from decimal import Decimal
from uuid import UUID, uuid4

from pydantic import BaseModel, Field, field_validator


class RecurringCashflow(BaseModel):
    id: UUID = Field(default_factory=uuid4)
    start_date: str = ""
    end_date: str = ""
    frequency: str = "monthly"
    amount: Decimal = Field(default=Decimal("0"))
    category: str = ""

    @field_validator("frequency")
    @classmethod
    def _frequency_known(cls, v: str) -> str:
        if v not in {"daily", "weekly", "monthly", "yearly"}:
            raise ValueError(f"unknown frequency: {v}")
        return v

    @field_validator("amount")
    @classmethod
    def _amount_nonzero(cls, v: Decimal) -> Decimal:
        if v == 0:
            raise ValueError("amount must be non-zero")
        return v