carbon/components/Dropdown.js

import React, { PureComponent } from 'react'
import Downshift from 'downshift'
import matchSorter from 'match-sorter'
import ArrowDown from './svg/Arrowdown'
import CheckMark from './svg/Checkmark'
import { COLORS } from '../lib/constants'

class Dropdown extends PureComponent {
  state = {
    inputValue: this.props.selected.name,
    itemsToShow: this.props.list
  }

  onUserAction = changes => {
    this.setState(({ inputValue, itemsToShow }) => {
      if (Object.prototype.hasOwnProperty.call(changes, 'inputValue')) {
        if (changes.type === Downshift.stateChangeTypes.keyDownEscape) {
          inputValue = this.userInputtedValue
        } else {
          inputValue = changes.inputValue
          this.userInputtedValue = changes.inputValue
        }
      }

      itemsToShow = this.userInputtedValue
        ? matchSorter(this.props.list, this.userInputtedValue, { keys: ['name'] })
        : this.props.list

      if (
        Object.prototype.hasOwnProperty.call(changes, 'highlightedIndex') &&
        (changes.type === Downshift.stateChangeTypes.keyDownArrowUp ||
          changes.type === Downshift.stateChangeTypes.keyDownArrowDown)
      ) {
        inputValue = itemsToShow[changes.highlightedIndex].name
        this.props.onChange(itemsToShow[changes.highlightedIndex])
      }

      if (Object.prototype.hasOwnProperty.call(changes, 'isOpen')) {
        this.userInputtedValue = ''

        // clear on open
        if (changes.isOpen) {
          inputValue = ''
        }

        // set on close
        if (changes.isOpen === false && !inputValue) {
          inputValue = this.props.selected.name
        }
      }

      return { inputValue, itemsToShow }
    })
  }

  userInputtedValue = ''

  render() {
    const { button, color, list, selected, onChange } = this.props

    const minWidth = calcMinWidth(button, selected, list)

    return (
      <Downshift
        inputValue={this.state.inputValue}
        render={renderDropdown({ button, color, list: this.state.itemsToShow, selected, minWidth })}
        selectedItem={selected}
        defaultHighlightedIndex={list.findIndex(it => it === selected)}
        itemToString={item => item.name}
        onChange={onChange}
        onUserAction={this.onUserAction}
      />
    )
  }
}

const renderDropdown = ({ button, color, list, minWidth, selected }) => ({
  isOpen,
  highlightedIndex,
  setHighlightedIndex,
  selectHighlightedItem,
  selectedItem,
  getRootProps,
  getButtonProps,
  getInputProps,
  getItemProps
}) => {
  return (
    <DropdownContainer {...getRootProps({ refKey: 'innerRef' })} minWidth={minWidth}>
      <SelectedItem
        getButtonProps={getButtonProps}
        getInputProps={getInputProps}
        isOpen={isOpen}
        color={color}
        button={button}
      >
        {selectedItem.name}
      </SelectedItem>
      {isOpen ? (
        <ListItems color={color}>
          {list.map((item, index) => (
            <ListItem
              key={index}
              color={color}
              {...getItemProps({
                item,
                isSelected: selectedItem === item,
                isHighlighted: highlightedIndex === index
              })}
            >
              {item.name}
            </ListItem>
          ))}
        </ListItems>
      ) : null}
    </DropdownContainer>
  )
}

const DropdownContainer = ({ children, innerRef, minWidth, ...rest }) => {
  return (
    <div {...rest} ref={innerRef} className="dropdown-container">
      {children}
      <style jsx>
        {`
          .dropdown-container {
            min-width: ${minWidth}px;
            cursor: pointer;
            user-select: none;
          }
        `}
      </style>
    </div>
  )
}

const SelectedItem = ({ getButtonProps, getInputProps, children, isOpen, color, button }) => {
  const itemColor = color || COLORS.SECONDARY

  return (
    <span
      {...getButtonProps()}
      tabIndex="0"
      className={`dropdown-display ${isOpen ? 'is-open' : ''}`}
    >
      {button ? (
        <span className="dropdown-display-text">{children}</span>
      ) : (
        <input
          {...getInputProps({ placeholder: children, id: `downshift-input-${children}` })}
          className="dropdown-display-text"
        />
      )}
      <div role="button" className="dropdown-arrow">
        <ArrowDown fill={itemColor} />
      </div>
      <style jsx>
        {`
          .dropdown-display {
            display: flex;
            align-items: center;
            height: 100%;
            border: 1px solid ${itemColor};
            border-radius: 3px;
            padding: 8px 16px;
            outline: none;
          }
          .dropdown-display:hover {
            background: ${COLORS.HOVER};
          }

          .dropdown-display.is-open {
            border-radius: 3px 3px 0 0;
          }

          .dropdown-display-text {
            flex-grow: 1;
            color: ${itemColor};
            background: transparent;
            border: none;
            outline: none;
            font-size: inherit;
            font-family: inherit;
          }
          .is-open > .dropdown-arrow {
            transform: rotate(180deg);
          }
        `}
      </style>
    </span>
  )
}

const ListItems = ({ children, color }) => {
  return (
    <ul role="listbox" className="dropdown-list">
      {children}
      <style jsx>
        {`
          .dropdown-list {
            margin-top: -1px;
            border: 1px solid ${color || COLORS.SECONDARY};
            border-radius: 0 0 3px 3px;
            max-height: 350px;
            overflow-y: scroll;
          }
        `}
      </style>
    </ul>
  )
}

const ListItem = ({ children, color, isHighlighted, isSelected, ...rest }) => {
  const itemColor = color || COLORS.SECONDARY

  return (
    <li {...rest} role="option" className="dropdown-list-item">
      <span className="dropdown-list-item-text">{children}</span>
      {isSelected ? <CheckMark /> : null}
      <style jsx>
        {`
          .dropdown-list-item {
            display: flex;
            align-items: center;
            background: ${isHighlighted ? COLORS.HOVER : COLORS.BLACK};
            padding: 8px 16px;
            border-bottom: 1px solid ${itemColor};
          }

          .dropdown-list-item:last-child {
            border-bottom: none;
          }

          .dropdown-list-item:hover {
            background: ${COLORS.HOVER};
          }
          .dropdown-list-item-text {
            flex-grow: 1;
            color: ${itemColor};
          }
        `}
      </style>
    </li>
  )
}

function calcMinWidth(isButton, selected, list) {
  const items = isButton ? [...list, selected] : list

  return items.reduce((max, { name }) => {
    const wordSize = name.length * 10 + 32
    return wordSize > max ? wordSize : max
  }, 0)
}

export default Dropdown