/**
 * Pure, framework-free navigation for the docs sidebar. Given the front-matter of every page in
 * one language, {@link buildNavTree} assembles the **tabs -> groups -> ordered pages** tree the
 * sidebar renders; {@link flattenNav} linearises it into reading order (for prev/next);
 * {@link adjacentFor} and {@link breadcrumbFor} derive a single page's prev/next and breadcrumb.
 *
 * This is the structural piece a blog does not need (a blog is a flat, date-sorted list). Kept
 * fs-free (no `node:fs`, no `next`/`react` import) so it is trivially unit-testable and can be
 * shared with the React components; the on-disk layout is walked by the `Docs` reader, which
 * feeds this the parsed metadata.
 */
import type { Adjacent, Breadcrumb, DocMeta, NavConfigEntry, NavItem, NavTree } from "./types.js";
/** URL/ordering inputs {@link buildNavTree} needs beyond the page metadata itself. */
export interface NavBuildOptions {
    /** The section base path (e.g. `/docs`), passed through to `localePath`. */
    basePath?: string | undefined;
    /** The default locale code (served unprefixed unless `prefixDefaultLocale`). */
    defaultLocale: string;
    /**
     * The language this tree is being built for, which is what a per-locale tab/group label is
     * resolved against. Defaults to `defaultLocale` - so an existing caller that omits it keeps
     * getting the default-locale labels it always got.
     */
    lang?: string | undefined;
    /** When `true`, the default locale is URL-prefixed too. */
    prefixDefaultLocale?: boolean | undefined;
    /** When `false`, nav `href`s omit the trailing slash. Defaults to `true`; see `SiteConfig.trailingSlash`. */
    trailingSlash?: boolean | undefined;
    /** Optional tab display order + labels. */
    tabs?: NavConfigEntry[] | undefined;
    /** Optional group display order + labels. */
    groups?: NavConfigEntry[] | undefined;
}
/**
 * Assembles the sidebar navigation tree for one language from its pages' front-matter.
 *
 * Pages are bucketed by `tab` (a single implicit `""` tab when none is set - `multiTab` is then
 * `false` so the frontend hides the tab bar) and then by `group` (a `""` bucket for ungrouped
 * pages). Tabs and groups are ordered by the `tabs`/`groups` config first, then by their pages'
 * minimum `order`, then first-seen; pages within a group are ordered by `order` then title.
 * `hidden` pages are excluded.
 *
 * @param metas - every (non-hidden and hidden) page's front-matter for one language; `hidden`
 *   pages are filtered out here.
 * @param opts - URL options plus the optional tab/group ordering config.
 * @returns the ordered {@link NavTree}.
 */
export declare function buildNavTree(metas: DocMeta[], opts: NavBuildOptions): NavTree;
/**
 * Linearises a nav tree into its reading order: every page, tabs then groups then items, in the
 * order the sidebar shows them. The basis for prev/next.
 *
 * @param tree - the navigation tree.
 * @returns the flattened list of nav items.
 */
export declare function flattenNav(tree: NavTree): NavItem[];
/**
 * Finds the pages immediately before and after `slug` in the flattened reading order. Prev/next
 * cross group and tab boundaries (matching common docs UIs); either side is `undefined` at the
 * ends, and an unknown slug yields an empty result.
 *
 * @param slug - the current page slug.
 * @param flat - the flattened nav items (from {@link flattenNav}).
 * @returns the previous and next pages, if any.
 */
export declare function adjacentFor(slug: string, flat: NavItem[]): Adjacent;
/**
 * Builds a page's breadcrumb (`[tab?, group?, page]`) from the nav tree. Empty tab/group ids
 * (the implicit tab / ungrouped bucket) contribute no segment.
 *
 * @param slug - the page slug.
 * @param tree - the navigation tree the page lives in.
 * @returns the breadcrumb, or `undefined` when the slug is not in the tree (e.g. a hidden page).
 */
export declare function breadcrumbFor(slug: string, tree: NavTree): Breadcrumb | undefined;