"""Lock model."""
from datetime import datetime, timezone

from sqlalchemy import DateTime, String
from sqlalchemy.orm import Mapped, mapped_column

from app.models.base import Base, UUIDMixin


def _utc_now() -> datetime:
    return datetime.now(timezone.utc)


class Lock(Base, UUIDMixin):
    """Distributed lock record (fallback when Redis is unavailable)."""

    __tablename__ = "locks"

    lock_name: Mapped[str] = mapped_column(String(128), unique=True, nullable=False, index=True)
    owner_id: Mapped[str | None] = mapped_column(String(128), nullable=True)
    acquired_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, default=_utc_now
    )
    expires_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)