From d05054a5fccf09e0b40b3873630d51125212d81b Mon Sep 17 00:00:00 2001
From: tugcekucukoglu <tugcekucukoglu.860@gmail.com>
Date: Fri, 17 Nov 2023 21:10:06 +0300
Subject: [PATCH] Fixed #4841 - TreeSelect: Accessibility Improvements

---
 components/lib/treeselect/TreeSelect.vue | 69 +++++++++++++++++++++++-
 1 file changed, 67 insertions(+), 2 deletions(-)

diff --git a/components/lib/treeselect/TreeSelect.vue b/components/lib/treeselect/TreeSelect.vue
index 56bf6d987..285e78178 100644
--- a/components/lib/treeselect/TreeSelect.vue
+++ b/components/lib/treeselect/TreeSelect.vue
@@ -43,8 +43,19 @@
             </slot>
         </div>
         <Portal :appendTo="appendTo">
-            <transition name="p-connected-overlay" @enter="onOverlayEnter" @leave="onOverlayLeave" @after-leave="onOverlayAfterLeave" v-bind="ptm('transition')">
+            <transition name="p-connected-overlay" @enter="onOverlayEnter" @after-enter="onOverlayAfterEnter" @leave="onOverlayLeave" @after-leave="onOverlayAfterLeave" v-bind="ptm('transition')">
                 <div v-if="overlayVisible" :ref="overlayRef" @click="onOverlayClick" :class="[cx('panel'), panelClass]" @keydown="onOverlayKeydown" v-bind="{ ...panelProps, ...ptm('panel') }">
+                    <span
+                        ref="firstHiddenFocusableElementOnOverlay"
+                        role="presentation"
+                        aria-hidden="true"
+                        class="p-hidden-accessible p-hidden-focusable"
+                        :tabindex="0"
+                        @focus="onFirstHiddenFocus"
+                        v-bind="ptm('hiddenFirstFocusableEl')"
+                        :data-p-hidden-accessible="true"
+                        :data-p-hidden-focusable="true"
+                    ></span>
                     <slot name="header" :value="modelValue" :options="options"></slot>
                     <div :class="cx('wrapper')" :style="{ 'max-height': scrollHeight }" v-bind="ptm('wrapper')">
                         <TSTree
@@ -78,6 +89,17 @@
                         </div>
                     </div>
                     <slot name="footer" :value="modelValue" :options="options"></slot>
+                    <span
+                        ref="lastHiddenFocusableElementOnOverlay"
+                        role="presentation"
+                        aria-hidden="true"
+                        class="p-hidden-accessible p-hidden-focusable"
+                        :tabindex="0"
+                        @focus="onLastHiddenFocus"
+                        v-bind="ptm('hiddenLastFocusableEl')"
+                        :data-p-hidden-accessible="true"
+                        :data-p-hidden-focusable="true"
+                    ></span>
                 </div>
             </transition>
         </Portal>
@@ -161,11 +183,15 @@ export default {
             this.$emit('blur', event);
         },
         onClick(event) {
+            if (this.disabled) {
+                return;
+            }
+
             if (!this.disabled && (!this.overlay || !this.overlay.contains(event.target))) {
                 if (this.overlayVisible) this.hide();
                 else this.show();
 
-                this.$refs.focusInput.focus();
+                DomHandler.focus(this.$refs.focusInput);
             }
         },
         onSelectionChange(keys) {
@@ -186,6 +212,16 @@ export default {
         onNodeToggle(keys) {
             this.expandedKeys = keys;
         },
+        onFirstHiddenFocus(event) {
+            const focusableEl = event.relatedTarget === this.$refs.focusInput ? DomHandler.getFirstFocusableElement(this.overlay, ':not([data-p-hidden-focusable="true"])') : this.$refs.focusInput;
+
+            DomHandler.focus(focusableEl);
+        },
+        onLastHiddenFocus(event) {
+            const focusableEl = event.relatedTarget === this.$refs.focusInput ? DomHandler.getLastFocusableElement(this.overlay, ':not([data-p-hidden-focusable="true"])') : this.$refs.focusInput;
+
+            DomHandler.focus(focusableEl);
+        },
         onKeyDown(event) {
             switch (event.code) {
                 case 'ArrowDown':
@@ -199,7 +235,10 @@ export default {
 
                 case 'Escape':
                     this.onEscapeKey(event);
+                    break;
 
+                case 'Tab':
+                    this.onTabKey(event);
                     break;
 
                 default:
@@ -235,11 +274,30 @@ export default {
                 event.preventDefault();
             }
         },
+        onTabKey(event, pressedInInputText = false) {
+            if (!pressedInInputText) {
+                if (this.overlayVisible && this.hasFocusableElements()) {
+                    DomHandler.focus(this.$refs.firstHiddenFocusableElementOnOverlay);
+
+                    event.preventDefault();
+                } else {
+                    if (this.focusedOptionIndex !== -1) {
+                        this.onOptionSelect(event, this.visibleOptions[this.focusedOptionIndex]);
+                    }
+                }
+            }
+        },
+        hasFocusableElements() {
+            return DomHandler.getFocusableElements(this.overlay, ':not([data-p-hidden-focusable="true"])').length > 0;
+        },
         onOverlayEnter(el) {
             ZIndexUtils.set('overlay', el, this.$primevue.config.zIndex.overlay);
 
             DomHandler.addStyles(el, { position: 'absolute', top: '0', left: '0' });
             this.alignOverlay();
+            this.focus();
+        },
+        onOverlayAfterEnter() {
             this.bindOutsideClickListener();
             this.bindScrollListener();
             this.bindResizeListener();
@@ -256,6 +314,13 @@ export default {
         onOverlayAfterLeave(el) {
             ZIndexUtils.clear(el);
         },
+        focus() {
+            let focusableElements = DomHandler.getFocusableElements(this.overlay);
+
+            if (focusableElements && focusableElements.length > 0) {
+                focusableElements[0].focus();
+            }
+        },
         alignOverlay() {
             if (this.appendTo === 'self') {
                 DomHandler.relativePosition(this.overlay, this.$el);