Download cover bundle through the transfer queue (fix QProgressDialog NameError)

app/transfers.py

@@ -175,6 +175,33 @@ class Source:
         raise NotImplementedError
 
 
+class CoversBundleSource:
+    """Download the combined offline cover bundle (runs as a queue job)."""
+    label = "psppt-covers.zip"
+
+    def __init__(self, url=""):
+        self.url = url
+
+    def download(self, item, dest_dir, progress_cb=None, cancel_event=None):
+        from . import covers
+
+        def on_progress(done, total):
+            if progress_cb is None:
+                return
+            frac = (done / total) if total else 0.0
+            detail = (f"{done / (1 << 20):.0f} / {total / (1 << 20):.0f} MB"
+                      if total else "")
+            progress_cb("Downloading", frac, detail)
+
+        try:
+            result = covers.download_covers_bundle(self.url,
+                                                   progress_cb=on_progress,
+                                                   cancel_event=cancel_event)
+        except InterruptedError:
+            raise TransferCancelled() from None
+        return str(result)
+
+
 class FileCopySource(Source):
     """Copy a single local file (library -> PSP or PSP -> library).