"""Add card_payload to notification_outbox.

Revision ID: 400
Revises: 399
Create Date: 2026-07-14

Frozen JSON snapshot of an envelope's Feishu rich-card fields (action
buttons / stats / highlights / sections / subtitle / footer / body_size).

Motivation: the retry worker rebuilds the ``NotificationEnvelope`` FROM
the persisted outbox row and re-renders the card. The row stored only
the plain payload (title / body / url), so a retried card degraded to
the generic single "Open in Helix" button — the "一键续期" one-click
renewal button vanished from cloud-grant expiry reminders whose first
send failed and were resent by the worker. Persisting the rich-card
payload lets a retry re-render the identical card.

Nullable JSON, sparse — populated only for envelopes that carry rich-card
content (NULL for the common plain notification), TiDB-safe (no FK).
"""
from __future__ import annotations

import sqlalchemy as sa

from alembic import op

revision = "400"
down_revision = "399"
branch_labels = None
depends_on = None

_TABLE = "notification_outbox"
_COL = "card_payload"


def _has_column(bind, table: str, column: str) -> bool:
    return 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},
    ).scalar() is not None


def upgrade() -> None:
    bind = op.get_bind()
    if not _has_column(bind, _TABLE, _COL):
        op.add_column(_TABLE, sa.Column(_COL, sa.JSON(), nullable=True))


def downgrade() -> None:
    bind = op.get_bind()
    if _has_column(bind, _TABLE, _COL):
        op.drop_column(_TABLE, _COL)