"""add intent_steps for state machine (Спринт 6a)

Revision ID: a4c82f1b9e33
Revises: 3f1d9a5b7c42
Create Date: 2026-04-24 18:30:00.000000

Таблица шагов state machine внутри ветки. `allowed_next` — JSON-список кодов
шагов, в которые разрешён переход. `guards` — JSON-словарь с условиями
блокировки (наполняется в Спринте 6b).
"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa


revision: str = 'a4c82f1b9e33'
down_revision: Union[str, None] = '3f1d9a5b7c42'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.create_table(
        'intent_steps',
        sa.Column('id', sa.Integer(), autoincrement=True, nullable=False),
        sa.Column('intent_id', sa.Integer(), nullable=False),
        sa.Column('code', sa.String(length=50), nullable=False),
        sa.Column('name', sa.String(length=200), nullable=False),
        sa.Column('order_index', sa.Integer(), nullable=False, server_default='0'),
        sa.Column('system_prompt', sa.Text(), nullable=False, server_default=''),
        sa.Column('allowed_next_json', sa.Text(), nullable=False, server_default='[]'),
        sa.Column('guards_json', sa.Text(), nullable=False, server_default='{}'),
        sa.Column('created_at', sa.DateTime(timezone=True), nullable=False),
        sa.Column('updated_at', sa.DateTime(timezone=True), nullable=False),
        sa.ForeignKeyConstraint(
            ['intent_id'], ['intents.id'],
            name='fk_intent_steps_intent_id', ondelete='CASCADE',
        ),
        sa.PrimaryKeyConstraint('id'),
        sa.UniqueConstraint('intent_id', 'code', name='uq_intent_step_code'),
    )
    op.create_index('ix_intent_steps_intent_id', 'intent_steps', ['intent_id'], unique=False)


def downgrade() -> None:
    op.drop_index('ix_intent_steps_intent_id', table_name='intent_steps')
    op.drop_table('intent_steps')