/**
 * @module Async
 */
import type { HookContext, AsyncLazyable } from "../../../utilities/_module-exports.js";
import { type AsyncMiddlewareFn, type Invokable } from "../../../utilities/_module-exports.js";
import type { ErrorPolicy } from "../../../async/middlewares/_shared.js";
/**
 *
 * IMPORT_PATH: `"@daiso-tech/core/async"`
 * @group Middlewares
 */
export type OnFallbackData<TParameters extends unknown[] = unknown[], TFallbackValue = unknown, TContext extends HookContext = HookContext> = {
    error: unknown;
    fallbackValue: TFallbackValue;
    args: TParameters;
    context: TContext;
};
/**
 *
 * IMPORT_PATH: `"@daiso-tech/core/async"`
 * @group Middlewares
 */
export type OnFallback<TParameters extends unknown[] = unknown[], TFallbackValue = unknown, TContext extends HookContext = HookContext> = Invokable<[data: OnFallbackData<TParameters, TFallbackValue, TContext>]>;
/**
 *
 * IMPORT_PATH: `"@daiso-tech/core/async"`
 * @group Middlewares
 */
export type FallbackCallbacks<TParameters extends unknown[] = unknown[], TReturn = unknown, TContext extends HookContext = HookContext> = {
    /**
     * Callback function that will be called before fallback values is returned.
     */
    onFallback?: OnFallback<TParameters, TReturn, TContext>;
};
/**
 *
 * IMPORT_PATH: `"@daiso-tech/core/async"`
 * @group Middlewares
 */
export type FallbackSettings<TParameters extends unknown[] = unknown[], TReturn = unknown, TContext extends HookContext = HookContext> = FallbackCallbacks<TParameters, TReturn, TContext> & {
    fallbackValue: AsyncLazyable<TReturn>;
    /**
     * You can choose what errors you want to add fallback value. By default fallback value will be added to all errors.
     *
     * @default
     * ```ts
     * (_error: unknown) => true
     * ```
     */
    fallbackPolicy?: ErrorPolicy;
};
/**
 * The `fallback` middleware adds fallback value when an error occurs.
 *
 * IMPORT_PATH: `"@daiso-tech/core/async"`
 * @group Middlewares
 *
 * @example
 * ```ts
 * import { fallback } from "@daiso-tech/core/async";
 * import { AsyncHooks } from "@daiso-tech/core/utilities";
 *
 * const fetchData = new AsyncHooks(async (url: string): Promise<unknown> => {
 *   const response = await fetch(url);
 *   const json = await response.json();
 *   if (!response.ok) {
 *     throw json
 *   }
 *   return json;
 * }, [
 *   fallback({ fallbackValue: null })
 * ]);
 *
 * // Will return null when the fetch method throws an error.
 * console.log(await fetchData.invoke("URL_ENDPOINT"));
 * ```
 */
export declare function fallback<TParameters extends unknown[], TReturn, TContext extends HookContext>(settings: NoInfer<FallbackSettings<TParameters, TReturn, TContext>>): AsyncMiddlewareFn<TParameters, TReturn, TContext>;