"""add_chat_session_owner_scope

Revision ID: 002
Revises: 001
Create Date: 2026-07-14 07:54:32.969191

"""
from collections.abc import Sequence

import sqlalchemy as sa

from alembic import op

# revision identifiers, used by Alembic.
revision: str = '002'
down_revision: str | Sequence[str] | None = '001'
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None


def upgrade() -> None:
    conn = op.get_bind()
    is_sqlite = conn.engine.dialect.name == "sqlite"

    if is_sqlite:
        # SQLite：用 batch 模式加列（新增 NOT NULL 列需 batch recreating）
        with op.batch_alter_table("chat_sessions") as batch_op:
            batch_op.add_column(
                sa.Column("owner_scope", sa.String(length=80), nullable=False, server_default=""),
            )
            batch_op.create_index("ix_chat_sessions_owner_scope", ["owner_scope"])
        # 移除 server_default（仅 DDL 阶段需要）
        with op.batch_alter_table("chat_sessions") as batch_op:
            batch_op.alter_column("owner_scope", server_default=None)
    else:
        op.add_column(
            "chat_sessions",
            sa.Column("owner_scope", sa.String(length=80), nullable=False, server_default=""),
        )
        op.create_index(
            op.f("ix_chat_sessions_owner_scope"), "chat_sessions", ["owner_scope"], unique=False
        )
        op.alter_column("chat_sessions", "owner_scope", server_default=None)


def downgrade() -> None:
    conn = op.get_bind()
    is_sqlite = conn.engine.dialect.name == "sqlite"

    if is_sqlite:
        with op.batch_alter_table("chat_sessions") as batch_op:
            batch_op.drop_index("ix_chat_sessions_owner_scope")
            batch_op.drop_column("owner_scope")
    else:
        op.drop_index(op.f("ix_chat_sessions_owner_scope"), table_name="chat_sessions")
        op.drop_column("chat_sessions", "owner_scope")