"""Remember which alerts are already open.

Without this an alerting loop re-sends the same condition every time it runs, and
a channel that cries about the same stuck event every five minutes is a channel
people mute — after which it may as well not exist.

One row per condition. Opened when it starts, re-notified no more often than the
cooldown, and closed with a recovery notice when it clears, so nobody goes
chasing something that fixed itself.

Revision ID: b8d1f4a6c306
Revises: a7c9e3f5b205
"""

from typing import Sequence, Union

import sqlalchemy as sa
from alembic import op
from sqlalchemy.dialects.postgresql import UUID

revision: str = "b8d1f4a6c306"
down_revision: Union[str, Sequence[str], None] = "a7c9e3f5b205"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.create_table(
        "alert_state",
        sa.Column(
            "id", UUID(as_uuid=True), primary_key=True,
            server_default=sa.text("gen_random_uuid()"),
        ),
        sa.Column("alert_key", sa.String(60), nullable=False, unique=True),
        sa.Column("severity", sa.String(20), nullable=False),
        sa.Column("detail", sa.Text(), nullable=True),
        sa.Column("observed", sa.Integer(), nullable=True),
        sa.Column(
            "opened_at", sa.DateTime(timezone=True), nullable=False,
            server_default=sa.func.now(),
        ),
        sa.Column("last_notified_at", sa.DateTime(timezone=True), nullable=True),
        sa.Column("notify_count", sa.Integer(), nullable=False, server_default="0"),
        sa.Column("resolved_at", sa.DateTime(timezone=True), nullable=True),
    )
    op.create_index("ix_alert_state_open", "alert_state", ["resolved_at"])


def downgrade() -> None:
    op.drop_index("ix_alert_state_open", table_name="alert_state")
    op.drop_table("alert_state")