From fef7985be3ac1440d02f9ddc9f5aa141586a5259 Mon Sep 17 00:00:00 2001
From: Florian Dold <florian@dold.me>
Date: Tue, 5 Dec 2023 18:51:58 +0100
Subject: wallet-core: make conversion more robust against errors

---
 packages/taler-util/src/wallet-types.ts            |  15 +++
 .../taler-wallet-core/src/operations/withdraw.ts   | 123 +++++++++++++--------
 2 files changed, 92 insertions(+), 46 deletions(-)

(limited to 'packages')

diff --git a/packages/taler-util/src/wallet-types.ts b/packages/taler-util/src/wallet-types.ts
index 8e72a4949..f19a0dd10 100644
--- a/packages/taler-util/src/wallet-types.ts
+++ b/packages/taler-util/src/wallet-types.ts
@@ -2782,6 +2782,16 @@ export interface WithdrawalExchangeAccountDetails {
    */
   paytoUri: string;
 
+  /**
+   * Status that indicates whether the account can be used
+   * by the user to send funds for a withdrawal.
+   *
+   * ok: account should be shown to the user
+   * error: account should not be shown to the user, UIs might render the error (in conversionError),
+   *   especially in dev mode.
+   */
+  status: "ok" | "error";
+
   /**
    * Transfer amount. Might be in a different currency than the requested
    * amount for withdrawal.
@@ -2804,4 +2814,9 @@ export interface WithdrawalExchangeAccountDetails {
    * exchange.
    */
   creditRestrictions?: AccountRestriction[];
+
+  /**
+   * Error that happened when attempting to request the conversion rate.
+   */
+  conversionError?: TalerErrorDetail;
 }
diff --git a/packages/taler-wallet-core/src/operations/withdraw.ts b/packages/taler-wallet-core/src/operations/withdraw.ts
index 63c811e60..b9ba3058f 100644
--- a/packages/taler-wallet-core/src/operations/withdraw.ts
+++ b/packages/taler-wallet-core/src/operations/withdraw.ts
@@ -35,6 +35,7 @@ import {
   Duration,
   ExchangeBatchWithdrawRequest,
   ExchangeListItem,
+  ExchangeWireAccount,
   ExchangeWithdrawBatchResponse,
   ExchangeWithdrawRequest,
   ExchangeWithdrawResponse,
@@ -2584,6 +2585,76 @@ export async function acceptWithdrawalFromUri(
   };
 }
 
+async function fetchAccount(
+  ws: InternalWalletState,
+  instructedAmount: AmountJson,
+  acct: ExchangeWireAccount,
+  reservePub?: string,
+): Promise<WithdrawalExchangeAccountDetails> {
+  let paytoUri: string;
+  let transferAmount: AmountString | undefined = undefined;
+  let currencySpecification: CurrencySpecification | undefined = undefined;
+  if (acct.conversion_url != null) {
+    const reqUrl = new URL("cashin-rate", acct.conversion_url);
+    reqUrl.searchParams.set(
+      "amount_credit",
+      Amounts.stringify(instructedAmount),
+    );
+    const httpResp = await ws.http.fetch(reqUrl.href);
+    const respOrErr = await readSuccessResponseJsonOrErrorCode(
+      httpResp,
+      codecForCashinConversionResponse(),
+    );
+    if (respOrErr.isError) {
+      return {
+        status: "error",
+        paytoUri: acct.payto_uri,
+        conversionError: respOrErr.talerErrorResponse,
+      };
+    }
+    const resp = respOrErr.response;
+    paytoUri = acct.payto_uri;
+    transferAmount = resp.amount_debit;
+    const configUrl = new URL("config", acct.conversion_url);
+    const configResp = await ws.http.fetch(configUrl.href);
+    const configRespOrError = await readSuccessResponseJsonOrErrorCode(
+      configResp,
+      codecForConversionBankConfig(),
+    );
+    if (configRespOrError.isError) {
+      return {
+        status: "error",
+        paytoUri: acct.payto_uri,
+        conversionError: configRespOrError.talerErrorResponse,
+      };
+    }
+    const configParsed = configRespOrError.response;
+    currencySpecification = configParsed.fiat_currency_specification;
+  } else {
+    paytoUri = acct.payto_uri;
+    transferAmount = Amounts.stringify(instructedAmount);
+  }
+  paytoUri = addPaytoQueryParams(paytoUri, {
+    amount: Amounts.stringify(transferAmount),
+  });
+  if (reservePub != null) {
+    paytoUri = addPaytoQueryParams(paytoUri, {
+      message: `Taler Withdrawal ${reservePub}`,
+    });
+  }
+  const acctInfo: WithdrawalExchangeAccountDetails = {
+    status: "ok",
+    paytoUri,
+    transferAmount,
+    currencySpecification,
+    creditRestrictions: acct.credit_restrictions,
+  };
+  if (transferAmount != null) {
+    acctInfo.transferAmount = transferAmount;
+  }
+  return acctInfo;
+}
+
 /**
  * Gather information about bank accounts that can be used for
  * withdrawals.  This includes accounts that are in a different
@@ -2600,52 +2671,12 @@ async function fetchWithdrawalAccountInfo(
   const { exchangeDetails, instructedAmount } = req;
   const withdrawalAccounts: WithdrawalExchangeAccountDetails[] = [];
   for (let acct of exchangeDetails.wireInfo.accounts) {
-    let paytoUri: string;
-    let transferAmount: AmountString | undefined = undefined;
-    let currencySpecification: CurrencySpecification | undefined = undefined;
-    if (acct.conversion_url != null) {
-      const reqUrl = new URL("cashin-rate", acct.conversion_url);
-      reqUrl.searchParams.set(
-        "amount_credit",
-        Amounts.stringify(instructedAmount),
-      );
-      const httpResp = await ws.http.fetch(reqUrl.href);
-      const resp = await readSuccessResponseJsonOrThrow(
-        httpResp,
-        codecForCashinConversionResponse(),
-      );
-      paytoUri = acct.payto_uri;
-      transferAmount = resp.amount_debit;
-      const configUrl = new URL("config", acct.conversion_url);
-      const configResp = await ws.http.fetch(configUrl.href);
-      const configParsed = await readSuccessResponseJsonOrThrow(
-        configResp,
-        codecForConversionBankConfig(),
-      );
-      currencySpecification = configParsed.fiat_currency_specification;
-      if (req.reservePub) {
-      }
-    } else {
-      paytoUri = acct.payto_uri;
-      transferAmount = Amounts.stringify(instructedAmount);
-    }
-    paytoUri = addPaytoQueryParams(paytoUri, {
-      amount: Amounts.stringify(transferAmount),
-    });
-    if (req.reservePub != null) {
-      paytoUri = addPaytoQueryParams(paytoUri, {
-        message: `Taler Withdrawal ${req.reservePub}`,
-      });
-    }
-    const acctInfo: WithdrawalExchangeAccountDetails = {
-      paytoUri,
-      transferAmount,
-      currencySpecification,
-      creditRestrictions: acct.credit_restrictions,
-    };
-    if (transferAmount != null) {
-      acctInfo.transferAmount = transferAmount;
-    }
+    const acctInfo = await fetchAccount(
+      ws,
+      req.instructedAmount,
+      acct,
+      req.reservePub,
+    );
     withdrawalAccounts.push(acctInfo);
   }
   return withdrawalAccounts;
-- 
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