module DayFinder

# File lib/DayFinder.rb, line 9
def self.find d,m,year
  month_31 = [1,3,5,7,8,10,12]
  month_30 = [11,4,6,9]
  month_28=[2]
  leap = false
  leap = true if ((year % 4).zero? && (year % 100 != 0)) || (year % 400).zero?
  raise "day is invalid" if (m == 2) && (d >= 30)
  raise "month 2 date invalid" if !leap && m == 2 && d >= 29
  raise "Invalid date" if (month_31.include?(m) && d >= 32 && d != 0) || (month_30.include?(m) && d >= 31 && d != 0)
  raise "Day is invalid" if d <= 0
  raise "Month invalid " if !month_31.include?(m) && !month_30.include?(m) && !month_28.include?(m)

  if m > 2
    mo = m
  else
    mo = 12 + m
    year -= 1
  end
  y = year % 100
  c = year / 100
  x = d + (13 * (mo + 1)) / 5 + y + (y / 4) + (c / 4) + 5 * c
  w = x % 7
  weekday = %w[Saturday Sunday Monday Tuesday Wednesday Thursday Friday]
  # puts leap
  weekday[w]
end