feat: cancel playlist adding mid-operation (closes #840)

app/main.py

@@ -302,6 +302,11 @@ async def add(request):
     )
     return web.Response(text=serializer.encode(status))
 
+@routes.post(config.URL_PREFIX + 'cancel-add')
+async def cancel_add(request):
+    dqueue.cancel_add()
+    return web.Response(text=serializer.encode({'status': 'ok'}), content_type='application/json')
+
 @routes.post(config.URL_PREFIX + 'delete')
 async def delete(request):
     post = await request.json()
@@ -433,6 +438,7 @@ async def add_cors(request):
     return web.Response(text=serializer.encode({"status": "ok"}))
 
 app.router.add_route('OPTIONS', config.URL_PREFIX + 'add', add_cors)
+app.router.add_route('OPTIONS', config.URL_PREFIX + 'cancel-add', add_cors)
 
 async def on_prepare(request, response):
     if 'Origin' in request.headers:

app/ytdl.py

@@ -535,6 +535,11 @@ class DownloadQueue:
         self.active_downloads = set()
         self.semaphore = asyncio.Semaphore(int(self.config.MAX_CONCURRENT_DOWNLOADS))
         self.done.load()
+        self._add_canceled = False
+
+    def cancel_add(self):
+        self._add_canceled = True
+        log.info('Playlist add operation canceled by user')
 
     async def __import_queue(self):
         for k, v in self.queue.saved_items():
@@ -699,6 +704,9 @@ class DownloadQueue:
                 log.info(f'Item limit is set. Processing only first {playlist_item_limit} entries')
                 entries = entries[:playlist_item_limit]
             for index, etr in enumerate(entries, start=1):
+                if self._add_canceled:
+                    log.info(f'Playlist add canceled after processing {len(already)} entries')
+                    return {'status': 'ok', 'msg': f'Canceled - added {len(already)} items before cancel'}
                 etr["_type"] = "video"
                 etr[etype] = entry.get("id") or entry.get("channel_id") or entry.get("channel")
                 etr[f"{etype}_index"] = '{{0:0{0:d}d}}'.format(index_digits).format(index)
@@ -771,6 +779,8 @@ class DownloadQueue:
             f'{playlist_item_limit=} {auto_start=} {split_by_chapters=} {chapter_template=} '
             f'{subtitle_format=} {subtitle_language=} {subtitle_mode=}'
         )
+        if already is None:
+            self._add_canceled = False
         already = set() if already is None else already
         if url in already:
             log.info('recursion detected, skipping')