"""sys_role_permission 附件四权限列与方案锁挂载位合并（契约1.41）。

Revision ID: 0039_attachment_permissions_lock_merge
Revises: 0038_session_jti
Create Date: 2026-09-18

变更要点（仅库结构同步，Python 版已废弃不做功能实现）：
1. sys_role_permission 加 4 列：can_attachment_view / can_attachment_download /
   can_attachment_edit / can_attachment_upload——附件权限独立于主案权限，
   不跟随挂载主案权限；仅 OWN 行有意义（OTHER 行服务端拒绝置真）；
2. doc_document 方案锁「挂载/解除挂载」合并为单一「挂载」保护位：存量
   protect_unbind_attachment=1 并入 protect_bind_attachment（列保留）；
3. 双引擎幂等：先探测列存在再加（MySQL 与达梦升级互不冲突）。
"""

from __future__ import annotations

from collections.abc import Sequence

import sqlalchemy as sa
from alembic import op

revision: str = "0039_attachment_permissions_lock_merge"
down_revision: str | None = "0038_session_jti"
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None

_ATTACHMENT_COLUMNS = (
    "can_attachment_view",
    "can_attachment_download",
    "can_attachment_edit",
    "can_attachment_upload",
)


def _column_exists(table: str, column: str) -> bool:
    # 达梦 inspector 返回大写名，统一小写比较
    inspector = sa.inspect(op.get_bind())
    return column.lower() in {
        name.lower() for name in inspector.get_columns(table)
    }


def upgrade() -> None:
    for column in _ATTACHMENT_COLUMNS:
        if _column_exists("sys_role_permission", column):
            continue
        op.add_column(
            "sys_role_permission",
            sa.Column(column, sa.Boolean(), nullable=False, server_default=sa.false()),
        )
    op.execute(
        "UPDATE doc_document SET protect_bind_attachment = 1 "
        "WHERE protect_unbind_attachment = 1 AND protect_bind_attachment = 0"
    )


def downgrade() -> None:
    for column in reversed(_ATTACHMENT_COLUMNS):
        if not _column_exists("sys_role_permission", column):
            continue
        op.drop_column("sys_role_permission", column)