import uuid
from datetime import datetime, timezone

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

from app.db import Base


class UnlockRecord(Base):
    """A permanent unlock a seeker has purchased with essence (e.g. the
    listening tool). One row per (user, unlock_key).

    The unique constraint is defense-in-depth: today, idempotency (no double
    charge for an already-owned unlock) is enforced entirely by
    `app.inventory.purchase_unlock`'s row-locked check-then-insert. This
    constraint means any *other* code path that ever inserts an
    UnlockRecord without going through that lock still can't create a
    duplicate row for the same (user, unlock_key).
    """

    __tablename__ = "unlocks"
    __table_args__ = (UniqueConstraint("user_id", "unlock_key", name="uq_unlocks_user_key"),)

    id: Mapped[uuid.UUID] = mapped_column(primary_key=True, default=uuid.uuid4)
    user_id: Mapped[uuid.UUID] = mapped_column(ForeignKey("users.id"), index=True)
    unlock_key: Mapped[str] = mapped_column(String(64), index=True)
    unlocked_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
    )