1 files changed, 67 insertions, 0 deletions
diff --git a/app/assets/javascripts/content_editor/services/table_of_contents_utils.js b/app/assets/javascripts/content_editor/services/table_of_contents_utils.js
new file mode 100644
index 00000000000..dad917b2270
--- /dev/null
+++ b/app/assets/javascripts/content_editor/services/table_of_contents_utils.js
@@ -0,0 +1,67 @@
+export function fillEmpty(headings) {
+  for (let i = 0; i < headings.length; i += 1) {
+    let j = headings[i - 1]?.level || 0;
+    if (headings[i].level - j > 1) {
+      while (j < headings[i].level) {
+        headings.splice(i, 0, { level: j + 1, text: '' });
+        j += 1;
+      }
+    }
+  }
+
+  return headings;
+}
+
+const exitHeadingBranch = (heading, targetLevel) => {
+  let currentHeading = heading;
+
+  while (currentHeading.level > targetLevel) {
+    currentHeading = currentHeading.parent;
+  }
+
+  return currentHeading;
+};
+
+export function toTree(headings) {
+  fillEmpty(headings);
+
+  const tree = [];
+  let currentHeading;
+  for (let i = 0; i < headings.length; i += 1) {
+    const heading = headings[i];
+    if (heading.level === 1) {
+      const h = { ...heading, subHeadings: [] };
+      tree.push(h);
+      currentHeading = h;
+    } else if (heading.level > currentHeading.level) {
+      const h = { ...heading, subHeadings: [], parent: currentHeading };
+      currentHeading.subHeadings.push(h);
+      currentHeading = h;
+    } else if (heading.level <= currentHeading.level) {
+      currentHeading = exitHeadingBranch(currentHeading, heading.level - 1);
+
+      const h = { ...heading, subHeadings: [], parent: currentHeading };
+      (currentHeading?.subHeadings || headings).push(h);
+      currentHeading = h;
+    }
+  }
+
+  return tree;
+}
+
+export function getHeadings(editor) {
+  const headings = [];
+
+  editor.state.doc.descendants((node) => {
+    if (node.type.name !== 'heading') return false;
+
+    headings.push({
+      level: node.attrs.level,
+      text: node.textContent,
+    });
+
+    return true;
+  });
+
+  return toTree(headings);
+}