# timemsTZ2expire.mjs

    import ot from 'dayjs'
    import istimemsTZ from './istimemsTZ.mjs'

    /**
     * 毫秒時間轉到期時間
     *
     * Unit Test: {@link https://github.com/yuda-lyu/wsemi/blob/master/test/timemsTZ2expire.test.mjs Github}
     * @memberOf wsemi
     * @param {String} t 輸入毫秒時間字串
     * @param {String} [tNow=null] 輸入現在毫秒時間字串
     * @returns {String} 回傳到期時間字串
     * @example
     *
     * let t
     * let tNow = '2020-10-18T12:34:56.987+08:00'
     * let r
     *
     * t = '2020-10-18T12:34:58.987+08:00'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: true, msg: '2秒後', err: '' }
     *
     * t = '2020-10-18T04:34:58.987+00:00'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: true, msg: '2秒後', err: '' }
     *
     * t = '2020-10-18T04:34:58.987Z'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: true, msg: '2秒後', err: '' }
     *
     * t = '2020-10-18T12:34:58.123+08:00'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: true, msg: '1秒後', err: '' }
     *
     * t = '2020-10-18T12:37:58.987+08:00'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: true, msg: '3分鐘後', err: '' }
     *
     * t = '2020-10-18T16:37:58.987+08:00'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: true, msg: '4小時後，今天16:37', err: '' }
     *
     * t = '2020-10-23T16:37:58.987+08:00'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: false, msg: '5天後', err: '' }
     *
     * t = '2021-04-23T16:37:58.987+08:00'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: false, msg: '6個月後', err: '' }
     *
     * t = '2028-04-23T16:37:58.987+08:00'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: false, msg: '7年後', err: '' }
     *
     * t = '2018-04-23T16:37:58.987+08:00'
     * r = timemsTZ2expire(t, tNow)
     * console.log(r)
     * // => { today: null, msg: '', err: '時間已過' }
     *
     */
    function timemsTZ2expire(t, tNow = null) {

        //check
        if (!istimemsTZ(t)) {
            return {
                today: null,
                msg: '',
                err: '時間格式錯誤',
            }
        }

        //mnow
        let mnow = ot()
        if (istimemsTZ(tNow)) {
            mnow = ot(tNow, 'YYYY-MM-DDTHH:mm:ss.SSSZ') //統一轉+00:00時區再計算時間差
        }

        //mtime
        let mtime = ot(t, 'YYYY-MM-DDTHH:mm:ss.SSSZ') //統一轉+00:00時區再計算時間差

        //check
        if (mnow > mtime) {
            return {
                today: null,
                msg: '',
                err: '時間已過',
            }
        }

        //day
        let nowday = mnow.format('YYYY-MM-DD')
        let timeday = mtime.format('YYYY-MM-DD')
        let mnowday = ot(nowday, 'YYYY-MM-DD')
        let mtimeday = ot(timeday, 'YYYY-MM-DD')

        //diff
        let iseconds = mtime.diff(mnow, 'seconds')
        let iminutes = mtime.diff(mnow, 'minutes')
        let ihours = mtime.diff(mnow, 'hours')
        let idays = mtimeday.diff(mnowday, 'days')
        let iweeks = mtimeday.diff(mnowday, 'weeks')
        let imonths = mtimeday.diff(mnowday, 'months')
        let iyears = mtimeday.diff(mnowday, 'years')

        //c
        let today
        let c = '即將到來'
        if (iseconds >= 0) {
            today = true
            c = iseconds + '秒後'
        }
        if (iminutes > 0) {
            today = true
            c = iminutes + '分鐘後'
        }
        if (ihours > 0) {
            let hm = mtime.format('HH:mm')
            if (nowday === timeday) {
                today = true
                c = ihours + '小時後' + '，今天' + hm
            }
            else {
                today = false
                c = ihours + '小時後' + '，明天' + hm
            }
        }
        if (idays > 1) { //明天交由小時部份處理
            today = false
            if (idays === 2) {
                c = '後天'
            }
            else {
                c = idays + '天後'
            }
        }
        if (iweeks > 0) {
            today = false
            c = iweeks + '周後'
        }
        if (imonths > 0) {
            today = false
            c = imonths + '個月後'
        }
        if (iyears > 0) {
            today = false
            c = iyears + '年後'
        }

        return {
            today: today,
            msg: c,
            err: '',
        }
    }

    export default timemsTZ2expire