// ==UserScript==
// @name         豆瓣小组话题快速预览-douban group topic fast preview
// @namespace    https://openuserjs.org/scripts/dragoncat
// @version      0.1
// @license      MIT
// @description  可以在豆瓣小组列表页面快速预览帖子内容，无须再打开新窗口
// @author       铛铛铛铛铛/https://www.douban.com/people/48915223
// @copyright    1991-2018,铛铛铛铛铛-Dragoncat
// @match        https://www.douban.com/group/*
// @exclude      https://www.douban.com/group/topic/*
// @grant        none
// @downloadURL none
// ==/UserScript==

(function () {
  'use strict';
  const style = document.createElement("style")
  style.type = "text/css"
  style.innerHTML = `
#wrapper{
margin:0;
width: 100%;
box-sizing: border-box;
}
table.olt tr:not(.th):hover,table.olt tr:not(.th).active{
cursor: pointer;
background: #f2f8f2;
}
.grid-16-8 .article{
padding-right: 10px;

}
#iframe-wrapper{
width: -webkit-fill-available;
height: -webkit-fill-available;
margin:0 305px 0 686px;
top:0;
}
#priview{
width: -webkit-fill-available;
height: -webkit-fill-available;
background: #fefefe;
border: none;
box-shadow: 0 0 2px #00000038;
}
`
  document.head.appendChild(style)
  const grid = document.querySelector('.grid-16-8')
  const iframe = document.createElement("iframe")
  const iframeWrapper = document.createElement("div")
  const trs = document.querySelectorAll('table.olt tr:not(.th)')
  let prevTr
  iframeWrapper.id = "iframe-wrapper"
  iframe.srcdoc = '<style>p{color:#bbb;font-style:italic;font-size:12px;}a{color: #0f959d;text-decoration: none;}a:hover{color:red;}</style><p>/*话题快速预览 © <a href="https://www.douban.com/people/48915223/">铛铛铛铛铛</a>*/</p><p>Tips:<br/>因为豆瓣的原因，在预览里发表回应不会刷新页面，但实际是发表成功的</p>'
  iframe.id = "priview"
  iframeWrapper.appendChild(iframe)
  grid.insertBefore(iframeWrapper, document.querySelector('.extra'))
  trs.forEach(tr => {
    tr.onclick = tr.onmouseenter = function () {
      if (prevTr) prevTr.classList.remove('active')
      prevTr = tr
      tr.classList.add('active')
      iframe.removeAttribute('srcdoc')
      iframe.src = tr.querySelector('a').href
    }
  })
  window.addEventListener("scroll", function () {
    changepos()
  })
  changepos()

  function changepos() {
    if (document.documentElement.scrollTop > document.querySelector(".article").offsetTop) {
      iframeWrapper.style.position = "fixed"
    }
    else {
      iframeWrapper.style.position = "relative"
    }
  }
})();