module FFaker::IdentificationPL

def drivers_license
  FFaker.numerify('#####/##/####')
end

def generate_valid_pesel_date
  from = Date.new(1800, 1, 1)
  to = [Date.today, Date.new(2299, 12, 31)].min
  fetch_sample(from..to)
end

def identity_card
  letter_part = FFaker.letterify('???').upcase
  number_part = FFaker.numerify('#####')
  checksum = identity_card_checksum(letter_part, number_part)
  "#{letter_part}#{checksum}#{number_part}"
end

def identity_card_checksum(letter_part, number_part)
  a, b, c = letter_part.codepoints.map { |codepoints| codepoints - 55 }
  d, e, f, g, h = number_part.split('').map(&:to_i)
  (a * 7 + b * 3 + c + 7 * d + 3 * e + f + 7 * g + 3 * h) % 10
end

def pesel
  date = generate_valid_pesel_date
  birthdate = pesel_birthdate(date)
  serial_number = FFaker.numerify('####')
  checksum = pesel_checksum(birthdate, serial_number)
  "#{birthdate}#{serial_number}#{checksum}"
end

def pesel_birthdate(date)
  century_differentiator = pesel_century_differentiator(date.year)
  year = date.strftime('%y')
  month = century_differentiator.zero? ? date.strftime('%m') : date.month + century_differentiator
  day = date.strftime('%d')
  "#{year}#{month}#{day}"
end

def pesel_century_differentiator(year)
  case year
  when 1800..1899 then 80
  when 2000..2099 then 20
  when 2100..2199 then 40
  when 2200..2299 then 60
  else 0
  end
end

def pesel_checksum(date, serial_number)
  pesel_digits = "#{date}#{serial_number}".split('').map(&:to_i)
  a, b, c, d, e, f, g, h, i, j = pesel_digits
  (a * 9 + b * 7 + c * 3 + d + e * 9 + f * 7 + g * 3 + h + i * 9 + j * 7) % 10
end