Is there a way in ruby to find the beginning of the year in a 4-5-4 (Retail) Calendar

Question

I'm trying to build reporting for retail sales in a Rails app. I'm trying to write a Gem which can find the start and end dates of a retail month/quarter/season in a Retail Calendar

I'm having difficulty in determining the start of the year.

Ex: in 2014, the year starts on 2nd Feb. For 2015, it's 1st Feb and 2016 is 31st January.

Has anyone encountered such a requirement in Ruby or any other language.

Answer 1

require 'date'

# Class for 5-4-4, 4-5-4, and 4-4-5 calendars
class Calendar13

    def initialize (type = 454, yr_end_mo = 1)
        case type
        when 544, 454, 445 then @type = type
        else raise ArgumentError, "Bad calendar type #{type}"
        end
        if (1..12) === yr_end_mo then @yr_end_mo = yr_end_mo
        else raise ArgumentError, "Bad year-end month #{yr_end_mo}"
        end
    end

    # Return the ending date for a particular year
    def end_of_year (year)
        year += 1 unless @yr_end_mo == 12
        year_end = Date.new year, @yr_end_mo, -1
        wday = (year_end.wday + 1) % 7 # Saturday-origin day-of-week
        # Advance or retreat to closest Saturday
        if wday > 3 then year_end += 7 - wday
        elsif wday > 0 then year_end -= wday
        end
        year_end
    end

    # Return starting date for a particular year
    def start_of_year (year); end_of_year(year - 1) + 1; end

    # Return starting date for a particular month
    def start_of_month (year, month)
        start = start_of_year(year) + ((month - 1) / 3).to_i * 91
        case @type * 10 + (month - 1) % 3
        when 4451, 4541 then start += 28
        when 5441 then start += 35
        when 4452 then start += 56
        when 4542, 5442 then start += 63
        end
        start
    end

    # Return the ending date for a particular month
    def end_of_month (year, month)
        if month == 12 then end_of_year year
        else start_of_month(year, month + 1) - 1
        end
    end

    # Return the starting date for a particular quarter
    def start_of_quarter (year, quarter)
        start_of_month year, (quarter - 1) * 3 + 1
    end

    # Return the ending date for a particular quarter
    def end_of_quarter (year, quarter)
        if quarter == 4 then end_of_year year
        else start_of_quarter(year, quarter + 1) - 1
        end
    end

    # Return the number of weeks in a particular year
    def weeks_in_year (year)
        ((start_of_year(year + 1) - start_of_year(year)) / 7).to_i
    end

end

See also http://www.smythretail.com/general-retailing/how-to-set-up-a-4-5-4-calendar/.