remove dead code in track extensions

for iOS, it'll autodiscover the captions in the HLS stream when the viewer
is in its standard full-screen mode. the track extensions code that grabs
the HLS stream's WebVTT is thus unnecessary. this commits separates it out
in case it becomes useful in the future.

Gemfile

@@ -10,7 +10,6 @@ gem 'berkeley_library-docker', '~> 0.2.0'
 gem 'berkeley_library-logging', '~> 0.2'
 gem 'browser', '~> 4.2'
 gem 'jbuilder', '~> 2.7'
-gem 'm3u8', '~> 0.8.2'
 gem 'non-stupid-digest-assets', '~> 1.0' # Allow static pages (e.g. 404.html) to link to compiled assets
 gem 'omniauth-cas', '~> 2.0'
 gem 'puma', '~> 5.3', '>= 5.3.1'

Gemfile.lock

@@ -149,7 +149,6 @@ GEM
     loofah (2.21.4)
       crass (~> 1.0.2)
       nokogiri (>= 1.12.0)
-    m3u8 (0.8.2)
     mail (2.8.1)
       mini_mime (>= 0.1.1)
       net-imap
@@ -370,7 +369,6 @@ DEPENDENCIES
   dotenv-rails
   jbuilder (~> 2.7)
   listen (>= 3.0)
-  m3u8 (~> 0.8.2)
   non-stupid-digest-assets (~> 1.0)
   omniauth-cas (~> 2.0)
   puma (~> 5.3, >= 5.3.1)

lib/av_player/track_extensions.rb

@@ -5,7 +5,7 @@
 
 module BerkeleyLibrary
   module AV
-    class Track # rubocop:disable Metrics/ClassLength
+    class Track
       include BerkeleyLibrary::Logging
 
       COLLECTION_RE = %r{(^[^/]+)/}
@@ -22,12 +22,6 @@ def hls_uri
         @hls_uri ||= build_hls_uri
       end
 
-      def hls_vtt_uri
-        return @hls_vtt_uri if instance_variable_defined?(:@hls_vtt_uri)
-
-        @hls_vtt_uri ||= find_hls_vtt_uri
-      end
-
       def mpeg_dash_uri
         return @mpeg_dash_uri if instance_variable_defined?(:@mpeg_dash_uri)
 
@@ -76,27 +70,6 @@ def build_mpeg_dash_uri
         log_invalid_uri(relative_path, e)
       end
 
-      def find_hls_vtt_uri
-        return unless hls_uri_exists?
-        return unless (hls_manifest_uri = hls_uri)
-        return unless (hls_manifest = do_get(hls_manifest_uri, ignore_errors: true))
-        return unless (subtitle_list_uri = find_hls_subtitle_list_uri(hls_manifest))
-        return unless (hls_subtitle_list = do_get(subtitle_list_uri, ignore_errors: true))
-
-        vtt_playlist = M3u8::Playlist.read(hls_subtitle_list)
-        return unless (hls_vtt_path_relative = vtt_playlist.items.first.segment)
-
-        hls_uri.merge(hls_vtt_path_relative)
-      end
-
-      def find_hls_subtitle_list_uri(manifest)
-        return unless (playlist = M3u8::Playlist.read(manifest))
-        return unless (subtitle_list = playlist.items.find { |p| p.group_id == 'subs' })
-        return unless (subtitle_list_uri = subtitle_list.uri)
-
-        hls_uri.merge(subtitle_list_uri)
-      end
-
       def find_dash_vtt_uri
         return unless (dash_uri = mpeg_dash_uri)
         return unless (dash_manifest = do_get(dash_uri, ignore_errors: true))

spec/lib/av_player/track_extensions_spec.rb

@@ -140,25 +140,6 @@ module AV
           expected_uri = URI.join(AV::Config.wowza_base_uri, expected_vtt_path)
           expect(track.dash_vtt_uri).to eq(expected_uri)
         end
-
-        describe :hls_vtt_uri do
-          it 'returns the HLS VTT URI' do
-            track = Track.new(sort_order: 0, path: 'ROHOVideo/breslin1.mp4')
-            hls_uri = track.hls_uri
-
-            expected_manifest_path = '/ROHOVideo/mp4:breslin1.mp4/playlist.m3u8'
-            expect(hls_uri.path).to eq(expected_manifest_path) # just to be sure
-
-            stub_request(:head, hls_uri).to_return(status: 200)
-            stub_request(:get, hls_uri).to_return(body: File.read('spec/data/breslin1-playlist.m3u8'))
-            subtitle_list_uri = hls_uri.merge('subtitlelist_leng_w289808588.m3u8')
-            stub_request(:get, subtitle_list_uri).to_return(body: File.read('spec/data/subtitlelist_leng_w289808588.m3u8'))
-
-            expected_vtt_path = expected_manifest_path.sub(%r{[^/]+$}, 'subtitlechunk_leng_w289808588_0.webvtt')
-            expected_uri = URI.join(AV::Config.wowza_base_uri, expected_vtt_path)
-            expect(track.hls_vtt_uri).to eq(expected_uri)
-          end
-        end
       end
     end
   end