"""add immutable commercial billing periods and administration audit

Revision ID: 20260716_0021
Revises: 20260716_0020
Create Date: 2026-07-16 22:45:00
"""

from __future__ import annotations

from collections.abc import Sequence

import sqlalchemy as sa

from alembic import op

revision: str = "20260716_0021"
down_revision: str | None = "20260716_0020"
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None


def _require_postgresql() -> None:
    dialect_name = op.get_bind().dialect.name
    if dialect_name != "postgresql":
        raise RuntimeError(
            "20260716_0021 only supports PostgreSQL; "
            f"refusing to mutate {dialect_name} without transactional constraint DDL"
        )


def _require_empty_billing_lifecycle_for_downgrade() -> None:
    bind = op.get_bind()
    counts = {
        table_name: int(bind.scalar(sa.text(f"SELECT COUNT(*) FROM {table_name}")) or 0)
        for table_name in ("commercial_admin_events", "commercial_billing_periods")
    }
    if any(counts.values()):
        summary = ", ".join(f"{name}={count}" for name, count in counts.items())
        raise RuntimeError(
            "cannot downgrade commercial billing lifecycle: immutable periods or audit "
            f"facts exist ({summary})"
        )


def _json_object_default() -> sa.TextClause:
    return sa.text("'{}'::json")


def upgrade() -> None:
    _require_postgresql()
    _create_billing_periods()
    _create_admin_events()
    _backfill_current_periods_and_audit()
    _bind_usage_to_periods()
    _bind_costs_to_periods()
    _bind_reservations_to_periods()
    _create_period_overlap_guard()
    _create_append_only_triggers()


def _create_billing_periods() -> None:
    op.create_table(
        "commercial_billing_periods",
        sa.Column("id", sa.String(length=36), nullable=False),
        sa.Column("tenant_id", sa.String(length=64), nullable=False),
        sa.Column("subscription_id", sa.String(length=36), nullable=False),
        sa.Column("plan_id", sa.String(length=36), nullable=False),
        sa.Column("period_sequence", sa.Integer(), nullable=False),
        sa.Column("period_key", sa.String(length=64), nullable=False),
        sa.Column("status", sa.String(length=16), nullable=False, server_default="issued"),
        sa.Column("period_start", sa.DateTime(timezone=True), nullable=False),
        sa.Column("period_end", sa.DateTime(timezone=True), nullable=False),
        sa.Column("subscription_status_snapshot", sa.String(length=20), nullable=False),
        sa.Column("plan_code_snapshot", sa.String(length=80), nullable=False),
        sa.Column("plan_version_snapshot", sa.Integer(), nullable=False),
        sa.Column("pricing_model_snapshot", sa.String(length=24), nullable=False),
        sa.Column("billing_interval", sa.String(length=20), nullable=False),
        sa.Column("currency", sa.String(length=3), nullable=False),
        sa.Column("base_fee_snapshot", sa.Numeric(20, 4), nullable=False),
        sa.Column("seats_snapshot", sa.Integer(), nullable=False),
        sa.Column("source", sa.String(length=32), nullable=False),
        sa.Column("idempotency_key", sa.String(length=160), nullable=False),
        sa.Column("created_by", sa.String(length=120), nullable=False),
        sa.Column(
            "created_at",
            sa.DateTime(timezone=True),
            nullable=False,
            server_default=sa.func.now(),
        ),
        sa.CheckConstraint(
            "status = 'issued'",
            name="ck_commercial_billing_periods_status",
        ),
        sa.CheckConstraint(
            "subscription_status_snapshot IN ('trialing', 'active', 'past_due', "
            "'suspended', 'canceled', 'expired')",
            name="ck_commercial_billing_periods_subscription_status",
        ),
        sa.CheckConstraint(
            "pricing_model_snapshot IN ('subscription', 'usage', 'hybrid', 'pilot', 'custom')",
            name="ck_commercial_billing_periods_pricing_model",
        ),
        sa.CheckConstraint(
            "billing_interval IN ('monthly', 'quarterly', 'annual', 'contract')",
            name="ck_commercial_billing_periods_interval",
        ),
        sa.CheckConstraint(
            "source IN ('subscription_created', 'auto_renew', 'migration_backfill')",
            name="ck_commercial_billing_periods_source",
        ),
        sa.CheckConstraint(
            "period_sequence >= 1 AND period_end > period_start "
            "AND plan_version_snapshot >= 1 AND base_fee_snapshot >= 0 "
            "AND seats_snapshot > 0",
            name="ck_commercial_billing_periods_values",
        ),
        sa.CheckConstraint(
            "length(trim(period_key)) > 0 AND length(trim(plan_code_snapshot)) > 0 "
            "AND length(trim(currency)) = 3 AND length(trim(idempotency_key)) > 0 "
            "AND length(trim(created_by)) > 0",
            name="ck_commercial_billing_periods_keys",
        ),
        sa.ForeignKeyConstraint(
            ["tenant_id", "subscription_id"],
            ["tenant_subscriptions.tenant_id", "tenant_subscriptions.id"],
            name="fk_commercial_billing_periods_tenant_subscription",
            ondelete="RESTRICT",
        ),
        sa.ForeignKeyConstraint(
            ["tenant_id", "plan_id"],
            ["tenant_commercial_plans.tenant_id", "tenant_commercial_plans.id"],
            name="fk_commercial_billing_periods_tenant_plan",
            ondelete="RESTRICT",
        ),
        sa.PrimaryKeyConstraint("id"),
        sa.UniqueConstraint("tenant_id", "id", name="uq_commercial_billing_periods_tenant_id"),
        sa.UniqueConstraint(
            "tenant_id",
            "subscription_id",
            "id",
            name="uq_commercial_billing_periods_tenant_subscription_id",
        ),
        sa.UniqueConstraint(
            "tenant_id",
            "subscription_id",
            "period_sequence",
            name="uq_commercial_billing_periods_subscription_sequence",
        ),
        sa.UniqueConstraint(
            "tenant_id",
            "subscription_id",
            "period_key",
            name="uq_commercial_billing_periods_subscription_key",
        ),
        sa.UniqueConstraint(
            "tenant_id",
            "subscription_id",
            "period_start",
            name="uq_commercial_billing_periods_subscription_start",
        ),
        sa.UniqueConstraint(
            "tenant_id",
            "subscription_id",
            "idempotency_key",
            name="uq_commercial_billing_periods_subscription_request",
        ),
    )
    op.create_index(
        "ix_commercial_billing_periods_tenant_window",
        "commercial_billing_periods",
        ["tenant_id", "period_start", "period_end"],
    )
    op.create_index(
        "ix_commercial_billing_periods_subscription_window",
        "commercial_billing_periods",
        ["tenant_id", "subscription_id", "period_start", "period_end"],
    )


def _create_admin_events() -> None:
    op.create_table(
        "commercial_admin_events",
        sa.Column("id", sa.String(length=36), nullable=False),
        sa.Column("tenant_id", sa.String(length=64), nullable=False),
        sa.Column("actor_type", sa.String(length=16), nullable=False),
        sa.Column("actor_id", sa.String(length=120), nullable=False),
        sa.Column("request_id", sa.String(length=120), nullable=False),
        sa.Column("reason", sa.Text(), nullable=False),
        sa.Column("action", sa.String(length=48), nullable=False),
        sa.Column("resource_type", sa.String(length=24), nullable=False),
        sa.Column("resource_id", sa.String(length=36), nullable=False),
        sa.Column("resource_version", sa.Integer(), nullable=False),
        sa.Column("before_json", sa.JSON(), nullable=False, server_default=_json_object_default()),
        sa.Column("after_json", sa.JSON(), nullable=False, server_default=_json_object_default()),
        sa.Column(
            "occurred_at",
            sa.DateTime(timezone=True),
            nullable=False,
            server_default=sa.func.now(),
        ),
        sa.CheckConstraint(
            "actor_type IN ('user', 'system', 'migration')",
            name="ck_commercial_admin_events_actor_type",
        ),
        sa.CheckConstraint(
            "action IN ('plan_created', 'plan_activated', 'plan_retired', "
            "'subscription_created', 'subscription_activated', "
            "'subscription_transitioned', 'entitlement_created', "
            "'entitlement_updated', 'entitlement_activated', "
            "'billing_period_created', 'subscription_rolled_over', "
            "'legacy_state_imported')",
            name="ck_commercial_admin_events_action",
        ),
        sa.CheckConstraint(
            "resource_type IN ('plan', 'subscription', 'entitlement', 'billing_period')",
            name="ck_commercial_admin_events_resource_type",
        ),
        sa.CheckConstraint(
            "resource_version >= 1",
            name="ck_commercial_admin_events_resource_version",
        ),
        sa.CheckConstraint(
            "length(trim(actor_id)) > 0 AND length(trim(request_id)) > 0 "
            "AND length(trim(reason)) > 0 AND length(trim(resource_id)) > 0",
            name="ck_commercial_admin_events_required_text",
        ),
        sa.PrimaryKeyConstraint("id"),
        sa.UniqueConstraint("tenant_id", "id", name="uq_commercial_admin_events_tenant_id"),
        sa.UniqueConstraint(
            "tenant_id",
            "request_id",
            "action",
            "resource_type",
            "resource_id",
            name="uq_commercial_admin_events_request_resource",
        ),
    )
    op.create_index(
        "ix_commercial_admin_events_tenant_time",
        "commercial_admin_events",
        ["tenant_id", "occurred_at", "id"],
    )
    op.create_index(
        "ix_commercial_admin_events_tenant_resource",
        "commercial_admin_events",
        ["tenant_id", "resource_type", "resource_id", "occurred_at"],
    )
    op.create_index(
        "ix_commercial_admin_events_tenant_request",
        "commercial_admin_events",
        ["tenant_id", "request_id"],
    )


def _backfill_current_periods_and_audit() -> None:
    op.execute(
        """
        INSERT INTO commercial_billing_periods (
            id, tenant_id, subscription_id, plan_id, period_sequence, period_key,
            status, period_start, period_end, subscription_status_snapshot,
            plan_code_snapshot, plan_version_snapshot, pricing_model_snapshot,
            billing_interval, currency, base_fee_snapshot, seats_snapshot,
            source, idempotency_key, created_by
        )
        SELECT
            substr(digest, 1, 8) || '-' || substr(digest, 9, 4) || '-' ||
            substr(digest, 13, 4) || '-' || substr(digest, 17, 4) || '-' ||
            substr(digest, 21, 12),
            subscription.tenant_id,
            subscription.id,
            subscription.plan_id,
            1,
            'bp-' || substr(digest, 1, 24),
            'issued',
            subscription.current_period_start,
            subscription.current_period_end,
            subscription.status,
            plan.plan_code,
            plan.version,
            plan.pricing_model,
            subscription.billing_interval,
            subscription.currency,
            subscription.base_fee_snapshot,
            subscription.seats,
            'migration_backfill',
            'migration-0021:' || subscription.id,
            'migration:20260716_0021'
        FROM tenant_subscriptions AS subscription
        JOIN tenant_commercial_plans AS plan
          ON plan.tenant_id = subscription.tenant_id
         AND plan.id = subscription.plan_id
        CROSS JOIN LATERAL (
            SELECT md5(
                subscription.tenant_id || ':' || subscription.id || ':' ||
                subscription.current_period_start::text || ':' ||
                subscription.current_period_end::text
            ) AS digest
        ) AS identity
        """
    )
    for resource_type, table_name, version_column in (
        ("plan", "tenant_commercial_plans", "version"),
        ("subscription", "tenant_subscriptions", "version"),
        ("entitlement", "commercial_entitlements", "version"),
        ("billing_period", "commercial_billing_periods", "period_sequence"),
    ):
        op.execute(
            f"""
            INSERT INTO commercial_admin_events (
                id, tenant_id, actor_type, actor_id, request_id, reason, action,
                resource_type, resource_id, resource_version, before_json, after_json
            )
            SELECT
                substr(digest, 1, 8) || '-' || substr(digest, 9, 4) || '-' ||
                substr(digest, 13, 4) || '-' || substr(digest, 17, 4) || '-' ||
                substr(digest, 21, 12),
                resource.tenant_id,
                'migration',
                'migration:20260716_0021',
                'migration:0021:{resource_type}:' || resource.id,
                '0021 建立商业管理审计基线，不推断迁移前操作人或原始请求。',
                'legacy_state_imported',
                '{resource_type}',
                resource.id,
                resource.{version_column},
                '{{}}'::json,
                json_build_object('id', resource.id, 'version', resource.{version_column})
            FROM {table_name} AS resource
            CROSS JOIN LATERAL (
                SELECT md5(
                    resource.tenant_id || ':audit:{resource_type}:' || resource.id
                ) AS digest
            ) AS identity
            """
        )


def _bind_usage_to_periods() -> None:
    op.add_column(
        "usage_meter_events",
        sa.Column("billing_period_id", sa.String(length=36), nullable=True),
    )
    op.add_column(
        "usage_meter_events",
        sa.Column("quota_period_key", sa.String(length=64), nullable=True),
    )
    op.alter_column(
        "usage_meter_events",
        "period_key",
        existing_type=sa.String(length=32),
        type_=sa.String(length=64),
        existing_nullable=False,
    )
    op.execute(
        """
        UPDATE usage_meter_events AS usage
        SET billing_period_id = period.id,
            quota_period_key = usage.period_key,
            period_key = period.period_key
        FROM commercial_billing_periods AS period
        WHERE period.tenant_id = usage.tenant_id
          AND period.subscription_id = usage.subscription_id
          AND usage.occurred_at >= period.period_start
          AND usage.occurred_at < period.period_end
        """
    )
    _fail_if_unbound(
        "usage_meter_events",
        "billing_period_id IS NULL OR quota_period_key IS NULL",
        "existing usage facts do not map to one immutable current billing period",
    )
    op.alter_column(
        "usage_meter_events", "billing_period_id", existing_type=sa.String(36), nullable=False
    )
    op.alter_column(
        "usage_meter_events", "quota_period_key", existing_type=sa.String(64), nullable=False
    )
    op.drop_constraint("ck_usage_meter_events_keys", "usage_meter_events", type_="check")
    op.create_check_constraint(
        "ck_usage_meter_events_keys",
        "usage_meter_events",
        "length(trim(metric_key)) > 0 AND length(trim(unit)) > 0 "
        "AND length(trim(period_key)) > 0 AND length(trim(source_system)) > 0 "
        "AND length(trim(quota_period_key)) > 0 "
        "AND length(trim(idempotency_key)) > 0 "
        "AND length(trim(request_fingerprint)) > 0",
    )
    op.create_foreign_key(
        "fk_usage_meter_events_tenant_billing_period",
        "usage_meter_events",
        "commercial_billing_periods",
        ["tenant_id", "subscription_id", "billing_period_id"],
        ["tenant_id", "subscription_id", "id"],
        ondelete="RESTRICT",
    )
    op.drop_index("ix_usage_meter_events_quota_window", table_name="usage_meter_events")
    op.create_index(
        "ix_usage_meter_events_quota_window",
        "usage_meter_events",
        ["tenant_id", "subscription_id", "metric_key", "quota_period_key", "occurred_at"],
    )
    op.create_index(
        "ix_usage_meter_events_billing_period",
        "usage_meter_events",
        ["tenant_id", "billing_period_id", "occurred_at"],
    )


def _bind_costs_to_periods() -> None:
    op.add_column(
        "commercial_cost_events",
        sa.Column("billing_period_id", sa.String(length=36), nullable=True),
    )
    op.execute(
        """
        UPDATE commercial_cost_events AS cost
        SET billing_period_id = usage.billing_period_id
        FROM usage_meter_events AS usage
        WHERE usage.tenant_id = cost.tenant_id
          AND usage.subscription_id = cost.subscription_id
          AND usage.id = cost.usage_event_id
        """
    )
    op.execute(
        """
        UPDATE commercial_cost_events AS cost
        SET billing_period_id = period.id
        FROM commercial_billing_periods AS period
        WHERE cost.subscription_id IS NOT NULL
          AND cost.billing_period_id IS NULL
          AND period.tenant_id = cost.tenant_id
          AND period.subscription_id = cost.subscription_id
          AND cost.occurred_at >= period.period_start
          AND cost.occurred_at < period.period_end
        """
    )
    _fail_if_unbound(
        "commercial_cost_events",
        "subscription_id IS NOT NULL AND billing_period_id IS NULL",
        "existing subscription cost facts do not map to one immutable billing period",
    )
    op.create_check_constraint(
        "ck_commercial_cost_events_billing_period_pair",
        "commercial_cost_events",
        "(subscription_id IS NULL AND billing_period_id IS NULL) OR "
        "(subscription_id IS NOT NULL AND billing_period_id IS NOT NULL)",
    )
    op.create_foreign_key(
        "fk_commercial_cost_events_tenant_billing_period",
        "commercial_cost_events",
        "commercial_billing_periods",
        ["tenant_id", "subscription_id", "billing_period_id"],
        ["tenant_id", "subscription_id", "id"],
        ondelete="RESTRICT",
    )
    op.drop_index(
        "ix_commercial_cost_events_subscription_period",
        table_name="commercial_cost_events",
    )
    op.create_index(
        "ix_commercial_cost_events_subscription_period",
        "commercial_cost_events",
        ["tenant_id", "subscription_id", "billing_period_id", "occurred_at"],
    )


def _bind_reservations_to_periods() -> None:
    op.add_column(
        "commercial_runtime_reservations",
        sa.Column("billing_period_id", sa.String(length=36), nullable=True),
    )
    op.add_column(
        "commercial_runtime_reservations",
        sa.Column("quota_period_key", sa.String(length=64), nullable=True),
    )
    op.alter_column(
        "commercial_runtime_reservations",
        "period_key",
        existing_type=sa.String(length=32),
        type_=sa.String(length=64),
        existing_nullable=False,
    )
    op.execute(
        """
        UPDATE commercial_runtime_reservations AS reservation
        SET billing_period_id = period.id,
            quota_period_key = reservation.period_key,
            period_key = period.period_key
        FROM commercial_billing_periods AS period
        WHERE period.tenant_id = reservation.tenant_id
          AND period.subscription_id = reservation.subscription_id
          AND reservation.created_at >= period.period_start
          AND reservation.created_at < period.period_end
        """
    )
    _fail_if_unbound(
        "commercial_runtime_reservations",
        "billing_period_id IS NULL OR quota_period_key IS NULL",
        "existing runtime reservations do not map to one immutable billing period",
    )
    op.alter_column(
        "commercial_runtime_reservations",
        "billing_period_id",
        existing_type=sa.String(36),
        nullable=False,
    )
    op.alter_column(
        "commercial_runtime_reservations",
        "quota_period_key",
        existing_type=sa.String(64),
        nullable=False,
    )
    op.drop_constraint(
        "ck_commercial_runtime_reservations_keys",
        "commercial_runtime_reservations",
        type_="check",
    )
    op.create_check_constraint(
        "ck_commercial_runtime_reservations_keys",
        "commercial_runtime_reservations",
        "length(trim(run_id)) > 0 AND length(trim(tool_call_id)) > 0 "
        "AND length(trim(tool_type)) > 0 AND length(trim(tool_name)) > 0 "
        "AND length(trim(period_key)) > 0 AND length(trim(quota_period_key)) > 0 "
        "AND length(trim(request_fingerprint)) > 0",
    )
    op.create_foreign_key(
        "fk_commercial_runtime_reservations_tenant_billing_period",
        "commercial_runtime_reservations",
        "commercial_billing_periods",
        ["tenant_id", "subscription_id", "billing_period_id"],
        ["tenant_id", "subscription_id", "id"],
        ondelete="RESTRICT",
    )
    op.drop_index(
        "ix_commercial_runtime_reservations_quota",
        table_name="commercial_runtime_reservations",
    )
    op.create_index(
        "ix_commercial_runtime_reservations_quota",
        "commercial_runtime_reservations",
        ["tenant_id", "subscription_id", "entitlement_id", "quota_period_key", "status"],
    )
    op.create_index(
        "ix_commercial_runtime_reservations_billing_period",
        "commercial_runtime_reservations",
        ["tenant_id", "billing_period_id", "status"],
    )


def _fail_if_unbound(table_name: str, predicate: str, message: str) -> None:
    op.execute(
        f"""
        DO $$
        BEGIN
            IF EXISTS (SELECT 1 FROM {table_name} WHERE {predicate}) THEN
                RAISE EXCEPTION '{message}';
            END IF;
        END;
        $$
        """
    )


def _create_append_only_triggers() -> None:
    for table_name in ("commercial_billing_periods", "commercial_admin_events"):
        op.execute(
            f"""
            CREATE TRIGGER trg_{table_name}_append_only
            BEFORE UPDATE OR DELETE ON {table_name}
            FOR EACH ROW EXECUTE FUNCTION prevent_commercial_events_mutation()
            """
        )


def _create_period_overlap_guard() -> None:
    op.execute(
        """
        CREATE FUNCTION prevent_commercial_billing_period_overlap()
        RETURNS trigger AS $$
        BEGIN
            PERFORM pg_advisory_xact_lock(
                hashtextextended(NEW.tenant_id || ':' || NEW.subscription_id, 0)
            );
            IF EXISTS (
                SELECT 1
                FROM commercial_billing_periods AS existing
                WHERE existing.tenant_id = NEW.tenant_id
                  AND existing.subscription_id = NEW.subscription_id
                  AND tstzrange(
                      existing.period_start,
                      existing.period_end,
                      '[)'
                  ) && tstzrange(NEW.period_start, NEW.period_end, '[)')
            ) THEN
                RAISE EXCEPTION 'commercial billing period overlaps an issued period';
            END IF;
            RETURN NEW;
        END;
        $$ LANGUAGE plpgsql
        """
    )
    op.execute(
        """
        CREATE TRIGGER trg_commercial_billing_periods_no_overlap
        BEFORE INSERT ON commercial_billing_periods
        FOR EACH ROW EXECUTE FUNCTION prevent_commercial_billing_period_overlap()
        """
    )


def downgrade() -> None:
    _require_postgresql()
    _require_empty_billing_lifecycle_for_downgrade()
    _unbind_reservations()
    _unbind_costs()
    _unbind_usage()
    op.execute(
        "DROP TRIGGER IF EXISTS trg_commercial_billing_periods_no_overlap "
        "ON commercial_billing_periods"
    )
    for table_name in ("commercial_admin_events", "commercial_billing_periods"):
        op.execute(f"DROP TRIGGER IF EXISTS trg_{table_name}_append_only ON {table_name}")
    op.drop_table("commercial_admin_events")
    op.drop_table("commercial_billing_periods")
    op.execute("DROP FUNCTION IF EXISTS prevent_commercial_billing_period_overlap()")


def _unbind_reservations() -> None:
    op.drop_index(
        "ix_commercial_runtime_reservations_billing_period",
        table_name="commercial_runtime_reservations",
    )
    op.drop_index(
        "ix_commercial_runtime_reservations_quota",
        table_name="commercial_runtime_reservations",
    )
    op.create_index(
        "ix_commercial_runtime_reservations_quota",
        "commercial_runtime_reservations",
        ["tenant_id", "subscription_id", "entitlement_id", "period_key", "status"],
    )
    op.drop_constraint(
        "fk_commercial_runtime_reservations_tenant_billing_period",
        "commercial_runtime_reservations",
        type_="foreignkey",
    )
    op.drop_constraint(
        "ck_commercial_runtime_reservations_keys",
        "commercial_runtime_reservations",
        type_="check",
    )
    op.create_check_constraint(
        "ck_commercial_runtime_reservations_keys",
        "commercial_runtime_reservations",
        "length(trim(run_id)) > 0 AND length(trim(tool_call_id)) > 0 "
        "AND length(trim(tool_type)) > 0 AND length(trim(tool_name)) > 0 "
        "AND length(trim(period_key)) > 0 "
        "AND length(trim(request_fingerprint)) > 0",
    )
    op.drop_column("commercial_runtime_reservations", "quota_period_key")
    op.drop_column("commercial_runtime_reservations", "billing_period_id")
    op.alter_column(
        "commercial_runtime_reservations",
        "period_key",
        existing_type=sa.String(length=64),
        type_=sa.String(length=32),
        existing_nullable=False,
    )


def _unbind_costs() -> None:
    op.drop_index(
        "ix_commercial_cost_events_subscription_period",
        table_name="commercial_cost_events",
    )
    op.create_index(
        "ix_commercial_cost_events_subscription_period",
        "commercial_cost_events",
        ["tenant_id", "subscription_id", "occurred_at"],
    )
    op.drop_constraint(
        "fk_commercial_cost_events_tenant_billing_period",
        "commercial_cost_events",
        type_="foreignkey",
    )
    op.drop_constraint(
        "ck_commercial_cost_events_billing_period_pair",
        "commercial_cost_events",
        type_="check",
    )
    op.drop_column("commercial_cost_events", "billing_period_id")


def _unbind_usage() -> None:
    op.drop_index("ix_usage_meter_events_billing_period", table_name="usage_meter_events")
    op.drop_index("ix_usage_meter_events_quota_window", table_name="usage_meter_events")
    op.create_index(
        "ix_usage_meter_events_quota_window",
        "usage_meter_events",
        ["tenant_id", "subscription_id", "metric_key", "period_key", "occurred_at"],
    )
    op.drop_constraint(
        "fk_usage_meter_events_tenant_billing_period",
        "usage_meter_events",
        type_="foreignkey",
    )
    op.drop_constraint("ck_usage_meter_events_keys", "usage_meter_events", type_="check")
    op.create_check_constraint(
        "ck_usage_meter_events_keys",
        "usage_meter_events",
        "length(trim(metric_key)) > 0 AND length(trim(unit)) > 0 "
        "AND length(trim(period_key)) > 0 AND length(trim(source_system)) > 0 "
        "AND length(trim(idempotency_key)) > 0 "
        "AND length(trim(request_fingerprint)) > 0",
    )
    op.drop_column("usage_meter_events", "quota_period_key")
    op.drop_column("usage_meter_events", "billing_period_id")
    op.alter_column(
        "usage_meter_events",
        "period_key",
        existing_type=sa.String(length=64),
        type_=sa.String(length=32),
        existing_nullable=False,
    )