import type { BaseBigNumber } from '../abstracts/base_big_number';
/**
 * Pure binary-search helper for locating the checkpoint slot that contains a
 * given child-chain block. Extracted from `RootChain.findRootBlockFromChild`
 * so the algorithm can be unit-tested without instantiating the class
 * hierarchy or the plugin-injected `utils.BN`.
 *
 * The helper is plugin-agnostic: it uses only the methods declared on
 * `BaseBigNumber`, which every plugin's BigNumber implementation extends
 * (`MaticBigNumber` for `@maticnetwork/maticjs-ethers`, bn.js for the web3
 * plugin, and so on). The constructor for those instances is plugin-specific,
 * so the caller passes it in via the `bn` factory.
 *
 * Two correctness properties this helper enforces — both broken in earlier
 * inline versions of the algorithm:
 *
 *  1. The single-candidate early exit (`start.eq(end)`) verifies that the
 *     candidate's range actually contains the child block. Without this
 *     check, a child block past every existing checkpoint causes the search
 *     to converge on `currentHeaderBlock / 10000` and falsely accept it,
 *     producing a proof that embeds a non-existent or unrelated checkpoint.
 *
 *  2. The two contract reads (`currentHeaderBlock`, `headerBlocks(slot)`) are
 *     parameterised on a single block tag — the caller wires both reads to
 *     the same L1 block tag as the upstream existence check, so the search
 *     and the existence check observe a consistent chain view.
 */
export type BNFactory = (value: number | string) => BaseBigNumber;
export interface CheckpointSlotInputs {
    /** Constructs a BigNumber of the same plugin-injected type as the inputs. */
    bn: BNFactory;
    /** Child-chain block number whose containing checkpoint we want. */
    childBlockNumber: BaseBigNumber;
    /** Reads the RootChain `currentHeaderBlock()` storage value. */
    readCurrentHeaderBlock: () => Promise<BaseBigNumber>;
    /** Reads `headerBlocks(headerId)` for `headerId = slot * CHECKPOINT_INTERVAL`. */
    readHeaderBlocks: (headerId: BaseBigNumber) => Promise<{
        start: BaseBigNumber;
        end: BaseBigNumber;
    }>;
}
/**
 * @returns the header id (`slot * CHECKPOINT_INTERVAL`) of the checkpoint
 * containing the child block.
 * @throws if the child block is not contained in any submitted checkpoint.
 */
export declare function findCheckpointSlot(opts: CheckpointSlotInputs): Promise<BaseBigNumber>;