Fix copy and paste text inconsistent on mWeb

src/libs/Clipboard/index.js

@@ -1,9 +1,50 @@
 // on Web/desktop this import will be replaced with `react-native-web`
 import {Clipboard} from 'react-native-web';
 import lodashGet from 'lodash/get';
+import CONST from '../../CONST';
+import * as Browser from '../Browser';
 
 const canSetHtml = () => lodashGet(navigator, 'clipboard.write');
 
+/**
+ * Deprecated method to write the content as HTML to clipboard.
+ * @param {String} html HTML representation
+ * @param {String} text Plain text representation
+ */
+function setHTMLSync(html, text) {
+    const node = document.createElement('span');
+    node.textContent = html;
+    node.style.all = 'unset';
+    node.style.opacity = '0';
+    node.style.position = 'absolute';
+    node.style.whiteSpace = 'pre-wrap';
+    node.style.userSelect = 'text';
+    node.addEventListener('copy', (e) => {
+        e.stopPropagation();
+        e.preventDefault();
+        e.clipboardData.clearData();
+        e.clipboardData.setData('text/html', html);
+        e.clipboardData.setData('text/plain', text);
+    });
+    document.body.appendChild(node);
+
+    const selection = window.getSelection();
+    selection.removeAllRanges();
+    const range = document.createRange();
+    range.selectNodeContents(node);
+    selection.addRange(range);
+
+    try {
+        document.execCommand('copy');
+    } catch (e) {
+        // The 'copy' command can throw a SecurityError exception, we ignore this exception on purpose.
+        // See https://dvcs.w3.org/hg/editing/raw-file/tip/editing.html#the-copy-command for more details.
+    }
+
+    selection.removeAllRanges();
+    document.body.removeChild(node);
+}
+
 /**
  * Writes the content as HTML if the web client supports it.
  * @param {String} html HTML representation
@@ -18,13 +59,21 @@ const setHtml = (html, text) => {
         throw new Error('clipboard.write is not supported on this platform, thus HTML cannot be copied.');
     }
 
-    navigator.clipboard.write([
-        // eslint-disable-next-line no-undef
-        new ClipboardItem({
-            'text/html': new Blob([html], {type: 'text/html'}),
-            'text/plain': new Blob([text], {type: 'text/plain'}),
-        }),
-    ]);
+    if (CONST.BROWSER.SAFARI === Browser.getBrowser()) {
+        // Safari sanitize "text/html" data before writing to the pasteboard when using Clipboard API,
+        // whitespaces in the start of line are stripped away. We use the deprecated method to copy
+        // contents as HTML and keep whitespaces in the start of line on Safari.
+        // See https://webkit.org/blog/10855/async-clipboard-api/ for more details.
+        setHTMLSync(html, text);
+    } else {
+        navigator.clipboard.write([
+            // eslint-disable-next-line no-undef
+            new ClipboardItem({
+                'text/html': new Blob([html], {type: 'text/html'}),
+                'text/plain': new Blob([text], {type: 'text/plain'}),
+            }),
+        ]);
+    }
 };
 
 /**