oqyude
363d440d53
- All domain monetary fields now use Decimal: - Account.balance, Asset.value, Asset.growth_rate - Liability.balance, Liability.interest, Liability.payment - Transaction.amount, RecurringCashflow.amount - ExchangeRate.rate - ForecastScenario.income_multiplier, expense_multiplier, growth_multiplier - CurrencyConverter: all arithmetic in Decimal, quantize to 0.01 with ROUND_HALF_UP - ForecastService: Decimal arithmetic throughout (income, expenses, balance, growth, liability cost) - ScenarioService: Decimal multipliers, deepcopy safe with Decimal fields - assistant.py: _DecimalEncoder for json.dumps (Decimal -> str in JSON) Pydantic v2 + Decimal: - model_dump(mode='json') converts Decimal to str (JSON-safe) - model_validate() parses str back to Decimal - Round-trip preserves precision (100.50 stays 100.50) Tests: 63/63 pass.
84 lines
2.4 KiB
Python
84 lines
2.4 KiB
Python
from decimal import Decimal, ROUND_HALF_UP
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from pydantic import BaseModel, Field, field_validator
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CURRENCY_SYMBOLS = {
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"RUB": "₽",
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"USD": "$",
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"EUR": "€",
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"GBP": "£",
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"CNY": "¥",
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"JPY": "¥",
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"KZT": "₸",
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"UAH": "₴",
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}
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class ExchangeRate(BaseModel):
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from_currency: str = "USD"
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to_currency: str = "RUB"
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rate: Decimal = Field(default=Decimal("80"))
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@field_validator("rate")
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@classmethod
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def _rate_positive(cls, v: Decimal) -> Decimal:
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if v <= 0:
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raise ValueError("rate must be positive")
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return v
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DEFAULT_RATES: list[ExchangeRate] = [
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ExchangeRate(from_currency="USD", to_currency="RUB", rate=Decimal("80")),
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]
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class CurrencyError(Exception):
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pass
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class CurrencyConverter:
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def __init__(self, rates: list[ExchangeRate] | None = None):
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self._rates: dict[tuple[str, str], Decimal] = {}
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if rates:
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for r in rates:
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self.set_rate(r.from_currency, r.to_currency, r.rate)
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def set_rate(
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self,
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from_currency: str,
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to_currency: str,
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rate: Decimal | float | int | str,
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) -> None:
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d = Decimal(str(rate)) if not isinstance(rate, Decimal) else rate
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if d <= 0:
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raise CurrencyError(f"Rate must be positive: {d}")
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self._rates[(from_currency, to_currency)] = d
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self._rates[(to_currency, from_currency)] = Decimal("1") / d
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def get_rate(self, from_currency: str, to_currency: str) -> Decimal:
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if from_currency == to_currency:
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return Decimal("1")
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try:
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return self._rates[(from_currency, to_currency)]
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except KeyError:
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raise CurrencyError(f"No exchange rate: {from_currency} → {to_currency}")
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def convert(
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self,
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amount: Decimal | float | int | str,
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from_currency: str,
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to_currency: str,
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) -> Decimal:
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a = Decimal(str(amount)) if not isinstance(amount, Decimal) else amount
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if from_currency == to_currency:
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return a
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rate = self.get_rate(from_currency, to_currency)
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return (a * rate).quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
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def get_symbol(self, currency: str) -> str:
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return CURRENCY_SYMBOLS.get(currency, currency)
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@classmethod
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def with_defaults(cls) -> "CurrencyConverter":
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return cls(DEFAULT_RATES)
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