return latest conversation messages in stream item api

test plan:
* send a message to another user
* make a couple replies
* view /api/v1/users/self/activity_stream
* it should include 3 of the latest messages

closes #COMMS-1374

Change-Id: Iccff8c8a665ee8883aa61b7ebafaaceaf3060f41
Reviewed-on: https://gerrit.instructure.com/160748
Reviewed-by: Steven Burnett <sburnett@instructure.com>
Product-Review: Steven Burnett <sburnett@instructure.com>
QA-Review: Steven Burnett <sburnett@instructure.com>
Tested-by: Jenkins

app/models/conversation.rb

@@ -29,6 +29,11 @@ class Conversation < ActiveRecord::Base
 
   validates_length_of :subject, :maximum => maximum_string_length, :allow_nil => true
 
+  attr_accessor :latest_messages_from_stream_item
+  self.send_to_stream_update_block = lambda { |conversation|
+    User.where(:id => conversation.conversation_message_participants.distinct.except(:order).pluck(:user_id)).to_a
+  }
+
   def participants(reload = false)
     if !@participants || reload
       Conversation.preload_participants([self])

app/models/conversation_participant.rb

@@ -348,6 +348,7 @@ class ConversationParticipant < ActiveRecord::Base
       update_cached_data
       save
     end
+    self.conversation.queue_update_stream_items
   end
 
   def update_attributes(hash)

app/models/stream_item.rb

@@ -61,6 +61,8 @@ class StreamItem < ActiveRecord::Base
       res.total_root_discussion_entries = data.delete(:total_root_discussion_entries)
     when 'Submission'
       data['body'] = nil
+    when 'Conversation'
+      res.latest_messages_from_stream_item = data.delete(:latest_messages)
     end
     if data.has_key?('users')
       users = data.delete('users')
@@ -125,6 +127,18 @@ class StreamItem < ActiveRecord::Base
     if res['participant_count'] <= 8
       res['participants'] = conversation.participants.map{ |u| prepare_user(u) }
     end
+
+    messages = conversation.conversation_messages.human.order(:created_at => :desc).limit(LATEST_ENTRY_LIMIT).to_a.reverse
+    res['latest_messages'] = messages.map do |message|
+      {
+        "id" => message.id,
+        "created_at" => message.created_at,
+        "author_id" => message.author_id,
+        "message" => message.body.present? ? message.body[0, 4.kilobytes] : "",
+        "participating_user_ids" => message.conversation_message_participants.active.pluck(:user_id).sort
+      }
+    end
+
     res
   end
 
@@ -152,7 +166,7 @@ class StreamItem < ActiveRecord::Base
     item.try(:destroy)
   end
 
-  ROOT_DISCUSSION_ENTRY_LIMIT = 3
+  LATEST_ENTRY_LIMIT = 3
   def generate_data(object)
     self.context ||= object.try(:context) unless object.is_a?(Message)
 
@@ -161,7 +175,7 @@ class StreamItem < ActiveRecord::Base
       res = object.attributes
       res['user_ids_that_can_see_responses'] = object.user_ids_who_have_posted_and_admins if object.require_initial_post?
       res['total_root_discussion_entries'] = object.root_discussion_entries.active.count
-      res[:root_discussion_entries] = object.root_discussion_entries.active.reverse[0,ROOT_DISCUSSION_ENTRY_LIMIT].reverse.map do |entry|
+      res[:root_discussion_entries] = object.root_discussion_entries.active.order(:created_at => :desc).limit(LATEST_ENTRY_LIMIT).to_a.reverse.map do |entry|
         hash = entry.attributes
         hash['user_short_name'] = entry.user.short_name if entry.user
         hash['message'] = hash['message'][0, 4.kilobytes] if hash['message'].present?
@@ -420,6 +434,10 @@ class StreamItem < ActiveRecord::Base
           res.readonly!
         end
       end
+    when Conversation
+      if res.latest_messages_from_stream_item
+        res.latest_messages_from_stream_item.select!{|m| m["participating_user_ids"].include?(viewing_user_id)}
+      end
     end
 
     res

lib/api/v1/stream_item.rb

@@ -58,7 +58,7 @@ module Api::V1::StreamItem
         hash['total_root_discussion_entries'] = data.total_root_discussion_entries
         hash['require_initial_post'] = data.require_initial_post
         hash['user_has_posted'] = data.respond_to?(:user_has_posted) ? data.user_has_posted : nil
-        hash['root_discussion_entries'] = (data.root_discussion_entries || [])[0,StreamItem::ROOT_DISCUSSION_ENTRY_LIMIT].map do |entry|
+        hash['root_discussion_entries'] = (data.root_discussion_entries || [])[0,StreamItem::LATEST_ENTRY_LIMIT].map do |entry|
           {
             'user' => {
               'user_id' => entry.user_id,
@@ -75,6 +75,7 @@ module Api::V1::StreamItem
         hash['private'] = data.private
         hash['participant_count'] = data.participant_count
         hash['html_url'] = conversation_url(stream_item.asset_id)
+        hash['latest_messages'] = data.latest_messages_from_stream_item if data.latest_messages_from_stream_item.present?
       when 'Message'
         hash['message_id'] = stream_item.asset_id
         # this type encompasses a huge number of different types of messages,

spec/apis/v1/stream_items_api_spec.rb

@@ -295,8 +295,8 @@ describe UsersController, type: :request do
   it "should format Conversation" do
     @sender = User.create!(:name => 'sender')
     @conversation = Conversation.initiate([@user, @sender], false)
-    @conversation.add_message(@sender, "hello")
-    @message = @conversation.conversation_messages.last
+    @message = @conversation.add_message(@sender, "hello")
+
     json = api_call(:get, "/api/v1/users/activity_stream.json",
                     { :controller => "users", :action => "activity_stream", :format => 'json' }).first
     expect(json).to eq({
@@ -308,12 +308,20 @@ describe UsersController, type: :request do
       'updated_at' => StreamItem.last.updated_at.as_json,
       'title' => nil,
       'message' => nil,
-
       'private' => false,
       'html_url' => "http://www.example.com/conversations/#{@conversation.id}",
-
-      'participant_count' => 2
+      'participant_count' => 2,
+      'latest_messages' => [
+        {'id' => @message.id, "created_at" => @message.created_at.as_json,
+          "author_id" => @sender.id, "message" => "hello",
+          "participating_user_ids" => [@user.id, @sender.id]}]
     })
+
+    @conversation.conversation_participants.where(:user_id => @user).first.remove_messages(@message)
+    # should update the latest messages and not show them the one they can't see anymore
+    json = api_call(:get, "/api/v1/users/activity_stream.json",
+      { :controller => "users", :action => "activity_stream", :format => 'json' }).first
+    expect(json["latest_messages"]).to be_blank
   end
 
   it "should format Message" do