/**
 * @typedef {import('$types/base').Comment} Comment
 */

/**
 * @param {import('$types/base').Result<Comment>} comments 
 * @returns {import('$types/base').CommentTreeNode[]}
 */
export function buildCommentTree(comments) {
  /** @type {Comment[]} */
  let roots = [];
  /** @type {Map<number, Comment[]>} */
  let refs = new Map();

  comments.forEach((comment, id) => {
    if (comment.parentCommentId == null) {
      roots.push(comment);
    } else {
      if (!refs.has(comment.parentCommentId)) {
        refs.set(comment.parentCommentId, []);
      }
      refs.get(comment.parentCommentId)?.push(comment);
    }
  });

  return roots.map(r => buildFromRoot(refs, r));
}

/**
 * @param {Map<number, Comment[]>} refs 
 * @param {Comment} comment 
 * @returns {import('$types/base').CommentTreeNode}
 */
function buildFromRoot(refs, comment) {
  return {
    parent: comment,
    children: refs.get(comment.id)?.map(c => {
      return buildFromRoot(refs, c);
    }) || []
  }
}