// ==UserScript==
// @name         NTHU ccxp Dump Course Classmate
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  dump classmate in current course to csv
// @author       You
// @match        https://www.ccxp.nthu.edu.tw/ccxp/COURSE/JH/7/7.2/7.2.16/JH72g003.php
// @grant        none
// ==/UserScript==
(function() {
    'use strict';
    function download(name, content) {
        let element = document.createElement('a');
        let url = URL.createObjectURL(new Blob([content], { type: "text/csv" }));

        element.setAttribute('href', url);
        element.setAttribute('download', name);

        element.style.display = 'none';
        document.body.appendChild(element);

        element.click();

        document.body.removeChild(element);
        URL.revokeObjectURL(url);
    }

    let buttons = document.querySelector("form[name='form1'] p");
    buttons.innerHTML += `<input type="button" value="產生修課同學名單 (CSV 格式)">`;
    buttons.querySelector("input:last-child").onclick = function() {
        let courseInfo = document.querySelector("table.class3");
        const courseId = courseInfo.querySelector("td:nth-of-type(1)").innerText;
        const courseName = courseInfo.querySelector("td:nth-of-type(2)").innerText.split("\n")[0];

        let result = [];

        for (let row of document.querySelector("table:not(.class2):not(.class3)").querySelectorAll("tr")) {
            let [_, id, studentId, studentName, studentDepartment, studentEmail] = [...(Array.from(row.children).map(el => el.innerText))];
            result.push(`${id},${studentId},${studentName},${studentDepartment},${studentEmail}`)
        }

        download(`${courseId} ${courseName}.csv`, result.join("\n"));
    }
})();