import { Component } from 'react';

export interface IBackButtonHandler {
  onBackButtonPressed: () => boolean;
}
export interface IBackButtonHandlerProps {
  registerBackButtonHandler: (handler: IBackButtonHandler) => () => void;
}

interface IProps extends IBackButtonHandler, IBackButtonHandlerProps {}

// a IBackButtonHandler adaptor for stateless functional components
export class BackButtonHandler extends Component<IProps> {
  private unregisterBackButtonHandler: (() => void) | undefined;

  constructor(props: IProps) {
    super(props);
  }

  public componentDidMount() {
    this.unregisterBackButtonHandler = this.props.registerBackButtonHandler(
      this
    );
  }

  public componentWillUnmount() {
    if (this.unregisterBackButtonHandler) {
      this.unregisterBackButtonHandler();
    }
  }

  public onBackButtonPressed = () => {
    return this.props.onBackButtonPressed();
  };

  public render() {
    return null;
  }
}