From 46a15320a9e91e756d0d9d5e3caaac08939d17d5 Mon Sep 17 00:00:00 2001
From: Ndricim Rrapi <ndricim.rrapi@sap.com>
Date: Thu, 28 Apr 2022 16:48:44 +0200
Subject: [PATCH] Disable keyboard accessibility on confirmation modal
 background elements  (#2672)

---
 core/src/ConfirmationModal.svelte             |  10 +-
 core/src/utilities/helpers/iframe-helpers.js  |  37 ++++++
 .../utilities/helpers/iframe-helpers.spec.js  | 109 ++++++++++++++++++
 3 files changed, 154 insertions(+), 2 deletions(-)

diff --git a/core/src/ConfirmationModal.svelte b/core/src/ConfirmationModal.svelte
index 24456a06c2..0653290acf 100644
--- a/core/src/ConfirmationModal.svelte
+++ b/core/src/ConfirmationModal.svelte
@@ -1,8 +1,8 @@
 <script>
-  import { createEventDispatcher, onMount } from 'svelte';
+  import { createEventDispatcher, onMount, onDestroy } from 'svelte';
   import { LuigiI18N } from './core-api';
   import { KEYCODE_ESC } from './utilities/keycode.js';
-  import { EscapingHelpers, NavigationHelpers } from './utilities/helpers';
+  import { EscapingHelpers, NavigationHelpers, IframeHelpers } from './utilities/helpers';
 
   const dispatch = createEventDispatcher();
 
@@ -15,6 +15,10 @@
     success: 'message-success',
   };
 
+  onDestroy(()=> {
+    IframeHelpers.enableA11YKeyboardBackdropExceptClassName('.fd-message-box-docs-static');
+  })
+
   onMount(() => {
     const defaultSettings = {
       icon: iconMapping[settings.type],
@@ -29,6 +33,8 @@
     };
     settings = Object.assign(defaultSettings, settings);
 
+    IframeHelpers.disableA11YKeyboardExceptClassName('.fd-message-box-docs-static');
+
     const focusedButton = settings.buttonConfirm
       ? 'confirm-button'
       : 'dismiss-button';
diff --git a/core/src/utilities/helpers/iframe-helpers.js b/core/src/utilities/helpers/iframe-helpers.js
index b597f09eac..a1154536ba 100644
--- a/core/src/utilities/helpers/iframe-helpers.js
+++ b/core/src/utilities/helpers/iframe-helpers.js
@@ -303,6 +303,43 @@ class IframeHelpersClass {
     });
   }
 
+  /**
+   * Sets tabindex for all elements to -1, except for one element and all its children which needs the focus.
+   * Setting tabindex to a negative value removes keyboard acessibility from the specified elements.
+   * @param {string} targetElementClassName the class name/s of the element to be excluded
+   */
+  disableA11YKeyboardExceptClassName(targetElementClassName) {
+    const nodeList = document.querySelectorAll('*');
+    [...nodeList].forEach(element => {
+      const isNotAChildOfTargetElement = !element.closest(targetElementClassName);
+      const prevTabIndex = element.getAttribute('tabindex');
+      // save tabIndex in case one already exists
+      if ((prevTabIndex || prevTabIndex === 0) && isNotAChildOfTargetElement) {
+        element.setAttribute('oldtab', prevTabIndex);
+      }
+      // set tabindex to negative only if the current element is not a descendant of element with class 'targetElementClassName'
+      isNotAChildOfTargetElement ? element.setAttribute('tabindex', '-1') : '';
+    });
+  }
+
+  /**
+   * Resets tabindex value to previous value if it exists, or remove altogether if not.
+   * Applies to all elements except for the target element which we do not touch
+   */
+  enableA11YKeyboardBackdropExceptClassName(targetElementClassName) {
+    const nodeList = document.querySelectorAll('*');
+    [...nodeList].forEach(element => {
+      const restoreVal = element.getAttribute('oldtab');
+      const isNotAChildOfTargetElement = !element.closest(targetElementClassName);
+      if (restoreVal) {
+        element.setAttribute('tabindex', restoreVal);
+        element.removeAttribute('oldtab');
+      } else {
+        isNotAChildOfTargetElement ? element.removeAttribute('tabindex') : '';
+      }
+    });
+  }
+
   applyCoreStateData(data) {
     return {
       ...data,
diff --git a/core/test/utilities/helpers/iframe-helpers.spec.js b/core/test/utilities/helpers/iframe-helpers.spec.js
index 40d4a260db..f198078b21 100644
--- a/core/test/utilities/helpers/iframe-helpers.spec.js
+++ b/core/test/utilities/helpers/iframe-helpers.spec.js
@@ -344,4 +344,113 @@ describe('Iframe-helpers', () => {
       assert.deepEqual(IframeHelpers.applyCoreStateData(undefined), expected);
     });
   });
+
+  describe('disable/enable keyboard accessibility on background elements', () => {
+    /**
+     * Ths function produces this html containing 6 DOM elements inside a body tag
+     * <html>
+     * <head>
+     *    <title>Mocked DOM</title>
+     * </head>
+     * <body>
+     *   <div>
+     *     <span class="outsideModal">I am some text</span>
+     *     <span tabindex="0" class="oldTabIndexOutsideModal">I am a text span with existing tabindex value</span>
+     *     <div class="modalElement">
+     *        <button>Click me</button>
+     *        <button class="oldTabIndexInModal" tabindex="1">Click that</button>
+     *     </div>
+     *   </div>
+     * </body>
+     * </html>
+     *
+     * @returns mocked data
+     */
+    const getMockedDocument = () => {
+      let doc = document.implementation.createHTMLDocument('Mocked DOM');
+
+      const divParent = doc.createElement('div');
+      divParent.className = 'divParent';
+      doc.body.appendChild(divParent);
+
+      const spanChild = doc.createElement('span');
+      spanChild.textContent = 'I am some text';
+      spanChild.className = 'spanChild';
+      divParent.appendChild(spanChild);
+
+      const spanChild2 = doc.createElement('span');
+      spanChild2.textContent = 'I am a text span with existing tabindex value';
+      spanChild2.setAttribute('tabindex', '0');
+      spanChild2.className = 'oldTabIndexOutsideModal';
+
+      divParent.appendChild(spanChild2);
+      divParent.appendChild(spanChild2);
+
+      const divChild = doc.createElement('div');
+      divChild.className = 'modalElement';
+
+      const childButton1 = doc.createElement('button');
+      childButton1.textContent = 'Click me';
+      childButton1.className = 'childButton1';
+
+      const childButton2 = doc.createElement('button');
+      childButton2.textContent = 'Click that';
+      childButton2.className = 'oldTabIndexInModal';
+      childButton2.setAttribute('tabindex', '1');
+
+      divChild.appendChild(childButton1);
+      divChild.appendChild(childButton2);
+      divParent.appendChild(divChild);
+      return doc;
+    };
+
+    describe('disableA11YKeyboardExceptClassName', () => {
+      beforeEach(() => {
+        global.document = getMockedDocument();
+      });
+
+      it('saves old tabindex value properly', () => {
+        IframeHelpers.disableA11YKeyboardExceptClassName('.modalElement');
+        assert.equal(global.document.getElementsByClassName('oldTabIndexOutsideModal')[0].getAttribute('oldtab'), 0);
+        assert.isNull(global.document.getElementsByClassName('oldTabIndexInModal')[0].getAttribute('oldtab'));
+      });
+
+      it('set tabindex properly on all but specified classname element', () => {
+        IframeHelpers.disableA11YKeyboardExceptClassName('.modalElement');
+        assert.equal(global.document.getElementsByClassName('divParent')[0].getAttribute('tabindex'), -1);
+        assert.equal(global.document.getElementsByClassName('spanChild')[0].getAttribute('tabindex'), -1);
+        assert.equal(global.document.getElementsByClassName('oldTabIndexOutsideModal')[0].getAttribute('tabindex'), -1);
+        assert.isNull(global.document.getElementsByClassName('modalElement')[0].getAttribute('tabindex'));
+        assert.isNull(global.document.getElementsByClassName('childButton1')[0].getAttribute('tabindex'));
+        assert.equal(global.document.getElementsByClassName('oldTabIndexInModal')[0].getAttribute('tabindex'), 1);
+      });
+    });
+
+    describe('enableA11YKeyboardBackdrop', () => {
+      beforeEach(() => {
+        global.document = getMockedDocument();
+        IframeHelpers.disableA11YKeyboardExceptClassName('.modalElement');
+      });
+
+      it('check oldtab property properly removed', () => {
+        IframeHelpers.enableA11YKeyboardBackdropExceptClassName('.modalElement');
+        assert.isNull(global.document.getElementsByClassName('divParent')[0].getAttribute('oldtab'));
+        assert.isNull(global.document.getElementsByClassName('spanChild')[0].getAttribute('oldtab'));
+        assert.isNull(global.document.getElementsByClassName('oldTabIndexOutsideModal')[0].getAttribute('oldtab'));
+        assert.isNull(global.document.getElementsByClassName('modalElement')[0].getAttribute('oldtab'));
+        assert.isNull(global.document.getElementsByClassName('childButton1')[0].getAttribute('oldtab'));
+        assert.isNull(global.document.getElementsByClassName('oldTabIndexInModal')[0].getAttribute('oldtab'));
+      });
+
+      it('check oldtabindex value properly restored', () => {
+        IframeHelpers.enableA11YKeyboardBackdropExceptClassName('.modalElement');
+        assert.isNull(global.document.getElementsByClassName('divParent')[0].getAttribute('tabindex'));
+        assert.isNull(global.document.getElementsByClassName('spanChild')[0].getAttribute('tabindex'));
+        assert.equal(global.document.getElementsByClassName('oldTabIndexOutsideModal')[0].getAttribute('tabindex'), 0);
+        assert.isNull(global.document.getElementsByClassName('modalElement')[0].getAttribute('tabindex'));
+        assert.isNull(global.document.getElementsByClassName('childButton1')[0].getAttribute('tabindex'));
+        assert.equal(global.document.getElementsByClassName('oldTabIndexInModal')[0].getAttribute('tabindex'), 1);
+      });
+    });
+  });
 });