// @flow
import { Component, type Node } from 'react';

type RenderFn<T> = (value: T) => Node;

export type ProviderProps<T> = {
  value: T,
  children?: Node
};

export type ConsumerProps<T> = {
  children: RenderFn<T> | [RenderFn<T>],
  observedBits?: number
};

export type ConsumerState<T> = {
  value: T
};

export type Provider<T> = Component<ProviderProps<T>>;
export type Consumer<T> = Component<ConsumerProps<T>, ConsumerState<T>>;

export type Context<T> = {
  Provider: Class<Provider<T>>,
  Consumer: Class<Consumer<T>>
};

declare export default function createReactContext<T>(
  defaultValue: T,
  calculateChangedBits?: (prev: T, next: T) => number
): Context<T>;