/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */

import React, {Fragment, useCallback, useState} from 'react';
import ListItem from './ListItem';
import styles from './List.css';

export type Item = {|
  id: number,
  isComplete: boolean,
  text: string,
|};

type Props = {||};

export default function List(props: Props) {
  const [newItemText, setNewItemText] = useState<string>('');
  const [items, setItems] = useState<Array<Item>>([
    {id: 1, isComplete: true, text: 'First'},
    {id: 2, isComplete: true, text: 'Second'},
    {id: 3, isComplete: false, text: 'Third'},
  ]);
  const [uid, setUID] = useState<number>(4);

  const handleClick = useCallback(
    () => {
      if (newItemText !== '') {
        setItems([
          ...items,
          {
            id: uid,
            isComplete: false,
            text: newItemText,
          },
        ]);
        setUID(uid + 1);
        setNewItemText('');
      }
    },
    [newItemText, items, uid],
  );

  const handleKeyPress = useCallback(
    event => {
      if (event.key === 'Enter') {
        handleClick();
      }
    },
    [handleClick],
  );

  const handleChange = useCallback(
    event => {
      setNewItemText(event.currentTarget.value);
    },
    [setNewItemText],
  );

  const removeItem = useCallback(
    itemToRemove => setItems(items.filter(item => item !== itemToRemove)),
    [items],
  );

  const toggleItem = useCallback(
    itemToToggle => {
      // Dont use indexOf()
      // because editing props in DevTools creates a new Object.
      const index = items.findIndex(item => item.id === itemToToggle.id);

      setItems(
        items
          .slice(0, index)
          .concat({
            ...itemToToggle,
            isComplete: !itemToToggle.isComplete,
          })
          .concat(items.slice(index + 1)),
      );
    },
    [items],
  );

  return (
    <Fragment>
      <h1>List</h1>
      <input
        type="text"
        placeholder="New list item..."
        className={styles.Input}
        value={newItemText}
        onChange={handleChange}
        onKeyPress={handleKeyPress}
      />
      <button
        className={styles.IconButton}
        disabled={newItemText === ''}
        onClick={handleClick}>
        <span role="img" aria-label="Add item">
          ➕
        </span>
      </button>
      <ul className={styles.List}>
        {items.map(item => (
          <ListItem
            key={item.id}
            item={item}
            removeItem={removeItem}
            toggleItem={toggleItem}
          />
        ))}
      </ul>
    </Fragment>
  );
}
