"""The distributor's view of the app-owned task's sub_tasks (ADR-0055).

Intention-revealing methods over parameterised SQL. SQL rather than the
SQLModel mirrors because the FastAPI app registers the legacy
``backend.app.db.models`` mirrors of ``sub_task``, and importing the
``infrastructure.postgres`` mirror of the same table into one process
double-registers it and crashes the app at import (contained here until the
DDD cut-over).
"""

import json
from datetime import datetime, timezone
from typing import Any
from uuid import UUID

from sqlalchemy import text
from sqlmodel import Session


class ModellingRunTasks:
    def __init__(self, session: Session) -> None:
        self._session = session

    def already_distributed(self, task_id: UUID) -> bool:
        """Whether the task already has sub_tasks — i.e. a distributor has
        already fanned it out (the 409 guard against double-submits)."""
        row = self._session.connection().execute(
            text("SELECT 1 FROM sub_task WHERE task_id = :task_id LIMIT 1"),
            {"task_id": task_id},
        ).first()
        return row is not None

    def create_batch_subtasks(
        self, task_id: UUID, messages: list[dict[str, Any]]
    ) -> None:
        """Pre-create one ``waiting`` sub_task per batch message under the
        app-owned task. Each sub_task's inputs are its exact message payload
        (minus the self-referential subtask_id) — the fixed progress
        denominator and the batch's re-run recipe."""
        now = datetime.now(timezone.utc)
        self._session.connection().execute(
            text(
                "INSERT INTO sub_task (id, task_id, status, inputs, updated_at)"
                " VALUES (:id, :task_id, 'waiting', :inputs, :updated_at)"
            ),
            [
                {
                    "id": message["subtask_id"],
                    "task_id": task_id,
                    "inputs": json.dumps(
                        {k: v for k, v in message.items() if k != "subtask_id"}
                    ),
                    "updated_at": now,
                }
                for message in messages
            ],
        )
        self._session.commit()