Add accesibility features to quick share dropdown

- Adds appropriate aria attributes
- Uses button element for dropdown items as it's more semantically correct
- Uses trap-focus lib to trap focus when the drowpdown is active
- Adds custom handling for arrow up and down

Signed-off-by: fenn-cs <fenn25.fn@gmail.com>

Author: nfebe

apps/files_sharing/src/components/SharingEntryQuickShareSelect.vue

@@ -1,16 +1,32 @@
 <template>
-	<div :class="{ 'active': showDropdown, 'share-select': true }" ref="quickShareDropdown">
-		<span class="trigger-text" @click="toggleDropdown">
+	<div ref="quickShareDropdownContainer"
+		:class="{ 'active': showDropdown, 'share-select': true }"
+		tabindex="0"
+		@keydown.down="handleArrowDown"
+		@keydown.up="handleArrowUp">
+		<span :id="dropdownId"
+			class="trigger-text"
+			:aria-expanded="showDropdown"
+			:aria-haspopup="true"
+			aria-label="Quick share options dropdown"
+			@click="toggleDropdown">
 			{{ selectedOption }}
 			<DropdownIcon :size="15" />
 		</span>
-		<div v-if="showDropdown" class="share-select-dropdown-container">
-			<div v-for="option in options"
+		<div v-if="showDropdown"
+			ref="quickShareDropdown"
+			class="share-select-dropdown-container"
+			:aria-labelledby="dropdownId"
+			tabindex="0"
+			@keydown.esc="closeDropdown">
+			<button v-for="option in options"
 				:key="option"
 				:class="{ 'dropdown-item': true, 'selected': option === selectedOption }"
+				tabindex="0"
+				:aria-selected="option === selectedOption"
 				@click="selectOption(option)">
 				{{ option }}
-			</div>
+			</button>
 		</div>
 	</div>
 </template>
@@ -26,6 +42,8 @@ import {
 	ATOMIC_PERMISSIONS,
 } from '../lib/SharePermissionsToolBox.js'
 
+import { createFocusTrap } from 'focus-trap'
+
 export default {
 	components: {
 		DropdownIcon,
@@ -45,6 +63,7 @@ export default {
 		return {
 			selectedOption: '',
 			showDropdown: this.toggle,
+			focusTrap: null,
 		}
 	},
 	computed: {
@@ -102,6 +121,10 @@ export default {
 				return BUNDLED_PERMISSIONS.READ_ONLY
 			}
 		},
+		dropdownId() {
+			// Generate a unique ID for ARIA attributes
+			return `dropdown-${Math.random().toString(36).substr(2, 9)}`
+		},
 	},
 	watch: {
 		toggle(toggleValue) {
@@ -110,15 +133,26 @@ export default {
 	},
 	mounted() {
 		this.initializeComponent()
-		window.addEventListener('click', this.handleClickOutside);
+		window.addEventListener('click', this.handleClickOutside)
 	},
 	beforeDestroy() {
-    // Remove the global click event listener to prevent memory leaks
-    window.removeEventListener('click', this.handleClickOutside);
-    },
+		// Remove the global click event listener to prevent memory leaks
+		window.removeEventListener('click', this.handleClickOutside)
+	},
 	methods: {
 		toggleDropdown() {
 			this.showDropdown = !this.showDropdown
+			if (this.showDropdown) {
+				this.$nextTick(() => {
+					this._useFocusTrap()
+				})
+			} else {
+				this._clearFocusTrap()
+			}
+		},
+		closeDropdown() {
+			this.showDropdown = false
+			this._clearFocusTrap()
 		},
 		selectOption(option) {
 			this.selectedOption = option
@@ -134,12 +168,46 @@ export default {
 			this.selectedOption = this.preSelectedOption
 		},
 		handleClickOutside(event) {
-			const dropdownElement = this.$refs.quickShareDropdown;
+			const dropdownContainer = this.$refs.quickShareDropdownContainer
+
+			if (dropdownContainer && !dropdownContainer.contains(event.target)) {
+				this.showDropdown = false
+			}
+		},
+		_useFocusTrap() {
+			const dropdownElement = this.$refs.quickShareDropdown
+			this.focusTrap = createFocusTrap(dropdownElement, {
+				allowOutsideClick: true,
+			})
 
-			if (dropdownElement && !dropdownElement.contains(event.target)) {
-				this.showDropdown = false;
+			this.focusTrap.activate()
+		},
+		_clearFocusTrap() {
+			this.focusTrap?.deactivate()
+			this.focusTrap = null
+		},
+		shiftFocusForward() {
+			const currentElement = document.activeElement
+			let nextElement = currentElement.nextElementSibling
+			if (nextElement) {
+				nextElement = this.$refs.quickShareDropdown.firstElementChild
+			}
+			nextElement.focus()
+		},
+		shiftFocusBackward() {
+			const currentElement = document.activeElement
+			let previousElement = currentElement.previousElementSibling
+			if (!previousElement) {
+				previousElement = this.$refs.quickShareDropdown.lastElementChild
 			}
-       },
+			previousElement.focus()
+		},
+		handleArrowUp() {
+			this.shiftFocusBackward()
+		},
+		handleArrowDown() {
+			this.shiftFocusForward()
+		},
 	},
 
 }
@@ -161,6 +229,8 @@ export default {
 
 	.share-select-dropdown-container {
 		position: absolute;
+		display: flex;
+		flex-direction: column;
 		top: 100%;
 		left: 0;
 		background-color: var(--color-main-background);
@@ -172,6 +242,15 @@ export default {
 		.dropdown-item {
 			padding: 8px;
 			font-size: 12px;
+			background: none;
+			border: none;
+			border-radius: 0;
+			font: inherit;
+			cursor: pointer;
+			color: inherit;
+			outline: none;
+			width: 100%;
+			white-space: nowrap;
 
 			&:hover {
 				background-color: #f2f2f2;