// ==UserScript==
// @name         Weread-Progress-Show （微信读书阅读进度显示）
// @namespace    https://github.com/ralix/Weread-Progress-Show
// @version      1.0
// @description  在网页版微信读书右下角显示当前阅读进度
// @match        https://weread.qq.com/*
// @grant        GM_addStyle
// @license      MIT
// @downloadURL none
// ==/UserScript==

var currentChapterRatio;
var nextChapterRatio;

(function () {
    'use strict';


    // Listen for scroll events
    window.addEventListener('scroll', updateSrollRatio);

    // watch chapter change
    watchChapterChange();

})();

function watchChapterChange(){

        // 查找具有class="chapterItem"的元素
    //let chapterItems = document.getElementsByClassName("chapterItem");
    let chapterItems = document.querySelectorAll(".chapterItem");

    // 创建一个 MutationObserver 实例
    var observer = new MutationObserver(function(mutations) {
      mutations.forEach(function(mutation) {
        // 检查属性变化的类型
        if (mutation.type === "attributes") {
          // 属性发生变化。 evoke when chapter changes.
          updateChapterRatio(chapterItems);
          console.log("属性发生变化：" + mutation.attributeName);
        }
      });
    });

    // 配置观察选项
    var config = { attributes: true };

    // 开始观察目标元素列表中的每个元素
    for (var i = 0; i < chapterItems.length; i++) {
      observer.observe(chapterItems[i], config);
    }

}

//evoke when sroll changes
function updateSrollRatio(){
  const scrollPosition = window.scrollY;
//  console.log("scrollPosition: "+scrollPosition);
  const maxScrollPosition = document.documentElement.scrollHeight - window.innerHeight;
//  console.log("maxScrollPosition: "+maxScrollPosition);

  let scrollRatio;
  let totalRatio;

  if(maxScrollPosition != 0){
    scrollRatio = scrollPosition / maxScrollPosition;

    totalRatio = (nextChapterRatio - currentChapterRatio) * scrollRatio + currentChapterRatio;

    totalRatio = totalRatio.toFixed(1);
//      console.log(currentChapterRatio);
//      console.log(nextChapterRatio);


    updateProgressBox(totalRatio);

  }

}


function updateChapterRatio(chapterItems) {

    let chapterTotal = chapterItems.length;

    for (let i = 0; i < chapterTotal; i++) {
        let className = chapterItems[i].className;
        if (className.includes("chapterItem_current")) {
            currentChapterRatio = parseFloat(((i / chapterTotal) * 100).toFixed(1));
            nextChapterRatio = parseFloat((( (i+1) / chapterTotal) * 100).toFixed(1)) ;

            updateProgressBox(currentChapterRatio);
        }
    }
}



//show the percentage result
function updateProgressBox(result){

    let progressBox = document.querySelector("#progressBox");

    if (!progressBox){
        progressBox = document.createElement('div');
        progressBox.setAttribute('id', 'progressBox');
    }

    progressBox.innerHTML = result + "%";

    GM_addStyle('#progressBox {position: fixed; bottom: 60px; right: 5px; width: 50px; \
    height: 30px; \
    font-size: xx-small; \
    padding: 0px; \
    align-items: center; \
    align-content: center; \
    text-align: center; \
    display: flex; \
    justify-content: center; \
    background-color: #6b6b6b; \
    color: #fff; \
    border-radius: 5px;\ }')

    document.body.appendChild(progressBox);
}