import React, { useRef, useState, useEffect } from 'react';
import styles from './index.less';
import classnames from 'classnames';

function AnchorTabber(props) {
  const root = useRef(null);
  const header = useRef(null);
  const {
    attrbute = 'data-anchor',
    offsetY = 60,
    list = [],
    initialKey = list[0]?.key,
    children,
  } = props;
  const [state, setState] = useState({
    activeKey: initialKey,
  });
  const [key2Bottom, setKey2Bottom] = useState({
    key2Bottom: {},
  });
  /** @type { HTMLDivElement } */
  const scrollElement = document.querySelector('#root').firstChild;
  function scrollTo(key) {
    // if(!scrollElement) {
    //   scrollElement = document.querySelector('#root').firstChild;
    // }

    const attribute = attrbute;
    /** @type { HTMLDivElement } */
    const targetEl = root.current?.querySelector(`[${attribute}=${key}]`);
    if (targetEl) {
      const clientRect = targetEl.getBoundingClientRect();
      const top = scrollElement.scrollTop + clientRect.top - offsetY;
      scrollElement.scrollTo({
        top,
        behavior: 'smooth',
      });
      // targetEl.scrollIntoView({ behavior: 'smooth', block: 'start' });
    }
  }

  function updateElementsPosition() {
    const elements = document.querySelectorAll(`[${attrbute}]`);
    Array.from(elements).forEach(element => {
      const targetAttr = element.getAttribute(`${attrbute}`);
      const clientRect = element.getBoundingClientRect();

      const bottom = clientRect.top + scrollElement.scrollTop;
      key2Bottom[targetAttr] = bottom;
    });
    setKey2Bottom(key2Bottom);
  }

  function handleScroll() {
    const top = scrollElement.scrollTop + offsetY;
    // eslint-disable-next-line no-unused-vars
    const target = Object.entries(key2Bottom)
      .sort(([, v1], [, v2]) => v2 - v1)
      .find(([, v]) => v <= top);
    if (target) {
      setState({
        activeKey: target[0],
      });
    }
  }

  useEffect(() => {
    updateElementsPosition();
    // document.addEventListener('touchstart', updateElementsPosition);
    scrollElement.addEventListener('scroll', handleScroll);
    return () => {
      // document.removeEventListener('touchstart', updateElementsPosition);
      scrollElement.removeEventListener('scroll', handleScroll);
    };
  });

  function handleItemClick(tabber) {
    scrollTo(tabber.key);
  }

  function render() {
    let { activeKey } = state;
    if(typeof(activeKey) === "undefined") {
      activeKey = initialKey
    }
    
    return (
      <div className={styles.mAnchorTabber}>
        <div className={styles.header} ref={header}>
          {list?.map(tabber => (
            <div
              className={classnames(styles.item, { [styles.active]: activeKey === tabber.key })}
              onClick={() => handleItemClick(tabber)}
            >
              {tabber.name}
            </div>
          ))}
        </div>
        <div className={styles.container} ref={root}>
          {children}
        </div>
      </div>
    );
  }

  return render();
}


export default AnchorTabber;

.mAnchorTabber {
  .header {
    display: flex;
    align-items: center;
    position: sticky;
    top: 0;
    height: .len(46) [];
    box-sizing: border-box;
    box-shadow: 0 .len(2) [] .len(2) [] .len(1) [] #c4c4c4;
    background-color: @basecolor;
    .item {
      height: 100%;
      flex-grow: 1;
      flex-shrink: 0;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 400;
      font-size: @font-size-base-normal;
      line-height: .len(20) [];
      &.active {
        background-color: @bgc-product-detail;
        color: @basecolor;
      }
    }
  }
}

import React from 'react';
import { connect } from 'dva';

import AnchorTabber from '@/components/m/AnchorTabber';

@connect(({ common }) => ({
  common,
}))
class ApplicationsRecord extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      list: [
        {
          name: 'test1',
          key: 'test1',
        },
        {
          name: 'test2',
          key: 'test2',
        },
        {
          name: 'test3',
          key: 'test3',
        },
      ],
    };
  }

  render() {
    const { list } = this.state;
    const index2Attr = {
      0: 'test1',
      100: 'test2',
      200: 'test3',
    };
    return (
      <AnchorTabber list={list}>
        <ul className="list">
          {new Array(1000).fill(null).map((_item, index) => (
            <li data-anchor={index2Attr[index]}>{index}</li>
          ))}
        </ul>
      </AnchorTabber>
    );
  }
}
export default ApplicationsRecord;