Before I post this blog , I did search around for this function.
I still prefer a simple one , that's why I would like to share with you.
Basically , I was using google calenda's api.
But I am using the public feed , so I don't need to register so called google api developer account.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
public function getHolidayList() {

        $feedUrl = "http://www.google.com/calendar/feeds/en.usa%23holiday%40group.v.calendar.google.com/public/full?singleevents=true&futureevents=true&max-results=99&orderby=starttime&sortorder=a";

//about the parameters fo this feed , you could look it up at google calendar 's api document

//parameters I used , are to show 99 records , it should be enough for most cases





//we don't get PTO on all holidays :( , so , this array is to define holidays I need

        $presetHoliday = array(

            "Labor Day",

            "Christmas Eve",

            "Christmas Day",

            "New Year's Day",

            "Memorial Day",

            "Independence Day",

            "Thanksgiving Day"

        );

        $holidays = array();

        $calendar = simplexml_load_file($feedUrl);

        foreach ($calendar->entry as $item) {

            if (in_array(trim((string) $item->title), $presetHoliday)) { // remove this condition if you need to get all holidays

                $ns_gd = $item->children('http://schemas.google.com/g/2005');

                $gCalDate = date("Y-m-d", strtotime($ns_gd->when->attributes()->startTime));

                $holidays[$gCalDate]=(string) $item->title;

                

                //harcoded , because we need to define black friday is also holiday , but google doesn't think so

                if((string) $item->title=="Thanksgiving Day")

                {

                  $gCalDate = date("Y-m-d", strtotime($ns_gd->when->attributes()->startTime)+ 86400);

                  $holidays[$gCalDate]="Black Friday";  

                }

                

            }

        }

       //$holidays is the result 

        

    }