Change motd banner to motd modal

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

cypress/fixtures/banner.txt

@@ -1 +0,0 @@
-This is the mock banner call

cypress/fixtures/banner.txt.license

@@ -1,3 +0,0 @@
-SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
-
-SPDX-License-Identifier: CC0-1.0

cypress/integration/banner.spec.ts

@@ -1,80 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-const BANNER_LOCAL_STORAGE_KEY = 'banner.lastModified'
-const MOCK_LAST_MODIFIED = 'mockETag'
-const bannerMockContent = 'This is the mock banner call'
-
-describe('Banner', () => {
-  beforeEach(() => {
-    cy.intercept({
-      method: 'GET',
-      url: '/mock-backend/public/banner.txt'
-    }, {
-      statusCode: 200,
-      headers: { 'Last-Modified': MOCK_LAST_MODIFIED },
-      body: bannerMockContent
-    })
-
-    cy.intercept({
-      method: 'HEAD',
-      url: '/mock-backend/public/banner.txt'
-    }, {
-      statusCode: 200,
-      headers: { 'Last-Modified': MOCK_LAST_MODIFIED }
-    })
-      .as('headBanner')
-
-    cy.visit('/')
-    localStorage.removeItem(BANNER_LOCAL_STORAGE_KEY)
-    expect(localStorage.getItem(BANNER_LOCAL_STORAGE_KEY)).to.be.null
-  })
-
-  it('shows the correct alert banner text', () => {
-    cy.get('[data-cy="motd-banner"]')
-      .contains(bannerMockContent)
-  })
-
-  it('can be dismissed', () => {
-    cy.get('[data-cy="motd-banner"]')
-      .contains(bannerMockContent)
-    cy.get('button[data-cy="motd-dismiss"]')
-      .click()
-      .then(() => {
-        expect(localStorage.getItem(BANNER_LOCAL_STORAGE_KEY))
-          .to
-          .equal(MOCK_LAST_MODIFIED)
-      })
-    cy.get('[data-cy="no-motd-banner"]')
-      .should('exist')
-    cy.get('[data-cy="motd-banner"]')
-      .should('not.exist')
-  })
-
-  it('won\'t show again on reload', () => {
-    cy.get('[data-cy="motd-banner"]')
-      .contains(bannerMockContent)
-    cy.get('button[data-cy="motd-dismiss"]')
-      .click()
-      .then(() => {
-        expect(localStorage.getItem(BANNER_LOCAL_STORAGE_KEY))
-          .to
-          .equal(MOCK_LAST_MODIFIED)
-      })
-    cy.get('[data-cy="no-motd-banner"]')
-      .should('exist')
-    cy.get('[data-cy="motd-banner"]')
-      .should('not.exist')
-    cy.reload()
-    cy.get('main')
-      .should('exist')
-    cy.wait('@headBanner')
-    cy.get('[data-cy="no-motd-banner"]')
-      .should('exist')
-    cy.get('[data-cy="motd-banner"]')
-      .should('not.exist')
-  })
-})

cypress/integration/motd.spec.ts

@@ -0,0 +1,91 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+const MOTD_LOCAL_STORAGE_KEY = 'motd.lastModified'
+const MOCK_LAST_MODIFIED = 'mockETag'
+const motdMockContent = 'This is the mock Motd call'
+
+describe('Motd', () => {
+  const mockExistingMotd = () => {
+    cy.intercept('GET', '/mock-backend/public/motd.txt', {
+      statusCode: 200,
+      headers: { 'Last-Modified': MOCK_LAST_MODIFIED },
+      body: motdMockContent
+    })
+
+    cy.intercept('HEAD', '/mock-backend/public/motd.txt', {
+      statusCode: 200,
+      headers: { 'Last-Modified': MOCK_LAST_MODIFIED }
+    })
+  }
+
+  beforeEach(() => {
+    localStorage.removeItem(MOTD_LOCAL_STORAGE_KEY)
+  })
+
+  it('shows the correct alert Motd text', () => {
+    mockExistingMotd()
+    cy.visit('/')
+    cy.get('[data-cy="motd"]').contains(motdMockContent)
+  })
+
+  it('can be dismissed', () => {
+    mockExistingMotd()
+    cy.visit('/')
+    cy.get('[data-cy="motd"]').contains(motdMockContent)
+    cy.get('button[data-cy="motd-dismiss"]')
+      .click()
+      .then(() => {
+        expect(localStorage.getItem(MOTD_LOCAL_STORAGE_KEY)).to.equal(MOCK_LAST_MODIFIED)
+      })
+    cy.get('[data-cy="motd"]').should('not.exist')
+  })
+
+  it("won't show again after dismiss and reload", () => {
+    mockExistingMotd()
+    cy.visit('/')
+    cy.get('[data-cy="motd"]').contains(motdMockContent)
+    cy.get('button[data-cy="motd-dismiss"]')
+      .click()
+      .then(() => {
+        expect(localStorage.getItem(MOTD_LOCAL_STORAGE_KEY)).to.equal(MOCK_LAST_MODIFIED)
+      })
+    cy.get('[data-cy="motd"]').should('not.exist')
+    cy.reload()
+    cy.get('main').should('exist')
+    cy.get('[data-cy="motd"]').should('not.exist')
+  })
+
+  it("will show again after reload without dismiss", () => {
+    mockExistingMotd()
+    cy.visit('/')
+    cy.get('[data-cy="motd"]').contains(motdMockContent)
+    cy.reload()
+    cy.get('main').should('exist')
+    cy.get('[data-cy="motd"]').contains(motdMockContent)
+  })
+
+  it("won't show again after dismiss and page navigation", () => {
+    mockExistingMotd()
+    cy.visit('/')
+    cy.get('[data-cy="motd"]').contains(motdMockContent)
+    cy.get('button[data-cy="motd-dismiss"]')
+      .click()
+      .then(() => {
+        expect(localStorage.getItem(MOTD_LOCAL_STORAGE_KEY)).to.equal(MOCK_LAST_MODIFIED)
+      })
+    cy.get('[data-cy="motd"]').should('not.exist')
+    cy.get('#navLinkHistory').click()
+    cy.get('main').should('exist')
+    cy.get('[data-cy="motd"]').should('not.exist')
+  })
+
+  it("won't show if no file exists", () => {
+    cy.visit('/')
+    cy.get('main').should('exist')
+    cy.get('[data-cy="motd"]').should('not.exist')
+  })
+})

cypress/support/config.ts

@@ -68,4 +68,12 @@ Cypress.Commands.add('loadConfig', (additionalConfig?: Partial<typeof config>) =
 
 beforeEach(() => {
   cy.loadConfig()
+
+  cy.intercept('GET', '/mock-backend/public/motd.txt', {
+    body: '404 Not Found!',
+    statusCode: 404
+  })
+  cy.intercept('HEAD', '/mock-backend/public/motd.txt', {
+    statusCode: 404
+  })
 })

cypress/support/visit-test-editor.ts

@@ -20,8 +20,8 @@ beforeEach(() => {
   cy.intercept(`/mock-backend/api/private/notes/${ testNoteId }-get`, {
     "content": "",
     "metadata": {
-      "id": "ABC11",
-      "alias": "banner",
+      "id": "mock_note_id",
+      "alias": "mockNote",
       "version": 2,
       "viewCount": 0,
       "updateTime": "2021-04-24T09:27:51.000Z",

locales/en.json

@@ -455,6 +455,7 @@
         "export": "Export",
         "refresh": "Refresh",
         "cancel": "Cancel",
+        "dismiss": "Dismiss",
         "ok": "OK",
         "close": "Close",
         "save": "Save",
@@ -495,5 +496,8 @@
                 "other": "There was an error while registering your account. Just try it again."
             }
         }
+    },
+    "motd": {
+        "title": "Information"
     }
 }

public/mock-backend/api/private/config

@@ -18,10 +18,6 @@
     "name": "DEMO Corp",
     "logo": "/mock-backend/public/img/demo.png"
   },
-  "banner": {
-    "text": "This is the test banner text",
-    "timestamp": "2020-05-22T20:46:08.962Z"
-  },
   "customAuthNames": {
     "ldap": "FooBar",
     "oauth2": "Olaf2",

public/mock-backend/public/banner.txt

@@ -1 +0,0 @@
-This is the test banner text

public/mock-backend/public/motd.txt

@@ -0,0 +1 @@
+This is the test motd text

src/components/application-loader/initializers/fetch-and-set-banner.ts

@@ -1,54 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { setBanner } from '../../../redux/banner/methods'
-import { defaultFetchConfig } from '../../../api/utils'
-import { Logger } from '../../../utils/logger'
-
-export const BANNER_LOCAL_STORAGE_KEY = 'banner.lastModified'
-const log = new Logger('Banner')
-
-export const fetchAndSetBanner = async (customizeAssetsUrl: string): Promise<void> => {
-  const cachedLastModified = window.localStorage.getItem(BANNER_LOCAL_STORAGE_KEY)
-  const bannerUrl = `${customizeAssetsUrl}banner.txt`
-
-  if (cachedLastModified) {
-    const response = await fetch(bannerUrl, {
-      ...defaultFetchConfig,
-      method: 'HEAD'
-    })
-    if (response.status !== 200) {
-      return
-    }
-    if (response.headers.get('Last-Modified') === cachedLastModified) {
-      setBanner({
-        lastModified: cachedLastModified,
-        text: ''
-      })
-      return
-    }
-  }
-
-  const response = await fetch(bannerUrl, {
-    ...defaultFetchConfig
-  })
-
-  if (response.status !== 200) {
-    return
-  }
-
-  const bannerText = await response.text()
-
-  const lastModified = response.headers.get('Last-Modified')
-  if (!lastModified) {
-    log.warn("'Last-Modified' not found for banner.txt!")
-  }
-
-  setBanner({
-    lastModified: lastModified,
-    text: bannerText
-  })
-}

src/components/application-loader/initializers/fetch-motd.ts

@@ -0,0 +1,56 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { setMotd } from '../../../redux/motd/methods'
+import { defaultFetchConfig } from '../../../api/utils'
+import { Logger } from '../../../utils/logger'
+
+export const MOTD_LOCAL_STORAGE_KEY = 'motd.lastModified'
+const log = new Logger('Motd')
+
+/**
+ * Fetches the current motd from the backend and sets the content in the global application state.
+ * If the motd hasn't changed since the last time then the global application state won't be changed.
+ * To check if the motd has changed the "last modified" header from the request
+ * will be compared to the saved value from the browser's local storage.
+ *
+ * @param customizeAssetsUrl the URL where the motd.txt can be found.
+ * @return A promise that gets resolved if the motd was fetched successfully.
+ */
+export const fetchMotd = async (customizeAssetsUrl: string): Promise<void> => {
+  const cachedLastModified = window.localStorage.getItem(MOTD_LOCAL_STORAGE_KEY)
+  const motdUrl = `${customizeAssetsUrl}motd.txt`
+
+  if (cachedLastModified) {
+    const response = await fetch(motdUrl, {
+      ...defaultFetchConfig,
+      method: 'HEAD'
+    })
+    if (response.status !== 200) {
+      return
+    }
+    if (response.headers.get('Last-Modified') === cachedLastModified) {
+      return
+    }
+  }
+
+  const response = await fetch(motdUrl, {
+    ...defaultFetchConfig
+  })
+
+  if (response.status !== 200) {
+    return
+  }
+
+  const motdText = await response.text()
+
+  const lastModified = response.headers.get('Last-Modified')
+  if (!lastModified) {
+    log.warn("'Last-Modified' not found for motd.txt!")
+  }
+
+  setMotd(motdText, lastModified)
+}

src/components/application-loader/initializers/index.ts

@@ -6,7 +6,7 @@
 
 import { setUpI18n } from './i18n/i18n'
 import { refreshHistoryState } from '../../../redux/history/methods'
-import { fetchAndSetBanner } from './fetch-and-set-banner'
+import { fetchMotd } from './fetch-motd'
 import { setApiUrl } from '../../../redux/api-url/methods'
 import { fetchAndSetUser } from '../../login-page/auth/utils'
 import { fetchFrontendConfig } from './fetch-frontend-config'
@@ -47,8 +47,8 @@ export const createSetUpTaskList = (
       task: fetchAndSetUser()
     },
     {
-      name: 'Banner',
-      task: fetchAndSetBanner(customizeAssetsUrl)
+      name: 'Motd',
+      task: fetchMotd(customizeAssetsUrl)
     },
     {
       name: 'Load history state',

src/components/common/modals/common-modal.tsx

@@ -13,7 +13,7 @@ import { ShowIf } from '../show-if/show-if'
 
 export interface CommonModalProps {
   show: boolean
-  onHide: () => void
+  onHide?: () => void
   titleI18nKey?: string
   title?: string
   closeButton?: boolean

src/components/common/motd-banner/motd-banner.tsx

@@ -1,47 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import React, { useCallback } from 'react'
-import { Alert, Button } from 'react-bootstrap'
-import { setBanner } from '../../../redux/banner/methods'
-import { ForkAwesomeIcon } from '../fork-awesome/fork-awesome-icon'
-import { BANNER_LOCAL_STORAGE_KEY } from '../../application-loader/initializers/fetch-and-set-banner'
-import { useApplicationState } from '../../../hooks/common/use-application-state'
-
-export const MotdBanner: React.FC = () => {
-  const bannerState = useApplicationState((state) => state.banner)
-
-  const dismissBanner = useCallback(() => {
-    if (bannerState.lastModified) {
-      window.localStorage.setItem(BANNER_LOCAL_STORAGE_KEY, bannerState.lastModified)
-    }
-    setBanner({
-      text: '',
-      lastModified: null
-    })
-  }, [bannerState])
-
-  if (bannerState.text === undefined) {
-    return null
-  }
-
-  if (!bannerState.text) {
-    return <span data-cy={'no-motd-banner'} />
-  }
-
-  return (
-    <Alert
-      data-cy={'motd-banner'}
-      variant='primary'
-      dir='auto'
-      className='mb-0 text-center d-flex flex-row justify-content-center'>
-      <span className='flex-grow-1 align-self-center text-black'>{bannerState.text}</span>
-      <Button data-cy={'motd-dismiss'} variant='outline-primary' size='sm' className='mx-2' onClick={dismissBanner}>
-        <ForkAwesomeIcon icon='times' />
-      </Button>
-    </Alert>
-  )
-}

src/components/common/motd-modal/motd-modal.tsx

@@ -0,0 +1,60 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import React, { Fragment, useCallback, useMemo } from 'react'
+import { Button, Modal } from 'react-bootstrap'
+import { CommonModal } from '../modals/common-modal'
+import { Trans, useTranslation } from 'react-i18next'
+import { useApplicationState } from '../../../hooks/common/use-application-state'
+import { dismissMotd } from '../../../redux/motd/methods'
+
+/**
+ * Reads the motd from the global application state and shows it in a modal.
+ * If the modal gets dismissed by the user then the "last modified" identifier will be written into the local storage
+ * to prevent that the motd will be shown again until it gets changed.
+ */
+export const MotdModal: React.FC = () => {
+  useTranslation()
+  const motdState = useApplicationState((state) => state.motd)
+
+  const domContent = useMemo(() => {
+    if (!motdState) {
+      return null
+    }
+    return motdState.text
+      ?.split('\n')
+      .map((line) => <span>{line}</span>)
+      .reduce((previousLine, currentLine, currentLineIndex) => (
+        <Fragment key={currentLineIndex}>
+          {previousLine}
+          <br />
+          {currentLine}
+        </Fragment>
+      ))
+  }, [motdState])
+
+  const dismiss = useCallback(() => {
+    if (!motdState) {
+      return
+    }
+    dismissMotd()
+  }, [motdState])
+
+  if (motdState === null || motdState.dismissed) {
+    return null
+  } else {
+    return (
+      <CommonModal data-cy={'motd'} show={!!motdState} titleI18nKey={'motd.title'}>
+        <Modal.Body>{domContent}</Modal.Body>
+        <Modal.Footer>
+          <Button variant={'success'} onClick={dismiss} data-cy={'motd-dismiss'}>
+            <Trans i18nKey={'common.dismiss'} />
+          </Button>
+        </Modal.Footer>
+      </CommonModal>
+    )
+  }
+}

src/components/document-read-only-page/document-read-only-page.tsx

@@ -10,7 +10,7 @@ import { useParams } from 'react-router'
 import { useApplyDarkMode } from '../../hooks/common/use-apply-dark-mode'
 import { useDocumentTitleWithNoteTitle } from '../../hooks/common/use-document-title-with-note-title'
 import { updateNoteTitleByFirstHeading } from '../../redux/note-details/methods'
-import { MotdBanner } from '../common/motd-banner/motd-banner'
+import { MotdModal } from '../common/motd-modal/motd-modal'
 import { ShowIf } from '../common/show-if/show-if'
 import { AppBar, AppBarMode } from '../editor-page/app-bar/app-bar'
 import { EditorPagePathParams } from '../editor-page/editor-page'
@@ -24,6 +24,7 @@ import { useApplicationState } from '../../hooks/common/use-application-state'
 import { useNoteMarkdownContentWithoutFrontmatter } from '../../hooks/common/use-note-markdown-content-without-frontmatter'
 import { EditorToRendererCommunicatorContextProvider } from '../editor-page/render-context/editor-to-renderer-communicator-context-provider'
 import { useSendFrontmatterInfoFromReduxToRenderer } from '../editor-page/renderer-pane/hooks/use-send-frontmatter-info-from-redux-to-renderer'
+import { UiNotifications } from '../notifications/ui-notifications'
 
 export const DocumentReadOnlyPage: React.FC = () => {
   useTranslation()
@@ -40,8 +41,9 @@ export const DocumentReadOnlyPage: React.FC = () => {
 
   return (
     <EditorToRendererCommunicatorContextProvider>
+      <UiNotifications />
+      <MotdModal />
       <div className={'d-flex flex-column mvh-100 bg-light'}>
-        <MotdBanner />
         <AppBar mode={AppBarMode.BASIC} />
         <div className={'container'}>
           <ErrorWhileLoadingNoteAlert show={error} />

src/components/editor-page/editor-page.tsx

@@ -9,7 +9,7 @@ import { useTranslation } from 'react-i18next'
 import { useApplyDarkMode } from '../../hooks/common/use-apply-dark-mode'
 import { useDocumentTitleWithNoteTitle } from '../../hooks/common/use-document-title-with-note-title'
 import { setCheckboxInMarkdownContent, updateNoteTitleByFirstHeading } from '../../redux/note-details/methods'
-import { MotdBanner } from '../common/motd-banner/motd-banner'
+import { MotdModal } from '../common/motd-modal/motd-modal'
 import { ShowIf } from '../common/show-if/show-if'
 import { ErrorWhileLoadingNoteAlert } from '../document-read-only-page/ErrorWhileLoadingNoteAlert'
 import { LoadingNoteAlert } from '../document-read-only-page/LoadingNoteAlert'
@@ -126,7 +126,7 @@ export const EditorPage: React.FC = () => {
   return (
     <EditorToRendererCommunicatorContextProvider>
       <UiNotifications />
-      <MotdBanner />
+      <MotdModal />
       <div className={'d-flex flex-column vh-100'}>
         <AppBar mode={AppBarMode.EDITOR} />
         <div className={'container'}>

src/components/landing-layout/landing-layout.tsx

@@ -7,7 +7,7 @@
 import React, { Fragment } from 'react'
 import { Container } from 'react-bootstrap'
 import { useDocumentTitle } from '../../hooks/common/use-document-title'
-import { MotdBanner } from '../common/motd-banner/motd-banner'
+import { MotdModal } from '../common/motd-modal/motd-modal'
 import { Footer } from './footer/footer'
 import { HeaderBar } from './navigation/header-bar/header-bar'
 import { UiNotifications } from '../notifications/ui-notifications'
@@ -18,8 +18,8 @@ export const LandingLayout: React.FC = ({ children }) => {
   return (
     <Fragment>
       <UiNotifications />
+      <MotdModal />
       <Container className='text-light d-flex flex-column mvh-100'>
-        <MotdBanner />
         <HeaderBar />
         <div className={'d-flex flex-column justify-content-between flex-fill text-center'}>
           <main>{children}</main>

src/redux/banner/methods.ts

@@ -1,15 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { store } from '..'
-import { BannerActionType, BannerState, SetBannerAction } from './types'
-
-export const setBanner = (state: BannerState): void => {
-  store.dispatch({
-    type: BannerActionType.SET_BANNER,
-    state
-  } as SetBannerAction)
-}

src/redux/banner/reducers.ts

@@ -1,25 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { Reducer } from 'redux'
-import { BannerActions, BannerActionType, BannerState } from './types'
-
-export const initialState: BannerState = {
-  text: undefined,
-  lastModified: null
-}
-
-export const BannerReducer: Reducer<BannerState, BannerActions> = (
-  state: BannerState = initialState,
-  action: BannerActions
-) => {
-  switch (action.type) {
-    case BannerActionType.SET_BANNER:
-      return action.state
-    default:
-      return state
-  }
-}

src/redux/banner/types.ts

@@ -1,23 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
- *
- * SPDX-License-Identifier: AGPL-3.0-only
- */
-
-import { Action } from 'redux'
-
-export enum BannerActionType {
-  SET_BANNER = 'banner/set'
-}
-
-export type BannerActions = SetBannerAction
-
-export interface SetBannerAction extends Action<BannerActionType> {
-  type: BannerActionType.SET_BANNER
-  state: BannerState
-}
-
-export interface BannerState {
-  text: string | undefined
-  lastModified: string | null
-}

src/redux/index.ts

@@ -8,8 +8,8 @@ import { combineReducers, createStore, Reducer } from 'redux'
 import { Config } from '../api/config/types'
 import { ApiUrlReducer } from './api-url/reducers'
 import { ApiUrlObject } from './api-url/types'
-import { BannerReducer } from './banner/reducers'
-import { BannerState } from './banner/types'
+import { MotdReducer } from './motd/reducers'
+import { OptionalMotdState } from './motd/types'
 import { ConfigReducer } from './config/reducers'
 import { DarkModeConfigReducer } from './dark-mode/reducers'
 import { DarkModeConfig } from './dark-mode/types'
@@ -29,7 +29,7 @@ import { RendererStatus } from './renderer-status/types'
 export interface ApplicationState {
   user: OptionalUserState
   config: Config
-  banner: BannerState
+  motd: OptionalMotdState
   history: HistoryEntry[]
   apiUrl: ApiUrlObject
   editorConfig: EditorConfig
@@ -42,7 +42,7 @@ export interface ApplicationState {
 export const allReducers: Reducer<ApplicationState> = combineReducers<ApplicationState>({
   user: UserReducer,
   config: ConfigReducer,
-  banner: BannerReducer,
+  motd: MotdReducer,
   apiUrl: ApiUrlReducer,
   history: HistoryReducer,
   editorConfig: EditorConfigReducer,

src/redux/motd/methods.ts

@@ -0,0 +1,31 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { store } from '..'
+import { DismissMotdAction, MotdActionType, SetMotdAction } from './types'
+
+/**
+ * Sets a not-dismissed motd message in the global application state.
+ *
+ * @param text The motd text content
+ * @param lastModified An identifier that describes when the motd was changed the last time.
+ */
+export const setMotd = (text: string, lastModified: string | null): void => {
+  store.dispatch({
+    type: MotdActionType.SET_MOTD,
+    text,
+    lastModified
+  } as SetMotdAction)
+}
+
+/**
+ * Dismisses the currently saved motd message.
+ */
+export const dismissMotd = (): void => {
+  store.dispatch({
+    type: MotdActionType.DISMISS_MOTD
+  } as DismissMotdAction)
+}

src/redux/motd/reducers.ts

@@ -0,0 +1,60 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { Reducer } from 'redux'
+import { MotdActions, MotdActionType, MotdState, OptionalMotdState } from './types'
+import { MOTD_LOCAL_STORAGE_KEY } from '../../components/application-loader/initializers/fetch-motd'
+
+/**
+ * A reducer that modifies the {@link OptionalMotdState motd state} in the global application state.
+ */
+export const MotdReducer: Reducer<OptionalMotdState, MotdActions> = (
+  state: OptionalMotdState = null,
+  action: MotdActions
+) => {
+  switch (action.type) {
+    case MotdActionType.SET_MOTD:
+      return createNewMotdState(action.text, action.lastModified)
+    case MotdActionType.DISMISS_MOTD:
+      return createDismissedMotdState(state)
+    default:
+      return state
+  }
+}
+
+/**
+ * Creates a new {@link MotdState motd state} by copying the old state and setting the dismissed flag.
+ * It also writes the "last-modified" identifier into the browser's local storage.
+ *
+ * @param oldState The current motd state that should be copied
+ * @return The new state
+ */
+const createDismissedMotdState = (oldState: OptionalMotdState): OptionalMotdState => {
+  if (oldState === null) {
+    return null
+  } else {
+    if (oldState.lastModified) {
+      window.localStorage.setItem(MOTD_LOCAL_STORAGE_KEY, oldState.lastModified)
+    }
+    return {
+      ...oldState,
+      dismissed: true
+    }
+  }
+}
+
+/**
+ * Creates a new not-dismissed motd state.
+ * @param text The motd text
+ * @param lastModified An identifier that describes when the motd text was changed the last time
+ */
+const createNewMotdState = (text: string, lastModified: string | null): MotdState => {
+  return {
+    text,
+    lastModified,
+    dismissed: false
+  }
+}

src/redux/motd/types.ts

@@ -0,0 +1,32 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { Action } from 'redux'
+
+export enum MotdActionType {
+  SET_MOTD = 'motd/set',
+  DISMISS_MOTD = 'motd/dismiss'
+}
+
+export type MotdActions = SetMotdAction | DismissMotdAction
+
+export interface SetMotdAction extends Action<MotdActionType> {
+  type: MotdActionType.SET_MOTD
+  text: string
+  lastModified: string | null
+}
+
+export interface DismissMotdAction extends Action<MotdActionType> {
+  type: MotdActionType.DISMISS_MOTD
+}
+
+export interface MotdState {
+  text: string
+  lastModified: string | null
+  dismissed: boolean
+}
+
+export type OptionalMotdState = MotdState | null