working implementation of the mime-types gem

Gemfile

@@ -10,3 +10,4 @@ gem "appraisal"
 gem "fog"
 gem "bundler"
 gem "cocaine"
+gem "mime-types"

Gemfile.lock

@@ -69,6 +69,7 @@ DEPENDENCIES
   bundler
   cocaine
   fog
+  mime-types
   mocha
   rake
   shoulda

lib/paperclip/upfile.rb

@@ -6,22 +6,26 @@ module Paperclip
 
     # Infer the MIME-type of the file from the extension.
     def content_type
-      type = (self.original_filename.match(/\.(\w+)$/)[1] rescue "octet-stream").downcase
-      case type
-      when %r"jp(e|g|eg)"            then "image/jpeg"
-      when %r"tiff?"                 then "image/tiff"
-      when %r"png", "gif", "bmp"     then "image/#{type}"
-      when %r"svg"                   then "image/svg+xml"
-      when "txt"                     then "text/plain"
-      when %r"html?"                 then "text/html"
-      when "js"                      then "application/js"
-      when "csv", "xml", "css"       then "text/#{type}"
+      types = MIME::Types.type_for(self.original_filename)
+      if types.length == 0
+        type_from_file_command
+      elsif types.length == 1
+        types.first.content_type
       else
-        # On BSDs, `file` doesn't give a result code of 1 if the file doesn't exist.
-        content_type = (Paperclip.run("file", "-b --mime-type :file", :file => self.path).split(':').last.strip rescue "application/x-#{type}")
-        content_type = "application/x-#{type}" if content_type.match(/\(.*?\)/)
-        content_type
+        iterate_over_array_to_find_best_option(types)
+      end
+    end
+
+    def iterate_over_array_to_find_best_option(types)
+      types.reject {|type| type.content_type.match(/\/x-/) }.first
     end
+
+    def type_from_file_command
+    #  On BSDs, `file` doesn't give a result code of 1 if the file doesn't exist.
+      type = (self.original_filename.match(/\.(\w+)$/)[1] rescue "octet-stream").downcase
+      mime_type = (Paperclip.run("file", "-b --mime-type :file", :file => self.path).split(':').last.strip rescue "application/x-#{type}")
+      mime_type = "application/x-#{type}" if mime_type.match(/\(.*?\)/)
+      mime_type
     end
 
     # Returns the file's normal name.

test/helper.rb

@@ -8,6 +8,7 @@ require 'mocha'
 require 'active_record'
 require 'active_record/version'
 require 'active_support'
+require 'mime/types'
 
 puts "Testing against version #{ActiveRecord::VERSION::STRING}"
 

test/upfile_test.rb

@@ -10,9 +10,9 @@ class UpfileTest < Test::Unit::TestCase
     %w(txt)          => 'text/plain',
     %w(htm html)     => 'text/html',
     %w(csv)          => 'text/csv',
-    %w(xml)          => 'text/xml',
+    %w(xml)          => 'application/xml',
     %w(css)          => 'text/css',
-    %w(js)           => 'application/js',
+    %w(js)           => 'application/javascript',
     %w(foo)          => 'application/x-foo'
   }.each do |extensions, content_type|
     extensions.each do |extension|