date_helper.rb

REGEX_1 = /(\d{1,2})[st|nd|rd|th]?{2}\s{1}(January|Jan|February|Feb|March|Mar|April|Apr|May|June|Jun|July|Jul|August|Aug|September|Sep|October|Oct|November|Nov|December|Dec),?\s(\d{2,4})/
REGEX_2 = /(January|Jan|February|Feb|March|Mar|April|Apr|May|June|Jun|July|Jul|August|Aug|September|Sep|October|Oct|November|Nov|December|Dec)\s{1}(0\d{1}|\d{1,2})[st|nd|rd|th]{2}?(,?)\s(\d{2,4})/
REGEX_3 = /(0\d{1}|\d{1}|1\d{1})\/(0\d{1}|\d{1}|1\d{1})\/(\d{2,4})/
MONTH_STR_TO_NUM={
  "JANUARY": 1,
  "January": 1,
  "Jan": 1,
  "FEBRUARY": 2,
  "February": 2,
  "Feb": 2,
  "MARCH": 3,
  "March": 3,
  "Mar": 3,
  "APRIL": 4,
  "April": 4,
  "Apr": 4,
  "MAY": 5,
  "May": 5,
  "JUNE": 6,
  "June": 6,
  "Jun": 6,
  "JULY": 7,
  "July": 7,
  "Jul": 7,
  "AUGUST": 8,
  "August": 8,
  "Aug": 8,
  "SEPTEMBER": 9,
  "September": 9,
  "Sep": 9,
  "OCTOBER": 10,
  "October": 10,
  "Oct": 10,
  "NOVEMBER": 11,
  "November": 11,
  "Nov": 11,
  "DECEMBER": 12,
  "December": 12,
  "Dec": 12
}

def match_to_date_set1(md)
  return nil if md.nil?
  dates = []
  md.each do |dates_found|
    month = MONTH_STR_TO_NUM[:"#{dates_found[1]}"]
    day = dates_found[0].to_i
    year = dates_found[2].to_i
    begin
      dates << Date.new(year, month, day)
    rescue ArgumentError
      begin 
        date_str = "#{year}/#{month}/#{day}"
        d = Date.strptime(date_str, "%Y/%-m/%-d")
        dates << d
      rescue ArgumentError
        # remap the variables and try again
        month = Date::MONTHNAMES[MONTH_STR_TO_NUM[:"#{dates_found[1]}"]]
        day = dates_found[2].to_i
        year = "19#{dates_found[0].to_i}"
        date_str = "#{month} #{day} #{year}"
        dates << Date.parse(date_str)
      end
    end
  end
  return dates
end

def match_to_date_set2(md)
  return nil if md.nil?
  dates = []
  md.each do |dates_found|
    month = MONTH_STR_TO_NUM[:"#{dates_found[0]}"]
    day = dates_found[1].to_i
    year = dates_found[3]
    begin
      dates << Date.new(year, month, day)
    rescue ArgumentError
      begin
        year = year.length == 2 ? "19#{year}" : year
        dates << Date.new(year, month, day)
      rescue ArgumentError
        begin
          month = Date::MONTHNAMES[MONTH_STR_TO_NUM[:"#{dates_found[0]}"]]
          day = dates_found[1].to_i
          year = dates_found[3].length == 2 ? "19#{dates_found[3]}" : dates_found[3]
          date_str = "#{month} #{day} #{year}"
          dates << Date.parse(date_str)
        rescue ArgumentError
          month = Date::MONTHNAMES[MONTH_STR_TO_NUM[:"#{dates_found[0]}"]]
          day = dates_found[3].to_i
          year = dates_found[1].length == 2 ? "19#{dates_found[1].to_i}" : dates_found[1].to_i
          date_str = "#{month} #{day} #{year}"
          dates << Date.parse(date_str)
        end
      end
    end
  end
  return dates
end

def match_to_date_set3(md)
  return nil if md.nil?
  dates = []
  md.each do |dates_found|
    month = Date::MONTHNAMES[dates_found[0].to_i]
    day = dates_found[1].to_i
    year = dates_found[2]
    date_str = "#{month} #{day} #{year}"
    dates << Date.parse(date_str)
  end
  return dates
end