posts.rb: vote on behalf of correct user when moving favorites.

Bug: when an approver moves the favorites of a post, each favorite is
removed from the child post and added to the parent post. For gold+
users, this triggers an upvote, but these upvotes were performed by the
approver rather than the favoriter.

app/models/post.rb

@@ -943,7 +943,7 @@ class Post < ActiveRecord::Base
 
     def add_favorite!(user)
       Favorite.add(self, user)
-      vote!("up") if CurrentUser.is_gold?
+      vote!("up", user) if user.is_gold?
     rescue PostVote::Error
     end
 
@@ -953,7 +953,7 @@ class Post < ActiveRecord::Base
 
     def remove_favorite!(user)
       Favorite.remove(self, user)
-      unvote! if CurrentUser.is_gold?
+      unvote!(user) if user.is_gold?
     rescue PostVote::Error
     end
 
@@ -1063,27 +1063,25 @@ class Post < ActiveRecord::Base
       !PostVote.exists?(:user_id => user.id, :post_id => id)
     end
 
-    def vote!(score)
-      unless CurrentUser.is_voter?
+    def vote!(score, voter = CurrentUser.user)
+      unless voter.is_voter?
         raise PostVote::Error.new("You do not have permission to vote")
       end
 
-      unless can_be_voted_by?(CurrentUser.user)
+      unless can_be_voted_by?(voter)
         raise PostVote::Error.new("You have already voted for this post")
       end
 
-      PostVote.create!(:post_id => id, :score => score)
+      votes.create!(user: voter, score: vote)
       reload # PostVote.create modifies our score. Reload to get the new score.
     end
 
-    def unvote!
-      if can_be_voted_by?(CurrentUser.user)
+    def unvote!(voter = CurrentUser.user)
+      if can_be_voted_by?(voter)
         raise PostVote::Error.new("You have not voted for this post")
       else
-        vote = PostVote.where("post_id = ? and user_id = ?", id, CurrentUser.user.id).first
-        vote.destroy
-
-        self.reload
+        votes.where(user: voter).destroy_all
+        reload
       end
     end
   end

app/models/post_vote.rb

@@ -35,7 +35,7 @@ class PostVote < ActiveRecord::Base
   end
 
   def initialize_user
-    self.user_id = CurrentUser.user.id
+    self.user_id ||= CurrentUser.user.id
   end
 
   def update_post_on_destroy

app/models/user.rb

@@ -77,6 +77,7 @@ class User < ActiveRecord::Base
   #after_create :notify_sock_puppets
   has_many :feedback, :class_name => "UserFeedback", :dependent => :destroy
   has_many :posts, :foreign_key => "uploader_id"
+  has_many :post_votes
   has_many :bans, lambda {order("bans.id desc")}
   has_one :recent_ban, lambda {order("bans.id desc")}, :class_name => "Ban"
   has_one :api_key