Have made a gem to retrieve holidays from Google Calendar

I've made a gem to retrieve national holidays from Google Calendar with simple interface.

github.com

What motivates me is there is no suitable gem for my purpose as far as I can see.

What I want to do

What I want to do and some features the gem provides are below:

• List holidays in a particular month
• List holidays in a particular year
• Check a date whether it is a holiday or not
• Retrieve holidays of a lot of countries

Plus, I want to do these thing with LESS API ACCESS to Google Calendar.

Strengths

Notable features are CACHEING and PRELOAD. There are some tools which have similar features, but they need API access every time.

As for my gem, it needs a few API access when you use the preload feature properly.

For example, when you pass date_range: 1.year as a preload parameter, it is going to retrieve and cache holidays from "this day last year" to "this day next year" at initialization. As far as you access days only in this range, the gem never calls Google API.

In adittion, the caching feature adopts LRU algorithm to care about memory leak.

How to use it

Sample code is below:

require "holidays_from_google_calendar"

usa_holidays = HolidaysFromGoogleCalendar::Holidays.new do |config|
  config.calendar = {
    nation: "usa",
    language: "en"
  }

  config.credential = {
    api_key: "YOUR OWN GOOGLE API KEY"
  }
end

usa_holidays.in_year(Date.parse("2016-02-06")) # Retrieve 2016's holidays
=> [#<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42df748 @date=Fri, 01 Jan 2016, @name="New Year's Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42def28 @date=Mon, 18 Jan 2016, @name="Martin Luther King Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42de820 @date=Sun, 14 Feb 2016, @name="Valentine's Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42de0f0 @date=Mon, 15 Feb 2016, @name="Presidents' Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42dd808 @date=Sun, 13 Mar 2016, @name="Daylight Saving Time starts">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42dc8e0 @date=Sun, 27 Mar 2016, @name="Easter Sunday">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab3b40 @date=Wed, 13 Apr 2016, @name="Thomas Jefferson's Birthday">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab36b8 @date=Sun, 08 May 2016, @name="Mother's Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab3230 @date=Mon, 30 May 2016, @name="Memorial Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab2d08 @date=Sun, 19 Jun 2016, @name="Father's Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab26a0 @date=Mon, 04 Jul 2016, @name="Independence Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab21a0 @date=Mon, 05 Sep 2016, @name="Labor Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab1cc8 @date=Mon, 10 Oct 2016, @name="Columbus Day (regional holiday)">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab1610 @date=Mon, 31 Oct 2016, @name="Halloween">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab0f30 @date=Sun, 06 Nov 2016, @name="Daylight Saving Time ends">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab0a58 @date=Tue, 08 Nov 2016, @name="Election Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab0648 @date=Fri, 11 Nov 2016, @name="Veterans Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d4ab0238 @date=Thu, 24 Nov 2016, @name="Thanksgiving Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42d7f20 @date=Sat, 24 Dec 2016, @name="Christmas Eve">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42d7a70 @date=Sun, 25 Dec 2016, @name="Christmas Day">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42d7660 @date=Mon, 26 Dec 2016, @name="Christmas Day observed">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42d70e8 @date=Sat, 31 Dec 2016, @name="New Year's Eve">,

usa_holidays.in_month(Date.parse("3rd March 2016")) # Retrieve holidays of March, 2016
=> [#<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42dd808 @date=Sun, 13 Mar 2016, @name="Daylight Saving Time starts">,
 #<HolidaysFromGoogleCalendar::Holiday:0x007ff7d42dc8e0 @date=Sun, 27 Mar 2016, @name="Easter Sunday">]

usa_holidays.holiday?(Date.parse("Oct 31 2016")) # Halloween
=> true

usa_holidays.holiday?(Date.parse("April 16th 2016")) # Satruday
=> true

usa_holidays.holiday?(Date.parse("April 17th 2016")) # Sunday
=> true

usa_holidays.holiday?(Date.parse("Aug 2 2016")) # Weekday (Tuesday)
=> false

Impression

I need to learn data structures and algorithms more and more.