refactor(grpc): convert WalletUnlocker to class

Convert the walletUnlocker object to a class with an interface that is
consistent with the Lightning class.

app/lib/lnd/lightning.js

@@ -25,7 +25,7 @@ type LightningSubscriptionsType = {
  */
 class Lightning {
   mainWindow: BrowserWindow
-  lnd: any
+  service: any
   lndConfig: LndConfig
   subscriptions: LightningSubscriptionsType
   _fsm: StateMachine
@@ -40,7 +40,7 @@ class Lightning {
 
   constructor(lndConfig: LndConfig) {
     this.mainWindow = null
-    this.lnd = null
+    this.service = null
     this.lndConfig = lndConfig
     this.subscriptions = {
       channelGraph: null,
@@ -89,11 +89,11 @@ class Lightning {
       const credentials = grpc.credentials.combineChannelCredentials(sslCreds, macaroonCreds)
 
       // Create a new gRPC client instance.
-      this.lnd = new rpc.lnrpc.Lightning(host, credentials)
+      this.service = new rpc.lnrpc.Lightning(host, credentials)
 
       // Wait for the gRPC connection to be established.
       return new Promise((resolve, reject) => {
-        grpc.waitForClientReady(this.lnd, getDeadline(2), err => {
+        grpc.waitForClientReady(this.service, getDeadline(2), err => {
           if (err) {
             return reject(err)
           }
@@ -109,8 +109,8 @@ class Lightning {
   onBeforeDisconnect() {
     mainLog.info('Disconnecting from Lightning gRPC service')
     this.unsubscribe()
-    if (this.lnd) {
-      this.lnd.close()
+    if (this.service) {
+      this.service.close()
     }
   }
 
@@ -121,7 +121,7 @@ class Lightning {
     mainLog.info('Shutting down Lightning daemon')
     this.unsubscribe()
     return new Promise((resolve, reject) => {
-      this.lnd.stopDaemon({}, (err, data) => {
+      this.service.stopDaemon({}, (err, data) => {
         if (err) {
           return reject(err)
         }
@@ -137,8 +137,8 @@ class Lightning {
   /**
    * Hook up lnd restful methods.
    */
-  lndMethods(event: Event, msg: string, data: any) {
-    return methods(this.lnd, mainLog, event, msg, data)
+  registerMethods(event: Event, msg: string, data: any) {
+    return methods(this.service, mainLog, event, msg, data)
   }
 
   /**

app/lib/lnd/subscribe/channelgraph.js

@@ -2,7 +2,7 @@ import { status } from 'grpc'
 import { mainLog } from '../../utils/log'
 
 export default function subscribeToChannelGraph() {
-  const call = this.lnd.subscribeChannelGraph({})
+  const call = this.service.subscribeChannelGraph({})
 
   call.on('data', channelGraphData => {
     mainLog.info('CHANNELGRAPH:', channelGraphData)

app/lib/lnd/subscribe/invoices.js

@@ -2,7 +2,7 @@ import { status } from 'grpc'
 import { mainLog } from '../../utils/log'
 
 export default function subscribeToInvoices() {
-  const call = this.lnd.subscribeInvoices({})
+  const call = this.service.subscribeInvoices({})
 
   call.on('data', invoice => {
     mainLog.info('INVOICE:', invoice)

app/lib/lnd/subscribe/transactions.js

@@ -2,7 +2,7 @@ import { status } from 'grpc'
 import { mainLog } from '../../utils/log'
 
 export default function subscribeToTransactions() {
-  const call = this.lnd.subscribeTransactions({})
+  const call = this.service.subscribeTransactions({})
 
   call.on('data', transaction => {
     mainLog.info('TRANSACTION:', transaction)

app/lib/lnd/walletUnlocker.js

@@ -1,23 +1,54 @@
-import fs from 'fs'
+// @flow
+
 import grpc from 'grpc'
 import { loadSync } from '@grpc/proto-loader'
-import walletUnlockerMethods from './walletUnlockerMethods'
+import StateMachine from 'javascript-state-machine'
+import LndConfig from './config'
+import { getDeadline, validateHost, createSslCreds, createMacaroonCreds } from './util'
+import methods from './walletUnlockerMethods'
 import { mainLog } from '../utils/log'
 
-export const initWalletUnlocker = lndConfig => {
-  const walletUnlockerObj = walletUnlocker(lndConfig)
-  const walletUnlockerMethodsCallback = (event, msg, data) =>
-    walletUnlockerMethods(lndConfig, walletUnlockerObj, mainLog, event, msg, data)
+/**
+ * Creates an LND grpc client lightning service.
+ * @returns {WalletUnlocker}
+ */
+class WalletUnlocker {
+  service: any
+  lndConfig: LndConfig
+  _fsm: StateMachine
 
-  return walletUnlockerMethodsCallback
-}
+  // Transitions provided by the state machine.
+  connect: any
+  disconnect: any
+  terminate: any
+  is: any
+  can: any
+  state: string
+
+  constructor(lndConfig: LndConfig) {
+    this.service = null
+    this.lndConfig = lndConfig
+
+    // Initialize the state machine.
+    this._fsm()
+  }
 
-export const walletUnlocker = lndConfig => {
-  const lndCert = fs.readFileSync(lndConfig.cert)
-  const credentials = grpc.credentials.createSsl(lndCert)
+  // ------------------------------------
+  // FSM Callbacks
+  // ------------------------------------
 
+  /**
+   * Connect to the gRPC interface and verify it is functional.
+   * @return {Promise<rpc.lnrpc.WalletUnlocker>}
+   */
+  async onBeforeConnect() {
+    mainLog.info('Connecting to WalletUnlocker gRPC service')
+    const { rpcProtoPath, host, cert, macaroon } = this.lndConfig
+
+    // Verify that the host is valid before creating a gRPC client that is connected to it.
+    return await validateHost(host).then(async () => {
       // Load the gRPC proto file.
-  // The following options object closely approximates the existing behavior of grpc.load
+      // The following options object closely approximates the existing behavior of grpc.load.
       // See https://github.com/grpc/grpc-node/blob/master/packages/grpc-protobufjs/README.md
       const options = {
         keepCase: true,
@@ -26,11 +57,61 @@ export const walletUnlocker = lndConfig => {
         defaults: true,
         oneofs: true
       }
-  const packageDefinition = loadSync(lndConfig.rpcProtoPath, options)
+      const packageDefinition = loadSync(rpcProtoPath, options)
 
       // Load gRPC package definition as a gRPC object hierarchy.
       const rpc = grpc.loadPackageDefinition(packageDefinition)
 
-  // Instantiate a new connection to the WalletUnlocker interface.
-  return new rpc.lnrpc.WalletUnlocker(lndConfig.host, credentials)
+      // Create ssl and macaroon credentials to use with the gRPC client.
+      const [sslCreds, macaroonCreds] = await Promise.all([
+        createSslCreds(cert),
+        createMacaroonCreds(macaroon)
+      ])
+      const credentials = grpc.credentials.combineChannelCredentials(sslCreds, macaroonCreds)
+
+      // Create a new gRPC client instance.
+      this.service = new rpc.lnrpc.WalletUnlocker(host, credentials)
+
+      // Wait for the gRPC connection to be established.
+      return new Promise((resolve, reject) => {
+        grpc.waitForClientReady(this.service, getDeadline(2), err => {
+          if (err) {
+            return reject(err)
+          }
+          return resolve()
+        })
+      })
+    })
+  }
+
+  /**
+   * Discomnnect the gRPC service.
+   */
+  onBeforeDisconnect() {
+    mainLog.info('Disconnecting from WalletUnlocker gRPC service')
+    if (this.service) {
+      this.service.close()
+    }
+  }
+
+  // ------------------------------------
+  // Helpers
+  // ------------------------------------
+
+  /**
+   * Hook up lnd restful methods.
+   */
+  registerMethods(event: Event, msg: string, data: any) {
+    return methods(this.service, mainLog, event, msg, data, this.lndConfig)
+  }
 }
+
+StateMachine.factory(WalletUnlocker, {
+  init: 'ready',
+  transitions: [
+    { name: 'connect', from: 'ready', to: 'connected' },
+    { name: 'disconnect', from: 'connected', to: 'ready' }
+  ]
+})
+
+export default WalletUnlocker

app/lib/lnd/walletUnlockerMethods/index.js

@@ -1,7 +1,7 @@
 import { dirname } from 'path'
 import * as walletController from '../methods/walletController'
 
-export default function(lndConfig, walletUnlocker, log, event, msg, data) {
+export default function(walletUnlocker, log, event, msg, data, lndConfig) {
   const decorateError = error => {
     switch (error.code) {
       // wallet already exists

app/lib/zap/controller.js

@@ -4,12 +4,13 @@ import { app, ipcMain, dialog, BrowserWindow } from 'electron'
 import pick from 'lodash.pick'
 import Store from 'electron-store'
 import StateMachine from 'javascript-state-machine'
+import { mainLog } from '../utils/log'
+import { isLndRunning } from '../lnd/util'
+
 import LndConfig from '../lnd/config'
 import Lightning from '../lnd/lightning'
 import Neutrino from '../lnd/neutrino'
-import { initWalletUnlocker } from '../lnd/walletUnlocker'
-import { mainLog } from '../utils/log'
-import { isLndRunning } from '../lnd/util'
+import WalletUnlocker from '../lnd/walletUnlocker'
 
 type onboardingOptions = {
   type: 'local' | 'custom' | 'btcpayserver',
@@ -53,6 +54,7 @@ class ZapController {
   mainWindow: BrowserWindow
   neutrino: Neutrino
   lightning: Lightning
+  walletUnlocker: WalletUnlocker
   splashScreenTime: number
   lndConfig: LndConfig
   _fsm: StateMachine
@@ -244,24 +246,24 @@ class ZapController {
   /**
    * Start the wallet unlocker.
    */
-  startWalletUnlocker() {
+  async startWalletUnlocker() {
     mainLog.info('Establishing connection to Wallet Unlocker gRPC interface...')
+    this.walletUnlocker = new WalletUnlocker(this.lndConfig)
+
+    // Connect to the WalletUnlocker interface.
     try {
-      const walletUnlockerMethods = initWalletUnlocker(this.lndConfig)
+      await this.walletUnlocker.connect()
 
-      // Listen for all gRPC restful methods
-      ipcMain.on('walletUnlocker', (event, { msg, data }) => {
-        walletUnlockerMethods(event, msg, data)
-      })
+      // Listen for all gRPC restful methods and pass to gRPC.
+      ipcMain.on('walletUnlocker', (event, { msg, data }) =>
+        this.walletUnlocker.registerMethods(event, msg, data)
+      )
 
       // Notify the renderer that the wallet unlocker is active.
       this.sendMessage('walletUnlockerGrpcActive')
-    } catch (error) {
-      dialog.showMessageBox({
-        type: 'error',
-        message: `Unable to start lnd wallet unlocker. Please check your lnd node and try again: ${error}`
-      })
-      app.quit()
+    } catch (err) {
+      mainLog.warn('Unable to connect to WalletUnlocker gRPC interface: %o', err)
+      throw err
     }
   }
 
@@ -279,7 +281,7 @@ class ZapController {
       this.lightning.subscribe(this.mainWindow)
 
       // Listen for all gRPC restful methods and pass to gRPC.
-      ipcMain.on('lnd', (event, { msg, data }) => this.lightning.lndMethods(event, msg, data))
+      ipcMain.on('lnd', (event, { msg, data }) => this.lightning.registerMethods(event, msg, data))
 
       // Let the renderer know that we are connected.
       this.sendMessage('lightningGrpcActive')

test/unit/lnd/lightning.spec.js

@@ -15,7 +15,7 @@ describe('Lightning', function() {
         expect(this.lightning.mainWindow).toBeNull()
       })
       it('should set the "lnd" property to null', () => {
-        expect(this.lightning.lnd).toBeNull()
+        expect(this.lightning.service).toBeNull()
       })
       it('should initialise the "subscriptions" object with null values', () => {
         expect(this.lightning.subscriptions).toMatchObject({