
   );
 
-  const transactionId = constructTransactionIdentifier({
-    tag: TransactionType.Refresh,
-    refreshGroupId,
-  });
-
   if (resp.status === HttpStatusCode.NotFound) {
     const errDetails = await readUnexpectedResponseDetails(resp);
     const transitionInfo = await wex.db.runReadWriteTx(
@@ -671,6 +673,65 @@ async function refreshMelt(
     return;
   }
 
+  const exchangeBaseUrl = oldCoin.exchangeBaseUrl;
+  const currency = Amounts.currencyOf(oldDenom.value);
+
+  if (resp.status === HttpStatusCode.Gone) {
+    const errDetail = await readTalerErrorResponse(resp);
+    switch (errDetail.code) {
+      case TalerErrorCode.EXCHANGE_GENERIC_DENOMINATION_REVOKED:
+      case TalerErrorCode.EXCHANGE_GENERIC_DENOMINATION_EXPIRED: {
+        logger.warn(`refresh ${transactionId} requires redenomination`);
+        await fetchFreshExchange(wex, exchangeBaseUrl, {
+          forceUpdate: true,
+        });
+        await updateWithdrawalDenoms(wex, exchangeBaseUrl);
+        await wex.db.runReadWriteTx(
+          ["refreshGroups", "refreshSessions", "denominations"],
+          async (tx) => {
+            const rg = await tx.refreshGroups.get(refreshGroupId);
+            if (!rg) {
+              return;
+            }
+            if (rg.timestampFinished) {
+              return;
+            }
+            const rs = await tx.refreshSessions.get([
+              refreshGroupId,
+              coinIndex,
+            ]);
+            if (!rs) {
+              return;
+            }
+            if (rs.norevealIndex !== undefined) {
+              return;
+            }
+            const candidates = await getCandidateWithdrawalDenomsTx(
+              wex,
+              tx,
+              exchangeBaseUrl,
+              currency,
+            );
+            // We can just replace the existing coin selection, because melt is atomic,
+            // and thus it's not possible that some denoms in the selection were already
+            // withdrawn.
+            const input = Amounts.parseOrThrow(rg.inputPerCoin[rs.coinIndex]);
+            const newSel = selectWithdrawalDenominations(input, candidates);
+            rs.amountRefreshOutput = newSel.totalCoinValue;
+            rs.newDenoms = newSel.selectedDenoms.map((x) => ({
+              count: x.count,
+              denomPubHash: x.denomPubHash,
+            }));
+            await tx.refreshSessions.put(rs);
+          },
+        );
+        break;
+      }
+    }
+
+    throwUnexpectedRequestError(resp, errDetail);
+  }
+
   if (resp.status === HttpStatusCode.Conflict) {
     // Just log for better diagnostics here, error status
     // will be handled later.
diff --git a/packages/taler-wallet-core/src/withdraw.ts b/packages/taler-wallet-core/src/withdraw.ts
index 625d5dca4..9d9d2bea6 100644
--- a/packages/taler-wallet-core/src/withdraw.ts
+++ b/packages/taler-wallet-core/src/withdraw.ts
@@ -1194,7 +1194,7 @@ async function processPlanchetVerifyAndStoreCoin(
  * Make sure that denominations that currently can be used for withdrawal
  * are validated, and the result of validation is stored in the database.
  */
-async function updateWithdrawalDenoms(
+export async function updateWithdrawalDenoms(
   wex: WalletExecutionContext,
   exchangeBaseUrl: string,
 ): Promise<void> {
-- 
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