"""A rule can cover every host, or every host in an inventory group (#5464):
the covering rule keeps one child rule per host under it.

Revision ID: 0041_alert_rule_covers
Revises: 0040_alert_event_actor
Create Date: 2026-10-09
"""
from typing import Sequence, Union
from alembic import op
import sqlalchemy as sa

revision: str = "0041_alert_rule_covers"
down_revision: Union[str, None] = "0040_alert_event_actor"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.add_column("alert_rules", sa.Column("covers", sa.String(16), nullable=False,
                                           server_default="resource"))
    op.add_column("alert_rules", sa.Column("cover_group", sa.String(128), nullable=True))
    op.add_column("alert_rules", sa.Column(
        "parent_id", sa.String(36), sa.ForeignKey("alert_rules.id", ondelete="CASCADE"),
        nullable=True))
    op.create_index("ix_alert_rules_parent_id", "alert_rules", ["parent_id"])


def downgrade() -> None:
    op.drop_index("ix_alert_rules_parent_id", table_name="alert_rules")
    op.drop_column("alert_rules", "parent_id")
    op.drop_column("alert_rules", "cover_group")
    op.drop_column("alert_rules", "covers")