refactor: extract block dnd element helpers

rust/spikes/leptos-tiptap-spike/src/editor_runtime/block_dnd.rs

@@ -85,6 +85,26 @@ pub(crate) fn element_within_handle_shell(element: &Element, handle_selector: &s
     element.closest(handle_selector).ok().flatten().is_some()
 }
 
+pub(crate) fn direct_block_from_element(mut element: Element, root: &Element) -> Option<Element> {
+    loop {
+        let parent = element.parent_element()?;
+        if parent.is_same_node(Some(root)) {
+            return Some(element);
+        }
+        element = parent;
+    }
+}
+
+pub(crate) fn top_level_block_index(root: &Element, block: &Element) -> Option<usize> {
+    let children = root.children();
+    (0..children.length()).find_map(|index| {
+        children
+            .item(index)
+            .filter(|child| child.is_same_node(Some(block)))
+            .map(|_| index as usize)
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;