import uuid
from datetime import datetime

from pydantic import BaseModel, field_validator


class BudgetCreate(BaseModel):
    category_id: uuid.UUID
    month: str  # YYYY-MM
    limit_cents: int

    @field_validator("limit_cents")
    @classmethod
    def limit_positive(cls, v: int) -> int:
        if v <= 0:
            raise ValueError("limit_cents must be positive")
        return v

    @field_validator("month")
    @classmethod
    def month_format(cls, v: str) -> str:
        parts = v.split("-")
        if len(parts) != 2 or not all(p.isdigit() for p in parts):
            raise ValueError("month must be in YYYY-MM format")
        return v


class BudgetUpdate(BaseModel):
    limit_cents: int

    @field_validator("limit_cents")
    @classmethod
    def limit_positive(cls, v: int) -> int:
        if v <= 0:
            raise ValueError("limit_cents must be positive")
        return v


class BudgetResponse(BaseModel):
    id: uuid.UUID
    category_id: uuid.UUID
    category_name: str
    category_color: str | None
    month: str
    limit_cents: int
    spent_cents: int
    remaining_cents: int
    created_at: datetime
    updated_at: datetime

    model_config = {"from_attributes": True}