Work in progress, keeping avatars locally

This introduces a new model to store the avatars and 3 uploads per user (gravatar, system and custom)

user can then pick which they want.

app/models/user_avatar.rb

@@ -0,0 +1,53 @@
+require_dependency 'letter_avatar'
+
+class UserAvatar < ActiveRecord::Base
+  MAX_SIZE = 240
+
+  belongs_to :user
+  belongs_to :system_upload, class_name: 'Upload', dependent: :destroy
+  belongs_to :gravatar_upload, class_name: 'Upload', dependent: :destroy
+  belongs_to :custom_upload, class_name: 'Upload', dependent: :destroy
+
+  def contains_upload?(id)
+    system_upload_id == id || gravatar_upload_id == id || custom_upload_id == id
+  end
+
+  # updates the letter based avatar
+  def update_system_avatar!
+    system_upload.destroy! if system_upload
+    file = File.open(LetterAvatar.generate(user.username, MAX_SIZE), "r")
+    self.system_upload = Upload.create_for(user_id, file, "avatar.png", file.size)
+    save!
+  end
+
+  def update_gravatar!
+    self.last_gravatar_download_attempt = Time.new
+    gravatar_url = "http://www.gravatar.com/avatar/#{user.email_hash}.png?s=500&d=404"
+    tempfile = FileHelper.download(gravatar_url, 1.megabyte, "gravatar")
+
+    upload = Upload.create_for(user.id, tempfile, 'gravatar.png', File.size(tempfile.path))
+
+    gravatar_upload.destroy! if gravatar_upload
+    self.gravatar_upload = upload
+    save!
+  rescue OpenURI::HTTPError
+    save!
+  ensure
+    tempfile.unlink if tempfile
+  end
+
+end
+
+# == Schema Information
+#
+# Table name: user_avatars
+#
+#  id                             :integer          not null, primary key
+#  user_id                        :integer          not null
+#  system_upload_id               :integer
+#  custom_upload_id               :integer
+#  gravatar_upload_id             :integer
+#  last_gravatar_download_attempt :datetime
+#  created_at                     :datetime
+#  updated_at                     :datetime
+#