1 files changed, 245 insertions, 0 deletions
diff --git a/src/wallet-impl/refund.ts b/src/wallet-impl/refund.ts
new file mode 100644
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+++ b/src/wallet-impl/refund.ts
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+/*
+ This file is part of GNU Taler
+ (C) 2019 GNUnet e.V.
+
+ 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/>
+ */
+
+import {
+  MerchantRefundResponse,
+  RefundRequest,
+  MerchantRefundPermission,
+} from "../talerTypes";
+import { PurchaseRecord, Stores, CoinRecord, CoinStatus } from "../dbTypes";
+import { getTimestampNow } from "../walletTypes";
+import {
+  oneShotMutate,
+  oneShotGet,
+  runWithWriteTransaction,
+  oneShotIterIndex,
+} from "../util/query";
+import { InternalWalletState } from "./state";
+import { parseRefundUri } from "../util/taleruri";
+import { Logger } from "../util/logging";
+import { AmountJson } from "../util/amounts";
+import * as Amounts from "../util/amounts";
+import { getTotalRefreshCost, refresh } from "./refresh";
+
+const logger = new Logger("refund.ts");
+
+export async function getFullRefundFees(
+  ws: InternalWalletState,
+  refundPermissions: MerchantRefundPermission[],
+): Promise<AmountJson> {
+  if (refundPermissions.length === 0) {
+    throw Error("no refunds given");
+  }
+  const coin0 = await oneShotGet(
+    ws.db,
+    Stores.coins,
+    refundPermissions[0].coin_pub,
+  );
+  if (!coin0) {
+    throw Error("coin not found");
+  }
+  let feeAcc = Amounts.getZero(
+    Amounts.parseOrThrow(refundPermissions[0].refund_amount).currency,
+  );
+
+  const denoms = await oneShotIterIndex(
+    ws.db,
+    Stores.denominations.exchangeBaseUrlIndex,
+    coin0.exchangeBaseUrl,
+  ).toArray();
+
+  for (const rp of refundPermissions) {
+    const coin = await oneShotGet(ws.db, Stores.coins, rp.coin_pub);
+    if (!coin) {
+      throw Error("coin not found");
+    }
+    const denom = await oneShotGet(ws.db, Stores.denominations, [
+      coin0.exchangeBaseUrl,
+      coin.denomPub,
+    ]);
+    if (!denom) {
+      throw Error(`denom not found (${coin.denomPub})`);
+    }
+    // FIXME:  this assumes that the refund already happened.
+    // When it hasn't, the refresh cost is inaccurate.  To fix this,
+    // we need introduce a flag to tell if a coin was refunded or
+    // refreshed normally (and what about incremental refunds?)
+    const refundAmount = Amounts.parseOrThrow(rp.refund_amount);
+    const refundFee = Amounts.parseOrThrow(rp.refund_fee);
+    const refreshCost = getTotalRefreshCost(
+      denoms,
+      denom,
+      Amounts.sub(refundAmount, refundFee).amount,
+    );
+    feeAcc = Amounts.add(feeAcc, refreshCost, refundFee).amount;
+  }
+  return feeAcc;
+}
+
+async function submitRefunds(
+  ws: InternalWalletState,
+  contractTermsHash: string,
+): Promise<void> {
+  const purchase = await oneShotGet(ws.db, Stores.purchases, contractTermsHash);
+  if (!purchase) {
+    console.error(
+      "not submitting refunds, contract terms not found:",
+      contractTermsHash,
+    );
+    return;
+  }
+  const pendingKeys = Object.keys(purchase.refundsPending);
+  if (pendingKeys.length === 0) {
+    return;
+  }
+  for (const pk of pendingKeys) {
+    const perm = purchase.refundsPending[pk];
+    const req: RefundRequest = {
+      coin_pub: perm.coin_pub,
+      h_contract_terms: purchase.contractTermsHash,
+      merchant_pub: purchase.contractTerms.merchant_pub,
+      merchant_sig: perm.merchant_sig,
+      refund_amount: perm.refund_amount,
+      refund_fee: perm.refund_fee,
+      rtransaction_id: perm.rtransaction_id,
+    };
+    console.log("sending refund permission", perm);
+    // FIXME: not correct once we support multiple exchanges per payment
+    const exchangeUrl = purchase.payReq.coins[0].exchange_url;
+    const reqUrl = new URL("refund", exchangeUrl);
+    const resp = await ws.http.postJson(reqUrl.href, req);
+    if (resp.status !== 200) {
+      console.error("refund failed", resp);
+      continue;
+    }
+
+    // Transactionally mark successful refunds as done
+    const transformPurchase = (
+      t: PurchaseRecord | undefined,
+    ): PurchaseRecord | undefined => {
+      if (!t) {
+        console.warn("purchase not found, not updating refund");
+        return;
+      }
+      if (t.refundsPending[pk]) {
+        t.refundsDone[pk] = t.refundsPending[pk];
+        delete t.refundsPending[pk];
+      }
+      return t;
+    };
+    const transformCoin = (
+      c: CoinRecord | undefined,
+    ): CoinRecord | undefined => {
+      if (!c) {
+        console.warn("coin not found, can't apply refund");
+        return;
+      }
+      const refundAmount = Amounts.parseOrThrow(perm.refund_amount);
+      const refundFee = Amounts.parseOrThrow(perm.refund_fee);
+      c.status = CoinStatus.Dirty;
+      c.currentAmount = Amounts.add(c.currentAmount, refundAmount).amount;
+      c.currentAmount = Amounts.sub(c.currentAmount, refundFee).amount;
+
+      return c;
+    };
+
+    await runWithWriteTransaction(
+      ws.db,
+      [Stores.purchases, Stores.coins],
+      async tx => {
+        await tx.mutate(Stores.purchases, contractTermsHash, transformPurchase);
+        await tx.mutate(Stores.coins, perm.coin_pub, transformCoin);
+      },
+    );
+    refresh(ws, perm.coin_pub);
+  }
+
+  ws.badge.showNotification();
+  ws.notifier.notify();
+}
+
+export async function acceptRefundResponse(
+  ws: InternalWalletState,
+  refundResponse: MerchantRefundResponse,
+): Promise<string> {
+  const refundPermissions = refundResponse.refund_permissions;
+
+  if (!refundPermissions.length) {
+    console.warn("got empty refund list");
+    throw Error("empty refund");
+  }
+
+  /**
+   * Add refund to purchase if not already added.
+   */
+  function f(t: PurchaseRecord | undefined): PurchaseRecord | undefined {
+    if (!t) {
+      console.error("purchase not found, not adding refunds");
+      return;
+    }
+
+    t.timestamp_refund = getTimestampNow();
+
+    for (const perm of refundPermissions) {
+      if (
+        !t.refundsPending[perm.merchant_sig] &&
+        !t.refundsDone[perm.merchant_sig]
+      ) {
+        t.refundsPending[perm.merchant_sig] = perm;
+      }
+    }
+    return t;
+  }
+
+  const hc = refundResponse.h_contract_terms;
+
+  // Add the refund permissions to the purchase within a DB transaction
+  await oneShotMutate(ws.db, Stores.purchases, hc, f);
+  ws.notifier.notify();
+
+  await submitRefunds(ws, hc);
+
+  return hc;
+}
+
+/**
+ * Accept a refund, return the contract hash for the contract
+ * that was involved in the refund.
+ */
+export async function applyRefund(
+  ws: InternalWalletState,
+  talerRefundUri: string,
+): Promise<string> {
+  const parseResult = parseRefundUri(talerRefundUri);
+
+  if (!parseResult) {
+    throw Error("invalid refund URI");
+  }
+
+  const refundUrl = parseResult.refundUrl;
+
+  logger.trace("processing refund");
+  let resp;
+  try {
+    resp = await ws.http.get(refundUrl);
+  } catch (e) {
+    console.error("error downloading refund permission", e);
+    throw e;
+  }
+
+  const refundResponse = MerchantRefundResponse.checked(resp.responseJson);
+  return acceptRefundResponse(ws, refundResponse);
+}