"""channel aliases across department sections

Revision ID: 0011
Revises: 0010
Create Date: 2026-06-08

"""
from typing import Sequence, Union

import sqlalchemy as sa
from alembic import op

revision: str = "0011"
down_revision: Union[str, None] = "0010"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.add_column("channels", sa.Column("source_channel_id", sa.Integer(), nullable=True))
    op.create_foreign_key(
        "fk_channels_source_channel_id",
        "channels",
        "channels",
        ["source_channel_id"],
        ["id"],
        ondelete="SET NULL",
    )
    op.drop_constraint("channels_identifier_key", "channels", type_="unique")
    op.create_unique_constraint(
        "uq_channels_section_identifier",
        "channels",
        ["section_id", "identifier"],
    )
    op.create_index("ix_channels_source_channel_id", "channels", ["source_channel_id"])


def downgrade() -> None:
    op.drop_index("ix_channels_source_channel_id", table_name="channels")
    op.drop_constraint("uq_channels_section_identifier", "channels", type_="unique")
    op.create_unique_constraint("channels_identifier_key", "channels", ["identifier"])
    op.drop_constraint("fk_channels_source_channel_id", "channels", type_="foreignkey")
    op.drop_column("channels", "source_channel_id")