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#!/usr/bin/env python3
"""An amount of money (USD) represented as an integral count of
cents."""
import re
from typing import Optional, Tuple
import math_utils
class CentCount(object):
"""A class for representing monetary amounts potentially with
different currencies meant to avoid floating point rounding
issues by treating amount as a simple integral count of cents.
"""
def __init__(self, centcount, currency: str = 'USD', *, strict_mode=False):
self.strict_mode = strict_mode
if isinstance(centcount, str):
ret = CentCount._parse(centcount)
if ret is None:
raise Exception(f'Unable to parse money string "{centcount}"')
centcount = ret[0]
currency = ret[1]
if isinstance(centcount, float):
centcount = int(centcount * 100.0)
if not isinstance(centcount, int):
centcount = int(centcount)
self.centcount = centcount
if not currency:
self.currency: Optional[str] = None
else:
self.currency = currency
def __repr__(self):
a = float(self.centcount)
a /= 100
a = round(a, 2)
s = f'{a:,.2f}'
if self.currency is not None:
return f'{s} {self.currency}'
else:
return f'${s}'
def __pos__(self):
return CentCount(centcount=self.centcount, currency=self.currency)
def __neg__(self):
return CentCount(centcount=-self.centcount, currency=self.currency)
def __add__(self, other):
if isinstance(other, CentCount):
if self.currency == other.currency:
return CentCount(
centcount=self.centcount + other.centcount,
currency=self.currency,
)
else:
raise TypeError('Incompatible currencies in add expression')
else:
if self.strict_mode:
raise TypeError('In strict_mode only two moneys can be added')
else:
return self.__add__(CentCount(other, self.currency))
def __sub__(self, other):
if isinstance(other, CentCount):
if self.currency == other.currency:
return CentCount(
centcount=self.centcount - other.centcount,
currency=self.currency,
)
else:
raise TypeError('Incompatible currencies in add expression')
else:
if self.strict_mode:
raise TypeError('In strict_mode only two moneys can be added')
else:
return self.__sub__(CentCount(other, self.currency))
def __mul__(self, other):
if isinstance(other, CentCount):
raise TypeError('can not multiply monetary quantities')
else:
return CentCount(
centcount=int(self.centcount * float(other)),
currency=self.currency,
)
def __truediv__(self, other):
if isinstance(other, CentCount):
raise TypeError('can not divide monetary quantities')
else:
return CentCount(
centcount=int(float(self.centcount) / float(other)),
currency=self.currency,
)
def __int__(self):
return self.centcount.__int__()
def __float__(self):
return self.centcount.__float__() / 100.0
def truncate_fractional_cents(self):
x = int(self)
self.centcount = int(math_utils.truncate_float(x))
return self.centcount
def round_fractional_cents(self):
x = int(self)
self.centcount = int(round(x, 2))
return self.centcount
__radd__ = __add__
def __rsub__(self, other):
if isinstance(other, CentCount):
if self.currency == other.currency:
return CentCount(
centcount=other.centcount - self.centcount,
currency=self.currency,
)
else:
raise TypeError('Incompatible currencies in sub expression')
else:
if self.strict_mode:
raise TypeError('In strict_mode only two moneys can be added')
else:
return CentCount(
centcount=int(other) - self.centcount,
currency=self.currency,
)
__rmul__ = __mul__
#
# Override comparison operators to also compare currency.
#
def __eq__(self, other):
if other is None:
return False
if isinstance(other, CentCount):
return self.centcount == other.centcount and self.currency == other.currency
if self.strict_mode:
raise TypeError("In strict mode only two CentCounts can be compared")
else:
return self.centcount == int(other)
def __ne__(self, other):
result = self.__eq__(other)
if result is NotImplemented:
return result
return not result
def __lt__(self, other):
if isinstance(other, CentCount):
if self.currency == other.currency:
return self.centcount < other.centcount
else:
raise TypeError('can not directly compare different currencies')
else:
if self.strict_mode:
raise TypeError('In strict mode, only two CentCounts can be compated')
else:
return self.centcount < int(other)
def __gt__(self, other):
if isinstance(other, CentCount):
if self.currency == other.currency:
return self.centcount > other.centcount
else:
raise TypeError('can not directly compare different currencies')
else:
if self.strict_mode:
raise TypeError('In strict mode, only two CentCounts can be compated')
else:
return self.centcount > int(other)
def __le__(self, other):
return self < other or self == other
def __ge__(self, other):
return self > other or self == other
def __hash__(self) -> int:
return hash(self.__repr__)
CENTCOUNT_RE = re.compile(r"^([+|-]?)(\d+)(\.\d+)$")
CURRENCY_RE = re.compile(r"^[A-Z][A-Z][A-Z]$")
@classmethod
def _parse(cls, s: str) -> Optional[Tuple[int, str]]:
centcount = None
currency = None
s = s.strip()
chunks = s.split(' ')
try:
for chunk in chunks:
if CentCount.CENTCOUNT_RE.match(chunk) is not None:
centcount = int(float(chunk) * 100.0)
elif CentCount.CURRENCY_RE.match(chunk) is not None:
currency = chunk
except Exception:
pass
if centcount is not None and currency is not None:
return (centcount, currency)
elif centcount is not None:
return (centcount, 'USD')
return None
@classmethod
def parse(cls, s: str) -> 'CentCount':
chunks = CentCount._parse(s)
if chunks is not None:
return CentCount(chunks[0], chunks[1])
raise Exception(f'Unable to parse money string "{s}"')
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