"""offboarding_processes: per-channel session-enforcement proof column.

The offboarding force-logout path (`_push_force_logout`) previously
returned only a bool and swallowed per-vendor failures, so IT had no
durable record of whether a leaver's Google/Feishu session + Google
account were actually cut — the exact question the P0051 offboarding
incident surfaced (Google `users.signOut` was silently 403-ing on a
scope gap for weeks with nobody the wiser).

This adds a nullable JSON column `session_enforcement` to record the
outcome of each identity-plane cutoff channel (google_session /
google_account / feishu_session) so the offboarding detail page and the
person-detail 离职 tab can display proof, and a failed channel can be
re-run and re-recorded. Nullable, no backfill (existing rows simply have
no recorded enforcement snapshot until the next force-logout / re-run).

Revision ID: 383
Revises: 382
"""
from __future__ import annotations

import sqlalchemy as sa

from alembic import op

revision = "383"
down_revision = "382"
branch_labels = None
depends_on = None

TABLE = "offboarding_processes"
COLUMN = "session_enforcement"


def _column_exists(bind, table: str, column: str) -> bool:
    return bool(
        bind.execute(
            sa.text(
                "SELECT 1 FROM information_schema.columns "
                "WHERE table_schema = DATABASE() "
                "AND table_name = :t AND column_name = :c"
            ),
            {"t": table, "c": column},
        ).first()
    )


def upgrade() -> None:
    bind = op.get_bind()
    if not _column_exists(bind, TABLE, COLUMN):
        op.add_column(TABLE, sa.Column(COLUMN, sa.JSON(), nullable=True))


def downgrade() -> None:
    bind = op.get_bind()
    if _column_exists(bind, TABLE, COLUMN):
        op.drop_column(TABLE, COLUMN)