fix: Whitespace in pasted HTML is not handled according to the HTML spec

packages/core/src/plugins/html-deserializer/utils/htmlStringToDOMNode.ts

@@ -1,16 +1,66 @@
 /**
- * Convert HTML string into HTML element.
+ * Convert HTML string into HTML element with custom white-space handling.
  */
 export const htmlStringToDOMNode = (
   rawHtml: string,
-  stripWhitespace = true
+  stripWhitespace = true,
+  preElementBehavior = true
 ) => {
   const node = document.createElement('body');
   node.innerHTML = rawHtml;
-
-  if (stripWhitespace) {
-    node.innerHTML = node.innerHTML.replaceAll(/(\r\n|[\t\n\r])/g, '');
+  const computedStyle = window.getComputedStyle(node);
+  // Process based on the specified white-space value
+  switch (computedStyle.whiteSpace) {
+    case 'normal': {
+      if (stripWhitespace) {
+        // Collapse spaces and tabs, wrap text, remove end-of-line spaces
+        node.innerHTML = node.innerHTML.replaceAll(/[\t\r]*\n[\t\r ]*/g, ' ');
+      }
+      break;
+    }
+    case 'nowrap': {
+      if (stripWhitespace) {
+        // Collapse spaces and tabs, no text wrap, remove end-of-line spaces
+        node.innerHTML = node.innerHTML.replaceAll(/[\t\r]*\n[\t\r ]*/g, ' ');
+      }
+      break;
+    }
+    case 'pre': {
+      // Preserve spaces and tabs, no text wrap, preserve end-of-line spaces
+      break;
+    }
+    case 'pre-wrap': {
+      // Preserve spaces and tabs, wrap text, preserve end-of-line spaces
+      break;
+    }
+    case 'pre-line': {
+      if (stripWhitespace) {
+        // Preserve spaces, collapse tabs, wrap text, remove end-of-line spaces
+        node.innerHTML = node.innerHTML.replaceAll('\t', ' ');
+      }
+      break;
+    }
+    case 'break-spaces': {
+      // Preserve spaces and tabs, wrap text, wrap end-of-line spaces
+      node.innerHTML = node.innerHTML.replaceAll(/[\t\r ]/g, ' ');
+      break;
+    }
+    default: {
+      // Use 'normal' behavior if the specified value is not recognized
+      break;
+    }
+  }
+  if (preElementBehavior) {
+    // Check if the first element within the body is a PRE element
+    const firstElement = node.firstElementChild;
+    if (
+      firstElement &&
+      firstElement.tagName === 'PRE' &&
+      rawHtml.startsWith('\n')
+    ) {
+      // Remove the leading newline character as per the HTML spec
+      firstElement.textContent = rawHtml.slice(1);
+    }
   }
-
   return node;
 };