"""Alert rules: a condition that fires on a rise, and the reading before this one.

Revision ID: 0049_alert_on_a_rise
Revises: 0048_tickets
Create Date: 2026-10-30
"""
from typing import Sequence, Union

import sqlalchemy as sa
from alembic import op

revision: str = "0049_alert_on_a_rise"
down_revision: Union[str, None] = "0048_tickets"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    # ALTER TYPE ... ADD VALUE cannot run inside a transaction block.
    with op.get_context().autocommit_block():
        op.execute("ALTER TYPE alertoperator ADD VALUE IF NOT EXISTS 'rose'")
    op.add_column("alert_states", sa.Column("last_value", sa.Float, nullable=True))


def downgrade() -> None:
    # Postgres can't drop an enum value; 'rose' stays in the type, unused.
    op.execute("DELETE FROM alert_rules WHERE operator = 'rose'")
    op.drop_column("alert_states", "last_value")