// data
const data = [
  {
    id: 1,
    合并的列頭1: '數(shù)據(jù)11',
    合并的列頭2: '數(shù)據(jù)12',
    _style: { font: { sz: 14, bold: true, color: { rgb: 'FFFFAA00' } } },
    _merges: [{ s: { c: 1, r: 0 }, e: { c: 4, r: 0 } }],
  },
]

const utils = {
  writeFile(data, { tableName = 'sheet1', fileName = '下載', type = 'xlsx', title, head } = {}) {
    const bookType = { xlsx: 'xlsx', xls: 'biff8' }
    // 處理數(shù)據(jù)
    const tmpdata = this.dataHandle(data, title, head)
    // 設(shè)置區(qū)域 比如表格從A1到D10
    const outputPos = Object.keys(tmpdata)
    // tmpdata['B1'].s =  // 單元格樣式
    // tmpdata['!merges'] = [{ s: { c: 1, r: 0 }, e: { c: 4, r: 0 } }] // 合并單元格

    const wb = {
      SheetNames: [tableName], //保存的表標(biāo)題
      Sheets: {
        [tableName]: {
          ...tmpdata, // 數(shù)據(jù)
          '!ref': outputPos[0] + ':' + outputPos[outputPos.length - 1], // 設(shè)置填充區(qū)域
        },
      },
    }

    const xlsxDataStr = XLSX.write(wb, { ...this.wopts, bookType: bookType[type] })
    const bolb = new Blob([this.str2Buffer(xlsxDataStr)])

    this.saveAs(bolb, `${fileName}.${type}`)
  },
  // 瀏覽器下載
  saveAs(data, fileName) {
    const tmpa = document.createElement('a')
    tmpa.download = fileName
    tmpa.href = URL.createObjectURL(data)
    tmpa.click()
    setTimeout(function() {
      URL.revokeObjectURL(data)
    }, 100)
  },
  // 處理數(shù)據(jù) ==> { A1: {v:1}, A2: {v:2} }
  dataHandle(head = [], title = [], data = []) {
    const tmpdata = {}
    ;[...head, ...title, ...data].forEach((item, index) => {
      const row = index + 1
      const { _style, _merges, ...other } = item
      Object.values(other).forEach((i, ind) => {
        const col = this.transNum2Char(ind)
        const val = { v: i }
        if (_style) val.s = _style
        tmpdata[col + row] = val
      })
    })
    return tmpdata
  },
  // 保存格式
  wopts: { bookType: 'xlsx', bookSST: false, type: 'binary', cellStyles: true },
  // 0 > A,  26 > AA
  transNum2Char(num) {
    // 保存每一位的 unicode 碼
    let arr = []
    // 679 % 26 % 26 % 26  ===> [3, 1, 0]
    while (num >= 26) {
      arr.push((num % 26) + 1) // 0-25 需轉(zhuǎn)換成 1-26
      num = parseInt(num / 26)
    }
    arr.push(num + 1) // 0-25 需轉(zhuǎn)換成 1-26
    return arr
      .reverse()
      .map((i) => String.fromCharCode(i + 64))
      .join('')
  },
  // 將字符串轉(zhuǎn)換成 buffer
  str2Buffer(s) {
    const buf = new ArrayBuffer(s.length)
    const view = new Uint8Array(buf)
    for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xff
    return buf
  },
}