convert flatten array to tree structure based on leftIndent. From Word Pargraphs.

convert_to_tree_based_on_left_indent.js

  const makeTree = (paragraphs) => {
    const findParentLevel = (levels, level) => {
      if (levels[level]) {
        return level;
      }
      return findParentLevel(levels, level - 1);
    };

    const tree = paragraphs.reduce(
      (acc, p) => {
        const level = Math.abs(Math.floor(p.data.leftIndent / 18));
        const levelData = {
          id: p.id,
          data: p.data,
          children: [],
          title: p.data.title,
          parentId: null,
          key: p.id,
        };
        if (level === 0) {
          acc.result.push(levelData);
          acc.levels = { 0: levelData };
        } else {
          const parentLevel = findParentLevel(acc.levels, level - 1);

          acc.levels[parentLevel].children.push({
            ...levelData,
            parentId: acc.levels[parentLevel].id,
          });
          acc.levels[parentLevel + 1] = levelData;
        }

        return acc;
      },
      { result: [], levels: {} }
    );