Pre_Seg_Server/backend/routers/tasks.py

"""Processing task query endpoints."""

import logging
from datetime import datetime, timezone
from typing import List

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.orm import Session

from celery_app import celery_app
from database import get_db
from models import ProcessingTask, Project
from progress_events import publish_task_progress_event
from schemas import ProcessingTaskOut
from statuses import (
    PROJECT_STATUS_PARSING,
    PROJECT_STATUS_PENDING,
    PROJECT_STATUS_READY,
    TASK_ACTIVE_STATUSES,
    TASK_STATUS_CANCELLED,
    TASK_STATUS_FAILED,
    TASK_STATUS_QUEUED,
)
from worker_tasks import parse_project_media

router = APIRouter(prefix="/api/tasks", tags=["Tasks"])
logger = logging.getLogger(__name__)


def _now() -> datetime:
    return datetime.now(timezone.utc)


def _get_task_or_404(task_id: int, db: Session) -> ProcessingTask:
    task = db.query(ProcessingTask).filter(ProcessingTask.id == task_id).first()
    if not task:
        raise HTTPException(status_code=404, detail="Task not found")
    return task


def _project_status_after_stop(project: Project) -> str:
    return PROJECT_STATUS_READY if project.frames else PROJECT_STATUS_PENDING


@router.get("", response_model=List[ProcessingTaskOut], summary="List processing tasks")
def list_tasks(
    project_id: int | None = None,
    status: str | None = None,
    limit: int = 50,
    db: Session = Depends(get_db),
) -> List[ProcessingTask]:
    """Return recent background processing tasks."""
    query = db.query(ProcessingTask)
    if project_id is not None:
        query = query.filter(ProcessingTask.project_id == project_id)
    if status is not None:
        query = query.filter(ProcessingTask.status == status)
    return query.order_by(ProcessingTask.created_at.desc()).limit(limit).all()


@router.get("/{task_id}", response_model=ProcessingTaskOut, summary="Get processing task")
def get_task(task_id: int, db: Session = Depends(get_db)) -> ProcessingTask:
    """Return one background task by id."""
    return _get_task_or_404(task_id, db)


@router.post("/{task_id}/cancel", response_model=ProcessingTaskOut, summary="Cancel processing task")
def cancel_task(task_id: int, db: Session = Depends(get_db)) -> ProcessingTask:
    """Cancel a queued/running background task and revoke the Celery job when possible."""
    task = _get_task_or_404(task_id, db)
    if task.status not in TASK_ACTIVE_STATUSES:
        raise HTTPException(
            status_code=status.HTTP_409_CONFLICT,
            detail=f"Task is not cancellable in status: {task.status}",
        )

    if task.celery_task_id:
        try:
            celery_app.control.revoke(task.celery_task_id, terminate=True, signal="SIGTERM")
        except Exception as exc:  # noqa: BLE001
            logger.warning("Failed to revoke celery task %s: %s", task.celery_task_id, exc)

    task.status = TASK_STATUS_CANCELLED
    task.progress = 100
    task.message = "任务已取消"
    task.error = "Cancelled by user"
    task.finished_at = _now()
    if task.project:
        task.project.status = _project_status_after_stop(task.project)

    db.commit()
    db.refresh(task)
    publish_task_progress_event(task)
    return task


@router.post("/{task_id}/retry", response_model=ProcessingTaskOut, status_code=status.HTTP_202_ACCEPTED, summary="Retry processing task")
def retry_task(task_id: int, db: Session = Depends(get_db)) -> ProcessingTask:
    """Create a fresh queued task from a failed or cancelled task."""
    previous = _get_task_or_404(task_id, db)
    if previous.status not in {TASK_STATUS_FAILED, TASK_STATUS_CANCELLED}:
        raise HTTPException(
            status_code=status.HTTP_409_CONFLICT,
            detail=f"Task is not retryable in status: {previous.status}",
        )
    if previous.project_id is None:
        raise HTTPException(status_code=400, detail="Task has no project_id")

    project = db.query(Project).filter(Project.id == previous.project_id).first()
    if not project:
        raise HTTPException(status_code=404, detail="Project not found")
    if not project.video_path:
        raise HTTPException(status_code=400, detail="Project has no media uploaded")

    payload = dict(previous.payload or {})
    payload.setdefault("source_type", project.source_type or "video")
    payload["retry_of"] = previous.id

    task = ProcessingTask(
        task_type=previous.task_type,
        status=TASK_STATUS_QUEUED,
        progress=0,
        message=f"重试任务已入队（源任务 #{previous.id}）",
        project_id=project.id,
        payload=payload,
    )
    project.status = PROJECT_STATUS_PARSING
    db.add(task)
    db.commit()
    db.refresh(task)
    publish_task_progress_event(task)

    async_result = parse_project_media.delay(task.id)
    task.celery_task_id = async_result.id
    db.commit()
    db.refresh(task)
    publish_task_progress_event(task)
    return task