check for recently submitted urls before showing the story submission page

this is already done after submitting, which turns it into an
upvote, but now it will catch it when hitting the page from the
bookmarklet so the user doesn't have to fill out tags and stuff
first just to find out it's already submitted.

since this requires no confirmation, don't count it as an upvote
automatically, just redirect to the story page

app/controllers/stories_controller.rb

@@ -87,6 +87,13 @@ class StoriesController < ApplicationController
     if params[:url].present?
       @story.url = params[:url]
 
+      # if this story was already submitted, don't bother the user filling out
+      # tags and stuff, just redirect them right away
+      if s = Story.find_recent_similar_by_url(@story.url)
+        flash[:success] = "This URL has already been submitted recently."
+        return redirect_to s.comments_url
+      end
+
       if params[:title].present?
         @story.title = params[:title]
       end