From b1546eeaa2e80f6d6a655c598764201c26cd850f Mon Sep 17 00:00:00 2001
From: Leni Kadali <52788034+lenikadali@users.noreply.github.com>
Date: Sat, 14 Sep 2024 12:44:41 +0300
Subject: [PATCH] Add release date to track metadata

Fixes #185

This commit adds the DATE metadata field to the transcoded MP3 and
FLAC files. The FLAC documentation we can find seems to suggest using
DATE for this purpose[1]. For MP3, `date` also seems to be an
acceptable field name[2]. We've verified that the data shows up in the
metadata displayed by VLC[3] for both formats.

[1] https://xiph.org/vorbis/doc/v-comment.html#fieldnames
[2] https://docs.mp3tag.de/format/
[3] https://www.videolan.org/vlc/

Co-authored-by: Chris Lowis <chris.lowis@gofreerange.com>
---
 app/models/track.rb                   |  5 ++++-
 app/models/transcode_command.rb       |  6 ++++--
 test/models/track_test.rb             | 10 ++++++++++
 test/models/transcode_command_test.rb |  8 ++++++--
 4 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/app/models/track.rb b/app/models/track.rb
index 245d76a1..788ccd74 100644
--- a/app/models/track.rb
+++ b/app/models/track.rb
@@ -27,12 +27,15 @@ def preview_duration
   end
 
   def metadata
-    {
+    data = {
       track_title: title,
       track_number: number,
       album_title: album.title,
       artist_name: artist.name
     }
+
+    data[:release_date] = album.released_on if album.released_on
+    data
   end
 
   def transcode
diff --git a/app/models/transcode_command.rb b/app/models/transcode_command.rb
index 5854fde5..3c42d8c6 100644
--- a/app/models/transcode_command.rb
+++ b/app/models/transcode_command.rb
@@ -5,14 +5,16 @@ class TranscodeCommand
     track_title: 'TIT2',
     track_number: 'TRCK',
     album_title: 'TALB',
-    artist_name: 'TPE1'
+    artist_name: 'TPE1',
+    release_date: 'DATE'
   }.freeze
 
   METADATA_KEYS_VS_FLAC_TAGS = {
     track_title: 'TITLE',
     track_number: 'TRACKNUMBER',
     album_title: 'ALBUM',
-    artist_name: 'ARTIST'
+    artist_name: 'ARTIST',
+    release_date: 'DATE'
   }.freeze
 
   def initialize(input, output, format, metadata = {}, image = nil)
diff --git a/test/models/track_test.rb b/test/models/track_test.rb
index 3782c642..b9342dd0 100644
--- a/test/models/track_test.rb
+++ b/test/models/track_test.rb
@@ -103,6 +103,16 @@ class TrackTest < ActiveSupport::TestCase
     assert_equal track.number, metadata[:track_number]
     assert_equal track.album.title, metadata[:album_title]
     assert_equal track.album.artist.name, metadata[:artist_name]
+    assert_not metadata.key?(:release_date)
+  end
+
+  test '#metadata when album has released_on' do
+    album = create(:album, released_on: Time.zone.today)
+    track = create(:track, album:)
+
+    metadata = track.metadata
+
+    assert_equal track.album.released_on, metadata[:release_date]
   end
 
   test '#number' do
diff --git a/test/models/transcode_command_test.rb b/test/models/transcode_command_test.rb
index 26a3593d..11508446 100644
--- a/test/models/transcode_command_test.rb
+++ b/test/models/transcode_command_test.rb
@@ -47,7 +47,8 @@ class TranscodeCommandTest < ActiveSupport::TestCase
       track_title: 'track-title',
       track_number: 'track-number',
       album_title: 'album-title',
-      artist_name: 'artist-name'
+      artist_name: 'artist-name',
+      release_date: 'release-date'
     }
     command_string = TranscodeCommand.new(@input, @output, :mp3v0, metadata).generate
     assert_contains_pair(command_string, ['-write_id3v2', '1'])
@@ -56,6 +57,7 @@ class TranscodeCommandTest < ActiveSupport::TestCase
     assert_contains_pair(command_string, ['-metadata', 'TRCK="track-number"'])
     assert_contains_pair(command_string, ['-metadata', 'TALB="album-title"'])
     assert_contains_pair(command_string, ['-metadata', 'TPE1="artist-name"'])
+    assert_contains_pair(command_string, ['-metadata', 'DATE="release-date"'])
   end
 
   test 'adds metadata tags for FLAC format' do
@@ -63,13 +65,15 @@ class TranscodeCommandTest < ActiveSupport::TestCase
       track_title: 'track-title',
       track_number: 'track-number',
       album_title: 'album-title',
-      artist_name: 'artist-name'
+      artist_name: 'artist-name',
+      release_date: 'release-date'
     }
     command_string = TranscodeCommand.new(@input, @output, :flac, metadata).generate
     assert_contains_pair(command_string, ['-metadata', 'TITLE="track-title"'])
     assert_contains_pair(command_string, ['-metadata', 'TRACKNUMBER="track-number"'])
     assert_contains_pair(command_string, ['-metadata', 'ALBUM="album-title"'])
     assert_contains_pair(command_string, ['-metadata', 'ARTIST="artist-name"'])
+    assert_contains_pair(command_string, ['-metadata', 'DATE="release-date"'])
   end
 
   test 'transcodes audio to mp3 using libmp3lame codec highest audio quality' do