feat: real-time download progress, cancel support, admin auto-poll

backend/app/routes/download.py

@@ -12,7 +12,10 @@ from app.schemas import DownloadRequest, DownloadResponse, TaskStatus
 from app.database import get_db, async_session
 from app.models import Video, DownloadLog
 from app.auth import get_current_user, optional_auth
-from app.services.downloader import download_video, get_video_path, detect_platform
+from app.services.downloader import (
+    download_video, get_video_path, detect_platform,
+    register_task, get_progress, request_cancel, cleanup_task,
+)
 
 logger = logging.getLogger(__name__)
 router = APIRouter(prefix="/api", tags=["download"])
@@ -107,7 +110,7 @@ async def _log_download(video_id: int, request: Request):
 
 
 async def _do_download(task_id: str, url: str, format_id: str):
-    """Background download task."""
+    """Background download task with real-time progress and cancel support."""
     from app.database import async_session
     async with async_session() as db:
         video = (await db.execute(select(Video).where(Video.task_id == task_id))).scalar_one_or_none()
@@ -117,10 +120,9 @@ async def _do_download(task_id: str, url: str, format_id: str):
             video.status = "downloading"
             await db.commit()
 
-            def update_progress(pct):
-                pass  # Progress tracking in sync context is complex; keep simple
+            register_task(task_id)
+            result = download_video(url, format_id, task_id=task_id)
 
-            result = download_video(url, format_id, progress_callback=update_progress)
             video.title = result["title"]
             video.thumbnail = result["thumbnail"]
             video.duration = result["duration"]
@@ -133,9 +135,13 @@ async def _do_download(task_id: str, url: str, format_id: str):
             await db.commit()
         except Exception as e:
             logger.error(f"Download failed for {task_id}: {e}")
+            is_cancel = "Cancelled" in str(e) or "DownloadCancelled" in type(e).__name__
             video.status = "error"
-            video.error_message = str(e)[:500]
+            video.error_message = "下载已取消，请重试" if is_cancel else str(e)[:500]
+            video.progress = 0
             await db.commit()
+        finally:
+            cleanup_task(task_id)
 
 
 @router.post("/download", response_model=DownloadResponse)
@@ -167,16 +173,29 @@ async def get_download_status(task_id: str, db: AsyncSession = Depends(get_db)):
     video = (await db.execute(select(Video).where(Video.task_id == task_id))).scalar_one_or_none()
     if not video:
         raise HTTPException(status_code=404, detail="Task not found")
+    # Inject real-time progress for active downloads
+    progress = get_progress(task_id) if video.status == "downloading" else video.progress
     return TaskStatus(
         task_id=video.task_id,
         status=video.status,
-        progress=video.progress,
+        progress=progress,
         title=video.title,
         error_message=video.error_message or "",
         video_id=video.id if video.status == "done" else None,
     )
 
 
+@router.post("/download/{task_id}/cancel")
+async def cancel_download(task_id: str, db: AsyncSession = Depends(get_db)):
+    video = (await db.execute(select(Video).where(Video.task_id == task_id))).scalar_one_or_none()
+    if not video:
+        raise HTTPException(status_code=404, detail="Task not found")
+    if video.status != "downloading":
+        raise HTTPException(status_code=400, detail="Task is not downloading")
+    request_cancel(task_id)
+    return {"ok": True, "message": "Cancel requested"}
+
+
 @router.get("/file/{video_id}")
 async def download_file(video_id: int, request: Request, background_tasks: BackgroundTasks, user: dict = Depends(get_current_user), db: AsyncSession = Depends(get_db)):
     video = (await db.execute(select(Video).where(Video.id == video_id))).scalar_one_or_none()