import uuid
from datetime import datetime, timezone

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

from app.db import Base


class Device(Base):
    """A paired hardware sensor node (ESP32-P4 etc.), belonging to exactly
    one user. Authenticates telemetry via a bearer token whose hash — never
    the raw value — is stored here, identical convention to
    `AuthSession.token_hash` (see `app/models/auth_session.py`)."""

    __tablename__ = "devices"

    id: Mapped[uuid.UUID] = mapped_column(primary_key=True, default=uuid.uuid4)
    user_id: Mapped[uuid.UUID] = mapped_column(ForeignKey("users.id"), index=True)
    name: Mapped[str] = mapped_column(String(64))
    token_hash: Mapped[str] = mapped_column(String(64), unique=True, index=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
    )
    last_seen_at: Mapped[datetime | None] = mapped_column(
        DateTime(timezone=True), nullable=True
    )