import type { Client } from '../../clients/createClient.js';
import type { Transport } from '../../clients/transports/createTransport.js';
import type { ErrorType } from '../../errors/utils.js';
import type { Chain } from '../../types/chain.js';
import type { HasTransportType } from '../../types/transport.js';
import { type StringifyErrorType } from '../../utils/stringify.js';
import type { GetBlockReturnType } from './getBlock.js';
declare const blockFields: readonly ["size", "totalDifficulty", "transactions", "uncles", "withdrawals"];
export type BlockHeader<chain extends Chain | undefined = Chain> = Omit<GetBlockReturnType<chain, false, 'latest'>, (typeof blockFields)[number]>;
export type OnBlockHeaderParameter<chain extends Chain | undefined = Chain> = BlockHeader<chain>;
export type OnBlockHeader<chain extends Chain | undefined = Chain> = (blockHeader: OnBlockHeaderParameter<chain>, prevBlockHeader: OnBlockHeaderParameter<chain> | undefined) => void;
export type WatchBlockHeadersParameters<chain extends Chain | undefined = Chain> = {
    /** The callback to call when a new block header is received. */
    onBlockHeader: OnBlockHeader<chain>;
    /** The callback to call when an error occurs while watching block headers. */
    onError?: ((error: Error) => void) | undefined;
};
export type WatchBlockHeadersReturnType = () => void;
export type WatchBlockHeadersErrorType = StringifyErrorType | ErrorType;
/**
 * Watches and returns incoming block headers.
 *
 * - Docs: https://viem.sh/docs/actions/public/watchBlockHeaders
 * - JSON-RPC Methods: Uses a WebSocket or IPC subscription via [`eth_subscribe`](https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_subscribe) and the `"newHeads"` event.
 *
 * @param client - Client to use
 * @param parameters - {@link WatchBlockHeadersParameters}
 * @returns A function that can be invoked to stop watching for new block headers. {@link WatchBlockHeadersReturnType}
 *
 * @example
 * import { createPublicClient, webSocket } from 'viem'
 * import { watchBlockHeaders } from 'viem/actions'
 * import { mainnet } from 'viem/chains'
 *
 * const client = createPublicClient({
 *   chain: mainnet,
 *   transport: webSocket(),
 * })
 * const unwatch = watchBlockHeaders(client, {
 *   onBlockHeader: (blockHeader) => console.log(blockHeader),
 * })
 */
export declare function watchBlockHeaders<transport extends Transport, chain extends Chain | undefined>(client: Client<transport, chain>, { onBlockHeader, onError, }: HasTransportType<transport, 'webSocket' | 'ipc'> extends true ? WatchBlockHeadersParameters<chain> : never): WatchBlockHeadersReturnType;
export {};
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