"""补齐 0001 create_all 未覆盖的老库列（显式清单，禁止内省全库）

0001 对「已存在的表」不会 ALTER。下列列在 ORM / 0001 注释中视为新库默认字段，
但 staging/production 等自 squash 前就存在的库需要本迁移显式 add_column。

新增 ORM 字段时：禁止改已部署 revision id；在本文件追加列定义，或新建 0020_* 迁移。

Revision ID: 0019_align_legacy_schema
Revises: 0018_users_language_preference
"""

from __future__ import annotations

import sys
from pathlib import Path
from typing import Sequence, Union

import sqlalchemy as sa

# versions/ -> alembic/
_ALEMBIC_DIR = Path(__file__).resolve().parents[1]
if str(_ALEMBIC_DIR) not in sys.path:
    sys.path.insert(0, str(_ALEMBIC_DIR))

from script_helpers import add_column_if_missing, drop_column_if_exists, table_exists

revision: str = "0019_align_legacy_schema"
down_revision: Union[str, None] = "0018_users_language_preference"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None

# (table, column) — 仅列「0002–0018 未 add_column 且老库常缺」的字段
_LEGACY_COLUMNS: tuple[tuple[str, sa.Column], ...] = (
    (
        "segments",
        sa.Column("audio_duration_seconds", sa.Integer(), nullable=True),
    ),
    (
        "conversations",
        sa.Column("deleted_at", sa.DateTime(timezone=True), nullable=True),
    ),
    (
        "segments",
        sa.Column("tts_audio_urls", sa.JSON(), nullable=True),
    ),
    (
        "conversation_messages",
        sa.Column("tts_audio_urls", sa.JSON(), nullable=True),
    ),
)


def upgrade() -> None:
    for table_name, column in _LEGACY_COLUMNS:
        if not table_exists(table_name):
            continue
        add_column_if_missing(table_name, column)


def downgrade() -> None:
    for table_name, column in reversed(_LEGACY_COLUMNS):
        if not table_exists(table_name):
            continue
        drop_column_if_exists(table_name, column.name)