Merge pull request #6 from rll/unread_count_decoupled

Unread comment tracking

api/comment_threads.rb

@@ -3,7 +3,14 @@ get "#{APIPREFIX}/threads" do # retrieve threads by course
 end
 
 get "#{APIPREFIX}/threads/:thread_id" do |thread_id|
-  CommentThread.find(thread_id).to_hash(recursive: bool_recursive).to_json
+  thread = CommentThread.find(thread_id)
+
+  if params["user_id"] and bool_mark_as_read
+    user = User.only([:id, :read_states]).find_by(external_id: params["user_id"])
+    user.mark_as_read(thread) if user
+  end
+
+  thread.to_hash(recursive: bool_recursive, user_id: params["user_id"]).to_json
 end
 
 put "#{APIPREFIX}/threads/:thread_id" do |thread_id|

api/search.rb

@@ -40,7 +40,7 @@ get "#{APIPREFIX}/search/threads" do
     num_pages = results.total_pages
     page = [num_pages, [1, page].max].min
     {
-      collection: results.map{|t| CommentThread.search_result_to_hash(t, recursive: bool_recursive)},
+      collection: results.map{|t| CommentThread.search_result_to_hash(t, recursive: bool_recursive, user_id: params[:user_id])},
       num_pages: num_pages,
       page: page,
     }.to_json

api/users.rb

@@ -44,10 +44,7 @@ get "#{APIPREFIX}/users/:user_id/active_threads" do |user_id|
 end
 
 put "#{APIPREFIX}/users/:user_id" do |user_id|
-  user = User.where(external_id: user_id).first
-  if not user
-    user = User.new(external_id: user_id)
-  end
+  user = User.find_or_create_by(external_id: user_id)
   user.update_attributes(params.slice(*%w[username email default_sort_key]))
   if user.errors.any?
     error 400, user.errors.full_messages.to_json

lib/helpers.rb

@@ -51,6 +51,10 @@ helpers do
     value_to_boolean params["recursive"]
   end
 
+  def bool_mark_as_read
+    value_to_boolean params["mark_as_read"]
+  end
+
   def bool_complete
     value_to_boolean params["complete"]
   end
@@ -79,7 +83,7 @@ helpers do
       cached_results = Sinatra::Application.cache.get(memcached_key)
       if cached_results
         return {
-          collection: cached_results[:collection_ids].map{|id| CommentThread.find(id).to_hash(recursive: bool_recursive)},
+          collection: cached_results[:collection_ids].map{|id| CommentThread.find(id).to_hash(recursive: bool_recursive, user_id: params["user_id"])},
           num_pages: cached_results[:num_pages],
           page: cached_results[:page],
         }.to_json
@@ -119,7 +123,7 @@ helpers do
         Sinatra::Application.cache.set(memcached_key, cached_results, CommentService.config[:cache_timeout][:threads_query].to_i)
       end
       {
-        collection: paged_comment_threads.map{|t| t.to_hash(recursive: bool_recursive)},
+        collection: paged_comment_threads.map{|t| t.to_hash(recursive: bool_recursive, user_id: params["user_id"])},
         num_pages: num_pages,
         page: page,
       }.to_json

models/comment_thread.rb

@@ -165,8 +165,43 @@ class CommentThread < Content
     if params[:recursive]
       doc = doc.merge("children" => root_comments.map{|c| c.to_hash(recursive: true)})
     end
-    doc = doc.merge("comments_count" => comments.count)
+
+    comments_count = comments.count
+
+    if params[:user_id]
+      user = User.find_or_create_by(external_id: params[:user_id])
+      read_state = user.read_states.where(course_id: self.course_id).first
+      last_read_time = read_state.last_read_times[self.id.to_s] if read_state
+      # comments created by the user are excluded in the count
+      # this is rather like a hack but it avoids the following situation:
+      #   when you reply to a thread and while you are editing,
+      #   other people also replied to the thread. Now if we simply
+      #   update the last_read_time, then the other people's replies
+      #   will not be included in the unread_count; if we leave it
+      #   that way, then your own comment will be included in the
+      #   unread count
+      if last_read_time
+        unread_count = self.comments.where(
+            :updated_at => {:$gte => last_read_time},
+            :author_id => {:$ne => params[:user_id]},
+        ).count
+        read = last_read_time >= self.updated_at
+      else
+        unread_count = self.comments.where(:author_id => {:$ne => params[:user_id]}).count
+        read = false
+      end
+    else
+      # If there's no user, say it's unread and all comments are unread
+      unread_count = comments_count
+      read = false
+    end
+
+    doc = doc.merge("unread_comments_count" => unread_count)
+             .merge("read" => read)
+             .merge("comments_count" => comments_count)
+
     doc
+
   end
 
   def self.tag_name_valid?(tag)

models/user.rb

@@ -8,6 +8,7 @@ class User
   field :email, type: String
   field :default_sort_key, type: String, default: "date"
 
+  embeds_many :read_states
   has_many :comments, inverse_of: :author
   has_many :comment_threads, inverse_of: :author
   has_many :activities, class_name: "Notification", inverse_of: :actor
@@ -101,4 +102,23 @@ class User
     subscription
   end
 
+  def mark_as_read(thread)
+    read_state = read_states.find_or_create_by(course_id: thread.course_id)
+    read_state.last_read_times[thread.id] = Time.now.utc
+    read_state.save
+  end
+
+end
+
+class ReadState
+  include Mongoid::Document
+  field :course_id, type: String
+  field :last_read_times, type: Hash, default: {}
+  embedded_in :user
+
+  validates :course_id, uniqueness: true, presence: true
+  
+  def to_hash
+    to_json
+  end
 end