// ==UserScript==
// @name		天数倒计时
// @namespace	https://bbs.tampermonkey.net.cn/
// @version		0.1
// @description	每天提醒你距离目标日期的天数
// @author		Exisi
// @crontab    * 7-23 once * *
// @grant		GM_notification
// @grant		GM_getValue
// ==/UserScript==

/* ==UserConfig==
设置:
    Notice:
        title: 标题
        description: 请输入通知标题
    Year:
        title: 年
        description: 请输入年份，默认当前年份
    Month:
        title: 月
        description: 请输入年份，默认当前月份
    Day:
        title: 日
        description: 请输入天数，默认无
 ==/UserConfig== */


function getTotalDay(year, month) {
    let date = new Date(year, month, 0);
    return date.getDate();
}

function getDiffDay(date, aim_date){
    let diff = (aim_date - date) / 1000 / 3600 / 24;
    return diff;
}

return new Promise((resolve, reject) => {
    let date = new Date();
    let aim_date = new Date();
    let current = {
        year      : date.getFullYear(),
        month     : date.getMonth() + 1,
        day       : date.getDay(),
    }
    let target = {
        notice : GM_getValue('设置.Notice', '天数倒计时'),
        year   : GM_getValue('设置.Year', current.year),
        month  : GM_getValue('设置.Month', current.month),
        day    : GM_getValue('设置.Day', false),
    }
    let over = {
        year   : target.year >= current.year,
        month  : ( 0 < target.year <= 12 ) && ( target.year >= current.year ),
        day    : ( 0 < target.day  <= getTotalDay(target.year, target.month) ) && ( target.day >= current.day ),
    }
    if (over.year && over.month && over.day) {
        aim_date.setFullYear(target.year, target.month - 1 , target.day);
        let diff = getDiffDay(date, aim_date);
        GM_notification({
            title   : target.notice,
            text    : '剩余天数：'+ diff,
            timeout : 3000,
        });
        resolve();
    } else {
        resolve('倒计时完成，自动停止');
    }
});