feat: create a feeCollectorDepositFacet

Author: michaelfig

packages/vats/src/vat-bank.js

@@ -172,12 +172,6 @@ export function buildRootObject(_vatPowers) {
       /** @type {Store<string, Bank>} */
       const addressToBank = makeStore('address');
 
-      /** @type {NotifierRecord<string[]>} */
-      const {
-        notifier: accountsNotifier,
-        updater: accountsUpdater,
-      } = makeNotifierKit([...addressToBank.keys()]);
-
       /**
        * Create a new personal bank interface for a given address.
        *
@@ -257,22 +251,9 @@ export function buildRootObject(_vatPowers) {
           },
         });
         addressToBank.init(address, bank);
-        accountsUpdater.updateState([...addressToBank.keys()]);
         return bank;
       };
 
-      const bankDepositFacet = Far('bankDepositFacet', {
-        getAccountsNotifier() {
-          return accountsNotifier;
-        },
-        deposit(brand, account, payment) {
-          // The purse will do the proper verification as part of deposit.
-          const bank = getBankForAddress(account);
-          const purse = bank.getPurse(brand);
-          return E(purse).deposit(payment);
-        },
-      });
-
       return Far('bankManager', {
         /**
          * Returns assets as they are added to the bank.
@@ -282,9 +263,38 @@ export function buildRootObject(_vatPowers) {
         getAssetSubscription() {
           return harden(assetSubscription);
         },
-        getDepositFacet() {
-          return bankDepositFacet;
+        /**
+         * @param {string} denom
+         * @param {AssetIssuerKit} feeKit
+         * @returns {import('@agoric/eventual-send').EOnly<DepositFacet>}
+         */
+        getFeeCollectorDepositFacet(denom, feeKit) {
+          if (!bankCall) {
+            throw Error(`Bank doesn't implement fee collectors`);
+          }
+
+          /** @type {VirtualPurseController} */
+          const feeVpc = harden({
+            async *getBalances(_brand) {
+              // Never resolve!
+              yield new Promise(_ => {});
+            },
+            async pullAmount(_amount) {
+              throw Error(`Cannot pull from fee collector`);
+            },
+            async pushAmount(amount) {
+              const value = AmountMath.getValue(feeKit.brand, amount);
+              await bankCall({
+                type: 'VPURSE_GIVE_TO_FEE_COLLECTOR',
+                denom,
+                amount: `${value}`,
+              });
+            },
+          });
+          const vp = makeVirtualPurse(feeVpc, feeKit);
+          return E(vp).getDepositFacet();
         },
+
         /**
          * Add an asset to the bank, and publish it to the subscriptions.
          *

packages/vats/test/test-vat-bank.js

@@ -8,7 +8,7 @@ import { Far } from '@agoric/marshal';
 import { buildRootObject } from '../src/vat-bank';
 
 test('communication', async t => {
-  t.plan(24);
+  t.plan(29);
   const bankVat = E(buildRootObject)();
 
   /** @type {undefined | { fromBridge: (srcID: string, obj: any) => void }} */
@@ -54,6 +54,15 @@ test('communication', async t => {
           break;
         }
 
+        case 'VPURSE_GIVE_TO_FEE_COLLECTOR': {
+          const { amount, denom, type: _type, ...rest } = obj;
+          t.is(denom, 'ufee');
+          t.is(amount, '12');
+          t.deepEqual(rest, {});
+          ret = true;
+          break;
+        }
+
         default: {
           t.is(obj, null);
         }
@@ -131,4 +140,16 @@ test('communication', async t => {
       AmountMath.make(kit.brand, BigInt(balance.amount)),
     ),
   );
+
+  const { mint, ...feeKit } = makeIssuerKit('fee', AssetKind.NAT, {
+    decimalPlaces: 6,
+  });
+
+  // Try sending in some fees.
+  const feeAmount = AmountMath.make(feeKit.brand, 12n);
+  const feePayment = mint.mintPayment(feeAmount);
+  const feeReceived = await E(
+    E(bankMgr).getFeeCollectorDepositFacet('ufee', feeKit),
+  ).receive(feePayment);
+  t.assert(AmountMath.isEqual(feeReceived, feeAmount));
 });