wallet-core: insufficient balance details for p2p payments

1 files changed, 65 insertions, 7 deletions

diff --git a/packages/taler-wallet-core/src/operations/pay-peer.ts b/packages/taler-wallet-core/src/operations/pay-peer.ts
index 3d03c46db..3ee1795b0 100644
--- a/packages/taler-wallet-core/src/operations/pay-peer.ts
+++ b/packages/taler-wallet-core/src/operations/pay-peer.ts
@@ -62,6 +62,7 @@ import {
   PreparePeerPushPaymentResponse,
   RefreshReason,
   strcmp,
+  TalerErrorCode,
   TalerProtocolTimestamp,
   TransactionType,
   UnblindedSignature,
@@ -77,11 +78,13 @@ import {
   WithdrawalGroupStatus,
   WithdrawalRecordType,
 } from "../db.js";
+import { TalerError } from "../errors.js";
 import { InternalWalletState } from "../internal-wallet-state.js";
 import { makeTransactionId, spendCoins } from "../operations/common.js";
 import { readSuccessResponseJsonOrThrow } from "../util/http.js";
 import { checkDbInvariant } from "../util/invariants.js";
 import { GetReadOnlyAccess } from "../util/query.js";
+import { getPeerPaymentBalanceDetailsInTx } from "./balance.js";
 import { updateExchangeFromUrl } from "./exchanges.js";
 import { internalCreateWithdrawalGroup } from "./withdraw.js";
 
@@ -135,6 +138,7 @@ export type SelectPeerCoinsResult =
   | { type: "success"; result: PeerCoinSelection }
   | {
       type: "failure";
+      insufficientBalanceDetails: PayPeerInsufficientBalanceDetails;
     };
 
 export async function selectPeerCoins(
@@ -143,12 +147,16 @@ export async function selectPeerCoins(
     exchanges: typeof WalletStoresV1.exchanges;
     denominations: typeof WalletStoresV1.denominations;
     coins: typeof WalletStoresV1.coins;
+    coinAvailability: typeof WalletStoresV1.coinAvailability;
+    refreshGroups: typeof WalletStoresV1.refreshGroups;
   }>,
   instructedAmount: AmountJson,
 ): Promise<SelectPeerCoinsResult> {
   const exchanges = await tx.exchanges.iter().toArray();
+  const exchangeFeeGap: { [url: string]: AmountJson } = {};
+  const currency = Amounts.currencyOf(instructedAmount);
   for (const exch of exchanges) {
-    if (exch.detailsPointer?.currency !== instructedAmount.currency) {
+    if (exch.detailsPointer?.currency !== currency) {
       continue;
     }
     const coins = (
@@ -184,8 +192,8 @@ export async function selectPeerCoins(
         -Amounts.cmp(o1.value, o2.value) ||
         strcmp(o1.denomPubHash, o2.denomPubHash),
     );
-    let amountAcc = Amounts.zeroOfCurrency(instructedAmount.currency);
-    let depositFeesAcc = Amounts.zeroOfCurrency(instructedAmount.currency);
+    let amountAcc = Amounts.zeroOfCurrency(currency);
+    let depositFeesAcc = Amounts.zeroOfCurrency(currency);
     const resCoins: {
       coinPub: string;
       coinPriv: string;
@@ -194,6 +202,7 @@ export async function selectPeerCoins(
       denomSig: UnblindedSignature;
       ageCommitmentProof: AgeCommitmentProof | undefined;
     }[] = [];
+    let lastDepositFee = Amounts.zeroOfCurrency(currency);
     for (const coin of coinInfos) {
       if (Amounts.cmp(amountAcc, instructedAmount) >= 0) {
         break;
@@ -216,6 +225,7 @@ export async function selectPeerCoins(
         denomSig: coin.denomSig,
         ageCommitmentProof: coin.ageCommitmentProof,
       });
+      lastDepositFee = coin.feeDeposit;
     }
     if (Amounts.cmp(amountAcc, instructedAmount) >= 0) {
       const res: PeerCoinSelection = {
@@ -225,9 +235,48 @@ export async function selectPeerCoins(
       };
       return { type: "success", result: res };
     }
+    const diff = Amounts.sub(instructedAmount, amountAcc).amount;
+    exchangeFeeGap[exch.baseUrl] = Amounts.add(lastDepositFee, diff).amount;
+
     continue;
   }
-  return { type: "failure" };
+  // We were unable to select coins.
+  // Now we need to produce error details.
+
+  const infoGeneral = await getPeerPaymentBalanceDetailsInTx(ws, tx, {
+    currency,
+  });
+
+  const perExchange: PayPeerInsufficientBalanceDetails["perExchange"] = {};
+
+  for (const exch of exchanges) {
+    if (exch.detailsPointer?.currency !== currency) {
+      continue;
+    }
+    const infoExchange = await getPeerPaymentBalanceDetailsInTx(ws, tx, {
+      currency,
+      restrictExchangeTo: exch.baseUrl,
+    });
+    let gap = exchangeFeeGap[exch.baseUrl] ?? Amounts.zeroOfCurrency(currency);
+    if (Amounts.cmp(infoExchange.balanceMaterial, instructedAmount) < 0) {
+      // Show fee gap only if we should've been able to pay with the material amount
+      gap = Amounts.zeroOfAmount(currency);
+    }
+    perExchange[exch.baseUrl] = {
+      balanceAvailable: Amounts.stringify(infoExchange.balanceAvailable),
+      balanceMaterial: Amounts.stringify(infoExchange.balanceMaterial),
+      feeGapEstimate: Amounts.stringify(gap),
+    };
+  }
+
+  const errDetails: PayPeerInsufficientBalanceDetails = {
+    amountRequested: Amounts.stringify(instructedAmount),
+    balanceAvailable: Amounts.stringify(infoGeneral.balanceAvailable),
+    balanceMaterial: Amounts.stringify(infoGeneral.balanceMaterial),
+    perExchange,
+  };
+
+  return { type: "failure", insufficientBalanceDetails: errDetails };
 }
 
 export async function preparePeerPushPayment(
@@ -316,8 +365,12 @@ export async function initiatePeerToPeerPush(
   logger.info(`selected p2p coins (push): ${j2s(coinSelRes)}`);
 
   if (coinSelRes.type !== "success") {
-    // FIXME: use error code with details here
-    throw Error("insufficient balance");
+    throw TalerError.fromDetail(
+      TalerErrorCode.WALLET_PEER_PUSH_PAYMENT_INSUFFICIENT_BALANCE,
+      {
+        insufficientBalanceDetails: coinSelRes.insufficientBalanceDetails,
+      },
+    );
   }
 
   const purseSigResp = await ws.cryptoApi.signPurseCreation({
@@ -675,7 +728,12 @@ export async function acceptPeerPullPayment(
   logger.info(`selected p2p coins (pull): ${j2s(coinSelRes)}`);
 
   if (coinSelRes.type !== "success") {
-    throw Error("insufficient balance");
+    throw TalerError.fromDetail(
+      TalerErrorCode.WALLET_PEER_PUSH_PAYMENT_INSUFFICIENT_BALANCE,
+      {
+        insufficientBalanceDetails: coinSelRes.insufficientBalanceDetails,
+      },
+    );
   }
 
   const pursePub = peerPullInc.pursePub;