import { TransactionResponse } from "@ethersproject/providers";
import BigNumber from "bignumber.js";
export declare enum ApprovalState {
    UNKNOWN = 0,
    NOT_APPROVED = 1,
    PENDING = 2,
    APPROVED = 3
}
export declare function useApproveCallback(amount: BigNumber | null, tokenAddress: string, spender?: string): [ApprovalState, () => Promise<TransactionResponse | undefined>, boolean, boolean];