Initial python3 changes

Mostly just updating libraries, removing string encoding/decoding,
fixing some edge cases. No new functionality was added in this
commit.

lib/beetsplug/albumtypes.py

@@ -0,0 +1,65 @@
+# This file is part of beets.
+# Copyright 2021, Edgars Supe.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+
+"""Adds an album template field for formatted album types."""
+
+
+from beets.autotag.mb import VARIOUS_ARTISTS_ID
+from beets.library import Album
+from beets.plugins import BeetsPlugin
+
+
+class AlbumTypesPlugin(BeetsPlugin):
+    """Adds an album template field for formatted album types."""
+
+    def __init__(self):
+        """Init AlbumTypesPlugin."""
+        super().__init__()
+        self.album_template_fields['atypes'] = self._atypes
+        self.config.add({
+            'types': [
+                ('ep', 'EP'),
+                ('single', 'Single'),
+                ('soundtrack', 'OST'),
+                ('live', 'Live'),
+                ('compilation', 'Anthology'),
+                ('remix', 'Remix')
+            ],
+            'ignore_va': ['compilation'],
+            'bracket': '[]'
+        })
+
+    def _atypes(self, item: Album):
+        """Returns a formatted string based on album's types."""
+        types = self.config['types'].as_pairs()
+        ignore_va = self.config['ignore_va'].as_str_seq()
+        bracket = self.config['bracket'].as_str()
+
+        # Assign a left and right bracket or leave blank if argument is empty.
+        if len(bracket) == 2:
+            bracket_l = bracket[0]
+            bracket_r = bracket[1]
+        else:
+            bracket_l = ''
+            bracket_r = ''
+
+        res = ''
+        albumtypes = item.albumtypes.split('; ')
+        is_va = item.mb_albumartistid == VARIOUS_ARTISTS_ID
+        for type in types:
+            if type[0] in albumtypes and type[1]:
+                if not is_va or (type[0] not in ignore_va and is_va):
+                    res += f'{bracket_l}{type[1]}{bracket_r}'
+
+        return res