From 386ee5ab17f42863485abef062ebb677c3ca3326 Mon Sep 17 00:00:00 2001
From: Luke Wilde <lukew@serenityos.org>
Date: Mon, 31 Jan 2022 19:10:12 +0000
Subject: [PATCH] LibWeb: Implement Range.intersectsNode

---
 Userland/Libraries/LibWeb/DOM/Range.cpp | 27 +++++++++++++++++++++++++
 Userland/Libraries/LibWeb/DOM/Range.h   |  2 ++
 Userland/Libraries/LibWeb/DOM/Range.idl |  2 ++
 3 files changed, 31 insertions(+)

diff --git a/Userland/Libraries/LibWeb/DOM/Range.cpp b/Userland/Libraries/LibWeb/DOM/Range.cpp
index 0ba35e2499..7d4178f601 100644
--- a/Userland/Libraries/LibWeb/DOM/Range.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Range.cpp
@@ -421,4 +421,31 @@ NonnullRefPtr<Node> Range::common_ancestor_container() const
     return container;
 }
 
+// https://dom.spec.whatwg.org/#dom-range-intersectsnode
+bool Range::intersects_node(Node const& node) const
+{
+    // 1. If node’s root is different from this’s root, return false.
+    if (&node.root() != &root())
+        return false;
+
+    // 2. Let parent be node’s parent.
+    auto* parent = node.parent();
+
+    // 3. If parent is null, return true.
+    if (!parent)
+        return true;
+
+    // 4. Let offset be node’s index.
+    auto offset = node.index();
+
+    // 5. If (parent, offset) is before end and (parent, offset plus 1) is after start, return true
+    auto relative_position_to_end = position_of_boundary_point_relative_to_other_boundary_point(*parent, offset, m_end_container, m_end_offset);
+    auto relative_position_to_start = position_of_boundary_point_relative_to_other_boundary_point(*parent, offset + 1, m_start_container, m_start_offset);
+    if (relative_position_to_end == RelativeBoundaryPointPosition::Before && relative_position_to_start == RelativeBoundaryPointPosition::After)
+        return true;
+
+    // 6. Return false.
+    return false;
+}
+
 }
diff --git a/Userland/Libraries/LibWeb/DOM/Range.h b/Userland/Libraries/LibWeb/DOM/Range.h
index 6b62b1d44c..2d2b986d34 100644
--- a/Userland/Libraries/LibWeb/DOM/Range.h
+++ b/Userland/Libraries/LibWeb/DOM/Range.h
@@ -57,6 +57,8 @@ public:
         // Note: Its functionality (disabling a Range object) was removed, but the method itself is preserved for compatibility.
     }
 
+    bool intersects_node(Node const&) const;
+
 private:
     explicit Range(Document&);
 
diff --git a/Userland/Libraries/LibWeb/DOM/Range.idl b/Userland/Libraries/LibWeb/DOM/Range.idl
index bcede22cf8..17595288bf 100644
--- a/Userland/Libraries/LibWeb/DOM/Range.idl
+++ b/Userland/Libraries/LibWeb/DOM/Range.idl
@@ -27,4 +27,6 @@ interface Range : AbstractRange {
     Range cloneRange();
     undefined detach();
 
+    boolean intersectsNode(Node node);
+
 };