/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow strict
 */

declare export class Signal<T = unknown> {
  constructor(value?: T, options?: SignalOptions<T>): this;
  subscribe(fn: (value: T) => void): () => void;
  name?: string;
  valueOf(): T;
  toString(): string;
  toJSON(): T;
  peek(): T;
  brand: symbol;
  value: T;
}

export interface ReadonlySignal<T = unknown> {
  readonly value: T;
  peek(): T;
  subscribe(fn: (value: T) => void): () => void;
  valueOf(): T;
  toString(): string;
  toJSON(): T;
  brand: symbol;
}

export type SignalOptions<T = unknown> = {
  watched?: (this: Signal<T>) => void,
  unwatched?: (this: Signal<T>) => void,
  name?: string,
};

type EffectFn =
  | ((this: {dispose: () => void}) => void | (() => void))
  | (() => void | (() => void));

type EffectOptions = {
  name?: string,
};

declare export function batch<T>(fn: () => T): T;

declare export function computed<T>(
  fn: () => T,
  options?: SignalOptions<T>,
): ReadonlySignal<T>;

declare export function effect(
  fn: EffectFn,
  options?: EffectOptions,
): () => void;

declare export function signal<T>(
  value: T,
  options?: SignalOptions<T>,
): Signal<T>;

declare export function signal<T = void>(): Signal<T | void>;

declare export function untracked<T>(fn: () => T): T;