add #387 rssフィードにmp3のファイル情報を追加

podcastsに推奨されていたので、ファイルの情報を追加しました。

Author: odlovesq

Gemfile

@@ -37,6 +37,9 @@ gem 'rack-attack'
 gem 'google_drive'
 gem 'lazy_high_charts'
 
+# For RSS feed
+gem 'ruby-mp3info', :require => 'mp3info'
+
 group :development do
   gem 'web-console'
   gem 'spring'

Gemfile.lock

@@ -285,6 +285,7 @@ GEM
     rspec-retry (0.6.1)
       rspec-core (> 3.3)
     rspec-support (3.8.0)
+    ruby-mp3info (0.8.10)
     ruby_dep (1.5.0)
     ruby_parser (3.12.0)
       sexp_processor (~> 4.9)
@@ -428,6 +429,7 @@ DEPENDENCIES
   rake
   rspec-rails (~> 3.5)
   rspec-retry
+  ruby-mp3info
   sass-rails
   scrivito (~> 1.15.0)
   scrivito_section_widgets

app/models/podcast.rb

@@ -28,6 +28,20 @@ def exists?(offset: 0)
     File.exists?("#{DIR_PATH}/#{self.filename.to_i + offset}.md")
   end
 
+  def filesize
+    @size ||= File.size("#{DIR_PATH}/#{self.filename}.mp3")
+  end
+
+  def duration
+    return @duration if @duration
+
+    path = "#{DIR_PATH}/#{self.filename}.mp3"
+    open_opts = { :encoding => 'utf-8' }
+    Mp3Info.open(path, open_opts) do |mp3info|
+      @duration = Time.at(mp3info.length).utc.strftime('%H:%M:%S')
+    end
+  end
+
   def title
     @title ||= exists? ? self.content.lines.first[2..-1].strip.gsub('<br>', '') : ''
   end

app/views/podcasts/feed.rss.builder

@@ -23,7 +23,8 @@ xml.rss :version => "2.0", "xmlns:itunes" => "http://www.itunes.com/dtds/Podcast
         xml.guid({:isPermaLink => "false"}, @domainname + episode.url)
         xml.itunes :explicit, "clean"
         xml.pubDate episode.published_at.rfc2822
-        xml.enclosure({:url => @domainname + episode.url + ".mp3", :type => "audio/mpeg"})
+        xml.enclosure({:url => @domainname + episode.url + ".mp3", :length => episode.filesize, :type => "audio/mpeg"})
+        xml.itunes :duration, episode.duration
       end
     end
   end