import React, { useEffect, useState } from 'react'

/**
 * 顶部页面阅读进度条
 * @returns {JSX.Element}
 * @constructor
 */
const Progress = ({ targetRef, showPercent = true }) => {
  const [percent, changePercent] = useState(0)
  const scrollListener = () => {
    if (targetRef?.current) {
      const clientHeight = targetRef ? (targetRef.current.clientHeight) : 0
      const scrollY = window.pageYOffset
      const fullHeight = clientHeight - window.outerHeight
      let per = parseFloat(((scrollY / fullHeight * 100)).toFixed(0))
      if (per > 100) per = 100
      if (per < 0) per = 0
      changePercent(per)
    }
  }

  useEffect(() => {
    document.addEventListener('scroll', scrollListener)
    return () => document.removeEventListener('scroll', scrollListener)
  }, [percent])

  return (<div className='h-4 w-full shadow-2xl bg-gray-400'>
      <div className='h-4 bg-gray-600 duration-200' style={{ width: `${percent}%` }}>
        {showPercent && <div className='text-right text-white text-xs'>{percent}%</div>}
      </div>
  </div>)
}

export default Progress