Refactor QR scanner to move all error handling within component (#7885)

The QR scanner component error handling would sometimes redirect the
user to the wrong page. It was also confusingly handled in two places;
the action used to open the QR scanner, and the scanner component.
The error handling has now been corrected, simplified, and integrated
into the QR scanner component itself.

The old way of handling an error within the component was to close the
modal, then call the action to open it all over again. This action took
a route parameter, which instructed the action on which route to open
if the fullscreen UI needed to be opened (as the fullscreen UI is the
only one where the browser will show the camera permission prompt).

This redirection worked just fine for handling the initial opening
of the QR scanner modal. But for any subsequent errors the same action
was used with a _default route_, meaning the user could click "try
again" and find themselves on a completely different screen.

Instead, errors now trigger a state change instead of closing and re-
opening the modal. The permission checks in the action have been
integrated into the component as well.

One functional change is that the scenario where you have an invalid
QR code has been made an error. Previously this just showed the error
message below the video preview, but left the user with no way to try
again. There error page has a "Try again" button, so it seemed better
suited as an error. Also the message literally started with "Error:".

Another functional change is that _all_ errors during initialization
will result in the error UI being shown. Previously there was one error
case that would instead log to the console and leave the user stuck.

ui/app/components/app/modals/qr-scanner/qr-scanner.component.js

@@ -1,99 +1,139 @@
 import React, { Component } from 'react'
 import PropTypes from 'prop-types'
+import log from 'loglevel'
 import { BrowserQRCodeReader } from '@zxing/library'
+import { getEnvironmentType } from '../../../../../../app/scripts/lib/util'
+import { ENVIRONMENT_TYPE_FULLSCREEN } from '../../../../../../app/scripts/lib/enums'
 import Spinner from '../../../ui/spinner'
 import WebcamUtils from '../../../../../lib/webcam-utils'
 import PageContainerFooter from '../../../ui/page-container/page-container-footer/page-container-footer.component'
 
+const READY_STATE = {
+  ACCESSING_CAMERA: 'ACCESSING_CAMERA',
+  NEED_TO_ALLOW_ACCESS: 'NEED_TO_ALLOW_ACCESS',
+  READY: 'READY',
+}
+
 export default class QrScanner extends Component {
   static propTypes = {
     hideModal: PropTypes.func.isRequired,
-    qrCodeDetected: PropTypes.func,
-    scanQrCode: PropTypes.func,
-    error: PropTypes.bool,
-    errorType: PropTypes.string,
+    qrCodeDetected: PropTypes.func.isRequired,
   }
 
   static contextTypes = {
     t: PropTypes.func,
   }
 
-  constructor (props, context) {
+  constructor (props) {
     super(props)
 
-    this.state = {
-      ready: false,
-      msg: context.t('accessingYourCamera'),
-    }
+    this.state = this.getInitialState()
     this.codeReader = null
     this.permissionChecker = null
-    this.needsToReinit = false
+    this.mounted = false
 
     // Clear pre-existing qr code data before scanning
     this.props.qrCodeDetected(null)
   }
 
   componentDidMount () {
+    this.mounted = true
+    this.checkEnvironment()
+  }
+
+  componentDidUpdate (_, prevState) {
+    const { ready } = this.state
+
+    if (prevState.ready !== ready) {
+      if (ready === READY_STATE.READY) {
+        this.initCamera()
+      } else if (ready === READY_STATE.NEED_TO_ALLOW_ACCESS) {
+        this.checkPermissions()
+      }
+    }
+  }
+
+  getInitialState () {
+    return {
+      ready: READY_STATE.ACCESSING_CAMERA,
+      error: null,
+    }
+  }
+
+  checkEnvironment = async () => {
+    try {
+      const { environmentReady } = await WebcamUtils.checkStatus()
+      if (!environmentReady && getEnvironmentType() !== ENVIRONMENT_TYPE_FULLSCREEN) {
+        const currentUrl = new URL(window.location.href)
+        const currentHash = currentUrl.hash
+        const currentRoute = currentHash
+          ? currentHash.substring(1)
+          : null
+        global.platform.openExtensionInBrowser(currentRoute)
+      }
+    } catch (error) {
+      if (this.mounted) {
+        this.setState({ error })
+      }
+    }
+    // initial attempt is required to trigger permission prompt
     this.initCamera()
   }
 
-  async checkPermisisions () {
-    const { permissions } = await WebcamUtils.checkStatus()
-    if (permissions) {
-      clearTimeout(this.permissionChecker)
-      // Let the video stream load first...
-      setTimeout(_ => {
-        this.setState({
-          ready: true,
-          msg: this.context.t('scanInstructions'),
-        })
-        if (this.needsToReinit) {
-          this.initCamera()
-          this.needsToReinit = false
+  checkPermissions = async () => {
+    try {
+      const { permissions } = await WebcamUtils.checkStatus()
+      if (permissions) {
+        // Let the video stream load first...
+        await new Promise(resolve => setTimeout(resolve, 2000))
+        if (!this.mounted) {
+          return
         }
-      }, 2000)
-    } else {
-      // Keep checking for permissions
-      this.permissionChecker = setTimeout(_ => {
-        this.checkPermisisions()
-      }, 1000)
+        this.setState({ ready: READY_STATE.READY })
+      } else if (this.mounted) {
+        // Keep checking for permissions
+        this.permissionChecker = setTimeout(this.checkPermissions, 1000)
+      }
+    } catch (error) {
+      if (this.mounted) {
+        this.setState({ error })
+      }
     }
   }
 
   componentWillUnmount () {
+    this.mounted = false
     clearTimeout(this.permissionChecker)
     if (this.codeReader) {
       this.codeReader.reset()
     }
   }
 
-  initCamera () {
+  initCamera = async () => {
     this.codeReader = new BrowserQRCodeReader()
-    this.codeReader.getVideoInputDevices()
-      .then(() => {
-        clearTimeout(this.permissionChecker)
-        this.checkPermisisions()
-        this.codeReader.decodeFromInputVideoDevice(undefined, 'video')
-          .then(content => {
-            const result = this.parseContent(content.text)
-            if (result.type !== 'unknown') {
-              this.props.qrCodeDetected(result)
-              this.stopAndClose()
-            } else {
-              this.setState({ msg: this.context.t('unknownQrCode') })
-            }
-          })
-          .catch(err => {
-            if (err && err.name === 'NotAllowedError') {
-              this.setState({ msg: this.context.t('youNeedToAllowCameraAccess') })
-              clearTimeout(this.permissionChecker)
-              this.needsToReinit = true
-              this.checkPermisisions()
-            }
-          })
-      }).catch(err => {
-        console.error('[QR-SCANNER]: getVideoInputDevices threw an exception: ', err)
-      })
+    try {
+      await this.codeReader.getVideoInputDevices()
+      const content = await this.codeReader.decodeFromInputVideoDevice(undefined, 'video')
+      const result = this.parseContent(content.text)
+      if (!this.mounted) {
+        return
+      } else if (result.type !== 'unknown') {
+        this.props.qrCodeDetected(result)
+        this.stopAndClose()
+      } else {
+        this.setState({ error: new Error(this.context.t('unknownQrCode')) })
+      }
+    } catch (error) {
+      if (!this.mounted) {
+        return
+      }
+      if (error.name === 'NotAllowedError') {
+        log.info(`Permission denied: '${error}'`)
+        this.setState({ ready: READY_STATE.NEED_TO_ALLOW_ACCESS })
+      } else {
+        this.setState({ error })
+      }
+    }
   }
 
   parseContent (content) {
@@ -126,89 +166,108 @@ export default class QrScanner extends Component {
     if (this.codeReader) {
       this.codeReader.reset()
     }
-    this.setState({ ready: false })
     this.props.hideModal()
   }
 
   tryAgain = () => {
-    // close the modal
-    this.stopAndClose()
-    // wait for the animation and try again
-    setTimeout(_ => {
-      this.props.scanQrCode()
-    }, 1000)
+    clearTimeout(this.permissionChecker)
+    if (this.codeReader) {
+      this.codeReader.reset()
+    }
+    this.setState(this.getInitialState(), () => {
+      this.checkEnvironment()
+    })
   }
 
-  renderVideo () {
-    return (
-      <div className="qr-scanner__content__video-wrapper">
-        <video
-          id="video"
-          style={{
-            display: this.state.ready ? 'block' : 'none',
-          }}
-        />
-        { !this.state.ready ? <Spinner color="#F7C06C" /> : null}
-      </div>
-    )
-  }
+  renderError () {
+    const { t } = this.context
+    const { error } = this.state
 
-  renderErrorModal () {
     let title, msg
-
-    if (this.props.error) {
-      if (this.props.errorType === 'NO_WEBCAM_FOUND') {
-        title = this.context.t('noWebcamFoundTitle')
-        msg = this.context.t('noWebcamFound')
-      } else {
-        title = this.context.t('unknownCameraErrorTitle')
-        msg = this.context.t('unknownCameraError')
-      }
+    if (error.type === 'NO_WEBCAM_FOUND') {
+      title = t('noWebcamFoundTitle')
+      msg = t('noWebcamFound')
+    } else if (error.message === t('unknownQrCode')) {
+      msg = t('unknownQrCode')
+    } else {
+      title = t('unknownCameraErrorTitle')
+      msg = t('unknownCameraError')
     }
 
     return (
-      <div className="qr-scanner">
-        <div className="qr-scanner__close" onClick={this.stopAndClose}></div>
-
+      <>
         <div className="qr-scanner__image">
           <img src="images/webcam.svg" width={70} height={70} />
         </div>
-        <div className="qr-scanner__title">
-          { title }
-        </div>
+        {
+          title
+            ? (
+              <div className="qr-scanner__title">
+                { title }
+              </div>
+            )
+            : null
+        }
         <div className="qr-scanner__error">
           {msg}
         </div>
         <PageContainerFooter
           onCancel={this.stopAndClose}
           onSubmit={this.tryAgain}
-          cancelText={this.context.t('cancel')}
-          submitText={this.context.t('tryAgain')}
+          cancelText={t('cancel')}
+          submitText={t('tryAgain')}
           submitButtonType="confirm"
         />
-      </div>
+      </>
     )
   }
 
-  render () {
+  renderVideo () {
     const { t } = this.context
+    const { ready } = this.state
 
-    if (this.props.error) {
-      return this.renderErrorModal()
+    let message
+    if (ready === READY_STATE.ACCESSING_CAMERA) {
+      message = t('accessingYourCamera')
+    } else if (ready === READY_STATE.READY) {
+      message = t('scanInstructions')
+    } else if (ready === READY_STATE.NEED_TO_ALLOW_ACCESS) {
+      message = t('youNeedToAllowCameraAccess')
     }
 
     return (
-      <div className="qr-scanner">
-        <div className="qr-scanner__close" onClick={this.stopAndClose}></div>
+      <>
         <div className="qr-scanner__title">
           { `${t('scanQrCode')}` }
         </div>
         <div className="qr-scanner__content">
-          { this.renderVideo() }
+          <div className="qr-scanner__content__video-wrapper">
+            <video
+              id="video"
+              style={{
+                display: ready === READY_STATE.READY ? 'block' : 'none',
+              }}
+            />
+            { ready !== READY_STATE.READY ? <Spinner color="#F7C06C" /> : null}
+          </div>
         </div>
         <div className="qr-scanner__status">
-          {this.state.msg}
+          {message}
         </div>
+      </>
+    )
+  }
+
+  render () {
+    const { error } = this.state
+    return (
+      <div className="qr-scanner">
+        <div className="qr-scanner__close" onClick={this.stopAndClose}></div>
+        {
+          error
+            ? this.renderError()
+            : this.renderVideo()
+        }
       </div>
     )
   }

ui/app/components/app/modals/qr-scanner/qr-scanner.container.js

@@ -1,24 +1,13 @@
 import { connect } from 'react-redux'
 import QrScanner from './qr-scanner.component'
 
-import { hideModal, qrCodeDetected, showQrScanner } from '../../../../store/actions'
-import {
-  SEND_ROUTE,
-} from '../../../../helpers/constants/routes'
-
-const mapStateToProps = state => {
-  return {
-    error: state.appState.modal.modalState.props.error,
-    errorType: state.appState.modal.modalState.props.errorType,
-  }
-}
+import { hideModal, qrCodeDetected } from '../../../../store/actions'
 
 const mapDispatchToProps = dispatch => {
   return {
     hideModal: () => dispatch(hideModal()),
     qrCodeDetected: (data) => dispatch(qrCodeDetected(data)),
-    scanQrCode: () => dispatch(showQrScanner(SEND_ROUTE)),
   }
 }
 
-export default connect(mapStateToProps, mapDispatchToProps)(QrScanner)
+export default connect(null, mapDispatchToProps)(QrScanner)

ui/app/pages/send/send.container.js

@@ -53,10 +53,6 @@ import {
   isValidENSAddress,
 } from '../../helpers/utils/util'
 
-import {
-  SEND_ROUTE,
-} from '../../helpers/constants/routes'
-
 function mapStateToProps (state) {
   return {
     addressBook: getAddressBook(state),
@@ -111,7 +107,7 @@ function mapDispatchToProps (dispatch) {
     },
     updateSendErrors: newError => dispatch(updateSendErrors(newError)),
     resetSendState: () => dispatch(resetSendState()),
-    scanQrCode: () => dispatch(showQrScanner(SEND_ROUTE)),
+    scanQrCode: () => dispatch(showQrScanner()),
     qrCodeDetected: (data) => dispatch(qrCodeDetected(data)),
     updateSendTo: (to, nickname) => dispatch(updateSendTo(to, nickname)),
     fetchBasicGasEstimates: () => dispatch(fetchBasicGasEstimates()),

ui/app/pages/settings/contact-list-tab/add-contact/add-contact.container.js

@@ -3,9 +3,6 @@ import { compose } from 'recompose'
 import { connect } from 'react-redux'
 import { withRouter } from 'react-router-dom'
 import { addToAddressBook, showQrScanner, qrCodeDetected } from '../../../../store/actions'
-import {
-  CONTACT_ADD_ROUTE,
-} from '../../../../helpers/constants/routes'
 import {
   getQrCodeData,
 } from '../../../send/send.selectors'
@@ -19,7 +16,7 @@ const mapStateToProps = state => {
 const mapDispatchToProps = dispatch => {
   return {
     addToAddressBook: (recipient, nickname) => dispatch(addToAddressBook(recipient, nickname)),
-    scanQrCode: () => dispatch(showQrScanner(CONTACT_ADD_ROUTE)),
+    scanQrCode: () => dispatch(showQrScanner()),
     qrCodeDetected: (data) => dispatch(qrCodeDetected(data)),
   }
 }

ui/app/store/actions.js

@@ -12,7 +12,6 @@ import log from 'loglevel'
 import { ENVIRONMENT_TYPE_NOTIFICATION } from '../../../app/scripts/lib/enums'
 import { hasUnconfirmedTransactions } from '../helpers/utils/confirm-tx.util'
 import { setCustomGasLimit } from '../ducks/gas/gas.duck'
-import WebcamUtils from '../../lib/webcam-utils'
 import txHelper from '../../lib/tx-helper'
 
 export const actionConstants = {
@@ -550,25 +549,11 @@ export function unlockHardwareWalletAccount (index, deviceName, hdPath) {
   }
 }
 
-export function showQrScanner (ROUTE) {
+export function showQrScanner () {
   return (dispatch) => {
-    return WebcamUtils.checkStatus()
-      .then(status => {
-        if (!status.environmentReady) {
-          // We need to switch to fullscreen mode to ask for permission
-          global.platform.openExtensionInBrowser(`${ROUTE}`, `scan=true`)
-        } else {
-          dispatch(showModal({
-            name: 'QR_SCANNER',
-          }))
-        }
-      }).catch(e => {
-        dispatch(showModal({
-          name: 'QR_SCANNER',
-          error: true,
-          errorType: e.type,
-        }))
-      })
+    dispatch(showModal({
+      name: 'QR_SCANNER',
+    }))
   }
 }