"""device_alert_events

Adds an insert-only history log of device alert transitions (WARNING/CRITICAL/
FAILED only — CLEARED is not logged here). device_alerts remains the current-
state table and is untouched; this is purely additive, used to answer "when
was the most recent issue on this device" even after it has been resolved.

Also adds an optional rssi column to heartbeats, for a signal-strength
indicator once firmware starts reporting it on the heartbeat payload.

Revision ID: d4e5f6a7b8c9
Revises: c3d4e5f6a7b8
Create Date: 2026-07-13 00:00:00.000000
"""
from typing import Sequence, Union
import sqlalchemy as sa
from alembic import op

revision: str = "d4e5f6a7b8c9"
down_revision: Union[str, None] = "c3d4e5f6a7b8"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.create_table(
        "device_alert_events",
        sa.Column("id",            sa.BigInteger(), primary_key=True, autoincrement=True),
        sa.Column("device_serial", sa.String(128), nullable=False),
        sa.Column("subsystem",     sa.String(128), nullable=False),
        sa.Column("state",         sa.String(64),  nullable=False),
        sa.Column("message",       sa.Text(),      nullable=True),
        sa.Column("occurred_at",   sa.DateTime(timezone=True), nullable=False,
                  server_default=sa.func.now()),
    )
    op.create_index(
        "idx_device_alert_events_serial_occurred",
        "device_alert_events",
        ["device_serial", sa.text("occurred_at DESC")],
    )

    op.add_column("heartbeats", sa.Column("rssi", sa.Integer(), nullable=True))


def downgrade() -> None:
    op.drop_column("heartbeats", "rssi")
    op.drop_index("idx_device_alert_events_serial_occurred", table_name="device_alert_events")
    op.drop_table("device_alert_events")