ThinkPHP 获取指定日期后第N个工作日具体日期

思路：

1、获取到查询年份内所有工作日数据数组
2、获取到查询开始日期在工作日的索引
3、计算需查询日期索引
4、获得查询日期

/*创建日期类型记录表格*/
CREATE TABLE `tb_workday` (
`did` int(11) NOT NULL AUTO_INCREMENT,
`exact_date` varchar(32) NOT NULL COMMENT '具体日期：格式date("Ymd");(20170205)',
`date_year` varchar(32) NOT NULL COMMENT '具体日期：格式date("Y");(2017)',
`date_type` tinyint(2) NOT NULL COMMENT '日期类型：0、工作日；1、特殊工作日；2、法定节假日',
PRIMARY KEY (`did`)
) ENGINE=InnoDB AUTO_INCREMENT=829 DEFAULT CHARSET=utf8 COMMENT='各年工作日&法定节假日数据'

<?php

class work_days
{
  /**
   * 获取星期
   * @param $date
   * @return mixed
   */
  function get_week($date)
  {
    //强制转换日期格式
    $date_str = date('Y-m-d', strtotime($date));
    //封装成数组
    $arr = explode("-", $date_str);
    //参数赋值
    //年
    $year = $arr[0];
    //月，输出2位整型，不够2位右对齐
    $month = sprintf('%02d', $arr[1]);
    //日，输出2位整型，不够2位右对齐
    $day = sprintf('%02d', $arr[2]);
    //时分秒默认赋值为0；
    $hour = $minute = $second = 0;
    //转换成时间戳
    $strap = mktime($hour, $minute, $second, $month, $day, $year);
    //获取数字型星期几
    $number_wk = date("w", $strap);

    //获取数字对应的星期
    return $number_wk;

    //自定义星期数组
    //$weekArr = array("星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六");

    //获取数字对应的星期
    //return $weekArr[$number_wk];
  }


  /**
   * 获取指定日期段内每一天的日期
   * @param  string $startdate 开始日期
   * @param  string $enddate   结束日期
   * @return array
   */
  function getDateFromRange($startdate, $enddate)
  {
    $stimestamp = strtotime($startdate);
    $etimestamp = strtotime($enddate);

    // 计算日期段内有多少天
    $days = ($etimestamp - $stimestamp) / 86400 + 1;

    // 保存每天日期
    $_list_date = array();
    for ($i = 0; $i < $days; $i++) {
      $_list_date[] = date('Y-m-d', $stimestamp + (86400 * $i));
    }
    return $_list_date;
  }

  function curl_post($url, $data = null)
  {
    $curl = curl_init();
    curl_setopt($curl, CURLOPT_URL, $url);
    curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
    curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE);
    if (!empty($data)) {
      curl_setopt($curl, CURLOPT_POST, 1);
      curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
    }
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
    $output = curl_exec($curl);
    curl_close($curl);
    return $output;
  }

  /**
   * 更新数据库指定年份日期数据
   * @param $year
   * @return int
   */
  function updateDate($year)
  {
    $startDate = date('Y-m-d', strtotime($year . '-01-01'));
    $endDate = date('Y-m-d', strtotime('+1 year', strtotime($startDate)) - 86400);
    $_list_date = self::getDateFromRange($startDate, $endDate);

    $url = 'http://api.goseek.cn/Tools/holiday';//自行查找的免费API

    $m = M('tb_workday');
    $count = 0;

    foreach ($_list_date as $k => $_date) {
      $_ret = 0;
      $_date = date('Ymd', strtotime($_date));
      $_post_data = array('date' => $_date);
      $_ret_curl = curl_post($url, $_post_data);
      $_ret_curl = json_decode($_ret_curl, true);

      //工作日
      if ($_ret_curl['data'] == 0) {
        $dateData['exact_date'] = $_date;
        $dateData['date_year'] = $year;
        $dateData['date_type'] = 0;
        $_ret = $m->add($dateData) ? 1 : 0;
        unset($dateData);


        //工作日 判断是否为周末
        if (in_array(self::get_week($_date), array(0, 1))) {
          //特殊工作日
          $dateData['exact_date'] = $_date;
          $dateData['date_year'] = $year;
          $dateData['date_type'] = 1;
          $_ret = $m->add($dateData) ? 1 : 0;
          unset($dateData);
        }
      }

      //法定节假日
      if ($_ret_curl['data'] == 2) {
        $dateData['exact_date'] = $_date;
        $dateData['date_year'] = $year;
        $dateData['date_type'] = 2;
        $_ret = $m->add($dateData) ? 1 : 0;
        unset($dateData);
      }

      //休息日(周末) 暂不处理
      /*if ($_ret_curl['data'] == 1) {

      }*/
      $_ret && $count++;
      unset($_date, $_post_data, $_ret_curl, $_ret);
    }
    return $count;
  }

  /**
   * 获取当年所有工作日 (从数据库获取，数据库无数据则先更新数据)
   * @param string $year 当年年份
   * @return array
   */
  private function getWorkDays($year)
  {
    $m = M('tb_workday');
    $map['date_year'] = $year;
    $map['date_type'] = 0;
    $DateArray = $m->field('exact_date')->where($map)->select();
    if (!empty($DateArray)) {
      $DateArray = array_column($DateArray, 'exact_date');
      return $DateArray;
    } else {
      //更新数据库工作日数据
      $ret = self::updateDate($year);
      if ($ret > 0) {
        return self::getWorkDays($year);
      } else {
        return false;
      }
    }
  }

  /**
   * 获取开始日期后第N个工作日具体日期
   * @param $startdate string 计算开始日期  需包含年月日信息
   * @param $days      int 间隔天数
   * @return mixed 成功返回 对应日期，失败返回false
   */
  public function getNextWorkDate($startdate, $days)
  {
    $year = date('Y', strtotime($startdate));
    $startdate = date('Y-m-d', strtotime($startdate));

    $workDays = $this->getWorkDays($year);

    $search_key = array_search(date('Ymd', strtotime($startdate)), $workDays);

    if ($search_key === false) {//查询日期为非工作
      //获取查询日期前最近工作日
      $m = M('tb_workday');
      $map['date_year'] = $year;
      $map['date_type'] = 0;
      $map['DATE_FORMAT(`exact_date`,\'%Y-%m-%d\')'] = array('LT', $startdate);
      $_search_date = $m->where($map)->order('`exact_date` DESC')->getField('exact_date');
      $search_key = array_search($_search_date, $workDays);
      unset($m, $map, $_search_date);
    }

    $t_key = $search_key + $days;

    if ($t_key <= count($workDays) - 1) {
      return date('Y-m-d', strtotime($workDays[$t_key]));
    } else {
      //查询日期已跨年
      $n_days = $days - (count($workDays) - 1 - $search_key);
      $next_year = $year + 1;
      return $this->getNextWorkDate($next_year . '-01-01', $n_days - 1);
    }
  }
}


$startdate = '2018-09-28';
$days = 5;

$class = new work_days();
$_date_workday = $class->getNextWorkDate($startdate, $days);
echo $_date_workday;//2018-10-10