/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.dev/license
 */
import { DefaultExport } from '../util/default_export';
import { ProviderToken } from './provider_token';
/**
 * A helper function that allows to inject dependencies asynchronously,
 * which can be useful in cases when the dependency is not needed immediately and can be loaded lazily.
 *
 * NOTE: To enable lazy loading, the injected service must be auto-provided. This means it should be decorated with either `@Injectable({providedIn: 'root'})` or `@Service()`.
 *
 * @param loader A function that returns a promise resolving to the injectable service
 * @param options Configuration options for the async injection
 *
 * @returns A function that returns a promise resolving to the requested service instance.
 *
 * @usageNotes
 *
 * ```ts
 * class MyCmp {
 *  someSvc = injectAsync(() => import('..'));
 *
 *  async onClick() {
 *    (await this.someSvc()).handleClick();
 *  }
 * }
 *
 * // we can also configure prefetching:
 * injectAsync(.., {prefetch: onIdle})
 * ```
 *
 * @see [Lazy loading services](guide/di/lazy-loading-services)
 * @see [Injection context](guide/di/dependency-injection-context)
 *
 * @publicApi 22.0
 */
export declare function injectAsync<T>(loader: () => Promise<ProviderToken<T>>, options?: InjectAsyncOptions): () => Promise<T>;
export declare function injectAsync<T>(loader: () => Promise<DefaultExport<ProviderToken<T>>>, options?: InjectAsyncOptions): () => Promise<T>;
/**
 * Interface for `options` argument used within `injectAsync` call.
 *
 * @see [Prefetching the dependency](guide/di/lazy-loading-services#prefetching-the-dependency)
 *
 * @publicApi 22.0
 */
export interface InjectAsyncOptions {
    /**
     * A trigger to eagerly prefetch the lazy-loaded dependency before it is requested.
     *
     */
    prefetch?: PrefetchTrigger;
}
/**
 * A function that returns a promise which, when resolved, will trigger the prefetching of
 * the lazy-loaded dependency.
 *
 * @see {@link onIdle}
 * @see [Prefetching the dependency](guide/di/lazy-loading-services#prefetching-the-dependency)
 *
 * @publicApi 22.0
 */
export type PrefetchTrigger = () => Promise<void>;
/**
 * A `PrefetchTrigger` helper function to provide the logic of triggering dependency loading
 * when the browser becomes idle.
 *
 * Internally delegates to the configured {@link IdleService}, whose default implementation uses
 * [`requestIdleCallback`](https://developer.mozilla.org/docs/Web/API/Window/requestIdleCallback)
 * when available and falls back to `setTimeout` otherwise. The default behavior can be replaced
 * with `provideIdleServiceWith`.
 *
 * @usageNotes
 *
 * ```ts
 * injectAsync(import(...), {prefetch: onIdle})
 *
 * // or with custom idle options:
 * injectAsync(import(...), {prefetch: () => onIdle({timeout: 100})})
 * ```
 *
 * @see [Prefetching the dependency](guide/di/lazy-loading-services#prefetching-the-dependency)
 *
 * @publicApi 22.0
 */
export declare function onIdle(options?: {
    timeout?: number;
}): Promise<void>;