class Holidays::DateCalculator::Easter::Gregorian

def calculate_easter_for(year)
  y = year
  a = y % 19
  b = y / 100
  c = y % 100
  d = b / 4
  e = b % 4
  f = (b + 8) / 25
  g = (b - f + 1) / 3
  h = (19 * a + b - d - g + 15) % 30
  i = c / 4
  k = c % 4
  l = (32 + 2 * e + 2 * i - h - k) % 7
  m = (a + 11 * h + 22 * l) / 451
  month = (h + l - 7 * m + 114) / 31
  day = ((h + l - 7 * m + 114) % 31) + 1
  Date.civil(year, month, day)
end