"""Приглашения в группу: таблица group_invitations.

Идемпотентна (как 0005): на свежей БД таблицу создаёт 0001 (create_all из актуальных
моделей); на существующей — create_table здесь.

Revision ID: 0006_group_invitations
Revises: 0005_achievements
Create Date: 2026-06-17
"""
from typing import Sequence, Union

import sqlalchemy as sa
from sqlalchemy import inspect

from alembic import op

revision: str = "0006_group_invitations"
down_revision: Union[str, None] = "0005_achievements"
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)
    if "group_invitations" in insp.get_table_names():
        return
    op.create_table(
        "group_invitations",
        sa.Column("id", sa.Integer(), primary_key=True),
        sa.Column(
            "group_id",
            sa.Integer(),
            sa.ForeignKey("groups.id", ondelete="CASCADE"),
            nullable=False,
        ),
        sa.Column(
            "user_id",
            sa.Integer(),
            sa.ForeignKey("users.id", ondelete="CASCADE"),
            nullable=False,
        ),
        sa.Column(
            "invited_by_id",
            sa.Integer(),
            sa.ForeignKey("users.id", ondelete="SET NULL"),
            nullable=True,
        ),
        sa.Column("created_at", sa.DateTime(), nullable=False),
        sa.UniqueConstraint("group_id", "user_id", name="uq_group_invitation"),
    )
    op.create_index("ix_group_invitations_group_id", "group_invitations", ["group_id"])
    op.create_index("ix_group_invitations_user_id", "group_invitations", ["user_id"])


def downgrade() -> None:
    bind = op.get_bind()
    insp = inspect(bind)
    if "group_invitations" in insp.get_table_names():
        op.drop_table("group_invitations")