from decimal import Decimal
from uuid import UUID, uuid4

from pydantic import BaseModel, Field, field_validator


class ForecastScenario(BaseModel):
    id: UUID = Field(default_factory=uuid4)
    name: str = "baseline"
    income_multiplier: Decimal = Field(default=Decimal("1"))
    expense_multiplier: Decimal = Field(default=Decimal("1"))
    growth_multiplier: Decimal = Field(default=Decimal("1"))
    description: str = ""

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