57 lines
2.5 KiB
Python
57 lines
2.5 KiB
Python
"""Exact, nonnegative amounts in their original currency. No FX conversion."""
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import re
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from decimal import Decimal, InvalidOperation
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CURRENCIES={
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'CNY':2,'USD':2,'HKD':2,'GBP':2,'EUR':2,'JPY':0,'TWD':2,'SGD':2,
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'AUD':2,'CAD':2,'CHF':2,'NZD':2,'KRW':0,'THB':2,'MYR':2,'AED':2,
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'SAR':2,'IDR':2,'INR':2,'PHP':2,'VND':0,'KWD':3,'BHD':3,
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}
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MAX_AMOUNT=Decimal('999999999')
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def normalize_amount(value,currency):
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if currency not in CURRENCIES:
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raise ValueError('请选择支持的币种')
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if not isinstance(value,str) or len(value)>30 or not re.fullmatch(r'[0-9]+(?:\.[0-9]+)?',value):
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raise ValueError('金额须为不小于 0 的数字')
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try:
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amount=Decimal(value)
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if amount>MAX_AMOUNT:
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raise ValueError('金额不能超过 999999999')
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places=CURRENCIES[currency]
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normalized=amount.quantize(Decimal(1).scaleb(-places))
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if normalized!=amount:
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raise ValueError(f'{currency} 金额最多保留 {places} 位小数')
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return format(normalized,f'.{places}f')
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except InvalidOperation:
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raise ValueError('请输入有效金额') from None
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def format_money(money):
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if money is None:
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return '未填写'
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amount=normalize_amount(money['amount'],money['currency'])
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return f"{money['currency']} {Decimal(amount):,f}"
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def apply_balance(balances,cost,operation):
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if operation not in ('deduct','credit') or not cost:
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raise ValueError('更新余额时须填写本次金额和币种')
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currency=cost['currency']
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amount=Decimal(normalize_amount(cost['amount'],currency))
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current=next((item for item in balances if item['currency']==currency),None)
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if operation=='deduct' and current is None:
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raise ValueError(f'尚未记录 {currency} 余额，请先在卡片资料中添加')
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before={'currency':currency,'amount':normalize_amount(current['amount'] if current else '0',currency)}
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remaining=Decimal(before['amount'])-amount if operation=='deduct' else Decimal(before['amount'])+amount
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if remaining<0:
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raise ValueError(f'{currency} 余额不足，可取消更新余额后单独记录费用')
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after={'currency':currency,'amount':normalize_amount(format(remaining,'f'),currency)}
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updated=[dict(item) for item in balances if item['currency']!=currency]
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if current:
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updated=[dict(after) if item['currency']==currency else dict(item) for item in balances]
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else:
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updated.append(dict(after))
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return updated,before,after
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