wallet-core: implement insufficient balance details

For now, only for merchant payments

1 files changed, 73 insertions, 26 deletions

diff --git a/packages/taler-wallet-core/src/operations/pay-merchant.ts b/packages/taler-wallet-core/src/operations/pay-merchant.ts
index 05da0a020..6026e0860 100644
--- a/packages/taler-wallet-core/src/operations/pay-merchant.ts
+++ b/packages/taler-wallet-core/src/operations/pay-merchant.ts
@@ -73,6 +73,7 @@ import {
   TransactionType,
   URL,
   constructPayUri,
+  PayMerchantInsufficientBalanceDetails,
 } from "@gnu-taler/taler-util";
 import { EddsaKeypair } from "../crypto/cryptoImplementation.js";
 import {
@@ -131,11 +132,12 @@ import {
 import { getExchangeDetails } from "./exchanges.js";
 import { createRefreshGroup, getTotalRefreshCost } from "./refresh.js";
 import { GetReadOnlyAccess } from "../util/query.js";
+import { getMerchantPaymentBalanceDetails } from "./balance.js";
 
 /**
  * Logger.
  */
-const logger = new Logger("pay.ts");
+const logger = new Logger("pay-merchant.ts");
 
 /**
  * Compute the total cost of a payment to the customer.
@@ -817,7 +819,7 @@ async function handleInsufficientFunds(
     requiredMinimumAge: contractData.minimumAge,
   });
 
-  if (!res) {
+  if (res.type !== "success") {
     logger.trace("insufficient funds for coin re-selection");
     return;
   }
@@ -841,8 +843,7 @@ async function handleInsufficientFunds(
       if (!payInfo) {
         return;
       }
-      payInfo.payCoinSelection = res;
-      payInfo.payCoinSelection = res;
+      payInfo.payCoinSelection = res.coinSel;
       payInfo.payCoinSelectionUid = encodeCrock(getRandomBytes(32));
       await tx.purchases.put(p);
       await spendCoins(ws, tx, {
@@ -905,6 +906,8 @@ export async function selectCandidates(
       x.coinAvailability,
     ])
     .runReadOnly(async (tx) => {
+      // FIXME: Use the existing helper (from balance.ts) to
+      // get acceptable exchanges.
       const denoms: AvailableDenom[] = [];
       const exchanges = await tx.exchanges.iter().toArray();
       const wfPerExchange: Record<string, AmountJson> = {};
@@ -1030,6 +1033,7 @@ export function selectGreedy(
       // Don't use this coin if depositing it is more expensive than
       // the amount it would give the merchant.
       if (Amounts.cmp(aci.feeDeposit, aci.value) > 0) {
+        tally.lastDepositFee = Amounts.parseOrThrow(aci.feeDeposit);
         continue;
       }
 
@@ -1129,6 +1133,13 @@ export function selectForced(
   return selectedDenom;
 }
 
+export type SelectPayCoinsResult =
+  | {
+      type: "failure";
+      insufficientBalanceDetails: PayMerchantInsufficientBalanceDetails;
+    }
+  | { type: "success"; coinSel: PayCoinSelection };
+
 /**
  * Given a list of candidate coins, select coins to spend under the merchant's
  * constraints.
@@ -1142,7 +1153,7 @@ export function selectForced(
 export async function selectPayCoinsNew(
   ws: InternalWalletState,
   req: SelectPayCoinRequestNg,
-): Promise<PayCoinSelection | undefined> {
+): Promise<SelectPayCoinsResult> {
   const {
     contractTermsAmount,
     depositFeeLimit,
@@ -1168,6 +1179,7 @@ export async function selectPayCoinsNew(
     customerDepositFees: Amounts.zeroOfCurrency(currency),
     customerWireFees: Amounts.zeroOfCurrency(currency),
     wireFeeCoveredForExchange: new Set(),
+    lastDepositFee: Amounts.zeroOfCurrency(currency),
   };
 
   const prevPayCoins = req.prevPayCoins ?? [];
@@ -1207,7 +1219,44 @@ export async function selectPayCoinsNew(
   }
 
   if (!selectedDenom) {
-    return undefined;
+    const details = await getMerchantPaymentBalanceDetails(ws, {
+      acceptedAuditors: req.auditors,
+      acceptedExchanges: req.exchanges,
+      acceptedWireMethods: [req.wireMethod],
+      currency: Amounts.currencyOf(req.contractTermsAmount),
+      minAge: req.requiredMinimumAge ?? 0,
+    });
+    let feeGapEstimate: AmountJson;
+    if (
+      Amounts.cmp(
+        details.balanceMerchantDepositable,
+        req.contractTermsAmount,
+      ) >= 0
+    ) {
+      // FIXME: We can probably give a better estimate.
+      feeGapEstimate = Amounts.add(
+        tally.amountPayRemaining,
+        tally.lastDepositFee,
+      ).amount;
+    } else {
+      feeGapEstimate = Amounts.zeroOfAmount(req.contractTermsAmount);
+    }
+    return {
+      type: "failure",
+      insufficientBalanceDetails: {
+        amountRequested: Amounts.stringify(req.contractTermsAmount),
+        balanceAgeAcceptable: Amounts.stringify(details.balanceAgeAcceptable),
+        balanceAvailable: Amounts.stringify(details.balanceAvailable),
+        balanceMaterial: Amounts.stringify(details.balanceMaterial),
+        balanceMerchantAcceptable: Amounts.stringify(
+          details.balanceMerchantAcceptable,
+        ),
+        balanceMerchantDepositable: Amounts.stringify(
+          details.balanceMerchantDepositable,
+        ),
+        feeGapEstimate: Amounts.stringify(feeGapEstimate),
+      },
+    };
   }
 
   const finalSel = selectedDenom;
@@ -1244,11 +1293,14 @@ export async function selectPayCoinsNew(
     });
 
   return {
-    paymentAmount: Amounts.stringify(contractTermsAmount),
-    coinContributions: coinContributions.map((x) => Amounts.stringify(x)),
-    coinPubs,
-    customerDepositFees: Amounts.stringify(tally.customerDepositFees),
-    customerWireFees: Amounts.stringify(tally.customerWireFees),
+    type: "success",
+    coinSel: {
+      paymentAmount: Amounts.stringify(contractTermsAmount),
+      coinContributions: coinContributions.map((x) => Amounts.stringify(x)),
+      coinPubs,
+      customerDepositFees: Amounts.stringify(tally.customerDepositFees),
+      customerWireFees: Amounts.stringify(tally.customerWireFees),
+    },
   };
 }
 
@@ -1318,7 +1370,7 @@ export async function checkPaymentByProposalId(
       wireMethod: contractData.wireMethod,
     });
 
-    if (!res) {
+    if (res.type !== "success") {
       logger.info("not allowing payment, insufficient coins");
       return {
         status: PreparePayResultType.InsufficientBalance,
@@ -1327,10 +1379,11 @@ export async function checkPaymentByProposalId(
         noncePriv: proposal.noncePriv,
         amountRaw: Amounts.stringify(d.contractData.amount),
         talerUri,
+        balanceDetails: res.insufficientBalanceDetails,
       };
     }
 
-    const totalCost = await getTotalPaymentCost(ws, res);
+    const totalCost = await getTotalPaymentCost(ws, res.coinSel);
     logger.trace("costInfo", totalCost);
     logger.trace("coinsForPayment", res);
 
@@ -1340,7 +1393,7 @@ export async function checkPaymentByProposalId(
       proposalId: proposal.proposalId,
       noncePriv: proposal.noncePriv,
       amountEffective: Amounts.stringify(totalCost),
-      amountRaw: Amounts.stringify(res.paymentAmount),
+      amountRaw: Amounts.stringify(res.coinSel.paymentAmount),
       contractTermsHash: d.contractData.contractTermsHash,
       talerUri,
     };
@@ -1666,9 +1719,9 @@ export async function confirmPay(
 
   const contractData = d.contractData;
 
-  let maybeCoinSelection: PayCoinSelection | undefined = undefined;
+  let selectCoinsResult: SelectPayCoinsResult | undefined = undefined;
 
-  maybeCoinSelection = await selectPayCoinsNew(ws, {
+  selectCoinsResult = await selectPayCoinsNew(ws, {
     auditors: contractData.allowedAuditors,
     exchanges: contractData.allowedExchanges,
     wireMethod: contractData.wireMethod,
@@ -1681,9 +1734,9 @@ export async function confirmPay(
     forcedSelection: forcedCoinSel,
   });
 
-  logger.trace("coin selection result", maybeCoinSelection);
+  logger.trace("coin selection result", selectCoinsResult);
 
-  if (!maybeCoinSelection) {
+  if (selectCoinsResult.type === "failure") {
     // Should not happen, since checkPay should be called first
     // FIXME: Actually, this should be handled gracefully,
     // and the status should be stored in the DB.
@@ -1691,14 +1744,7 @@ export async function confirmPay(
     throw Error("insufficient balance");
   }
 
-  const coinSelection = maybeCoinSelection;
-
-  const depositPermissions = await generateDepositPermissions(
-    ws,
-    coinSelection,
-    d.contractData,
-  );
-
+  const coinSelection = selectCoinsResult.coinSel;
   const payCostInfo = await getTotalPaymentCost(ws, coinSelection);
 
   let sessionId: string | undefined;
@@ -2373,6 +2419,7 @@ async function acceptRefunds(
         await createRefreshGroup(
           ws,
           tx,
+          Amounts.currencyOf(refreshCoinsPubs[0].amount),
           refreshCoinsPubs,
           RefreshReason.Refund,
         );