Improve OS detection

app/decorators/asciicast_decorator.rb

@@ -77,10 +77,12 @@ class AsciicastDecorator < ApplicationDecorator
   private
 
   def os_from_user_agent
-    os_part = user_agent.split(' ')[2]
-    os = os_part.split('/').first
-
-    guess_os(os)
+    if user_agent =~ %r{^asciinema/\d(\.\d+)+ [^/\s]+/[^/\s]+ (.+)$}
+      os = $2.sub('-', '/').split('/').first.sub(/[dD]arwin/, 'OS X')
+      os[0].upcase + os[1..-1]
+    else
+      'unknown'
+    end
   end
 
   def os_from_uname

spec/decorators/asciicast_decorator_spec.rb

@@ -22,6 +22,16 @@ describe AsciicastDecorator do
         it { should == 'Linux' }
       end
 
+      context 'and the OS is *BSD (pre-0.9.9 client)' do
+        before do
+          asciicast.user_agent =
+            "asciinema/0.9.8 CPython/2.7.5 " \
+            "FreeBSD/10.0-RELEASE-p7-amd64-64bit-ELF"
+        end
+
+        it { should == 'FreeBSD' }
+      end
+
       context 'and the OS is Linux (0.9.9+ client)' do
         before do
           asciicast.user_agent =