"""Storage 辅助工具:idempotent task 行创建、本地形态简化封装。"""
from __future__ import annotations

from typing import Optional
from uuid import UUID

from sqlalchemy import select
from sqlalchemy.dialects.postgresql import insert

from .engine import session_scope
from .models import SENTINEL_USER_ID, Task


def ensure_local_task_row(
    task_id: UUID,
    task_dir: str = "",
    mode: str = "",
    description: str = "",
    model: str = "",
    model_profile: str = "",
    reasoning_effort: str = "",
    user_id: UUID = SENTINEL_USER_ID,
) -> None:
    """本地形态 idempotent INSERT tasks 行。

    用于 Session.append 首次写消息前打底,Step 2 阶段字段都是占位值;
    Step 3 引入 TaskState ORM 后,TaskState.save 会把字段更新成真实值。

    PG `INSERT ... ON CONFLICT DO NOTHING` 保证幂等且单 SQL,无 SELECT-then-INSERT
    竞态。
    """
    stmt = (
        insert(Task)
        .values(
            task_id=task_id,
            user_id=user_id,
            task_dir=task_dir,
            mode=mode,
            description=description,
            model=model,
            model_profile=model_profile,
            reasoning_effort=reasoning_effort,
        )
        .on_conflict_do_nothing(index_elements=["task_id"])
    )
    with session_scope() as s:
        s.execute(stmt)


def get_task(task_id: UUID) -> Optional[Task]:
    """读 tasks 行,不存在返回 None。"""
    with session_scope() as s:
        return s.execute(
            select(Task).where(Task.task_id == task_id)
        ).scalar_one_or_none()