playlist: Have the Factory create a visible Playlist

I either create or reuse an existing Playlist object when the
db-visible property changes to a new value.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

emmental/playlist/__init__.py

@@ -1,6 +1,7 @@
 # Copyright 2023 (c) Anna Schumaker.
 """An object for managing the visible and active playlists."""
 from gi.repository import GObject
+from . import playlist
 from .. import db
 
 
@@ -13,15 +14,37 @@ class Factory(GObject.GObject):
     db_previous = GObject.Property(type=db.playlist.Playlist)
     db_visible = GObject.Property(type=db.playlist.Playlist)
 
+    visible_playlist = GObject.Property(type=playlist.Playlist)
+
     def __init__(self, sql: db.Connection):
         """Initialize the Playlist Factory."""
         super().__init__(sql=sql)
         self.sql.bind_property("active-playlist", self, "db-active")
         self.connect("notify", self.__notify_db_playlists)
 
+    def __run_factory(self, label: str) -> None:
+        db_plist = self.get_property(f"db-{label}")
+        plist = self.get_property(f"{label}-playlist")
+
+        print(f"factory: {label} playlist is:",
+              "<None>" if db_plist is None else db_plist.name)
+
+        if db_plist is None:
+            plist.playlist = None
+            new = None
+        elif plist is None:
+            new = playlist.Playlist(self.sql, db_plist)
+        else:
+            plist.playlist = db_plist
+            return
+
+        self.set_property(f"{label}-playlist", new)
+
     def __notify_db_playlists(self, factory: GObject.GObject, param) -> None:
         match param.name:
-            case "db-active" | "db-previous" | "db-visible":
+            case "db-active" | "db-previous":
                 plist = self.get_property(param.name)
                 name = "<None>" if plist is None else plist.name
                 print(f"factory: {param.name[3:]} playlist is:", name)
+            case "db-visible":
+                self.__run_factory("visible")

tests/playlist/test_factory.py

@@ -61,3 +61,25 @@ class TestFactory(tests.util.TestCase):
         self.factory.db_visible = None
         self.assertRegex(mock_stdout.getvalue(),
                          "factory: visible playlist is: <None>")
+
+    def test_visible_playlist(self, mock_stdout: io.StringIO):
+        """Test creating a Playlist when setting the db_visible property."""
+        self.assertIsNone(self.factory.visible_playlist)
+
+        self.factory.db_visible = self.user_plist
+        self.assertIsInstance(self.factory.visible_playlist,
+                              emmental.playlist.playlist.Playlist)
+        self.assertEqual(self.factory.visible_playlist.sql, self.sql)
+        self.assertEqual(self.factory.visible_playlist.playlist,
+                         self.user_plist)
+
+        orig_id = id(self.factory.visible_playlist)
+        self.factory.db_visible = self.sql.playlists.collection
+        self.assertEqual(id(self.factory.visible_playlist), orig_id)
+        self.assertEqual(self.factory.visible_playlist.playlist,
+                         self.sql.playlists.collection)
+
+        visible = self.factory.visible_playlist
+        self.factory.db_visible = None
+        self.assertIsNone(self.factory.visible_playlist)
+        self.assertIsNone(visible.playlist)