-cleanup

4 files changed, 19 insertions, 609 deletions

diff --git a/packages/taler-wallet-core/src/operations/pay.ts b/packages/taler-wallet-core/src/operations/pay.ts
index ab59fff87..6b366f50d 100644
--- a/packages/taler-wallet-core/src/operations/pay.ts
+++ b/packages/taler-wallet-core/src/operations/pay.ts
@@ -24,7 +24,7 @@
 /**
  * Imports.
  */
-import { BridgeIDBKeyRange, GlobalIDB } from "@gnu-taler/idb-bridge";
+import { GlobalIDB } from "@gnu-taler/idb-bridge";
 import {
   AbsoluteTime,
   AgeRestriction,
@@ -47,7 +47,6 @@ import {
   j2s,
   Logger,
   NotificationType,
-  parsePaytoUri,
   parsePayUri,
   PayCoinSelection,
   PreparePayResult,
@@ -75,7 +74,6 @@ import {
   ProposalStatus,
   PurchaseRecord,
   WalletContractData,
-  WalletStoresV1,
 } from "../db.js";
 import {
   makeErrorDetail,
@@ -88,11 +86,8 @@ import {
 } from "../internal-wallet-state.js";
 import { assertUnreachable } from "../util/assertUnreachable.js";
 import {
-  AvailableCoinInfo,
-  CoinCandidateSelection,
   CoinSelectionTally,
   PreviousPayCoins,
-  selectForcedPayCoins,
   tallyFees,
 } from "../util/coinSelection.js";
 import {
@@ -104,11 +99,10 @@ import {
   throwUnexpectedRequestError,
 } from "../util/http.js";
 import { checkDbInvariant, checkLogicInvariant } from "../util/invariants.js";
-import { GetReadWriteAccess } from "../util/query.js";
 import { RetryInfo, RetryTags, scheduleRetry } from "../util/retries.js";
 import { spendCoins } from "../wallet.js";
 import { getExchangeDetails } from "./exchanges.js";
-import { createRefreshGroup, getTotalRefreshCost } from "./refresh.js";
+import { getTotalRefreshCost } from "./refresh.js";
 import { makeEventId } from "./transactions.js";
 
 /**
@@ -170,24 +164,6 @@ export async function getTotalPaymentCost(
     });
 }
 
-function isSpendableCoin(coin: CoinRecord, denom: DenominationRecord): boolean {
-  if (denom.isRevoked) {
-    return false;
-  }
-  if (!denom.isOffered) {
-    return false;
-  }
-  if (coin.status !== CoinStatus.Fresh) {
-    return false;
-  }
-  if (
-    AbsoluteTime.isExpired(AbsoluteTime.fromTimestamp(denom.stampExpireDeposit))
-  ) {
-    return false;
-  }
-  return true;
-}
-
 export interface CoinSelectionRequest {
   amount: AmountJson;
 
@@ -898,7 +874,7 @@ export type AvailableDenom = DenominationInfo & {
   numAvailable: number;
 };
 
-async function selectCandidates(
+export async function selectCandidates(
   ws: InternalWalletState,
   req: SelectPayCoinRequestNg,
 ): Promise<[AvailableDenom[], Record<string, AmountJson>]> {
@@ -937,7 +913,7 @@ async function selectCandidates(
           continue;
         }
         let ageLower = 0;
-        let ageUpper = Number.MAX_SAFE_INTEGER;
+        let ageUpper = AgeRestriction.AGE_UNRESTRICTED;
         if (req.requiredMinimumAge) {
           ageLower = req.requiredMinimumAge;
         }
@@ -1522,7 +1498,7 @@ export async function runPayForConfirmPay(
       return {
         type: ConfirmPayResultType.Done,
         contractTerms: purchase.download.contractTermsRaw,
-        transactionId: makeEventId(TransactionType.Payment, proposalId)
+        transactionId: makeEventId(TransactionType.Payment, proposalId),
       };
     }
     case OperationAttemptResultType.Error:
diff --git a/packages/taler-wallet-core/src/operations/peer-to-peer.ts b/packages/taler-wallet-core/src/operations/peer-to-peer.ts
index ffbc1fc97..48d422e0b 100644
--- a/packages/taler-wallet-core/src/operations/peer-to-peer.ts
+++ b/packages/taler-wallet-core/src/operations/peer-to-peer.ts
@@ -24,7 +24,8 @@ import {
   AcceptPeerPushPaymentRequest,
   AcceptPeerPushPaymentResponse,
   AgeCommitmentProof,
-  AmountJson, Amounts,
+  AmountJson,
+  Amounts,
   AmountString,
   buildCodecForObject,
   CheckPeerPullPaymentRequest,
@@ -34,7 +35,8 @@ import {
   Codec,
   codecForAmountString,
   codecForAny,
-  codecForExchangeGetContractResponse, constructPayPullUri,
+  codecForExchangeGetContractResponse,
+  constructPayPullUri,
   constructPayPushUri,
   ContractTermsUtil,
   decodeCrock,
@@ -58,14 +60,14 @@ import {
   TalerProtocolTimestamp,
   TransactionType,
   UnblindedSignature,
-  WalletAccountMergeFlags
+  WalletAccountMergeFlags,
 } from "@gnu-taler/taler-util";
 import {
   CoinStatus,
   MergeReserveInfo,
   ReserveRecordStatus,
   WalletStoresV1,
-  WithdrawalRecordType
+  WithdrawalRecordType,
 } from "../db.js";
 import { InternalWalletState } from "../internal-wallet-state.js";
 import { readSuccessResponseJsonOrThrow } from "../util/http.js";
@@ -339,7 +341,7 @@ export async function initiatePeerToPeerPush(
       exchangeBaseUrl: coinSelRes.exchangeBaseUrl,
       contractPriv: econtractResp.contractPriv,
     }),
-    transactionId: makeEventId(TransactionType.PeerPushDebit, pursePair.pub)
+    transactionId: makeEventId(TransactionType.PeerPushDebit, pursePair.pub),
   };
 }
 
@@ -552,9 +554,9 @@ export async function acceptPeerPushPayment(
   return {
     transactionId: makeEventId(
       TransactionType.PeerPushCredit,
-      wg.withdrawalGroupId
-    )
-  }
+      wg.withdrawalGroupId,
+    ),
+  };
 }
 
 /**
@@ -645,8 +647,8 @@ export async function acceptPeerPullPayment(
     transactionId: makeEventId(
       TransactionType.PeerPullDebit,
       req.peerPullPaymentIncomingId,
-    )
-  }
+    ),
+  };
 }
 
 export async function checkPeerPullPayment(
@@ -840,7 +842,7 @@ export async function initiatePeerRequestForPay(
     }),
     transactionId: makeEventId(
       TransactionType.PeerPullCredit,
-      wg.withdrawalGroupId
-    )
+      wg.withdrawalGroupId,
+    ),
   };
 }
diff --git a/packages/taler-wallet-core/src/util/coinSelection.test.ts b/packages/taler-wallet-core/src/util/coinSelection.test.ts
deleted file mode 100644
index fe9672116..000000000
--- a/packages/taler-wallet-core/src/util/coinSelection.test.ts
+++ /dev/null
@@ -1,322 +0,0 @@
-/*
- This file is part of GNU Taler
- (C) 2021 Taler Systems S.A.
-
- GNU Taler is free software; you can redistribute it and/or modify it under the
- terms of the GNU General Public License as published by the Free Software
- Foundation; either version 3, or (at your option) any later version.
-
- GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
- WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
- A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License along with
- GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
- */
-
-/**
- * Imports.
- */
-import test from "ava";
-import {
-  AgeRestriction,
-  AmountJson,
-  Amounts,
-  DenomKeyType,
-} from "@gnu-taler/taler-util";
-import { AvailableCoinInfo, selectPayCoinsLegacy } from "./coinSelection.js";
-
-function a(x: string): AmountJson {
-  const amt = Amounts.parse(x);
-  if (!amt) {
-    throw Error("invalid amount");
-  }
-  return amt;
-}
-
-function fakeAci(current: string, feeDeposit: string): AvailableCoinInfo {
-  return {
-    value: a(current),
-    availableAmount: a(current),
-    coinPub: "foobar",
-    denomPub: {
-      cipher: DenomKeyType.Rsa,
-      rsa_public_key: "foobar",
-      age_mask: 0,
-    },
-    feeDeposit: a(feeDeposit),
-    exchangeBaseUrl: "https://example.com/",
-    maxAge: AgeRestriction.AGE_UNRESTRICTED,
-  };
-}
-
-function fakeAciWithAgeRestriction(
-  current: string,
-  feeDeposit: string,
-): AvailableCoinInfo {
-  return {
-    value: a(current),
-    availableAmount: a(current),
-    coinPub: "foobar",
-    denomPub: {
-      cipher: DenomKeyType.Rsa,
-      rsa_public_key: "foobar",
-      age_mask: 2446657,
-    },
-    feeDeposit: a(feeDeposit),
-    exchangeBaseUrl: "https://example.com/",
-    maxAge: AgeRestriction.AGE_UNRESTRICTED,
-  };
-}
-
-test("it should be able to pay if merchant takes the fees", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAci("EUR:1.0", "EUR:0.1"),
-    fakeAci("EUR:1.0", "EUR:0.0"),
-  ];
-  acis.forEach((x, i) => (x.coinPub = String(i)));
-
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:2.0"),
-    depositFeeLimit: a("EUR:0.1"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-  });
-
-  if (!res) {
-    t.fail();
-    return;
-  }
-  t.deepEqual(res.coinPubs, ["1", "0"]);
-  t.pass();
-});
-
-test("it should take the last two coins if it pays less fees", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAci("EUR:1.0", "EUR:0.5"),
-    fakeAci("EUR:1.0", "EUR:0.0"),
-    // Merchant covers the fee, this one shouldn't be used
-    fakeAci("EUR:1.0", "EUR:0.0"),
-  ];
-  acis.forEach((x, i) => (x.coinPub = String(i)));
-
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:2.0"),
-    depositFeeLimit: a("EUR:0.5"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-  });
-
-  if (!res) {
-    t.fail();
-    return;
-  }
-  t.deepEqual(res.coinPubs, ["1", "2"]);
-  t.pass();
-});
-
-test("it should take the last coins if the merchant doest not take all the fee", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAci("EUR:1.0", "EUR:0.5"),
-    fakeAci("EUR:1.0", "EUR:0.5"),
-    // this coin should be selected instead of previous one with fee
-    fakeAci("EUR:1.0", "EUR:0.0"),
-  ];
-  acis.forEach((x, i) => (x.coinPub = String(i)));
-
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:2.0"),
-    depositFeeLimit: a("EUR:0.5"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-  });
-
-  if (!res) {
-    t.fail();
-    return;
-  }
-  t.deepEqual(res.coinPubs, ["2", "0"]);
-  t.pass();
-});
-
-test("it should use 3 coins to cover fees and payment", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAci("EUR:1.0", "EUR:0.5"), //contributed value 1 (fee by the merchant)
-    fakeAci("EUR:1.0", "EUR:0.5"), //contributed value .5
-    fakeAci("EUR:1.0", "EUR:0.5"), //contributed value .5
-  ];
-
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:2.0"),
-    depositFeeLimit: a("EUR:0.5"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-  });
-
-  if (!res) {
-    t.fail();
-    return;
-  }
-  t.true(res.coinPubs.length === 3);
-  t.pass();
-});
-
-test("it should return undefined if there is not enough coins", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAci("EUR:1.0", "EUR:0.5"),
-    fakeAci("EUR:1.0", "EUR:0.5"),
-    fakeAci("EUR:1.0", "EUR:0.5"),
-  ];
-
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:4.0"),
-    depositFeeLimit: a("EUR:0.2"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-  });
-
-  t.true(!res);
-  t.pass();
-});
-
-test("it should return undefined if there is not enough coins (taking into account fees)", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAci("EUR:1.0", "EUR:0.5"),
-    fakeAci("EUR:1.0", "EUR:0.5"),
-  ];
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:2.0"),
-    depositFeeLimit: a("EUR:0.2"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-  });
-  t.true(!res);
-  t.pass();
-});
-
-test("it should not count into customer fee if merchant can afford it", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAci("EUR:1.0", "EUR:0.1"),
-    fakeAci("EUR:1.0", "EUR:0.1"),
-  ];
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:2.0"),
-    depositFeeLimit: a("EUR:0.2"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-  });
-  t.truthy(res);
-  t.true(Amounts.cmp(res!.customerDepositFees, "EUR:0.0") === 0);
-  t.true(
-    Amounts.cmp(Amounts.sum(res!.coinContributions).amount, "EUR:2.0") === 0,
-  );
-  t.pass();
-});
-
-test("it should use the coins that spent less relative fee", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAci("EUR:1.0", "EUR:0.2"),
-    fakeAci("EUR:0.1", "EUR:0.2"),
-    fakeAci("EUR:0.05", "EUR:0.05"),
-    fakeAci("EUR:0.05", "EUR:0.05"),
-  ];
-  acis.forEach((x, i) => (x.coinPub = String(i)));
-
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:1.1"),
-    depositFeeLimit: a("EUR:0.4"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-  });
-  if (!res) {
-    t.fail();
-    return;
-  }
-  t.deepEqual(res.coinPubs, ["0", "2", "3"]);
-  t.pass();
-});
-
-test("coin selection 9", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAci("EUR:1.0", "EUR:0.2"),
-    fakeAci("EUR:0.2", "EUR:0.2"),
-  ];
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:1.2"),
-    depositFeeLimit: a("EUR:0.4"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-  });
-  if (!res) {
-    t.fail();
-    return;
-  }
-  t.true(res.coinContributions.length === 2);
-  t.true(
-    Amounts.cmp(Amounts.sum(res.coinContributions).amount, "EUR:1.2") === 0,
-  );
-  t.pass();
-});
-
-test("it should be able to use unrestricted coins for age restricted contract", (t) => {
-  const acis: AvailableCoinInfo[] = [
-    fakeAciWithAgeRestriction("EUR:1.0", "EUR:0.2"),
-    fakeAciWithAgeRestriction("EUR:0.2", "EUR:0.2"),
-  ];
-  const res = selectPayCoinsLegacy({
-    candidates: {
-      candidateCoins: acis,
-      wireFeesPerExchange: {},
-    },
-    contractTermsAmount: a("EUR:1.2"),
-    depositFeeLimit: a("EUR:0.4"),
-    wireFeeLimit: a("EUR:0"),
-    wireFeeAmortization: 1,
-    requiredMinimumAge: 13,
-  });
-  if (!res) {
-    t.fail();
-    return;
-  }
-  t.true(res.coinContributions.length === 2);
-  t.true(
-    Amounts.cmp(Amounts.sum(res.coinContributions).amount, "EUR:1.2") === 0,
-  );
-  t.pass();
-});
diff --git a/packages/taler-wallet-core/src/util/coinSelection.ts b/packages/taler-wallet-core/src/util/coinSelection.ts
index d2f12baf5..12f87a920 100644
--- a/packages/taler-wallet-core/src/util/coinSelection.ts
+++ b/packages/taler-wallet-core/src/util/coinSelection.ts
@@ -25,15 +25,11 @@
  */
 import {
   AgeCommitmentProof,
-  AgeRestriction,
   AmountJson,
   Amounts,
   DenominationPubKey,
-  ForcedCoinSel,
   Logger,
-  PayCoinSelection,
 } from "@gnu-taler/taler-util";
-import { checkLogicInvariant } from "./invariants.js";
 
 const logger = new Logger("coinSelection.ts");
 
@@ -194,245 +190,3 @@ export function tallyFees(
     wireFeeCoveredForExchange,
   };
 }
-
-/**
- * Given a list of candidate coins, select coins to spend under the merchant's
- * constraints.
- *
- * The prevPayCoins can be specified to "repair" a coin selection
- * by adding additional coins, after a broken (e.g. double-spent) coin
- * has been removed from the selection.
- *
- * This function is only exported for the sake of unit tests.
- */
-export function selectPayCoinsLegacy(
-  req: SelectPayCoinRequest,
-): PayCoinSelection | undefined {
-  const {
-    candidates,
-    contractTermsAmount,
-    depositFeeLimit,
-    wireFeeLimit,
-    wireFeeAmortization,
-  } = req;
-
-  if (candidates.candidateCoins.length === 0) {
-    return undefined;
-  }
-  const coinPubs: string[] = [];
-  const coinContributions: AmountJson[] = [];
-  const currency = contractTermsAmount.currency;
-
-  let tally: CoinSelectionTally = {
-    amountPayRemaining: contractTermsAmount,
-    amountWireFeeLimitRemaining: wireFeeLimit,
-    amountDepositFeeLimitRemaining: depositFeeLimit,
-    customerDepositFees: Amounts.getZero(currency),
-    customerWireFees: Amounts.getZero(currency),
-    wireFeeCoveredForExchange: new Set(),
-  };
-
-  const prevPayCoins = req.prevPayCoins ?? [];
-
-  // Look at existing pay coin selection and tally up
-  for (const prev of prevPayCoins) {
-    tally = tallyFees(
-      tally,
-      candidates.wireFeesPerExchange,
-      wireFeeAmortization,
-      prev.exchangeBaseUrl,
-      prev.feeDeposit,
-    );
-    tally.amountPayRemaining = Amounts.sub(
-      tally.amountPayRemaining,
-      prev.contribution,
-    ).amount;
-
-    coinPubs.push(prev.coinPub);
-    coinContributions.push(prev.contribution);
-  }
-
-  const prevCoinPubs = new Set(prevPayCoins.map((x) => x.coinPub));
-
-  // Sort by available amount (descending),  deposit fee (ascending) and
-  // denomPub (ascending) if deposit fee is the same
-  // (to guarantee deterministic results)
-  const candidateCoins = [...candidates.candidateCoins].sort(
-    (o1, o2) =>
-      -Amounts.cmp(o1.availableAmount, o2.availableAmount) ||
-      Amounts.cmp(o1.feeDeposit, o2.feeDeposit) ||
-      DenominationPubKey.cmp(o1.denomPub, o2.denomPub),
-  );
-
-  // FIXME:  Here, we should select coins in a smarter way.
-  // Instead of always spending the next-largest coin,
-  // we should try to find the smallest coin that covers the
-  // amount.
-
-  for (const aci of candidateCoins) {
-    // 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.availableAmount) > 0) {
-      continue;
-    }
-
-    if (Amounts.isZero(tally.amountPayRemaining)) {
-      // We have spent enough!
-      break;
-    }
-
-    // The same coin can't contribute twice to the same payment,
-    // by a fundamental, intentional limitation of the protocol.
-    if (prevCoinPubs.has(aci.coinPub)) {
-      continue;
-    }
-
-    if (req.requiredMinimumAge != null) {
-      const index = AgeRestriction.getAgeGroupIndex(
-        aci.denomPub.age_mask,
-        req.requiredMinimumAge,
-      );
-      // if (!aci.ageCommitmentProof) {
-      //   // No age restriction, can't use for this payment
-      //   continue;
-      // }
-      if (
-        aci.ageCommitmentProof &&
-        aci.ageCommitmentProof.proof.privateKeys.length < index
-      ) {
-        // Available age proofs to low, can't use for this payment
-        continue;
-      }
-    }
-
-    tally = tallyFees(
-      tally,
-      candidates.wireFeesPerExchange,
-      wireFeeAmortization,
-      aci.exchangeBaseUrl,
-      aci.feeDeposit,
-    );
-
-    let coinSpend = Amounts.max(
-      Amounts.min(tally.amountPayRemaining, aci.availableAmount),
-      aci.feeDeposit,
-    );
-
-    tally.amountPayRemaining = Amounts.sub(
-      tally.amountPayRemaining,
-      coinSpend,
-    ).amount;
-    coinPubs.push(aci.coinPub);
-    coinContributions.push(coinSpend);
-  }
-
-  if (Amounts.isZero(tally.amountPayRemaining)) {
-    return {
-      paymentAmount: contractTermsAmount,
-      coinContributions,
-      coinPubs,
-      customerDepositFees: tally.customerDepositFees,
-      customerWireFees: tally.customerWireFees,
-    };
-  }
-  return undefined;
-}
-
-export function selectForcedPayCoins(
-  forcedCoinSel: ForcedCoinSel,
-  req: SelectPayCoinRequest,
-): PayCoinSelection | undefined {
-  const {
-    candidates,
-    contractTermsAmount,
-    depositFeeLimit,
-    wireFeeLimit,
-    wireFeeAmortization,
-  } = req;
-
-  if (candidates.candidateCoins.length === 0) {
-    return undefined;
-  }
-  const coinPubs: string[] = [];
-  const coinContributions: AmountJson[] = [];
-  const currency = contractTermsAmount.currency;
-
-  let tally: CoinSelectionTally = {
-    amountPayRemaining: contractTermsAmount,
-    amountWireFeeLimitRemaining: wireFeeLimit,
-    amountDepositFeeLimitRemaining: depositFeeLimit,
-    customerDepositFees: Amounts.getZero(currency),
-    customerWireFees: Amounts.getZero(currency),
-    wireFeeCoveredForExchange: new Set(),
-  };
-
-  // Not supported by forced coin selection
-  checkLogicInvariant(!req.prevPayCoins);
-
-  // Sort by available amount (descending),  deposit fee (ascending) and
-  // denomPub (ascending) if deposit fee is the same
-  // (to guarantee deterministic results)
-  const candidateCoins = [...candidates.candidateCoins].sort(
-    (o1, o2) =>
-      -Amounts.cmp(o1.availableAmount, o2.availableAmount) ||
-      Amounts.cmp(o1.feeDeposit, o2.feeDeposit) ||
-      DenominationPubKey.cmp(o1.denomPub, o2.denomPub),
-  );
-
-  // FIXME:  Here, we should select coins in a smarter way.
-  // Instead of always spending the next-largest coin,
-  // we should try to find the smallest coin that covers the
-  // amount.
-
-  // Set of spent coin indices from candidate coins
-  const spentSet: Set<number> = new Set();
-
-  for (const forcedCoin of forcedCoinSel.coins) {
-    let aci: AvailableCoinInfo | undefined = undefined;
-    for (let i = 0; i < candidateCoins.length; i++) {
-      if (spentSet.has(i)) {
-        continue;
-      }
-      if (
-        Amounts.cmp(forcedCoin.value, candidateCoins[i].availableAmount) != 0
-      ) {
-        continue;
-      }
-      spentSet.add(i);
-      aci = candidateCoins[i];
-      break;
-    }
-
-    if (!aci) {
-      throw Error("can't find coin for forced coin selection");
-    }
-
-    tally = tallyFees(
-      tally,
-      candidates.wireFeesPerExchange,
-      wireFeeAmortization,
-      aci.exchangeBaseUrl,
-      aci.feeDeposit,
-    );
-
-    let coinSpend = Amounts.parseOrThrow(forcedCoin.contribution);
-
-    tally.amountPayRemaining = Amounts.sub(
-      tally.amountPayRemaining,
-      coinSpend,
-    ).amount;
-    coinPubs.push(aci.coinPub);
-    coinContributions.push(coinSpend);
-  }
-
-  if (Amounts.isZero(tally.amountPayRemaining)) {
-    return {
-      paymentAmount: contractTermsAmount,
-      coinContributions,
-      coinPubs,
-      customerDepositFees: tally.customerDepositFees,
-      customerWireFees: tally.customerWireFees,
-    };
-  }
-  return undefined;
-}