FEATURE: allows to jump to a date in a topic

app/controllers/posts_controller.rb

@@ -12,6 +12,7 @@ class PostsController < ApplicationController
     :show,
     :replies,
     :by_number,
+    :by_date,
     :short_link,
     :reply_history,
     :replyIids,
@@ -249,6 +250,11 @@ class PostsController < ApplicationController
     display_post(post)
   end
 
+  def by_date
+    post = find_post_from_params_by_date
+    display_post(post)
+  end
+
   def reply_history
     post = find_post_from_params
     render_serialized(post.reply_history(params[:max_replies].to_i, guardian), PostSerializer)
@@ -707,6 +713,16 @@ class PostsController < ApplicationController
     find_post_using(by_number_finder)
   end
 
+  def find_post_from_params_by_date
+    by_date_finder = TopicView.new(params[:topic_id], current_user)
+      .filtered_posts
+      .where("created_at >= ?", Time.zone.parse(params[:date]))
+      .order("created_at ASC")
+      .limit(1)
+
+    find_post_using(by_date_finder)
+  end
+
   def find_post_using(finder)
     # Include deleted posts if the user is staff
     finder = finder.with_deleted if current_user.try(:staff?)