sprinklers3/client/state/reactContext.tsx

import * as React from "react";

import { AppState } from "@client/state";

const StateContext = React.createContext<AppState | null>(null);

export interface ProvideStateProps {
  state: AppState;
  children: React.ReactNode;
}

export function ProvideState({ state, children }: ProvideStateProps) {
  return (
    <StateContext.Provider value={state}>{children}</StateContext.Provider>
  );
}

export interface ConsumeStateProps {
  children: (state: AppState) => React.ReactNode;
}

export function ConsumeState({ children }: ConsumeStateProps) {
  const consumeState = (state: AppState | null) => {
    if (state == null) {
      throw new Error(
        "Component with ConsumeState must be mounted inside ProvideState"
      );
    }
    return children(state);
  };
  return <StateContext.Consumer>{consumeState}</StateContext.Consumer>;
}

export function injectState<P extends { appState: AppState }>(
  Component: React.ComponentType<P>
): React.FunctionComponent<Omit<P, "appState">> {
  return function InjectState(props) {
    const state = React.useContext(StateContext);
    if (state == null) {
      throw new Error(
        "Component with injectState must be mounted inside ProvideState"
      );
    }
    // tslint:disable-next-line: no-object-literal-type-assertion
    const allProps: Readonly<P> = {...props, appState: state} as Readonly<P>;
    return <Component {...allProps} />;
  }
}