Ruby(/Rails) dates - bi-weekly and quarterly DateTime ranges

Question

I am trying to do reporting for a specific period, those periods supported being:

• "today": start = DateTime.now.beginning_of_day; end = start.end_of_day
• "this week": start = DateTime.now.beginning_of_week; end = start.end_of_week
• "this bi-week" (first half or second half of the month, relative to the current date of DateTime.now)
  • it is very important to be sure that the month is evenly divided, and cweek is not used; the start of the first bi-week should be the first of the month, and the end of the second bi-week should be the last of the month. The dividing date between the two should be the total number of days in the month divided by 2, rounded up (i.e. if there are 31 days, the second bi-week would start on the 15th, and not the 14th of the month).
• "this month": start = DateTime.now.beginning_of_month; end = start.end_of_month
• "last month": start = (DateTime.now - 1.month).beginning_of_month; end = start.end_of_month
• "this quarter": one of each of the four 3-month periods in the year, ie quarters. Ex: from 1/1/1999 to 3/31/1999 or from 10/1/2000 to 12/31/2000.
• "this year" = start = DateTime.now.beginning_of_year --> end = start.end_of_year

I'm having trouble calculating the bold date ranges based on the current date (assume DateTime.now).

How can I calculate the bi-weekly and quarterly period relative to the current date, DateTime.now?

Expected output

For the date May 7th, 2018 (5/7/2018):

• "this bi-week" should be the period of 5/1/2018 to 5/15/2018
• "this quarter" should be the period of 4/1/2018 to 6/30/2018

For the date February 29th, 2020 (2/29/2020), a leap year:

• "this bi-week" should be the period of 2/15/2018 to 2/29/2018
• "this quarter" should be the period of 1/1/2018 to 3/31/2018

Answer 1

What about this:

This bi-week:

def bi_week_limits_for(date)
  days_in_month = Time.days_in_month(date.month, date.year)
  # this will round down. 30/31-day months will output 15. 28 / 29-day will output 14. Adjust as per your requirements
  middle_day    = days_in_month / 2
  if date.day <= middle_day
    [date.beginning_of_month, date.change(day: middle_day)]
  else 
    [date.change(day: middle_day + 1), date.end_of_month]
  end 
end

In my console:

pry(main)> bi_week_limits_for Date.parse('29/2/2020')
=> [Sat, 15 Feb 2020, Sat, 29 Feb 2020]
pry(main)> bi_week_limits_for Date.parse('7/5/2018')
=> [Tue, 01 May 2018, Tue, 15 May 2018]

This quarter:

def bi_week_limits_for(date)
  [date.beginning_of_quarter, date.end_of_quarter]
end

In my console

pry(main)> date = Date.parse('7/5/2018')
=> Mon, 07 May 2018
pry(main)> quarter_limits_for date
=> [Sun, 01 Apr 2018, Sat, 30 Jun 2018]

pry(main)> date = Date.parse '29/2/2020'
=> Sat, 29 Feb 2020
pry(main)> quarter_limits_for date
=> [Wed, 01 Jan 2020, Tue, 31 Mar 2020]

Reference: https://apidock.com/rails/DateAndTime/Calculations/beginning_of_quarter