from decimal import Decimal
from uuid import UUID, uuid4

from pydantic import BaseModel, Field, field_validator


class Liability(BaseModel):
    id: UUID = Field(default_factory=uuid4)
    name: str = ""
    balance: Decimal = Field(default=Decimal("0"))
    interest: Decimal = Field(default=Decimal("0"))
    payment: Decimal = Field(default=Decimal("0"))

    @field_validator("interest", "payment")
    @classmethod
    def _non_negative(cls, v: Decimal) -> Decimal:
        if v < 0:
            raise ValueError("must be non-negative")
        return v