/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * A type that represents a value that may or may not be loaded. It differs from
 * LoadObject in that the `loading` state has a Promise that is meant to resolve
 * when the value is available (but as with LoadObject, an individual Loadable
 * is a value type and is not mutated when the status of a request changes).
 *
 * @emails oncall+recoil
 * @flow strict
 * @format
 */
'use strict';

const err = require('recoil-shared/util/Recoil_err');

const isPromise = require('recoil-shared/util/Recoil_isPromise');

const nullthrows = require('recoil-shared/util/Recoil_nullthrows');

declare class BaseLoadable<T> {
  getValue(): T,
  toPromise(): Promise<T>,
  valueMaybe(): T | void,
  valueOrThrow(): T,
  promiseMaybe(): Promise<T> | void,
  promiseOrThrow(): Promise<T>,
  errorMaybe(): mixed | void,
  errorOrThrow(): mixed,
  is(other: Loadable<mixed>): boolean,
  map<S>(_map: (T) => Promise<S> | Loadable<S> | S): Loadable<S>,
}
declare class ValueLoadable<T> extends BaseLoadable<T> {
  state: 'hasValue',
  contents: T,
  constructor(value: T): any,
  getValue(): T,
  toPromise(): Promise<T>,
  valueMaybe(): T,
  valueOrThrow(): T,
  promiseMaybe(): void,
  errorMaybe(): void,
  map<S>(map: (T) => Promise<S> | Loadable<S> | S): Loadable<S>,
}
declare class ErrorLoadable<T> extends BaseLoadable<T> {
  state: 'hasError',
  contents: mixed,
  constructor(error: mixed): any,
  getValue(): T,
  toPromise(): Promise<T>,
  valueMaybe(): void,
  promiseMaybe(): void,
  errorMaybe(): mixed,
  errorOrThrow(): mixed,
  map<S>(_map: (T) => Promise<S> | Loadable<S> | S): $ReadOnly<ErrorLoadable<S>>,
}
declare class LoadingLoadable<T> extends BaseLoadable<T> {
  state: 'loading',
  contents: Promise<T>,
  constructor(promise: Promise<T>): any,
  getValue(): T,
  toPromise(): Promise<T>,
  valueMaybe(): void,
  promiseMaybe(): Promise<T>,
  promiseOrThrow(): Promise<T>,
  errorMaybe(): void,
  map<S>(map: (T) => Promise<S> | Loadable<S> | S): $ReadOnly<LoadingLoadable<S>>,
}
export type Loadable<+T> = $ReadOnly<ValueLoadable<T>> | $ReadOnly<ErrorLoadable<T>> | $ReadOnly<LoadingLoadable<T>>;
export type ValueLoadableType<+T> = $ReadOnly<ValueLoadable<T>>;
export type ErrorLoadableType<+T> = $ReadOnly<ErrorLoadable<T>>;
export type LoadingLoadableType<+T> = $ReadOnly<LoadingLoadable<T>>;
declare function loadableWithValue<+T>(value: T): $ReadOnly<ValueLoadable<T>>;
declare function loadableWithError<+T>(error: mixed): $ReadOnly<ErrorLoadable<T>>;
declare function loadableWithPromise<+T>(promise: Promise<T>): $ReadOnly<LoadingLoadable<T>>;
declare function loadableLoading<+T>(): $ReadOnly<LoadingLoadable<T>>;
type UnwrapLoadables<Loadables> = $TupleMap<Loadables, <T>(Loadable<T>) => T>;
type LoadableAllOfTuple = <Tuple: $ReadOnlyArray<Loadable<mixed> | Promise<mixed> | mixed>>(tuple: Tuple) => Loadable<$TupleMap<Tuple, <V>(Loadable<V> | Promise<V> | V) => V>>;
type LoadableAllOfObj = <Obj: $ReadOnly<{
  [string]: Loadable<mixed> | Promise<mixed> | mixed,
  ...
}>>(obj: Obj) => Loadable<$ObjMap<Obj, <V>(Loadable<V> | Promise<V> | V) => V>>;
type LoadableAll = LoadableAllOfTuple & LoadableAllOfObj;
declare function loadableAllArray<Inputs: $ReadOnlyArray<Loadable<mixed>>>(inputs: Inputs): Loadable<UnwrapLoadables<Inputs>>;
declare function loadableAll<Inputs: $ReadOnlyArray<Loadable<mixed> | Promise<mixed> | mixed> | $ReadOnly<{
  [string]: Loadable<mixed> | Promise<mixed> | mixed,
  ...
}>>(inputs: Inputs): Loadable<$ReadOnlyArray<mixed> | $ReadOnly<{
  [string]: mixed,
  ...
}>>;
declare function isLoadable(x: mixed): boolean;
const LoadableStaticInterface = {
  of: <T>(value: Promise<T> | Loadable<T> | T): Loadable<T> => isPromise(value) ? loadableWithPromise(value) : isLoadable(value) ? value : loadableWithValue(value),
  error: <T>(error: mixed): $ReadOnly<ErrorLoadable<T>> => loadableWithError(error),
  // $FlowIssue[unclear-type]
  all: ((loadableAll: any): LoadableAll),
  isLoadable
};
module.exports = {
  loadableWithValue,
  loadableWithError,
  loadableWithPromise,
  loadableLoading,
  loadableAll,
  isLoadable,
  RecoilLoadable: LoadableStaticInterface
};