from datetime import datetime, timezone
from sqlalchemy import BigInteger, Column, DateTime, Index, String, Text, UniqueConstraint
from sqlalchemy.dialects.postgresql import JSONB
from database.postgres import Base


def _now():
    return datetime.now(timezone.utc)


class DeviceAlert(Base):
    """Current alert state per device+subsystem (upserted, not appended)."""
    __tablename__ = "device_alerts"
    __table_args__ = (
        UniqueConstraint("device_serial", "subsystem"),
        Index("idx_device_alerts_serial", "device_serial"),
    )

    id            = Column(BigInteger, primary_key=True, autoincrement=True)
    device_serial = Column(String(128), nullable=False)
    subsystem     = Column(String(128), nullable=False)
    state         = Column(String(64), nullable=False)
    message       = Column(Text)
    updated_at    = Column(DateTime(timezone=True), nullable=False, default=_now, onupdate=_now)


# NOTE: device_logs, commands, and heartbeats are NOT declared as ORM models here.
# device_logs is a partitioned table — SQLAlchemy ORM does not support declarative
# partitioned tables cleanly. All three tables are created via raw SQL in the
# Alembic migration and accessed via raw queries in database/core.py (SQLite now)
# and will be accessed via raw async SQL after Phase 5 cutover.