added cancel download feature

routes/playlist.py

@@ -9,6 +9,9 @@ from multiprocessing import Process
 
 playlist_bp = Blueprint('playlist', __name__)
 
+# Global dictionary to track running playlist download processes
+playlist_processes = {}
+
 def generate_random_filename(length=6):
     chars = string.ascii_lowercase + string.digits
     return ''.join(random.choice(chars) for _ in range(length)) + '.prg'
@@ -89,13 +92,63 @@ def handle_download():
     os.makedirs(prg_dir, exist_ok=True)
     prg_path = os.path.join(prg_dir, filename)
     
-    Process(
+    process = Process(
         target=download_task,
         args=(service, url, main, fallback, quality, fall_quality, real_time, prg_path)
-    ).start()
+    )
+    process.start()
+    # Track the running process using the generated filename.
+    playlist_processes[filename] = process
     
     return Response(
         json.dumps({"prg_file": filename}),
         status=202,
         mimetype='application/json'
     )
+
+@playlist_bp.route('/download/cancel', methods=['GET'])
+def cancel_download():
+    """
+    Cancel a running playlist download process by its process id (prg file name).
+    """
+    prg_file = request.args.get('prg_file')
+    if not prg_file:
+        return Response(
+            json.dumps({"error": "Missing process id (prg_file) parameter"}),
+            status=400,
+            mimetype='application/json'
+        )
+    
+    process = playlist_processes.get(prg_file)
+    prg_dir = './prgs'
+    prg_path = os.path.join(prg_dir, prg_file)
+
+    if process and process.is_alive():
+        # Terminate the running process and wait for it to finish
+        process.terminate()
+        process.join()
+        # Remove it from our tracking dictionary
+        del playlist_processes[prg_file]
+        
+        # Append a cancellation status to the log file
+        try:
+            with open(prg_path, 'a') as f:
+                f.write(json.dumps({"status": "cancel"}) + "\n")
+        except Exception as e:
+            return Response(
+                json.dumps({"error": f"Failed to write cancel status to file: {str(e)}"}),
+                status=500,
+                mimetype='application/json'
+            )
+        
+        return Response(
+            json.dumps({"status": "cancel"}),
+            status=200,
+            mimetype='application/json'
+        )
+    else:
+        return Response(
+            json.dumps({"error": "Process not found or already terminated"}),
+            status=404,
+            mimetype='application/json'
+        )