"""Пользователь: любимая фракция (личный выбор в профиле).

Идемпотентна: на свежей БД столбец создаёт 0001 (create_all из актуальных моделей) -> no-op;
на существующей БД добавляет столбец. render_as_batch включён в env.py (для SQLite).

Revision ID: 0010_user_favorite_faction
Revises: 0009_participant_eliminated
Create Date: 2026-09-07
"""
from typing import Sequence, Union

import sqlalchemy as sa
from sqlalchemy import inspect

from alembic import op

revision: str = "0010_user_favorite_faction"
down_revision: Union[str, None] = "0009_participant_eliminated"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    bind = op.get_bind()
    insp = inspect(bind)
    cols = {c["name"] for c in insp.get_columns("users")}
    if "favorite_faction_id" not in cols:
        with op.batch_alter_table("users") as b:
            b.add_column(sa.Column("favorite_faction_id", sa.Integer(), nullable=True))
            b.create_foreign_key(
                "fk_users_favorite_faction_id",
                "factions",
                ["favorite_faction_id"],
                ["id"],
                ondelete="SET NULL",
            )


def downgrade() -> None:
    bind = op.get_bind()
    insp = inspect(bind)
    cols = {c["name"] for c in insp.get_columns("users")}
    if "favorite_faction_id" in cols:
        with op.batch_alter_table("users") as b:
            b.drop_constraint("fk_users_favorite_faction_id", type_="foreignkey")
            b.drop_column("favorite_faction_id")