manifold/web/components/editor/mention-list.tsx

import { SuggestionProps } from '@tiptap/suggestion'
import clsx from 'clsx'
import { User } from 'common/user'
import { forwardRef, useEffect, useImperativeHandle, useState } from 'react'
import { Avatar } from '../avatar'

// copied from https://tiptap.dev/api/nodes/mention#usage
export const MentionList = forwardRef((props: SuggestionProps<User>, ref) => {
  const { items: users, command } = props

  const [selectedIndex, setSelectedIndex] = useState(0)
  useEffect(() => setSelectedIndex(0), [users])

  const submitUser = (index: number) => {
    const user = users[index]
    if (user) command({ id: user.id, label: user.username } as any)
  }

  const onUp = () =>
    setSelectedIndex((i) => (i + users.length - 1) % users.length)
  const onDown = () => setSelectedIndex((i) => (i + 1) % users.length)
  const onEnter = () => submitUser(selectedIndex)

  useImperativeHandle(ref, () => ({
    onKeyDown: ({ event }: any) => {
      if (event.key === 'ArrowUp') {
        onUp()
        return true
      }
      if (event.key === 'ArrowDown') {
        onDown()
        return true
      }
      if (event.key === 'Enter') {
        onEnter()
        return true
      }
      return false
    },
  }))

  return (
    <div className="w-42 absolute z-10 overflow-x-hidden rounded-md bg-white py-1 shadow-lg ring-1 ring-black ring-opacity-5 focus:outline-none">
      {!users.length ? (
        <span className="m-1 whitespace-nowrap">No results...</span>
      ) : (
        users.map((user, i) => (
          <button
            className={clsx(
              'flex h-8 w-full cursor-pointer select-none items-center gap-2 truncate px-4',
              selectedIndex === i ? 'bg-indigo-500 text-white' : 'text-gray-900'
            )}
            onClick={() => submitUser(i)}
          >
            <Avatar avatarUrl={user.avatarUrl} size="xs" />
            {user.username}
          </button>
        ))
      )}
    </div>
  )
})