grafana/public/app/features/dashboard/dashgrid/PanelHeader/PanelHeaderMenuItem.tsx

import { css } from '@emotion/css';
import React, { useState } from 'react';

import { PanelMenuItem, GrafanaTheme2 } from '@grafana/data';
import { selectors } from '@grafana/e2e-selectors';
import { Icon, toIconName, useStyles2 } from '@grafana/ui';

interface Props {
  children?: React.ReactNode;
}

export const PanelHeaderMenuItem = (props: Props & PanelMenuItem) => {
  const [ref, setRef] = useState<HTMLLIElement | null>(null);
  const isSubMenu = props.type === 'submenu';
  const isDivider = props.type === 'divider';
  const styles = useStyles2(getStyles);

  const icon = props.iconClassName ? toIconName(props.iconClassName) : undefined;

  return isDivider ? (
    <li className="divider" />
  ) : (
    <li
      className={isSubMenu ? `dropdown-submenu ${getDropdownLocationCssClass(ref)}` : undefined}
      ref={setRef}
      data-testid={selectors.components.Panels.Panel.menuItems(props.text)}
    >
      <a onClick={props.onClick} href={props.href} role="menuitem">
        {icon && <Icon name={icon} className={styles.menuIconClassName} />}
        <span className="dropdown-item-text" aria-label={selectors.components.Panels.Panel.headerItems(props.text)}>
          {props.text}
          {isSubMenu && <Icon name="angle-right" className={styles.shortcutIconClassName} />}
        </span>

        {props.shortcut && (
          <span className="dropdown-menu-item-shortcut">
            <Icon name="keyboard" className={styles.menuIconClassName} /> {props.shortcut}
          </span>
        )}
      </a>
      {props.children}
    </li>
  );
};

function getDropdownLocationCssClass(element: HTMLElement | null) {
  if (!element) {
    return 'invisible';
  }

  const wrapperPos = element.parentElement!.getBoundingClientRect();
  const pos = element.getBoundingClientRect();

  if (pos.width === 0) {
    return 'invisible';
  }

  if (wrapperPos.right + pos.width + 10 > window.innerWidth) {
    return 'pull-left';
  } else {
    return 'pull-right';
  }
}

function getStyles(theme: GrafanaTheme2) {
  return {
    menuIconClassName: css({
      marginRight: theme.spacing(1),
      'a::after': {
        display: 'none',
      },
    }),
    shortcutIconClassName: css({
      position: 'absolute',
      top: '7px',
      right: theme.spacing(0.5),
      color: theme.colors.text.secondary,
    }),
  };
}