set maximum time during which comments and stories can be downvoted

always allow a user to "unvote" if they're previously downvoted, but
after a certain number of days, don't accept new downvotes

there isn't really any benefit in downvoting old stuff that is
already off the front pages or on a dead comment thread, other than
to maliciously strip karma for particular users

app/controllers/comments_controller.rb

@@ -150,7 +150,7 @@ class CommentsController < ApplicationController
       return render :text => "invalid reason", :status => 400
     end
 
-    if !@user.can_downvote?
+    if !@user.can_downvote?(comment)
       return render :text => "not permitted to downvote", :status => 400
     end
 
@@ -260,6 +260,12 @@ private
   end
 
   def find_comment
-    Comment.where(:short_id => params[:id]).first
+    comment = Comment.where(:short_id => params[:id]).first
+    if @user && comment
+      comment.current_vote = Vote.where(:user_id => @user.id,
+        :story_id => comment.story_id, :comment_id => comment.id).first
+    end
+
+    comment
   end
 end

app/controllers/stories_controller.rb

@@ -213,7 +213,7 @@ class StoriesController < ApplicationController
       return render :text => "invalid reason", :status => 400
     end
 
-    if !@user.can_downvote?
+    if !@user.can_downvote?(story)
       return render :text => "not permitted to downvote", :status => 400
     end
 
@@ -239,7 +239,13 @@ private
   end
 
   def find_story
-    Story.where(:short_id => params[:story_id]).first
+    story = Story.where(:short_id => params[:story_id]).first
+    if @user && story
+      story.vote = Vote.where(:user_id => @user.id,
+        :story_id => story.id, :comment_id => nil).first.try(:vote)
+    end
+
+    story
   end
 
   def find_user_story

app/models/comment.rb

@@ -20,6 +20,9 @@ class Comment < ActiveRecord::Base
     :deliver_mention_notifications, :log_to_countinual
   after_destroy :unassign_votes
 
+  DOWNVOTABLE_DAYS = 7
+
+  # after this many minutes old, a comment cannot be edited
   MAX_EDIT_MINS = 90
 
   validate do
@@ -278,6 +281,14 @@ class Comment < ActiveRecord::Base
     end
   end
 
+  def is_downvotable?
+    if self.created_at
+      Time.now - self.created_at <= DOWNVOTABLE_DAYS.days
+    else
+      false
+    end
+  end
+
   def is_editable_by_user?(user)
     if user && user.id == self.user_id
       if self.is_moderated?

app/models/story.rb

@@ -10,10 +10,12 @@ class Story < ActiveRecord::Base
   validates_length_of :description, :maximum => (64 * 1024)
   validates_presence_of :user_id
 
+  DOWNVOTABLE_DAYS = 14
+
   # after this many minutes old, a story cannot be edited
   MAX_EDIT_MINS = 30
 
-  # days a story is considered recent
+  # days a story is considered recent, for resubmitting
   RECENT_DAYS = 30
 
   attr_accessor :vote, :already_posted_story, :fetched_content, :previewing,
@@ -220,6 +222,14 @@ class Story < ActiveRecord::Base
       "hotness = '#{self.calculated_hotness}' WHERE id = #{self.id.to_i}")
   end
 
+  def is_downvotable?
+    if self.created_at
+      Time.now - self.created_at <= DOWNVOTABLE_DAYS.days
+    else
+      false
+    end
+  end
+
   def is_editable_by_user?(user)
     if user && user.is_moderator?
       return true

app/models/user.rb

@@ -98,9 +98,26 @@ class User < ActiveRecord::Base
     true
   end
 
-  def can_downvote?
-    # TODO: maybe change this to require a certain level of karma
-    !is_new?
+  def can_downvote?(obj)
+    if is_new?
+      return false
+    elsif obj.is_a?(Story)
+      if obj.is_downvotable?
+        return true
+      elsif obj.vote == -1
+        # user can unvote
+        return true
+      end
+    elsif obj.is_a?(Comment)
+      if obj.is_downvotable?
+        return true
+      elsif obj.current_vote.try(:vote).to_i == -1
+        # user can unvote
+        return true
+      end
+    end
+
+    false
   end
 
   def check_session_token

app/views/comments/_comment.html.erb

@@ -14,7 +14,7 @@ class="comment <%= comment.current_vote ? (comment.current_vote[:vote] == 1 ?
         <%= link_to "", login_url, :class => "upvoter" %>
       <% end %>
       <div class="score"><%= comment.score %></div>
-      <% if @user && @user.can_downvote? %>
+      <% if @user && @user.can_downvote?(comment) %>
         <a class="downvoter"></a>
       <% else %>
         <span class="downvoter downvoter_stub"></span>

app/views/stories/_listdetail.html.erb

@@ -9,7 +9,7 @@ class="story <%= story.vote == 1 ? "upvoted" : (story.vote == -1 ?
       <%= link_to "", login_url, :class => "upvoter" %>
     <% end %>
     <div class="score"><%= story.upvotes - story.downvotes %></div>
-    <% if @user && @user.can_downvote? %>
+    <% if @user && @user.can_downvote?(story) %>
       <a class="downvoter"></a>
     <% else %>
       <span class="downvoter downvoter_stub"></span>