import xlsx from 'xlsx';
/**
 * 將Excel文件轉換為JSON
 * @param {File} file
 * @returns {Promise<any>}
 */
export async function parseFileToJson(file) {
  return new Promise((resolve, reject) => {
    if (file.type !== 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet') {
      reject({ msg: '僅支持Excel文件格式' });
    }
    let sheet = null;
    const fileReader = new FileReader();
    fileReader.onload = (e) => {
      const data = e.currentTarget.result;
      const workbook = xlsx.read(data, { type: 'binary' });
      const sheet = xlsx.utils.sheet_to_json(workbook.Sheets[workbook.SheetNames[0]]);
      resolve(sheet);
    };
    fileReader.readAsBinaryString(file);
  });
}

/**
 * 由JSON生成Excel并下載
 * @param {Array<{[colName: string]: string}>} json
 * @param {String} name
 * @returns {void}
 */
export function downloadExcel(json, name = 'output.xlsx') {
  const workbook = xlsx.utils.book_new();
  const sheet = xlsx.utils.json_to_sheet(json);
  xlsx.utils.book_append_sheet(workbook, sheet);
  xlsx.writeFile(workbook, name);
}