# XLSX

// xlsx.js
import XLSX from "xlsx";
import { WritingOptions } from "xlsx";

/**
 * 将workbook装化成blob对象
 */
const workbook2blob = workbook => {
  // 生成excel的配置项
  const wopts: WritingOptions = {
    // 要生成的文件类型
    bookType: "xlsx",
    // 是否生成Shared String Table，官方解释是，如果开启生成速度会下降，但在低版本IOS设备上有更好的兼容性
    bookSST: false,
    type: "binary"
  };
  const wbout = XLSX.write(workbook, wopts);
  // 将字符串转ArrayBuffer
  function s2ab(s) {
    const buf = new ArrayBuffer(s.length);
    const view = new Uint8Array(buf);
    for (let i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xff;
    return buf;
  }

  const blob = new Blob([s2ab(wbout)], {
    type: "application/octet-stream"
  });
  return blob;
};

/**
 * 将blob对象创建bloburl，然后用a标签实现弹出下载框
 */
export const openDownloadDialog = (blob, fileName) => {
  if (typeof blob == "object" && blob instanceof Blob) {
    blob = URL.createObjectURL(blob); // 创建blob地址
  }
  const aLink = document.createElement("a");
  aLink.href = blob;
  // HTML5新增的属性，指定保存文件名，可以不要后缀，注意，有时候 file:///模式下不会生效
  aLink.download = fileName || "";
  let event;
  if (window.MouseEvent) event = new MouseEvent("click");
  // 移动端
  else {
    event = document.createEvent("MouseEvents");
    event.initMouseEvent(
      "click",
      true,
      false,
      window,
      0,
      0,
      0,
      0,
      0,
      false,
      false,
      false,
      false,
      0,
      null
    );
  }
  aLink.dispatchEvent(event);
};

/**
 * 导出 Excel
 */
const exportExcel = (data, fileName) => {
  const sheet1 = XLSX.utils.json_to_sheet(data);
  const wb = XLSX.utils.book_new();
  XLSX.utils.book_append_sheet(wb, sheet1);
  const workbookBlob = workbook2blob(wb);
  // 导出最后的总表
  openDownloadDialog(workbookBlob, `${fileName}.xlsx`);
};

/**
 * 读取并解析excel, 并返回json格式
 */
export const parseExcel = file => {
  return new Promise((resolve, reject) => {
    if (!file) return reject();
    const fileReader = new FileReader();
    fileReader.readAsBinaryString(file);
    fileReader.onload = e => {
      const { target } = e;
      const data = target && target.result;
      try {
        const workbox = XLSX.read(data, {
          type: "binary"
        });
        const sheetName = workbox.SheetNames[0];
        const sheetData = XLSX.utils.sheet_to_json(workbox.Sheets[sheetName]);
        resolve(sheetData);
      } catch (e) {
        reject(e);
      }
    };
  });
};
export default exportExcel;

// test.js
const titleMap = {
  name: "姓名",
  age: "年龄",
  sex: "性别",
  inter: "国籍"
};

// 测试数据
const data = [
  { name: "张三", age: 18, sex: "男", inter: "中国" },
  { name: "李四", age: 18, sex: "男", inter: "美国" },
  { name: "王五", age: 18, sex: "男", inter: "韩国" },
  { name: "小二", age: 18, sex: "男", inter: "日本" }
];
const kvs = Object.entries(titleMap);

const exportData = data.map(item => {
  const row = {};
  kvs.forEach(([k, v]) => {
    row[v] = item[k];
  });
  return row;
});

exportExcel(exportData, "导出Excel");