"""add execution parent/depth columns

Revision ID: 006_add_execution_parent_depth
Revises: 005_persistent_user_memory
Create Date: 2026-04-08
"""
from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects.mysql import CHAR


revision = "006_add_execution_parent_depth"
down_revision = "005_persistent_user_memory"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.add_column(
        "executions",
        sa.Column("parent_execution_id", CHAR(36), nullable=True, comment="父执行ID"),
    )
    op.add_column(
        "executions",
        sa.Column("depth", sa.Integer(), nullable=False, server_default="0", comment="执行深度（根为0）"),
    )
    op.create_foreign_key(
        "fk_executions_parent_execution_id",
        "executions",
        "executions",
        ["parent_execution_id"],
        ["id"],
    )
    op.create_index(
        "ix_executions_parent_execution_id",
        "executions",
        ["parent_execution_id"],
        unique=False,
    )
    op.create_index("ix_executions_depth", "executions", ["depth"], unique=False)
    op.alter_column("executions", "depth", server_default=None)


def downgrade() -> None:
    op.drop_index("ix_executions_depth", table_name="executions")
    op.drop_index("ix_executions_parent_execution_id", table_name="executions")
    op.drop_constraint("fk_executions_parent_execution_id", "executions", type_="foreignkey")
    op.drop_column("executions", "depth")
    op.drop_column("executions", "parent_execution_id")