PsmType service rough scaffolding

packages/dai-plugin-mcd/contracts/addresses/kovan.json

@@ -68,7 +68,8 @@
   "MCD_JOIN_KNC_A": "0xE42427325A0e4c8e194692FfbcACD92C2C381598",
   "MCD_FLIP_KNC_A": "0xf14Ec3538C86A31bBf576979783a8F6dbF16d571",
 
-  "MCD_JOIN_PSM_USDC_A": "0xc2FB16712AD538EbcBabB00DfAC5fa511A4cc657",
-  "MCD_FLIP_PSM_USDC_A": "0x481d4eb969a821B6A8137D9c352aA7a7cBc4C8F2",
-  "PSM_USDC_A": "0xE13eF5966031A50A8df9D7612366a56e3BB36CB1"
+  "MCD_FLIP_PSM_USDC_A": "0x481d4eb969a821B6A8137D9c352aA7a7cBc4C8F2"
+  "MCD_JOIN_PSM_USDC_A": "0xaf774866c4b165b88c558C7891290698cf7Ed6B5",
+  "PSM_USDC_A": "0xAfB79e262B7A07666161B95992934eB0AE230Fb4",
+
 }

packages/dai-plugin-mcd/src/PsmType.js

@@ -0,0 +1,37 @@
+import assert from 'assert';
+import { stringToBytes } from './utils';
+import tracksTransactions from './utils/tracksTransactions';
+
+export default class PsmType {
+  constructor(
+    psmTypeService,
+    { currency, ilk, decimals },
+    options = { prefect: true }
+  ) {
+    assert(currency && ilk, 'currency and ilk are required');
+
+    this._psmTypeService = psmTypeService;
+    this.currency = currency;
+    this.decimals = decimals;
+    this.ilk = ilk;
+    this._ilkBytes = stringToBytes(this.ilk);
+    this.cache = {};
+    if (options.prefetch) this.prefetch();
+  }
+
+  get feeIn() {}
+
+  get feeOut() {}
+
+  prefetch() {}
+
+  async reset() {
+    this._prefetchPromise = null;
+    this.cache = {};
+  }
+
+  _getCached(name) {
+    assert(this.cache[name], `${name} is not cached`);
+    return this.cache[name];
+  }
+}

packages/dai-plugin-mcd/src/PsmTypeService.js

@@ -0,0 +1,27 @@
+import { PublicService } from '@makerdao/services-core';
+import { ServiceRoles } from './constants';
+import PsmType from './PsmType';
+
+const { PSM_TYPE } = ServiceRoles;
+
+export default class PsmService extends PublicService {
+  constructor(name = PSM_TYPE) {
+    super(name);
+    this.reset = this.resetAllPsmTypes;
+  }
+
+  initialize(settings = {}) {
+    this.settings = settings;
+    this.psmTypes = (settings.psmTypes || []).map(
+      psmType => new PsmType(this, psmType, { prefetch: settings.prefetch })
+    );
+  }
+
+  async connect() {
+    if (this.settings.prefetch) await this.prefetchAllCdpTypes();
+  }
+
+  async prefetchAllPsmTypes() {
+    await Promise.all(this.psmTypes.map(type => type.prefetch()));
+  }
+}

packages/dai-plugin-mcd/src/constants.js

@@ -6,7 +6,7 @@ export const ServiceRoles = {
   AUCTION: 'mcd:auction',
   SYSTEM_DATA: 'mcd:systemData',
   SAVINGS: 'mcd:savings',
-  PSM: 'mcd:psm'
+  PSM_TYPE: 'mcd:psmType'
 };
 
 export const WAD = new BigNumber('1e18');

packages/dai-plugin-mcd/src/index.js

@@ -12,12 +12,21 @@ import SavingsService from './SavingsService';
 import CdpTypeService from './CdpTypeService';
 import AuctionService from './AuctionService';
 import SystemDataService from './SystemDataService';
+import PsmService from './PsmService';
+
 import { ServiceRoles as ServiceRoles_ } from './constants';
 import BigNumber from 'bignumber.js';
 import wethAbi from '../contracts/abis/WETH9.json';
 
 export const ServiceRoles = ServiceRoles_;
-const { CDP_MANAGER, CDP_TYPE, SYSTEM_DATA, AUCTION, SAVINGS } = ServiceRoles;
+const {
+  CDP_MANAGER,
+  CDP_TYPE,
+  SYSTEM_DATA,
+  AUCTION,
+  SAVINGS,
+  PSM_TYPE
+} = ServiceRoles;
 
 // look up contract ABIs using abiMap.
 // if an exact match is not found, prefix-match against keys ending in *, e.g.
@@ -83,6 +92,10 @@ export const defaultCdpTypes = [
   { currency: ZRX, ilk: 'ZRX-A', decimals: 18 }
 ];
 
+export const defaultPsmTypes = [
+  { currency: USDC, ilk: 'PSM-USDC-A', decimals: 6 }
+];
+
 export const SAI = createCurrency('SAI');
 
 export const ALLOWANCE_AMOUNT = BigNumber(
@@ -102,7 +115,12 @@ export const defaultTokens = [
 export const McdPlugin = {
   addConfig: (
     _,
-    { cdpTypes = defaultCdpTypes, addressOverrides, prefetch = true } = {}
+    {
+      cdpTypes = defaultCdpTypes,
+      psmTypes = defaultPsmTypes,
+      addressOverrides,
+      prefetch = true
+    } = {}
   ) => {
     if (addressOverrides) {
       addContracts = mapValues(addContracts, (contractDetails, name) => ({
@@ -141,13 +159,15 @@ export const McdPlugin = {
         CDP_TYPE,
         AUCTION,
         SYSTEM_DATA,
-        SAVINGS
+        SAVINGS,
+        PSM_TYPE
       ],
       [CDP_TYPE]: [CdpTypeService, { cdpTypes, prefetch }],
       [CDP_MANAGER]: CdpManager,
       [SAVINGS]: SavingsService,
       [AUCTION]: AuctionService,
-      [SYSTEM_DATA]: SystemDataService
+      [SYSTEM_DATA]: SystemDataService,
+      [PSM_TYPE]: [PsmService, { psmTypes, prefetch }]
     };
   }
 };