refactored user promotion code, related to #1257

app/logical/user_promotion.rb

@@ -0,0 +1,52 @@
+class UserPromotion
+  attr_reader :user, :promoter, :new_level
+
+  def initialize(user, promoter, new_level)
+    @user = user
+    @promoter = promoter
+    @new_level = new_level
+  end
+
+  def promote!
+    user.level = new_level
+    user.inviter_id = promoter.id
+
+    validate
+    create_transaction_log_item
+    create_user_feedback
+
+    user.save
+  end
+
+private
+  
+  def validate
+    # admins can do anything
+    return if promoter.is_admin?
+
+    # can't promote/demote moderators
+    raise User::PrivilegeError if user.is_moderator?
+
+    # can't promote to admin      
+    raise User::PrivilegeError if new_level.to_i >= User::Levels::ADMIN
+  end
+
+  def create_transaction_log_item
+    TransactionLogItem.record_account_upgrade(user)
+  end
+
+  def create_user_feedback
+    if user.level > user.level_was
+      body_prefix = "Promoted"
+    elsif user.level < user.level_was
+      body_prefix = "Demoted"
+    else
+      body_prefix = "Updated"
+    end
+
+    user.feedback.create(
+      :category => "neutral",
+      :body => "#{body_prefix} by #{promoter.name} from #{user.level_string_was} to #{user.level_string}"
+    )
+  end
+end