const levels = ['province_id', 'district_id', 'admin_post_id', 'locality_id'];
const searchRoutes = ['/carteira', '/oportunidades', '/zonas', '/educacao'];

/** URL-scoped search context, never a saved investment or another browser tab. */
export function searchTerritoryHref(href: string, pageUrl: string): string {
    const base = 'https://portal.invalid';
    const source = new URL(pageUrl, base);
    const target = new URL(href, base);
    const supported = (path: string) => searchRoutes.some((route) => path === route || path.startsWith(`${route}/`));
    if (target.origin !== base || !supported(source.pathname) || !supported(target.pathname)) return href;
    const inherited = source.searchParams.has('catalogue_query')
        ? new URLSearchParams(source.searchParams.get('catalogue_query')!)
        : source.searchParams;
    // An explicit ancestor, including an explicit empty value, overrides its descendants.
    let changed = false;
    for (const field of levels) {
        if (target.searchParams.has(field)) {
            changed ||= target.searchParams.get(field) !== inherited.get(field);
        } else if (!changed && inherited.get(field)) {
            target.searchParams.set(field, inherited.get(field)!);
        }
    }
    return target.pathname + target.search + target.hash;
}