/**
 * Pure, DOM-free helpers shared by the docs navigation components (`DocsTabs`, `DocsSidebar`,
 * `DocsLanguagePicker`): which tab a path belongs to, a tab's first page, and the same page's URL in
 * another locale. Kept out of the components so the derivation is unit-testable and identical
 * everywhere (the tab bar, the left rail, and the language switcher).
 */
import type { NavTab, NavTree } from "../../../docs/types.js";
/**
 * The id of the tab whose pages include `path`, or `undefined` when no item matches (e.g. the docs
 * index, or a hidden page not in the tree). Matches against each item's resolved `href`.
 *
 * @param nav - the navigation tree.
 * @param path - the current page's URL path (typically `usePathname()`).
 * @returns the owning tab id, or `undefined`.
 */
export declare function tabIdForPath(nav: NavTree, path: string | undefined): string | undefined;
/**
 * The `href` of a tab's first page in reading order (its first group's first item), used as the
 * tab's own link target so clicking a tab navigates into that section.
 *
 * @param tab - the tab, or `undefined`.
 * @returns the first page's href, or `undefined` when the tab has no pages.
 */
export declare function firstHrefOf(tab: NavTab | undefined): string | undefined;
/**
 * The URL of the current page in another locale: extracts the page slug from `pathname` (the part
 * after the section base, e.g. `greeting` from `/fr/docs/greeting` or `/docs/greeting`) and rebuilds
 * the path for `targetLang` via the shared {@link localePath}, so the language picker's links match
 * the rendered routes exactly. Falls back to the locale's index when the path carries no slug.
 *
 * @param pathname - the current URL path (e.g. from `usePathname()`).
 * @param targetLang - the locale to switch to.
 * @param opts.basePath - the docs section base (e.g. `/docs`); defaults to `/blog` via `normalizeBasePath`.
 * @param opts.defaultLocale - the locale served without a URL prefix (unless prefixed below).
 * @param opts.prefixDefaultLocale - when `true`, the default locale is prefixed too.
 * @param opts.trailingSlash - when `false`, omit the trailing slash. Defaults to `true`.
 * @returns the root-relative URL of the same page in `targetLang`.
 */
export declare function switchLocaleHref(pathname: string, targetLang: string, opts: {
    basePath?: string | undefined;
    defaultLocale: string;
    prefixDefaultLocale?: boolean | undefined;
    trailingSlash?: boolean | undefined;
}): string;