From 0854b91c9070e616ec41b8d98ad2bca880e5c7f9 Mon Sep 17 00:00:00 2001
From: Philipp Wolfer <ph.wolfer@gmail.com>
Date: Sun, 3 Nov 2019 19:21:37 +0100
Subject: [PATCH] PICARD-1592: Preserve case for APEv2 tags

When reading APEv2 tags case insensitive, preserve existing casing.
---
 picard/formats/apev2.py    | 18 +++++++++++++-----
 test/formats/test_apev2.py | 21 ++++++++++++++++++++-
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/picard/formats/apev2.py b/picard/formats/apev2.py
index 25e98f271..cf610d86c 100644
--- a/picard/formats/apev2.py
+++ b/picard/formats/apev2.py
@@ -112,21 +112,26 @@ class APEv2File(File):
     }
     __rtranslate = dict([(v.lower(), k) for k, v in __translate.items()])
 
+    def __init__(self, filename):
+        super().__init__(filename)
+        self.__casemap = {}
+
     def _load(self, filename):
         log.debug("Loading file %r", filename)
+        self.__casemap = {}
         file = self._File(encode_filename(filename))
         metadata = Metadata()
         if file.tags:
             for origname, values in file.tags.items():
-                origname = origname.lower()
+                name_lower = origname.lower()
                 if (values.kind == mutagen.apev2.BINARY
-                    and origname.startswith("cover art")):
+                    and name_lower.startswith("cover art")):
                     if b'\0' in values.value:
                         descr, data = values.value.split(b'\0', 1)
                         try:
                             coverartimage = TagCoverArtImage(
                                 file=filename,
-                                tag=origname,
+                                tag=name_lower,
                                 data=data,
                             )
                         except CoverArtImageError as e:
@@ -139,7 +144,7 @@ class APEv2File(File):
                 if values.kind != mutagen.apev2.TEXT:
                     continue
                 for value in values:
-                    name = origname
+                    name = name_lower
                     if name == "year":
                         name = "date"
                         value = sanitize_date(value)
@@ -164,6 +169,7 @@ class APEv2File(File):
                                 value = value[:start]
                     elif name in self.__rtranslate:
                         name = self.__rtranslate[name]
+                    self.__casemap[name] = origname
                     metadata.add(name, value)
         self._info(metadata, file)
         return metadata
@@ -238,7 +244,9 @@ class APEv2File(File):
                     del tags[real_name]
 
     def _get_tag_name(self, name):
-        if name.startswith('lyrics:'):
+        if name in self.__casemap:
+            return self.__casemap[name]
+        elif name.startswith('lyrics:'):
             return 'Lyrics'
         elif name == 'date':
             return 'Year'
diff --git a/test/formats/test_apev2.py b/test/formats/test_apev2.py
index 15e80d564..85cfe4d4a 100644
--- a/test/formats/test_apev2.py
+++ b/test/formats/test_apev2.py
@@ -87,6 +87,25 @@ class CommonApeTests:
             self._read_case_insensitive_tag('tracknumber', 'Track')
             self._read_case_insensitive_tag('discnumber', 'Disc')
 
+        @skipUnlessTestfile
+        def test_ci_tags_preserve_case(self):
+            # Ensure values are not duplicated on repeated save and are saved
+            # case preserving.
+            for name in ('CUStom', 'ARtist'):
+                tags = {}
+                tags[name] = 'foo'
+                save_raw(self.filename, tags)
+                loaded_metadata = load_metadata(self.filename)
+                loaded_metadata[name.lower()] = 'bar'
+                save_metadata(self.filename, loaded_metadata)
+                raw_metadata = dict(load_raw(self.filename))
+                self.assertIn(name, raw_metadata)
+                self.assertEqual(
+                    raw_metadata[name],
+                    loaded_metadata[name.lower()])
+                self.assertEqual(1, len(raw_metadata[name]))
+                self.assertNotIn(name.upper(), raw_metadata)
+
         def _read_case_insensitive_tag(self, name, ape_name):
             upper_ape_name = ape_name.upper()
             metadata = {
@@ -97,7 +116,7 @@ class CommonApeTests:
             self.assertEqual(metadata[upper_ape_name], loaded_metadata[name])
             save_metadata(self.filename, loaded_metadata)
             raw_metadata = load_raw(self.filename)
-            self.assertIn(ape_name, raw_metadata.keys())
+            self.assertIn(upper_ape_name, raw_metadata.keys())
             self.assertEqual(metadata[upper_ape_name], raw_metadata[ape_name])