fix(NcAppSidebar): add focus trap on mobile

src/components/NcAppNavigationToggle/NcAppNavigationToggle.vue

@@ -22,18 +22,20 @@
  -
  -->
 <template>
-	<NcButton class="app-navigation-toggle"
-		type="tertiary"
-		:aria-expanded="open ? 'true' : 'false'"
-		:aria-label="label"
-		:title="label"
-		aria-controls="app-navigation-vue"
-		@click="toggleNavigation">
-		<template #icon>
-			<MenuOpenIcon v-if="open" :size="20" />
-			<MenuIcon v-else :size="20" />
-		</template>
-	</NcButton>
+	<div class="app-navigation-toggle-wrapper">
+		<NcButton class="app-navigation-toggle"
+			type="tertiary"
+			:aria-expanded="open ? 'true' : 'false'"
+			:aria-label="label"
+			:title="label"
+			aria-controls="app-navigation-vue"
+			@click="toggleNavigation">
+			<template #icon>
+				<MenuOpenIcon v-if="open" :size="20" />
+				<MenuIcon v-else :size="20" />
+			</template>
+		</NcButton>
+	</div>
 </template>
 
 <script>
@@ -75,11 +77,14 @@ export default {
 </script>
 
 <style scoped lang="scss">
-button.app-navigation-toggle {
+.app-navigation-toggle-wrapper {
 	position: absolute;
 	top: var(--app-navigation-padding);
 	right: calc(0px - var(--app-navigation-padding));
 	margin-right: - $clickable-area;
+}
+
+button.app-navigation-toggle {
 	background-color: var(--color-main-background);
 }
 </style>

src/components/NcAppSidebar/NcAppSidebar.vue

@@ -345,7 +345,10 @@ export default {
 		@after-enter="onAfterEnter"
 		@before-leave="onBeforeLeave"
 		@after-leave="onAfterLeave">
-		<aside id="app-sidebar-vue" class="app-sidebar">
+		<aside id="app-sidebar-vue"
+			ref="sidebar"
+			class="app-sidebar"
+			@keydown.esc.stop="isMobile && closeSidebar()">
 			<header :class="{
 					'app-sidebar-header--with-figure': hasFigure,
 					'app-sidebar-header--compact': compact,
@@ -447,7 +450,8 @@ export default {
 					</div>
 				</div>
 
-				<NcButton :title="closeTranslated"
+				<NcButton ref="closeButton"
+					:title="closeTranslated"
 					:aria-label="closeTranslated"
 					type="tertiary"
 					class="app-sidebar__close"
@@ -487,6 +491,8 @@ import NcEmptyContent from '../NcEmptyContent/index.js'
 import Focus from '../../directives/Focus/index.js'
 import Linkify from '../../directives/Linkify/index.js'
 import Tooltip from '../../directives/Tooltip/index.js'
+import { useIsSmallMobile } from '../../composables/useIsMobile/index.js'
+import { getTrapStack } from '../../utils/focusTrap.js'
 import { t } from '../../l10n.js'
 
 import ArrowRight from 'vue-material-design-icons/ArrowRight.vue'
@@ -495,6 +501,7 @@ import Star from 'vue-material-design-icons/Star.vue'
 import StarOutline from 'vue-material-design-icons/StarOutline.vue'
 
 import { vOnClickOutside as ClickOutside } from '@vueuse/components'
+import { createFocusTrap } from 'focus-trap'
 
 export default {
 	name: 'NcAppSidebar',
@@ -641,12 +648,19 @@ export default {
 		'dismiss-editing',
 	],
 
+	setup() {
+		return {
+			isMobile: useIsSmallMobile(),
+		}
+	},
+
 	data() {
 		return {
 			changeNameTranslated: t('Change name'),
 			closeTranslated: t('Close sidebar'),
 			favoriteTranslated: t('Favorite'),
 			isStarred: this.starred,
+			focusTrap: null,
 		}
 	},
 
@@ -666,14 +680,57 @@ export default {
 		starred() {
 			this.isStarred = this.starred
 		},
+
+		isMobile() {
+			this.toggleFocusTrap()
+		},
+	},
+
+	mounted() {
+		this.toggleFocusTrap()
 	},
 
 	beforeDestroy() {
 		// Make sure that the 'closed' event is dispatched even if this element is destroyed before the 'after-leave' event is received.
 		this.$emit('closed')
+		this.focusTrap?.deactivate()
 	},
 
 	methods: {
+		initFocusTrap() {
+			if (this.focusTrap) {
+				return
+			}
+
+			this.focusTrap = createFocusTrap([
+				// The sidebar itself
+				this.$refs.sidebar,
+				// Nextcloud Server header navigarion
+				document.querySelector('#header'),
+				// The app navigation toggle. Navigation can be opened above the sidebar
+				// Take the parent element, because the focus-trap requires a container with elements, not the element itself
+				document.querySelector('[aria-controls="app-navigation-vue"]')?.parentElement,
+			], {
+				allowOutsideClick: true,
+				fallbackFocus: this.$refs.closeButton,
+				trapStack: getTrapStack(),
+				escapeDeactivates: false,
+			})
+		},
+
+		/**
+		 * Activate focus trap if it is currently needed, otherwise deactivate
+		 */
+		 toggleFocusTrap() {
+			console.debug('toggleFocusTrap', this.isMobile)
+			if (this.isMobile) {
+				this.initFocusTrap()
+				this.focusTrap.activate()
+			} else {
+				this.focusTrap?.deactivate()
+			}
+		},
+
 		onBeforeEnter(element) {
 			/**
 			 * The sidebar is opening and the transition is in progress