import type { ContentNavNode } from '../types';

export function getPreviousNext(node: ContentNavNode) {
  const currentFullId = node.fullId;

  let previous: ContentNavNode | undefined;
  let next: ContentNavNode | undefined;
  let currentFound = false;

  for (const navNode of ERUDIT.contentNav.id2Node.values()) {
    if (currentFound) {
      next = navNode;
      break;
    }

    if (navNode.fullId === currentFullId) {
      currentFound = true;
    } else {
      previous = navNode;
    }
  }

  // If current inside book then next can't point outside of book
  if (next) {
    const currentBook = ERUDIT.contentNav.getBookFor(node);
    if (currentBook) {
      const nextBook = ERUDIT.contentNav.getBookFor(next);
      if (!nextBook || nextBook.fullId !== currentBook.fullId) {
        next = undefined;
      }
    }
  }

  return { previous, next };
}