extract TopicNotifier class from topic

extract TopicNotifier class from topic

diff --git a/app/controllers/topics_controller.rb b/app/controllers/topics_controller.rb
index f8d3585f3e..50ccc67abf 100644
--- a/app/controllers/topics_controller.rb
+++ b/app/controllers/topics_controller.rb
@@ -203,7 +203,7 @@ class TopicsController < ApplicationController
     @topic = Topic.where(id: params[:topic_id].to_i).first
     guardian.ensure_can_see!(@topic)
 
-    @topic.toggle_mute(current_user, v)
+    @topic.toggle_mute(current_user)
     render nothing: true
   end
 
diff --git a/app/models/topic.rb b/app/models/topic.rb
index 9563ddc2ec..ef15c0316f 100644
--- a/app/models/topic.rb
+++ b/app/models/topic.rb
@@ -112,9 +112,7 @@ class Topic < ActiveRecord::Base
 
   after_create do
     changed_to_category(category)
-    TopicUser.change(user_id, id,
-                     notification_level: TopicUser.notification_levels[:watching],
-                     notifications_reason_id: TopicUser.notification_reasons[:created_topic])
+    notifier.created_topic! user_id
     if archetype == Archetype.private_message
       DraftSequence.next!(user, Draft::NEW_PRIVATE_MESSAGE)
     else
@@ -162,10 +160,7 @@ class Topic < ActiveRecord::Base
   end
 
   def sanitize_title
-    if self.title.present?
-      self.title = sanitize(title, tags: [], attributes: [])
-      self.title.strip!
-    end
+    self.title = sanitize(title.to_s, tags: [], attributes: []).strip.presence
   end
 
   def new_version_required?
@@ -641,11 +636,6 @@ class Topic < ActiveRecord::Base
     TopicUser.where('starred_at > ?', sinceDaysAgo.days.ago).group('date(starred_at)').order('date(starred_at)').count
   end
 
-  # Enable/disable the mute on the topic
-  def toggle_mute(user, muted)
-    TopicUser.change(user, self.id, notification_level: muted?(user) ? TopicUser.notification_levels[:regular] : TopicUser.notification_levels[:muted] )
-  end
-
   def slug
     unless slug = read_attribute(:slug)
       return '' unless title.present?
@@ -661,17 +651,17 @@ class Topic < ActiveRecord::Base
   end
 
   def title=(t)
-    slug = ""
-    slug = (Slug.for(t).presence || "topic") if t.present?
+    slug = (Slug.for(t.to_s).presence || "topic")
     write_attribute(:slug, slug)
     write_attribute(:title,t)
   end
 
+  # NOTE: These are probably better off somewhere else.
+  #       Having a model know about URLs seems a bit strange.
   def last_post_url
     "/t/#{slug}/#{id}/#{posts_count}"
   end
 
-
   def self.url(id, slug, post_number=nil)
     url = "#{Discourse.base_url}/t/#{slug}/#{id}"
     url << "/#{post_number}" if post_number.to_i > 1
@@ -684,12 +674,6 @@ class Topic < ActiveRecord::Base
     url
   end
 
-  def muted?(user)
-    return false unless user && user.id
-    tu = topic_users.where(user_id: user.id).first
-    tu && tu.notification_level == TopicUser.notification_levels[:muted]
-  end
-
   def clear_pin_for(user)
     return unless user.present?
     TopicUser.change(user.id, id, cleared_pinned_at: Time.now)
@@ -703,21 +687,36 @@ class Topic < ActiveRecord::Base
     "#{Draft::EXISTING_TOPIC}#{id}"
   end
 
+  def notifier
+    @topic_notifier ||= TopicNotifier.new(self)
+  end
+
   # notification stuff
   def notify_watch!(user)
-    TopicUser.change(user, id, notification_level: TopicUser.notification_levels[:watching])
+    notifier.watch! user
   end
 
   def notify_tracking!(user)
-    TopicUser.change(user, id, notification_level: TopicUser.notification_levels[:tracking])
+    notifier.tracking! user
   end
 
   def notify_regular!(user)
-    TopicUser.change(user, id, notification_level: TopicUser.notification_levels[:regular])
+    notifier.regular! user
   end
 
   def notify_muted!(user)
-    TopicUser.change(user, id, notification_level: TopicUser.notification_levels[:muted])
+    notifier.muted! user
+  end
+
+  def muted?(user)
+    if user && user.id
+      notifier.muted?(user.id)
+    end
+  end
+
+  # Enable/disable the mute on the topic
+  def toggle_mute(user_id)
+    notifier.toggle_mute user_id
   end
 
   def auto_close_days=(num_days)
diff --git a/app/models/topic_notifier.rb b/app/models/topic_notifier.rb
new file mode 100644
index 0000000000..5ac1de2ed7
--- /dev/null
+++ b/app/models/topic_notifier.rb
@@ -0,0 +1,42 @@
+class TopicNotifier
+  def initialize(topic)
+    @topic = topic
+  end
+
+  { :watch!    => :watching,
+    :tracking! => :tracking,
+    :regular!  => :regular,
+    :muted!    => :muted }.each_pair do |method_name, level|
+
+    define_method method_name do |user_id|
+      change_level user_id, level
+    end
+
+  end
+
+  def created_topic!(user_id)
+    change_level user_id, :watching, :created_topic
+  end
+
+  # Enable/disable the mute on the topic
+  def toggle_mute(user_id)
+    change_level user_id, (muted?(user_id) ? levels[:regular] : levels[:muted])
+  end
+
+  def muted?(user_id)
+    tu = @topic.topic_users.where(user_id: user_id).first
+    tu && tu.notification_level == levels[:muted]
+  end
+
+  private
+
+  def levels
+    @notification_levels ||= TopicUser.notification_levels
+  end
+
+  def change_level(user_id, level, reason=nil)
+    attrs = {notification_level: levels[level]}
+    attrs.merge!(notifications_reason_id: TopicUser.notification_reasons[reason]) if reason
+    TopicUser.change(user_id, @topic.id, attrs)
+  end
+end
diff --git a/spec/controllers/topics_controller_spec.rb b/spec/controllers/topics_controller_spec.rb
index 01d9f531df..ff790c9fc1 100644
--- a/spec/controllers/topics_controller_spec.rb
+++ b/spec/controllers/topics_controller_spec.rb
@@ -282,12 +282,12 @@ describe TopicsController do
       end
 
       it "changes the user's starred flag when the parameter is present" do
-        Topic.any_instance.expects(:toggle_mute).with(@topic.user, true)
+        Topic.any_instance.expects(:toggle_mute).with(@topic.user)
         xhr :put, :mute, topic_id: @topic.id, starred: 'true'
       end
 
       it "removes the user's starred flag when the parameter is not true" do
-        Topic.any_instance.expects(:toggle_mute).with(@topic.user, false)
+        Topic.any_instance.expects(:toggle_mute).with(@topic.user)
         xhr :put, :unmute, topic_id: @topic.id, starred: 'false'
       end

GitHub sha: d7817cf3