[PHP] Google Calendar API v3 から祝日取得

gistfile1.php

<?php
function get_holidays_this_month($year, $month){
  // 月初日
  $first_day = mktime(0, 0, 0, intval($month), 1, intval($year));

  // 月末日
  $last_day = strtotime('-1 day', mktime(0, 0, 0, intval($month) + 1, 1, intval($year)));

  $api_key = 'YOUR API KEY HERE';
  $holidays_id = 'outid3el0qkcrsuf89fltf7a4qbacgt9@import.calendar.google.com';  // mozilla.org版
  //$holidays_id = 'japanese__ja@holiday.calendar.google.com';  // Google 公式版日本語
  //$holidays_id = 'japanese@holiday.calendar.google.com';  // Google 公式版英語
  $holidays_url = sprintf(
    'https://www.googleapis.com/calendar/v3/calendars/%s/events?'.
    'key=%s&timeMin=%s&timeMax=%s&maxResults=%d&orderBy=startTime&singleEvents=true',
    $holidays_id,
    $api_key,
    date('Y-m-d', $first_day).'T00:00:00Z' ,  // 取得開始日
    date('Y-m-d', $last_day).'T00:00:00Z' ,   // 取得終了日
    31            // 最大取得数
    );
  if ( $results = file_get_contents($holidays_url) ) {
    $results = json_decode($results);
    $holidays = array();
    foreach ($results->items as $item ) {
      $date  = strtotime((string) $item->start->date);
      $title = (string) $item->summary;
      $holidays[date('Y-m-d', $date)] = $title;
    }
    ksort($holidays);
  }
  return $holidays;
}