signal-desktop/ts/components/ModalHost.tsx

// Copyright 2019-2022 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only

import React, { useEffect } from 'react';
import { createPortal } from 'react-dom';
import FocusTrap from 'focus-trap-react';
import type { SpringValues } from '@react-spring/web';
import { animated } from '@react-spring/web';
import classNames from 'classnames';

import type { ModalConfigType } from '../hooks/useAnimated';
import type { Theme } from '../util/theme';
import { getClassNamesFor } from '../util/getClassNamesFor';
import { themeClassName } from '../util/theme';
import { useEscapeHandling } from '../hooks/useEscapeHandling';

export type PropsType = Readonly<{
  children: React.ReactElement;
  moduleClassName?: string;
  noMouseClose?: boolean;
  onClose: () => unknown;
  onEscape?: () => unknown;
  onTopOfEverything?: boolean;
  overlayStyles?: SpringValues<ModalConfigType>;
  theme?: Theme;
  useFocusTrap?: boolean;
}>;

export const ModalHost = React.memo(
  ({
    children,
    moduleClassName,
    noMouseClose,
    onClose,
    onEscape,
    onTopOfEverything,
    overlayStyles,
    theme,
    useFocusTrap = true,
  }: PropsType) => {
    const [root, setRoot] = React.useState<HTMLElement | null>(null);
    const [isMouseDown, setIsMouseDown] = React.useState(false);

    useEffect(() => {
      const div = document.createElement('div');
      document.body.appendChild(div);
      setRoot(div);

      return () => {
        document.body.removeChild(div);
        setRoot(null);
      };
    }, []);

    useEscapeHandling(onEscape || onClose);

    // This makes it easier to write dialogs to be hosted here; they won't have to worry
    //   as much about preventing propagation of mouse events.
    const handleMouseDown = React.useCallback(
      (e: React.MouseEvent) => {
        if (e.target === e.currentTarget) {
          setIsMouseDown(true);
        }
      },
      [setIsMouseDown]
    );
    const handleMouseUp = React.useCallback(
      (e: React.MouseEvent) => {
        setIsMouseDown(false);

        if (e.target === e.currentTarget && isMouseDown) {
          onClose();
        }
      },
      [onClose, isMouseDown, setIsMouseDown]
    );

    const className = classNames([
      theme ? themeClassName(theme) : undefined,
      onTopOfEverything ? 'module-modal-host--on-top-of-everything' : undefined,
    ]);
    const getClassName = getClassNamesFor('module-modal-host', moduleClassName);

    const modalContent = (
      <div className={className}>
        <animated.div
          role="presentation"
          className={getClassName('__overlay')}
          style={overlayStyles}
        />
        <div
          className={getClassName('__overlay-container')}
          onMouseDown={noMouseClose ? undefined : handleMouseDown}
          onMouseUp={noMouseClose ? undefined : handleMouseUp}
        >
          {children}
        </div>
      </div>
    );

    return root
      ? createPortal(
          useFocusTrap ? (
            <FocusTrap
              focusTrapOptions={{
                // This is alright because the overlay covers the entire screen
                allowOutsideClick: false,
              }}
            >
              {modalContent}
            </FocusTrap>
          ) : (
            modalContent
          ),
          root
        )
      : null;
  }
);