/**
 * imported from react-native
 */

import { MutableRefObject } from 'react';

/**
 * This is a helper function for when a component needs to be able to forward a ref
 * to a child component, but still needs to have access to that component as part of
 * its implementation.
 *
 * Its main use case is in wrappers for native components.
 *
 * Usage:
 *
 *   class MyView extends React.Component {
 *     _nativeRef = null;
 *
 *     _setNativeRef = setAndForwardRef({
 *       getForwardedRef: () => this.props.forwardedRef,
 *       setLocalRef: ref => {
 *         this._nativeRef = ref;
 *       },
 *     });
 *
 *     render() {
 *       return <View ref={this._setNativeRef} />;
 *     }
 *   }
 *
 *   const MyViewWithRef = React.forwardRef((props, ref) => (
 *     <MyView {...props} forwardedRef={ref} />
 *   ));
 *
 *   module.exports = MyViewWithRef;
 */

export type ForwardedRef<T> = () => MutableRefObject<T> | ((ref: T) => void);

function setAndForwardRef<T>({
  getForwardedRef,
  setLocalRef,
}: {
  getForwardedRef: ForwardedRef<T>;
  setLocalRef: (ref: T) => void;
}): (ref: T) => void {
  return function forwardRef(ref: T) {
    const forwardedRef = getForwardedRef();

    setLocalRef(ref);

    // Forward to user ref prop (if one has been specified)
    if (typeof forwardedRef === 'function') {
      // Handle function-based refs. String-based refs are handled as functions.
      forwardedRef(ref);
    } else if (typeof forwardedRef === 'object' && forwardedRef != null) {
      // Handle createRef-based refs
      forwardedRef.current = ref;
    }
  };
}

export default setAndForwardRef;