import type { Opening, OpeningCollection } from "../src/types.js";
/**
 * From/To transition index structure.
 * Maps position-only FEN to arrays of full FENs representing transitions.
 */
export interface FromToIndex {
    /** Maps position → array of next position FENs */
    to: Record<string, string[]>;
    /** Maps position → array of previous position FENs */
    from: Record<string, string[]>;
}
/**
 * Downloads and caches the pre-indexed from/to transition data from GitHub.
 * This file is generated by eco.json.tooling and maps position-only FENs to transition arrays.
 *
 * @returns Indexed transition data with to/from mappings
 *
 * @example
 * ```typescript
 * const index = await getFromToIndex();
 * const position = "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR";
 * const nextFens = index.to[position]; // FENs for e2-e4 position
 * ```
 */
export declare function getFromToIndex(): Promise<FromToIndex>;
/**
 * Gets the next and previous opening positions for a given FEN.
 * Returns full Opening objects (not just FEN strings) by looking up transitions
 * in the pre-indexed data and enriching with opening book information.
 *
 * Uses position-only FEN for lookup to handle transpositions.
 *
 * @param fen - The FEN string to look up transitions for
 * @param openings - Optional pre-loaded opening collection (will fetch if not provided)
 * @returns Object with next and from Opening arrays
 *
 * @example
 * ```typescript
 * // Get transitions for e2-e4 position
 * const { next, from } = await getFromTos(
 *   "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1"
 * );
 *
 * console.log(next[0].name); // "King's Pawn Opening: Sicilian Defense"
 * console.log(from[0].name); // "Starting Position"
 * ```
 */
export declare function getFromTos(fen: string, openings?: OpeningCollection): Promise<{
    next: Opening[];
    from: Opening[];
}>;
/**
 * Clears the cached fromToIndex, forcing a fresh download on next access.
 * Useful for testing or when data updates are expected.
 */
export declare function clearFromToCache(): void;
//# sourceMappingURL=fromTo.d.ts.map