import uuid
from datetime import datetime
from typing import TYPE_CHECKING

from sqlalchemy import (
    CheckConstraint,
    DateTime,
    ForeignKey,
    Integer,
    String,
    UniqueConstraint,
    Uuid,
    func,
)
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database import Base

if TYPE_CHECKING:
    from app.models.category import Category


class Budget(Base):
    __tablename__ = "budgets"
    __table_args__ = (
        UniqueConstraint("user_id", "category_id", "month", name="uq_budgets_user_category_month"),
        CheckConstraint("limit_cents > 0", name="ck_budgets_limit_positive"),
    )

    id: Mapped[uuid.UUID] = mapped_column(Uuid, primary_key=True, default=uuid.uuid4)
    user_id: Mapped[uuid.UUID] = mapped_column(
        Uuid, ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True
    )
    category_id: Mapped[uuid.UUID] = mapped_column(
        Uuid, ForeignKey("categories.id"), nullable=False
    )
    # Format YYYY-MM
    month: Mapped[str] = mapped_column(String(7), nullable=False)
    limit_cents: Mapped[int] = mapped_column(Integer, nullable=False)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=False), nullable=False, server_default=func.now()
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=False), nullable=False, server_default=func.now()
    )

    category: Mapped["Category"] = relationship("Category", lazy="raise")