feat(network-status): Notify users when they're working offline

src/HospitalRun.tsx

@@ -5,6 +5,7 @@ import { Switch, Route } from 'react-router-dom'
 
 import Breadcrumbs from './breadcrumbs/Breadcrumbs'
 import Navbar from './components/Navbar'
+import { NetworkStatusMessage } from './components/network-status'
 import PrivateRoute from './components/PrivateRoute'
 import Sidebar from './components/Sidebar'
 import Dashboard from './dashboard/Dashboard'
@@ -23,6 +24,7 @@ const HospitalRun = () => {
 
   return (
     <div>
+      <NetworkStatusMessage />
       <Navbar />
       <div className="container-fluid">
         <Sidebar />

src/__tests__/components/network-status/NetworkStatusMessage.test.tsx

@@ -0,0 +1,51 @@
+import { render, shallow } from 'enzyme'
+import React from 'react'
+
+import { useTranslation } from '../../../__mocks__/react-i18next'
+import { NetworkStatusMessage } from '../../../components/network-status'
+import { useNetworkStatus } from '../../../components/network-status/useNetworkStatus'
+
+jest.mock('../../../components/network-status/useNetworkStatus')
+const useNetworkStatusMock = (useNetworkStatus as unknown) as jest.MockInstance<
+  ReturnType<typeof useNetworkStatus>,
+  any
+>
+
+const englishTranslationsMock = {
+  'networkStatus.offline': 'you are working in offline mode',
+  'networkStatus.online': 'you are back online',
+}
+
+const useTranslationReturnValue = useTranslation() as any
+useTranslationReturnValue.t = (key: keyof typeof englishTranslationsMock) =>
+  englishTranslationsMock[key]
+const { t } = useTranslationReturnValue
+
+describe('NetworkStatusMessage', () => {
+  it('returns null if the app has always been online', () => {
+    useNetworkStatusMock.mockReturnValue({
+      isOnline: true,
+      wasOffline: false,
+    })
+    const wrapper = shallow(<NetworkStatusMessage />)
+    expect(wrapper.equals(null as any)).toBe(true)
+  })
+  it(`shows the message "${t('networkStatus.offline')}" if the app goes offline`, () => {
+    useNetworkStatusMock.mockReturnValue({
+      isOnline: false,
+      wasOffline: false,
+    })
+    const wrapper = render(<NetworkStatusMessage />)
+    expect(wrapper.text()).toContain(t('networkStatus.offline'))
+  })
+  it(`shows the message "${t(
+    'networkStatus.online',
+  )}" if the app goes back online after it was offline`, () => {
+    useNetworkStatusMock.mockReturnValue({
+      isOnline: true,
+      wasOffline: true,
+    })
+    const wrapper = render(<NetworkStatusMessage />)
+    expect(wrapper.text()).toContain(t('networkStatus.online'))
+  })
+})

src/components/network-status/NetworkStatusMessage.tsx

@@ -0,0 +1,57 @@
+import React, { useState } from 'react'
+import { useTranslation } from 'react-i18next'
+
+import { useNetworkStatus } from './useNetworkStatus'
+
+const ONLINE_COLOR = 'rgba(0, 255, 0, 0.55)'
+const OFFLINE_COLOR = 'rgba(255, 0, 0, 0.65)'
+const OPACITY_TRANSITION_TIME = 4000
+const BASE_STYLE = {
+  height: '50px',
+  pointerEvents: 'none' as 'none',
+  transition: `opacity ${OPACITY_TRANSITION_TIME}ms ease-in`,
+}
+
+export const NetworkStatusMessage = () => {
+  const { t } = useTranslation()
+  const { isOnline, wasOffline } = useNetworkStatus()
+  const [shouldRender, setShouldRender] = useState(true)
+  const [opacity, setOpacity] = useState(1)
+
+  if (isOnline && !wasOffline) {
+    return null
+  }
+
+  if (!isOnline && opacity !== 1) {
+    setShouldRender(true)
+    setOpacity(1)
+  }
+
+  if (isOnline && wasOffline && opacity !== 0) {
+    setOpacity(0)
+    setTimeout(() => {
+      setShouldRender(false)
+    }, OPACITY_TRANSITION_TIME)
+  }
+
+  if (!shouldRender) {
+    return null
+  }
+
+  const style = {
+    ...BASE_STYLE,
+    backgroundColor: isOnline ? ONLINE_COLOR : OFFLINE_COLOR,
+    opacity,
+  }
+
+  return (
+    <div
+      className={`fixed-bottom d-flex justify-content-center align-items-center ${
+        isOnline ? 'online' : 'offline'
+      }`}
+      style={style}
+    >
+      {isOnline ? t('networkStatus.online') : t('networkStatus.offline')}
+    </div>
+  )
+}

src/components/network-status/index.ts

@@ -0,0 +1,2 @@
+export { NetworkStatusMessage } from './NetworkStatusMessage'
+export { useNetworkStatus } from './useNetworkStatus'

src/components/network-status/types.ts

@@ -0,0 +1,4 @@
+export interface NetworkStatus {
+  isOnline: boolean
+  wasOffline: boolean
+}

src/components/network-status/useNetworkStatus.ts

@@ -0,0 +1,28 @@
+import { useState, useEffect } from 'react'
+
+import { NetworkStatus } from './types'
+
+export const useNetworkStatus = (): NetworkStatus => {
+  const isOnline = navigator.onLine
+  const [networkStatus, setNetworkStatus] = useState({
+    isOnline,
+    wasOffline: !isOnline,
+  })
+  const handleOnline = () => {
+    setNetworkStatus((prevState) => ({ ...prevState, isOnline: true }))
+  }
+  const handleOffline = () => {
+    setNetworkStatus((prevState) => ({ ...prevState, isOnline: false, wasOffline: true }))
+  }
+  useEffect(() => {
+    window.addEventListener('online', handleOnline)
+    window.addEventListener('offline', handleOffline)
+
+    return () => {
+      window.removeEventListener('online', handleOnline)
+      window.removeEventListener('offline', handleOffline)
+    }
+  }, [])
+
+  return networkStatus
+}

src/locales/enUs/translations/index.ts

@@ -2,6 +2,7 @@ import actions from './actions'
 import dashboard from './dashboard'
 import incidents from './incidents'
 import labs from './labs'
+import networkStatus from './network-status'
 import patient from './patient'
 import patients from './patients'
 import scheduling from './scheduling'
@@ -12,6 +13,7 @@ import states from './states'
 export default {
   ...actions,
   ...dashboard,
+  ...networkStatus,
   ...patient,
   ...patients,
   ...scheduling,

src/locales/enUs/translations/network-status/index.ts

@@ -0,0 +1,6 @@
+export default {
+  networkStatus: {
+    offline: 'you are working in offline mode',
+    online: 'you are back online',
+  },
+}