import re


_comma_number_re = re.compile(r'([0-9][0-9\,]+[0-9])')
_decimal_number_re = re.compile(r'([0-9]+\.[0-9]+)')
_pounds_re = re.compile(r'£([0-9\,]*[0-9]+)')
_dollars_re = re.compile(r'\$([0-9\.\,]*[0-9]+)')
_ordinal_re = re.compile(r'([0-9]+)(st|nd|rd|th)')
_number_re = re.compile(r'[0-9]+')

_units = [
  '',
  'one',
  'two',
  'three',
  'four',
  'five',
  'six',
  'seven',
  'eight',
  'nine',
  'ten',
  'eleven',
  'twelve',
  'thirteen',
  'fourteen',
  'fifteen',
  'sixteen',
  'seventeen',
  'eighteen',
  'nineteen'
]

_tens = [
  '',
  'ten',
  'twenty',
  'thirty',
  'forty',
  'fifty',
  'sixty',
  'seventy',
  'eighty',
  'ninety',
]

_digit_groups = [
  '',
  'thousand',
  'million',
  'billion',
  'trillion',
  'quadrillion',
]

_ordinal_suffixes = [
  ('one', 'first'),
  ('two', 'second'),
  ('three', 'third'),
  ('five', 'fifth'),
  ('eight', 'eighth'),
  ('nine', 'ninth'),
  ('twelve', 'twelfth'),
  ('ty', 'tieth'),
]

def _remove_commas(m):
  return m.group(1).replace(',', '')


def _expand_decimal_point(m):
  return m.group(1).replace('.', ' point ')


def _expand_dollars(m):
  match = m.group(1)
  parts = match.split('.')
  if len(parts) > 2:
    return match + ' dollars'  # Unexpected format
  dollars = int(parts[0]) if parts[0] else 0
  cents = int(parts[1]) if len(parts) > 1 and parts[1] else 0
  if dollars and cents:
    dollar_unit = 'dollar' if dollars == 1 else 'dollars'
    cent_unit = 'cent' if cents == 1 else 'cents'
    return '%s %s, %s %s' % (dollars, dollar_unit, cents, cent_unit)
  elif dollars:
    dollar_unit = 'dollar' if dollars == 1 else 'dollars'
    return '%s %s' % (dollars, dollar_unit)
  elif cents:
    cent_unit = 'cent' if cents == 1 else 'cents'
    return '%s %s' % (cents, cent_unit)
  else:
    return 'zero dollars'


def _standard_number_to_words(n, digit_group):
  parts = []
  if n >= 1000:
    # Format next higher digit group.
    parts.append(_standard_number_to_words(n // 1000, digit_group + 1))
    n = n % 1000

  if n >= 100:
    parts.append('%s hundred' % _units[n // 100])
  if n % 100 >= len(_units):
    parts.append(_tens[(n % 100) // 10])
    parts.append(_units[(n % 100) % 10])
  else:
    parts.append(_units[n % 100])
  if n > 0:
    parts.append(_digit_groups[digit_group])
  return ' '.join([x for x in parts if x])


def _number_to_words(n):
  # Handle special cases first, then go to the standard case:
  if n >= 1000000000000000000:
    return str(n)   # Too large, just return the digits
  elif n == 0:
    return 'zero'
  elif n % 100 == 0 and n % 1000 != 0 and n < 3000:
    return _standard_number_to_words(n // 100, 0) + ' hundred'
  else:
    return _standard_number_to_words(n, 0)


def _expand_number(m):
  return _number_to_words(int(m.group(0)))


def _expand_ordinal(m):
  num = _number_to_words(int(m.group(1)))
  for suffix, replacement in _ordinal_suffixes:
    if num.endswith(suffix):
      return num[:-len(suffix)] + replacement
  return num + 'th'


def normalize_numbers(text):
  text = re.sub(_comma_number_re, _remove_commas, text)
  text = re.sub(_pounds_re, r'\1 pounds', text)
  text = re.sub(_dollars_re, _expand_dollars, text)
  text = re.sub(_decimal_number_re, _expand_decimal_point, text)
  text = re.sub(_ordinal_re, _expand_ordinal, text)
  text = re.sub(_number_re, _expand_number, text)
  return text