From 112e0d885eec503da0344a63def3536d8d2bad68 Mon Sep 17 00:00:00 2001
From: Philipp Wolfer <ph.wolfer@gmail.com>
Date: Mon, 24 Jul 2023 15:51:59 +0200
Subject: [PATCH] PICARD-2685: Preserve calculated AcoustID and ReplayGain tags

Preserve calculated AcoustID fingerprint and ReplayGain tags set on a file
object when that file object gets moved between tracks.
---
 picard/file.py      | 14 ++++++++++----
 picard/util/tags.py | 19 ++++++++++++++++++-
 test/test_file.py   | 11 ++++++++---
 3 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/picard/file.py b/picard/file.py
index 003c3a6f6..8e33344a0 100644
--- a/picard/file.py
+++ b/picard/file.py
@@ -98,7 +98,10 @@ from picard.util.filenaming import (
 )
 from picard.util.preservedtags import PreservedTags
 from picard.util.scripttofilename import script_to_filename_with_metadata
-from picard.util.tags import PRESERVED_TAGS
+from picard.util.tags import (
+    CALCULATED_TAGS,
+    PRESERVED_TAGS,
+)
 
 from picard.ui.item import Item
 
@@ -305,9 +308,14 @@ class File(QtCore.QObject, Item):
             to_metadata[info] = from_metadata[info]
 
     def copy_metadata(self, metadata, preserve_deleted=True):
-        acoustid = self.metadata["acoustid_id"]
         saved_metadata = {}
 
+        # Keep current value for special tags that got calculated from audio content
+        for tag in CALCULATED_TAGS:
+            if tag not in metadata.deleted_tags and self.metadata[tag]:
+                saved_metadata[tag] = self.metadata[tag]
+
+        # Keep original values of preserved tags
         preserved_tags = PreservedTags()
         for tag, values in self.orig_metadata.rawitems():
             if tag in preserved_tags or tag in PRESERVED_TAGS:
@@ -321,8 +329,6 @@ class File(QtCore.QObject, Item):
                 del self.metadata[tag]
         self.metadata.update(saved_metadata)
 
-        if acoustid and "acoustid_id" not in metadata.deleted_tags:
-            self.metadata["acoustid_id"] = acoustid
         if images_changed:
             self.metadata_images_changed.emit()
 
diff --git a/picard/util/tags.py b/picard/util/tags.py
index f3e8c0601..9ea5ec2b2 100644
--- a/picard/util/tags.py
+++ b/picard/util/tags.py
@@ -3,7 +3,7 @@
 # Picard, the next-generation MusicBrainz tagger
 #
 # Copyright (C) 2007-2008, 2011 Lukáš Lalinský
-# Copyright (C) 2008-2009, 2018-2021 Philipp Wolfer
+# Copyright (C) 2008-2009, 2018-2021, 2023 Philipp Wolfer
 # Copyright (C) 2011 Johannes Weißl
 # Copyright (C) 2011-2013 Michael Wiencek
 # Copyright (C) 2012 Chad Wilson
@@ -144,6 +144,23 @@ PRESERVED_TAGS = (
     '~video',
 )
 
+# Tags that got generated in some way from the audio content.
+# Those can be set by Picard but the new values usually should be kept
+# when moving the file between tags.
+CALCULATED_TAGS = {
+    'acoustid_fingerprint',
+    'acoustid_id',
+    'replaygain_album_gain',
+    'replaygain_album_peak',
+    'replaygain_album_range',
+    'replaygain_reference_loudness',
+    'replaygain_track_gain',
+    'replaygain_track_peak',
+    'replaygain_track_range',
+    'r128_album_gain',
+    'r128_track_gain',
+}
+
 
 def display_tag_name(name):
     if ':' in name:
diff --git a/test/test_file.py b/test/test_file.py
index 56c3ef5ba..a75e1ef17 100644
--- a/test/test_file.py
+++ b/test/test_file.py
@@ -38,6 +38,7 @@ from picard.const.sys import (
 )
 from picard.file import File
 from picard.metadata import Metadata
+from picard.util.tags import CALCULATED_TAGS
 
 
 class DataObjectTest(PicardTestCase):
@@ -671,11 +672,15 @@ class FileCopyMetadataTest(PicardTestCase):
         self.assertEqual(self.file.metadata, new_metadata)
         self.assertEqual(self.file.metadata.deleted_tags, {'foo'})
 
-    def test_copy_metadata_must_not_clear_acoustid_id(self):
-        self.file.metadata['acoustid_id'] = 'foo'
+    def test_copy_metadata_must_keep_file_content_specific_tags(self):
+        for tag in CALCULATED_TAGS:
+            self.file.metadata[tag] = 'foo'
         new_metadata = Metadata()
         self.file.copy_metadata(new_metadata)
-        self.assertEqual(self.file.metadata['acoustid_id'], 'foo')
+        for tag in CALCULATED_TAGS:
+            self.assertEqual(
+                self.file.metadata[tag], 'foo',
+                f'Tag {tag}: {self.file.metadata[tag]!r} != "foo"')
 
     def test_copy_metadata_must_remove_deleted_acoustid_id(self):
         self.file.metadata['acoustid_id'] = 'foo'