mbsubmit: Add picard and markunmatched PromptChoices

Make it possible to open picard from the import menu when there are weak
recommendations. Add another menu option to print the tracks into a
beets-unmatched file for later parsing.

beetsplug/mbsubmit.py

@@ -21,6 +21,8 @@
 [1] https://wiki.musicbrainz.org/History:How_To_Parse_Track_Listings
 """
 
+import subprocess
+from pathlib import Path
 
 from beets import ui
 from beets.autotag import Recommendation
@@ -56,7 +58,32 @@ def __init__(self):
 
     def before_choose_candidate_event(self, session, task):
         if task.rec <= self.threshold:
-            return [PromptChoice("p", "Print tracks", self.print_tracks)]
+            return [
+                PromptChoice("p", "Print tracks", self.print_tracks),
+                PromptChoice(
+                    "f",
+                    'print tracks into a "beets-unmatched" File',
+                    self.markunmatched,
+                ),
+                PromptChoice(
+                    "o", "Open Picard with the relevent files", self.picard
+                ),
+            ]
+
+    def markunmatched(self, session, task):
+        fmt = self.config["format"].as_str()
+        for item in task.items:
+            unmatched_path = (
+                Path(item.path.decode("utf-8")).parent / "beets-unmatched"
+            )
+            with open(unmatched_path, "a") as p:
+                p.write(format(item, fmt) + "\n")
+
+    def picard(self, session, task):
+        paths = []
+        for p in task.paths:
+            paths.append(p.decode("utf-8"))
+        subprocess.Popen(["picard"] + paths)
 
     def print_tracks(self, session, task):
         for i in sorted(task.items, key=lambda i: i.track):

test/plugins/test_mbsubmit.py

@@ -61,7 +61,7 @@ def test_print_tracks_output_as_tracks(self):
                 self.importer.run()
 
         # Manually build the string for comparing the output.
-        tracklist = "Print tracks? " "02. Tag Title 2 - Tag Artist (0:01)"
+        tracklist = "Print tracks," "02. Tag Title 2 - Tag Artist (0:01)"
         self.assertIn(tracklist, output.getvalue())