3 files changed, 54 insertions, 0 deletions

diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index cb238c15ed8..8868e818daa 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -6,6 +6,7 @@
 #
 module Issuable
   extend ActiveSupport::Concern
+  include Mentionable
 
   included do
     belongs_to :project
@@ -96,4 +97,18 @@ module Issuable
   def votes_count
     upvotes + downvotes
   end
+
+  # Return all users participating on the discussion
+  def participants
+    users = []
+    users << author
+    users << assignee if is_assigned?
+    mentions = []
+    mentions << self.mentioned_users
+    notes.each do |note|
+      users << note.author
+      mentions << note.mentioned_users
+    end
+    users.concat(mentions.reduce([], :|)).uniq
+  end
 end
diff --git a/app/models/concerns/mentionable.rb b/app/models/concerns/mentionable.rb
new file mode 100644
index 00000000000..f22070f8504
--- /dev/null
+++ b/app/models/concerns/mentionable.rb
@@ -0,0 +1,37 @@
+# == Mentionable concern
+#
+# Contains common functionality shared between Issues and Notes
+#
+# Used by Issue, Note
+#
+module Mentionable
+  extend ActiveSupport::Concern
+
+  def mentioned_users
+    users = []
+    return users if mentionable_text.blank?
+    has_project = self.respond_to? :project
+    matches = mentionable_text.scan(/@[a-zA-Z][a-zA-Z0-9_\-\.]*/)
+    matches.each do |match|
+      identifier = match.delete "@"
+      if has_project
+        id = project.users_projects.joins(:user).where(users: { username: identifier }).pluck(:user_id).first
+      else
+        id = User.where(username: identifier).pluck(:id).first
+      end
+      users << User.find(id) unless id.blank?
+    end
+    users.uniq
+  end
+
+  def mentionable_text
+    if self.class == Issue
+      description
+    elsif self.class == Note
+      note
+    else
+      nil
+    end
+  end
+
+end
diff --git a/app/models/note.rb b/app/models/note.rb
index c2e664d1bcd..c23aab03bcc 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -19,6 +19,8 @@ require 'carrierwave/orm/activerecord'
 require 'file_size_validator'
 
 class Note < ActiveRecord::Base
+  include Mentionable
+
   attr_accessible :note, :noteable, :noteable_id, :noteable_type, :project_id,
                   :attachment, :line_code, :commit_id