PHP时间范围：本周、本月、下月等简写

在阅读TP5.1源码，发现其在时间范围上的写法很特别，个人第一次见，做一次记录

$timeRule = [
     'today'      => ['today', 'tomorrow'],
     'yesterday'  => ['yesterday', 'today'],
     'week'       => ['this week 00:00:00', 'next week 00:00:00'],
     'last week'  => ['last week 00:00:00', 'this week 00:00:00'],
     'month'      => ['first Day of this month 00:00:00', 'first Day of next month 00:00:00'],
     'last month' => ['first Day of last month 00:00:00', 'first Day of this month 00:00:00'],
     'year'       => ['this year 1/1', 'next year 1/1'],
     'last year'  => ['last year 1/1', 'this year 1/1'],
];

echo date('Y-m-d H:i:s', strtotime('this week 00:00:00'));

// 结果如下
2018-01-08 00:00:00

// 指定时间：本周第一天 + 1年2个月5天3小时5分钟
echo date('Y-m-d H:i:s', strtotime('this week 00:00:00 + 1year + 2month + 5day + 3hour + 5minute'));
// 返回结果
2019-03-13 03:05:00

// 根据年份中的第几周，获取周的开始时间，需要注意的是 $week 必须是2位数，不足前补0
strtotime($year . 'W' . $week);

echo strtotime('2018' . 'W' . '02');
//结果
2018-01-08

/**
 * 根据【年，周】，获取时间范围
 * @param $year
 * @param int $week
 * @return array|false
 */
function getWeekStartAndEnd ($year, $week = 1) {
    $year = (int)$year;
    $week = (int)$week;
    $date = new \DateTime;
    $date->setISODate($year, 53);
    $weeks = max($date->format("W"),52);

    //如果给定的周数大于周总数或小于等于0
    if($week > $weeks || $week <= 0){
        return false;
    }

    //如果周数小于10
    if($week < 10){
        $week = '0' . $week;
    }

    //当周起止时间戳
    $startTime = strtotime($year . 'W' . $week);

    //当周起止日期
    $weekDate['start'] = date("Y-m-d", $startTime);
    $weekDate['end'] = date("Y-m-d", $startTime + 7 * 24 * 3600 - 1);

    return $weekDate;
}