// +----------------------------------------------------------------------
// | CRMEB [ CRMEB赋能开发者，助力企业发展 ]
// +----------------------------------------------------------------------
// | Copyright (c) 2016~2021 https://www.crmeb.com All rights reserved.
// +----------------------------------------------------------------------
// | Licensed CRMEB并不是自由软件，未经许可不能去掉CRMEB相关版权
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// | Author: CRMEB Team <admin@crmeb.com>
// +----------------------------------------------------------------------

import { saveAs } from 'file-saver'
import XLSX from 'xlsx'

function datenum (v, date1904) {
    if (date1904) v += 1462
    let epoch = Date.parse(v)
    return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000)
}

function data2ws (data) {
    const ws = {}
    const range = { s: { c: 10000000, r: 10000000 }, e: { c: 0, r: 0 } }
    for (let R = 0; R !== data.length; ++R) {
        for (let C = 0; C !== data[R].length; ++C) {
            if (range.s.r > R) range.s.r = R
            if (range.s.c > C) range.s.c = C
            if (range.e.r < R) range.e.r = R
            if (range.e.c < C) range.e.c = C
            const cell = { v: data[R][C] }
            if (cell.v == null) continue
            const cellRef = XLSX.utils.encode_cell({ c: C, r: R })

            if (typeof cell.v === 'number') cell.t = 'n'
            else if (typeof cell.v === 'boolean') cell.t = 'b'
            else if (cell.v instanceof Date) {
                cell.t = 'n'
                cell.z = XLSX.SSF._table[14]
                cell.v = datenum(cell.v)
            } else cell.t = 's'

            ws[cellRef] = cell
        }
    }
    if (range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range)
    return ws
}
function Workbook () {
    if (!(this instanceof Workbook)) return new Workbook()
    this.SheetNames = []
    this.Sheets = {}
}

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
}

/*
* th => 表头
* data => 数据
* fileName => 文件名
* fileType => 文件类型
* sheetName => sheet页名
*/
export default function toExcel ({ th, data, fileName, fileType, sheetName }) {
    data.unshift(th)
    let wb = new Workbook()
    let ws = data2ws(data)
    sheetName = sheetName || 'sheet1'
    wb.SheetNames.push(sheetName)
    wb.Sheets[sheetName] = ws
    fileType = fileType || 'xlsx'
    let wbout = XLSX.write(wb, { bookType: fileType, bookSST: false, type: 'binary' })
    fileName = fileName || '列表'
    saveAs(new Blob([s2ab(wbout)], { type: 'application/octet-stream' }), `${fileName}.${fileType}`)
}