Merge branch 'remove-code-duplication'

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

22 files changed, 371 insertions, 434 deletions

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 141e7ba41de..94753093540 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -87,4 +87,3 @@ flay:
   tags:
     - ruby
     - mysql
-  allow_failure: true
diff --git a/app/controllers/concerns/issues_action.rb b/app/controllers/concerns/issues_action.rb
new file mode 100644
index 00000000000..effd4721949
--- /dev/null
+++ b/app/controllers/concerns/issues_action.rb
@@ -0,0 +1,14 @@
+module IssuesAction
+  extend ActiveSupport::Concern
+
+  def issues
+    @issues = get_issues_collection
+    @issues = @issues.page(params[:page]).per(ApplicationController::PER_PAGE)
+    @issues = @issues.preload(:author, :project)
+
+    respond_to do |format|
+      format.html
+      format.atom { render layout: false }
+    end
+  end
+end
diff --git a/app/controllers/concerns/merge_requests_action.rb b/app/controllers/concerns/merge_requests_action.rb
new file mode 100644
index 00000000000..f7a25111db9
--- /dev/null
+++ b/app/controllers/concerns/merge_requests_action.rb
@@ -0,0 +1,9 @@
+module MergeRequestsAction
+  extend ActiveSupport::Concern
+
+  def merge_requests
+    @merge_requests = get_merge_requests_collection
+    @merge_requests = @merge_requests.page(params[:page]).per(ApplicationController::PER_PAGE)
+    @merge_requests = @merge_requests.preload(:author, :target_project)
+  end
+end
diff --git a/app/controllers/dashboard_controller.rb b/app/controllers/dashboard_controller.rb
index b2c1fa4230c..087da935087 100644
--- a/app/controllers/dashboard_controller.rb
+++ b/app/controllers/dashboard_controller.rb
@@ -1,26 +1,12 @@
 class DashboardController < Dashboard::ApplicationController
+  include IssuesAction
+  include MergeRequestsAction
+
   before_action :event_filter, only: :activity
   before_action :projects, only: [:issues, :merge_requests]
 
   respond_to :html
 
-  def merge_requests
-    @merge_requests = get_merge_requests_collection
-    @merge_requests = @merge_requests.page(params[:page]).per(PER_PAGE)
-    @merge_requests = @merge_requests.preload(:author, :target_project)
-  end
-
-  def issues
-    @issues = get_issues_collection
-    @issues = @issues.page(params[:page]).per(PER_PAGE)
-    @issues = @issues.preload(:author, :project)
-
-    respond_to do |format|
-      format.html
-      format.atom { render layout: false }
-    end
-  end
-
   def activity
     @last_push = current_user.recent_push
 
diff --git a/app/controllers/groups_controller.rb b/app/controllers/groups_controller.rb
index fb4eb094f27..fb26a4e6fc3 100644
--- a/app/controllers/groups_controller.rb
+++ b/app/controllers/groups_controller.rb
@@ -1,4 +1,7 @@
 class GroupsController < Groups::ApplicationController
+  include IssuesAction
+  include MergeRequestsAction
+
   skip_before_action :authenticate_user!, only: [:show, :issues, :merge_requests]
   respond_to :html
   before_action :group, except: [:new, :create]
@@ -53,23 +56,6 @@ class GroupsController < Groups::ApplicationController
     end
   end
 
-  def merge_requests
-    @merge_requests = get_merge_requests_collection
-    @merge_requests = @merge_requests.page(params[:page]).per(PER_PAGE)
-    @merge_requests = @merge_requests.preload(:author, :target_project)
-  end
-
-  def issues
-    @issues = get_issues_collection
-    @issues = @issues.page(params[:page]).per(PER_PAGE)
-    @issues = @issues.preload(:author, :project)
-
-    respond_to do |format|
-      format.html
-      format.atom { render layout: false }
-    end
-  end
-
   def edit
   end
 
diff --git a/app/helpers/diff_helper.rb b/app/helpers/diff_helper.rb
index f47d5c4c742..b715ecd85d2 100644
--- a/app/helpers/diff_helper.rb
+++ b/app/helpers/diff_helper.rb
@@ -136,25 +136,11 @@ module DiffHelper
   end
 
   def inline_diff_btn
-    params_copy = params.dup
-    params_copy[:view] = 'inline'
-    # Always use HTML to handle case where JSON diff rendered this button
-    params_copy.delete(:format)
-
-    link_to url_for(params_copy), id: "inline-diff-btn", class: (diff_view == 'inline' ? 'btn active' : 'btn') do
-      'Inline'
-    end
+    diff_btn('Inline', 'inline', diff_view == 'inline')
   end
 
   def parallel_diff_btn
-    params_copy = params.dup
-    params_copy[:view] = 'parallel'
-    # Always use HTML to handle case where JSON diff rendered this button
-    params_copy.delete(:format)
-
-    link_to url_for(params_copy), id: "parallel-diff-btn", class: (diff_view == 'parallel' ? 'btn active' : 'btn') do
-      'Side-by-side'
-    end
+    diff_btn('Side-by-side', 'parallel', diff_view == 'parallel')
   end
 
   def submodule_link(blob, ref, repository = @repository)
@@ -191,4 +177,18 @@ module DiffHelper
   def editable_diff?(diff)
     !diff.deleted_file && @merge_request && @merge_request.source_project
   end
+
+  private
+
+  def diff_btn(title, name, selected)
+    params_copy = params.dup
+    params_copy[:view] = name
+
+    # Always use HTML to handle case where JSON diff rendered this button
+    params_copy.delete(:format)
+
+    link_to url_for(params_copy), id: "#{name}-diff-btn", class: (selected ? 'btn active' : 'btn') do
+      title
+    end
+  end
 end
diff --git a/app/helpers/gitlab_markdown_helper.rb b/app/helpers/gitlab_markdown_helper.rb
index 65813482120..98c6d9d5d2e 100644
--- a/app/helpers/gitlab_markdown_helper.rb
+++ b/app/helpers/gitlab_markdown_helper.rb
@@ -46,39 +46,13 @@ module GitlabMarkdownHelper
   end
 
   def markdown(text, context = {})
-    return "" unless text.present?
-
-    context.reverse_merge!(
-      path:         @path,
-      pipeline:     :default,
-      project:      @project,
-      project_wiki: @project_wiki,
-      ref:          @ref
-    )
-
-    user = current_user if defined?(current_user)
-
-    html = Gitlab::Markdown.render(text, context)
-    Gitlab::Markdown.post_process(html, pipeline: context[:pipeline], project: @project, user: user)
+    process_markdown(text, context)
   end
 
   # TODO (rspeicher): Remove all usages of this helper and just call `markdown`
   # with a custom pipeline depending on the content being rendered
   def gfm(text, options = {})
-    return "" unless text.present?
-
-    options.reverse_merge!(
-      path:         @path,
-      pipeline:     :default,
-      project:      @project,
-      project_wiki: @project_wiki,
-      ref:          @ref
-    )
-
-    user = current_user if defined?(current_user)
-
-    html = Gitlab::Markdown.gfm(text, options)
-    Gitlab::Markdown.post_process(html, pipeline: options[:pipeline], project: @project, user: user)
+    process_markdown(text, options, :gfm)
   end
 
   def asciidoc(text)
@@ -204,4 +178,26 @@ module GitlabMarkdownHelper
       ''
     end
   end
+
+  def process_markdown(text, options, method = :markdown)
+    return "" unless text.present?
+
+    options.reverse_merge!(
+      path:         @path,
+      pipeline:     :default,
+      project:      @project,
+      project_wiki: @project_wiki,
+      ref:          @ref
+    )
+
+    user = current_user if defined?(current_user)
+
+    html = if method == :gfm
+             Gitlab::Markdown.gfm(text, options)
+           else
+             Gitlab::Markdown.render(text, options)
+           end
+
+    Gitlab::Markdown.post_process(html, pipeline: options[:pipeline], project: @project, user: user)
+  end
 end
diff --git a/app/helpers/namespaces_helper.rb b/app/helpers/namespaces_helper.rb
index b3132a1f3ba..e7f3cb21038 100644
--- a/app/helpers/namespaces_helper.rb
+++ b/app/helpers/namespaces_helper.rb
@@ -17,15 +17,6 @@ module NamespacesHelper
     grouped_options_for_select(options, selected)
   end
 
-  def namespace_select_tag(id, opts = {})
-    css_class = "ajax-namespace-select "
-    css_class << "multiselect " if opts[:multiple]
-    css_class << (opts[:class] || '')
-    value = opts[:selected] || ''
-
-    hidden_field_tag(id, value, class: css_class)
-  end
-
   def namespace_icon(namespace, size = 40)
     if namespace.kind_of?(Group)
       group_icon(namespace)
diff --git a/app/helpers/selects_helper.rb b/app/helpers/selects_helper.rb
index 12fce8db701..7e54d4d1b5b 100644
--- a/app/helpers/selects_helper.rb
+++ b/app/helpers/selects_helper.rb
@@ -35,8 +35,20 @@ module SelectsHelper
   end
 
   def groups_select_tag(id, opts = {})
-    css_class = "ajax-groups-select "
-    css_class << "multiselect " if opts[:multiple]
+    opts[:class] ||= ''
+    opts[:class] << ' ajax-groups-select'
+    select2_tag(id, opts)
+  end
+
+  def namespace_select_tag(id, opts = {})
+    opts[:class] ||= ''
+    opts[:class] << ' ajax-namespace-select'
+    select2_tag(id, opts)
+  end
+
+  def select2_tag(id, opts = {})
+    css_class = ''
+    css_class << 'multiselect ' if opts[:multiple]
     css_class << (opts[:class] || '')
     value = opts[:selected] || ''
 
diff --git a/app/mailers/emails/issues.rb b/app/mailers/emails/issues.rb
index 2c035fbb70b..abdeefed5ef 100644
--- a/app/mailers/emails/issues.rb
+++ b/app/mailers/emails/issues.rb
@@ -1,53 +1,49 @@
 module Emails
   module Issues
     def new_issue_email(recipient_id, issue_id)
-      @issue = Issue.find(issue_id)
-      @project = @issue.project
-      @target_url = namespace_project_issue_url(@project.namespace, @project, @issue)
-      mail_new_thread(@issue,
-                      from: sender(@issue.author_id),
-                      to: recipient(recipient_id),
-                      subject: subject("#{@issue.title} (##{@issue.iid})"))
-
-      SentNotification.record(@issue, recipient_id, reply_key)
+      issue_mail_with_notification(issue_id, recipient_id) do
+        mail_new_thread(@issue, issue_thread_options(@issue.author_id, recipient_id))
+      end
     end
 
     def reassigned_issue_email(recipient_id, issue_id, previous_assignee_id, updated_by_user_id)
-      @issue = Issue.find(issue_id)
-      @previous_assignee = User.find_by(id: previous_assignee_id) if previous_assignee_id
-      @project = @issue.project
-      @target_url = namespace_project_issue_url(@project.namespace, @project, @issue)
-      mail_answer_thread(@issue,
-                         from: sender(updated_by_user_id),
-                         to: recipient(recipient_id),
-                         subject: subject("#{@issue.title} (##{@issue.iid})"))
-
-      SentNotification.record(@issue, recipient_id, reply_key)
+      issue_mail_with_notification(issue_id, recipient_id) do
+        @previous_assignee = User.find_by(id: previous_assignee_id) if previous_assignee_id
+        mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id))
+      end
     end
 
     def closed_issue_email(recipient_id, issue_id, updated_by_user_id)
-      @issue = Issue.find issue_id
-      @project = @issue.project
-      @updated_by = User.find updated_by_user_id
-      @target_url = namespace_project_issue_url(@project.namespace, @project, @issue)
-      mail_answer_thread(@issue,
-                         from: sender(updated_by_user_id),
-                         to: recipient(recipient_id),
-                         subject: subject("#{@issue.title} (##{@issue.iid})"))
-
-      SentNotification.record(@issue, recipient_id, reply_key)
+      issue_mail_with_notification(issue_id, recipient_id) do
+        @updated_by = User.find updated_by_user_id
+        mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id))
+      end
     end
 
     def issue_status_changed_email(recipient_id, issue_id, status, updated_by_user_id)
-      @issue = Issue.find issue_id
-      @issue_status = status
+      issue_mail_with_notification(issue_id, recipient_id) do
+        @issue_status = status
+        @updated_by = User.find updated_by_user_id
+        mail_answer_thread(@issue, issue_thread_options(updated_by_user_id, recipient_id))
+      end
+    end
+
+    private
+
+    def issue_thread_options(sender_id, recipient_id)
+      {
+        from: sender(sender_id),
+        to: recipient(recipient_id),
+        subject: subject("#{@issue.title} (##{@issue.iid})")
+      }
+    end
+
+    def issue_mail_with_notification(issue_id, recipient_id)
+      @issue = Issue.find(issue_id)
       @project = @issue.project
-      @updated_by = User.find updated_by_user_id
       @target_url = namespace_project_issue_url(@project.namespace, @project, @issue)
-      mail_answer_thread(@issue,
-                         from: sender(updated_by_user_id),
-                         to: recipient(recipient_id),
-                         subject: subject("#{@issue.title} (##{@issue.iid})"))
+
+      yield
 
       SentNotification.record(@issue, recipient_id, reply_key)
     end
diff --git a/app/mailers/emails/notes.rb b/app/mailers/emails/notes.rb
index 87ba94a583d..65f37e92677 100644
--- a/app/mailers/emails/notes.rb
+++ b/app/mailers/emails/notes.rb
@@ -1,49 +1,54 @@
 module Emails
   module Notes
     def note_commit_email(recipient_id, note_id)
-      @note = Note.find(note_id)
-      @commit = @note.noteable
-      @project = @note.project
-      @target_url = namespace_project_commit_url(@project.namespace, @project,
-                                                 @commit, anchor:
-                                                 "note_#{@note.id}")
-      mail_answer_thread(@commit,
-                         from: sender(@note.author_id),
-                         to: recipient(recipient_id),
-                         subject: subject("#{@commit.title} (#{@commit.short_id})"))
-
-      SentNotification.record_note(@note, recipient_id, reply_key)
+      note_mail_with_notification(note_id, recipient_id) do
+        @commit = @note.noteable
+        @target_url = namespace_project_commit_url(*note_target_url_options)
+
+        mail_answer_thread(@commit,
+                           from: sender(@note.author_id),
+                           to: recipient(recipient_id),
+                           subject: subject("#{@commit.title} (#{@commit.short_id})"))
+      end
     end
 
     def note_issue_email(recipient_id, note_id)
-      @note = Note.find(note_id)
-      @issue = @note.noteable
-      @project = @note.project
-      @target_url = namespace_project_issue_url(@project.namespace, @project,
-                                                @issue, anchor:
-                                                "note_#{@note.id}")
-      mail_answer_thread(@issue,
-                         from: sender(@note.author_id),
-                         to: recipient(recipient_id),
-                         subject: subject("#{@issue.title} (##{@issue.iid})"))
-
-      SentNotification.record_note(@note, recipient_id, reply_key)
+      note_mail_with_notification(note_id, recipient_id) do
+        @issue = @note.noteable
+        @target_url = namespace_project_issue_url(*note_target_url_options)
+        mail_answer_thread(@issue, note_thread_options(recipient_id))
+      end
     end
 
     def note_merge_request_email(recipient_id, note_id)
+      note_mail_with_notification(note_id, recipient_id) do
+        @merge_request = @note.noteable
+        @target_url = namespace_project_merge_request_url(*note_target_url_options)
+        mail_answer_thread(@merge_request, note_thread_options(recipient_id))
+      end
+    end
+
+    private
+
+    def note_target_url_options
+      [@project.namespace, @project, @note.noteable, anchor: "note_#{@note.id}"]
+    end
+
+    def note_thread_options(recipient_id)
+      {
+        from: sender(@note.author_id),
+        to: recipient(recipient_id),
+        subject: subject("#{@note.noteable.title} (##{@note.noteable.iid})")
+      }
+    end
+
+    def note_mail_with_notification(note_id, recipient_id)
       @note = Note.find(note_id)
-      @merge_request = @note.noteable
       @project = @note.project
-      @target_url = namespace_project_merge_request_url(@project.namespace,
-                                                        @project,
-                                                        @merge_request, anchor:
-                                                        "note_#{@note.id}")
-      mail_answer_thread(@merge_request,
-                         from: sender(@note.author_id),
-                         to: recipient(recipient_id),
-                         subject: subject("#{@merge_request.title} (##{@merge_request.iid})"))
-
-      SentNotification.record_note(@note, recipient_id, reply_key)
+
+      yield
+
+      SentNotification.record(@note, recipient_id, reply_key)
     end
   end
 end
diff --git a/app/models/project_services/slack_service/note_message.rb b/app/models/project_services/slack_service/note_message.rb
index 074478b292d..b15d9a14677 100644
--- a/app/models/project_services/slack_service/note_message.rb
+++ b/app/models/project_services/slack_service/note_message.rb
@@ -45,30 +45,27 @@ class SlackService
     def create_commit_note(commit)
       commit_sha = commit[:id]
       commit_sha = Commit.truncate_sha(commit_sha)
-      commit_link = "[commit #{commit_sha}](#{@note_url})"
-      title = format_title(commit[:message])
-      @message = "#{@user_name} commented on #{commit_link} in #{project_link}: *#{title}*"
+      commented_on_message(
+        "[commit #{commit_sha}](#{@note_url})",
+        format_title(commit[:message]))
     end
 
     def create_issue_note(issue)
-      issue_iid = issue[:iid]
-      note_link = "[issue ##{issue_iid}](#{@note_url})"
-      title = format_title(issue[:title])
-      @message = "#{@user_name} commented on #{note_link} in #{project_link}: *#{title}*"
+      commented_on_message(
+        "[issue ##{issue[:iid]}](#{@note_url})",
+        format_title(issue[:title]))
     end
 
     def create_merge_note(merge_request)
-      merge_request_id = merge_request[:iid]
-      merge_request_link = "[merge request ##{merge_request_id}](#{@note_url})"
-      title = format_title(merge_request[:title])
-      @message = "#{@user_name} commented on #{merge_request_link} in #{project_link}: *#{title}*"
+      commented_on_message(
+        "[merge request ##{merge_request[:iid]}](#{@note_url})",
+        format_title(merge_request[:title]))
     end
 
     def create_snippet_note(snippet)
-      snippet_id = snippet[:id]
-      snippet_link = "[snippet ##{snippet_id}](#{@note_url})"
-      title = format_title(snippet[:title])
-      @message = "#{@user_name} commented on #{snippet_link} in #{project_link}: *#{title}*"
+      commented_on_message(
+        "[snippet ##{snippet[:id]}](#{@note_url})",
+        format_title(snippet[:title]))
     end
 
     def description_message
@@ -78,5 +75,9 @@ class SlackService
     def project_link
       "[#{@project_name}](#{@project_url})"
     end
+
+    def commented_on_message(target_link, title)
+      @message = "#{@user_name} commented on #{target_link} in #{project_link}: *#{title}*"
+    end
   end
 end
diff --git a/app/services/issuable_base_service.rb b/app/services/issuable_base_service.rb
index 15b3825f96a..11d2b08bba7 100644
--- a/app/services/issuable_base_service.rb
+++ b/app/services/issuable_base_service.rb
@@ -28,6 +28,9 @@ class IssuableBaseService < BaseService
   end
 
   def filter_params(issuable_ability_name = :issue)
+    params[:assignee_id]  = "" if params[:assignee_id] == IssuableFinder::NONE
+    params[:milestone_id] = "" if params[:milestone_id] == IssuableFinder::NONE
+
     ability = :"admin_#{issuable_ability_name}"
 
     unless can?(current_user, ability, project)
@@ -36,4 +39,36 @@ class IssuableBaseService < BaseService
       params.delete(:assignee_id)
     end
   end
+
+  def update(issuable)
+    change_state(issuable)
+    filter_params
+    old_labels = issuable.labels.to_a
+
+    if params.present? && issuable.update_attributes(params.merge(updated_by: current_user))
+      issuable.reset_events_cache
+
+      if issuable.labels != old_labels
+        create_labels_note(
+          issuable,
+          issuable.labels - old_labels,
+          old_labels - issuable.labels)
+      end
+
+      handle_changes(issuable)
+      issuable.create_new_cross_references!(current_user)
+      execute_hooks(issuable, 'update')
+    end
+
+    issuable
+  end
+
+  def change_state(issuable)
+    case params.delete(:state_event)
+    when 'reopen'
+      reopen_service.new(project, current_user, {}).execute(issuable)
+    when 'close'
+      close_service.new(project, current_user, {}).execute(issuable)
+    end
+  end
 end
diff --git a/app/services/issues/update_service.rb b/app/services/issues/update_service.rb
index aa1fd79d22d..7c112f731a7 100644
--- a/app/services/issues/update_service.rb
+++ b/app/services/issues/update_service.rb
@@ -1,33 +1,7 @@
 module Issues
   class UpdateService < Issues::BaseService
     def execute(issue)
-      case params.delete(:state_event)
-      when 'reopen'
-        Issues::ReopenService.new(project, current_user, {}).execute(issue)
-      when 'close'
-        Issues::CloseService.new(project, current_user, {}).execute(issue)
-      end
-
-      params[:assignee_id]  = "" if params[:assignee_id] == IssuableFinder::NONE
-      params[:milestone_id] = "" if params[:milestone_id] == IssuableFinder::NONE
-
-      filter_params
-      old_labels = issue.labels.to_a
-
-      if params.present? && issue.update_attributes(params.merge(updated_by: current_user))
-        issue.reset_events_cache
-
-        if issue.labels != old_labels
-          create_labels_note(
-            issue, issue.labels - old_labels, old_labels - issue.labels)
-        end
-
-        handle_changes(issue)
-        issue.create_new_cross_references!(current_user)
-        execute_hooks(issue, 'update')
-      end
-
-      issue
+      update(issue)
     end
 
     def handle_changes(issue)
@@ -44,5 +18,13 @@ module Issues
         create_title_change_note(issue, issue.previous_changes['title'].first)
       end
     end
+
+    def reopen_service
+      Issues::ReopenService
+    end
+
+    def close_service
+      Issues::CloseService
+    end
   end
 end
diff --git a/app/services/merge_requests/update_service.rb b/app/services/merge_requests/update_service.rb
index d2849e5193f..a5db3776eb6 100644
--- a/app/services/merge_requests/update_service.rb
+++ b/app/services/merge_requests/update_service.rb
@@ -11,36 +11,7 @@ module MergeRequests
       params.except!(:target_project_id)
       params.except!(:source_branch)
 
-      case params.delete(:state_event)
-      when 'reopen'
-        MergeRequests::ReopenService.new(project, current_user, {}).execute(merge_request)
-      when 'close'
-        MergeRequests::CloseService.new(project, current_user, {}).execute(merge_request)
-      end
-
-      params[:assignee_id]  = "" if params[:assignee_id] == IssuableFinder::NONE
-      params[:milestone_id] = "" if params[:milestone_id] == IssuableFinder::NONE
-
-      filter_params
-      old_labels = merge_request.labels.to_a
-
-      if params.present? && merge_request.update_attributes(params.merge(updated_by: current_user))
-        merge_request.reset_events_cache
-
-        if merge_request.labels != old_labels
-          create_labels_note(
-            merge_request,
-            merge_request.labels - old_labels,
-            old_labels - merge_request.labels
-          )
-        end
-
-        handle_changes(merge_request)
-        merge_request.create_new_cross_references!(current_user)
-        execute_hooks(merge_request, 'update')
-      end
-
-      merge_request
+      update(merge_request)
     end
 
     def handle_changes(merge_request)
@@ -68,5 +39,13 @@ module MergeRequests
         merge_request.mark_as_unchecked
       end
     end
+
+    def reopen_service
+      MergeRequests::ReopenService
+    end
+
+    def close_service
+      MergeRequests::CloseService
+    end
   end
 end
diff --git a/app/services/notification_service.rb b/app/services/notification_service.rb
index a6b22348650..4b871f072d4 100644
--- a/app/services/notification_service.rb
+++ b/app/services/notification_service.rb
@@ -113,7 +113,7 @@ class NotificationService
     end
 
     # Add all users participating in the thread (author, assignee, comment authors)
-    participants = 
+    participants =
       if target.respond_to?(:participants)
         target.participants(note.author)
       else
@@ -276,35 +276,25 @@ class NotificationService
   # Remove users with disabled notifications from array
   # Also remove duplications and nil recipients
   def reject_muted_users(users, project = nil)
-    users = users.to_a.compact.uniq
-    users = users.reject(&:blocked?)
-
-    users.reject do |user|
-      next user.notification.disabled? unless project
-
-      member = project.project_members.find_by(user_id: user.id)
-
-      if !member && project.group
-        member = project.group.group_members.find_by(user_id: user.id)
-      end
-
-      # reject users who globally disabled notification and has no membership
-      next user.notification.disabled? unless member
-
-      # reject users who disabled notification in project
-      next true if member.notification.disabled?
-
-      # reject users who have N_GLOBAL in project and disabled in global settings
-      member.notification.global? && user.notification.disabled?
-    end
+    reject_users(users, :disabled?, project)
   end
 
   # Remove users with notification level 'Mentioned'
   def reject_mention_users(users, project = nil)
+    reject_users(users, :mention?, project)
+  end
+
+  # Reject users which method_name from notification object returns true.
+  #
+  # Example:
+  #   reject_users(users, :watch?, project)
+  #
+  def reject_users(users, method_name, project = nil)
     users = users.to_a.compact.uniq
+    users = users.reject(&:blocked?)
 
     users.reject do |user|
-      next user.notification.mention? unless project
+      next user.notification.send(method_name) unless project
 
       member = project.project_members.find_by(user_id: user.id)
 
@@ -313,19 +303,19 @@ class NotificationService
       end
 
       # reject users who globally set mention notification and has no membership
-      next user.notification.mention? unless member
+      next user.notification.send(method_name) unless member
 
       # reject users who set mention notification in project
-      next true if member.notification.mention?
+      next true if member.notification.send(method_name)
 
       # reject users who have N_MENTION in project and disabled in global settings
-      member.notification.global? && user.notification.mention?
+      member.notification.global? && user.notification.send(method_name)
     end
   end
 
   def reject_unsubscribed_users(recipients, target)
     return recipients unless target.respond_to? :subscriptions
-    
+
     recipients.reject do |user|
       subscription = target.subscriptions.find_by_user_id(user.id)
       subscription && !subscription.subscribed
@@ -343,7 +333,7 @@ class NotificationService
       recipients
     end
   end
-  
+
   def new_resource_email(target, project, method)
     recipients = build_recipients(target, project, target.author)
 
diff --git a/lib/gitlab/markdown/abstract_reference_filter.rb b/lib/gitlab/markdown/abstract_reference_filter.rb
new file mode 100644
index 00000000000..fd5b7eb9332
--- /dev/null
+++ b/lib/gitlab/markdown/abstract_reference_filter.rb
@@ -0,0 +1,100 @@
+require 'gitlab/markdown'
+
+module Gitlab
+  module Markdown
+    # Issues, Snippets and Merge Requests shares similar functionality in refernce filtering.
+    # All this functionality moved to this class
+    class AbstractReferenceFilter < ReferenceFilter
+      include CrossProjectReference
+
+      def self.object_class
+        # Implement in child class
+        # Example: MergeRequest
+      end
+
+      def self.object_name
+        object_class.name.underscore
+      end
+
+      def self.object_sym
+        object_name.to_sym
+      end
+
+      def self.data_reference
+        "data-#{object_name.dasherize}"
+      end
+
+      # Public: Find references in text (like `!123` for merge requests)
+      #
+      #   AnyReferenceFilter.references_in(text) do |match, object|
+      #     "<a href=...>PREFIX#{object}</a>"
+      #   end
+      #
+      # PREFIX - symbol that detects reference (like ! for merge requests)
+      # object - reference object (snippet, merget request etc)
+      # text - String text to search.
+      #
+      # Yields the String match, the Integer referenced object ID, and an optional String
+      # of the external project reference.
+      #
+      # Returns a String replaced with the return of the block.
+      def self.references_in(text)
+        text.gsub(object_class.reference_pattern) do |match|
+          yield match, $~[object_sym].to_i, $~[:project]
+        end
+      end
+
+      def self.referenced_by(node)
+        { object_sym => LazyReference.new(object_class, node.attr(data_reference)) }
+      end
+
+      delegate :object_class, :object_sym, :references_in, to: :class
+
+      def find_object(project, id)
+        # Implement in child class
+        # Example: project.merge_requests.find
+      end
+
+      def url_for_object(object, project)
+        # Implement in child class
+        # Example: project_merge_request_url
+      end
+
+      def call
+        replace_text_nodes_matching(object_class.reference_pattern) do |content|
+          object_link_filter(content)
+        end
+      end
+
+      # Replace references (like `!123` for merge requests) in text with links
+      # to the referenced object's details page.
+      #
+      # text - String text to replace references in.
+      #
+      # Returns a String with references replaced with links. All links
+      # have `gfm` and `gfm-OBJECT_NAME` class names attached for styling.
+      def object_link_filter(text)
+        references_in(text) do |match, id, project_ref|
+          project = project_from_ref(project_ref)
+
+          if project && object = find_object(project, id)
+            title = escape_once("#{object_title}: #{object.title}")
+            klass = reference_class(object_sym)
+            data  = data_attribute(project: project.id, object_sym => object.id)
+            url = url_for_object(object, project)
+
+            %(<a href="#{url}" #{data}
+                 title="#{title}"
+                 class="#{klass}">#{match}</a>)
+          else
+            match
+          end
+        end
+      end
+
+      def object_title
+        object_class.name.titleize
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/markdown/issue_reference_filter.rb b/lib/gitlab/markdown/issue_reference_filter.rb
index 481d282f7b1..1ed69e2f431 100644
--- a/lib/gitlab/markdown/issue_reference_filter.rb
+++ b/lib/gitlab/markdown/issue_reference_filter.rb
@@ -6,66 +6,17 @@ module Gitlab
     # issues that do not exist are ignored.
     #
     # This filter supports cross-project references.
-    class IssueReferenceFilter < ReferenceFilter
-      include CrossProjectReference
-
-      # Public: Find `#123` issue references in text
-      #
-      #   IssueReferenceFilter.references_in(text) do |match, issue, project_ref|
-      #     "<a href=...>##{issue}</a>"
-      #   end
-      #
-      # text - String text to search.
-      #
-      # Yields the String match, the Integer issue ID, and an optional String of
-      # the external project reference.
-      #
-      # Returns a String replaced with the return of the block.
-      def self.references_in(text)
-        text.gsub(Issue.reference_pattern) do |match|
-          yield match, $~[:issue].to_i, $~[:project]
-        end
-      end
-
-      def self.referenced_by(node)
-        { issue: LazyReference.new(Issue, node.attr("data-issue")) }
-      end
-
-      def call
-        replace_text_nodes_matching(Issue.reference_pattern) do |content|
-          issue_link_filter(content)
-        end
+    class IssueReferenceFilter < AbstractReferenceFilter
+      def self.object_class
+        Issue
       end
 
-      # Replace `#123` issue references in text with links to the referenced
-      # issue's details page.
-      #
-      # text - String text to replace references in.
-      #
-      # Returns a String with `#123` references replaced with links. All links
-      # have `gfm` and `gfm-issue` class names attached for styling.
-      def issue_link_filter(text)
-        self.class.references_in(text) do |match, id, project_ref|
-          project = self.project_from_ref(project_ref)
-
-          if project && issue = project.get_issue(id)
-            url = url_for_issue(id, project, only_path: context[:only_path])
-
-            title = escape_once("Issue: #{issue.title}")
-            klass = reference_class(:issue)
-            data  = data_attribute(project: project.id, issue: issue.id)
-
-            %(<a href="#{url}" #{data}
-                 title="#{title}"
-                 class="#{klass}">#{match}</a>)
-          else
-            match
-          end
-        end
+      def find_object(project, id)
+        project.get_issue(id)
       end
 
-      def url_for_issue(*args)
-        IssuesHelper.url_for_issue(*args)
+      def url_for_object(issue, project)
+        IssuesHelper.url_for_issue(issue.iid, project, only_path: context[:only_path])
       end
     end
   end
diff --git a/lib/gitlab/markdown/merge_request_reference_filter.rb b/lib/gitlab/markdown/merge_request_reference_filter.rb
index 5bc63269808..1f47f03c94e 100644
--- a/lib/gitlab/markdown/merge_request_reference_filter.rb
+++ b/lib/gitlab/markdown/merge_request_reference_filter.rb
@@ -6,65 +6,16 @@ module Gitlab
     # to merge requests that do not exist are ignored.
     #
     # This filter supports cross-project references.
-    class MergeRequestReferenceFilter < ReferenceFilter
-      include CrossProjectReference
-
-      # Public: Find `!123` merge request references in text
-      #
-      #   MergeRequestReferenceFilter.references_in(text) do |match, merge_request, project_ref|
-      #     "<a href=...>##{merge_request}</a>"
-      #   end
-      #
-      # text - String text to search.
-      #
-      # Yields the String match, the Integer merge request ID, and an optional
-      # String of the external project reference.
-      #
-      # Returns a String replaced with the return of the block.
-      def self.references_in(text)
-        text.gsub(MergeRequest.reference_pattern) do |match|
-          yield match, $~[:merge_request].to_i, $~[:project]
-        end
-      end
-
-      def self.referenced_by(node)
-        { merge_request: LazyReference.new(MergeRequest, node.attr("data-merge-request")) }
-      end
-
-      def call
-        replace_text_nodes_matching(MergeRequest.reference_pattern) do |content|
-          merge_request_link_filter(content)
-        end
+    class MergeRequestReferenceFilter < AbstractReferenceFilter
+      def self.object_class
+        MergeRequest
       end
 
-      # Replace `!123` merge request references in text with links to the
-      # referenced merge request's details page.
-      #
-      # text - String text to replace references in.
-      #
-      # Returns a String with `!123` references replaced with links. All links
-      # have `gfm` and `gfm-merge_request` class names attached for styling.
-      def merge_request_link_filter(text)
-        self.class.references_in(text) do |match, id, project_ref|
-          project = self.project_from_ref(project_ref)
-
-          if project && merge_request = project.merge_requests.find_by(iid: id)
-            title = escape_once("Merge Request: #{merge_request.title}")
-            klass = reference_class(:merge_request)
-            data  = data_attribute(project: project.id, merge_request: merge_request.id)
-
-            url = url_for_merge_request(merge_request, project)
-
-            %(<a href="#{url}" #{data}
-                 title="#{title}"
-                 class="#{klass}">#{match}</a>)
-          else
-            match
-          end
-        end
+      def find_object(project, id)
+        project.merge_requests.find_by(iid: id)
       end
 
-      def url_for_merge_request(mr, project)
+      def url_for_object(mr, project)
         h = Gitlab::Application.routes.url_helpers
         h.namespace_project_merge_request_url(project.namespace, project, mr,
                                             only_path: context[:only_path])
diff --git a/lib/gitlab/markdown/snippet_reference_filter.rb b/lib/gitlab/markdown/snippet_reference_filter.rb
index f783f951711..f7bd07c2a34 100644
--- a/lib/gitlab/markdown/snippet_reference_filter.rb
+++ b/lib/gitlab/markdown/snippet_reference_filter.rb
@@ -6,65 +6,16 @@ module Gitlab
     # snippets that do not exist are ignored.
     #
     # This filter supports cross-project references.
-    class SnippetReferenceFilter < ReferenceFilter
-      include CrossProjectReference
-
-      # Public: Find `$123` snippet references in text
-      #
-      #   SnippetReferenceFilter.references_in(text) do |match, snippet|
-      #     "<a href=...>$#{snippet}</a>"
-      #   end
-      #
-      # text - String text to search.
-      #
-      # Yields the String match, the Integer snippet ID, and an optional String
-      # of the external project reference.
-      #
-      # Returns a String replaced with the return of the block.
-      def self.references_in(text)
-        text.gsub(Snippet.reference_pattern) do |match|
-          yield match, $~[:snippet].to_i, $~[:project]
-        end
-      end
-
-      def self.referenced_by(node)
-        { snippet: LazyReference.new(Snippet, node.attr("data-snippet")) }
-      end
-
-      def call
-        replace_text_nodes_matching(Snippet.reference_pattern) do |content|
-          snippet_link_filter(content)
-        end
+    class SnippetReferenceFilter < AbstractReferenceFilter
+      def self.object_class
+        Snippet
       end
 
-      # Replace `$123` snippet references in text with links to the referenced
-      # snippets's details page.
-      #
-      # text - String text to replace references in.
-      #
-      # Returns a String with `$123` references replaced with links. All links
-      # have `gfm` and `gfm-snippet` class names attached for styling.
-      def snippet_link_filter(text)
-        self.class.references_in(text) do |match, id, project_ref|
-          project = self.project_from_ref(project_ref)
-
-          if project && snippet = project.snippets.find_by(id: id)
-            title = escape_once("Snippet: #{snippet.title}")
-            klass = reference_class(:snippet)
-            data  = data_attribute(project: project.id, snippet: snippet.id)
-
-            url = url_for_snippet(snippet, project)
-
-            %(<a href="#{url}" #{data}
-                 title="#{title}"
-                 class="#{klass}">#{match}</a>)
-          else
-            match
-          end
-        end
+      def find_object(project, id)
+        project.snippets.find_by(id: id)
       end
 
-      def url_for_snippet(snippet, project)
+      def url_for_object(snippet, project)
         h = Gitlab::Application.routes.url_helpers
         h.namespace_project_snippet_url(project.namespace, project, snippet,
                                         only_path: context[:only_path])
diff --git a/lib/gitlab/markdown/user_reference_filter.rb b/lib/gitlab/markdown/user_reference_filter.rb
index 2a594e1662e..ab5e1f6fe9e 100644
--- a/lib/gitlab/markdown/user_reference_filter.rb
+++ b/lib/gitlab/markdown/user_reference_filter.rb
@@ -85,13 +85,12 @@ module Gitlab
 
       def link_to_all
         project = context[:project]
-
         url = urls.namespace_project_url(project.namespace, project,
                                          only_path: context[:only_path])
         data = data_attribute(project: project.id)
-
         text = User.reference_prefix + 'all'
-        %(<a href="#{url}" #{data} class="#{link_class}">#{text}</a>)
+
+        link_tag(url, data, text)
       end
 
       def link_to_namespace(namespace)
@@ -105,16 +104,20 @@ module Gitlab
       def link_to_group(group, namespace)
         url = urls.group_url(group, only_path: context[:only_path])
         data = data_attribute(group: namespace.id)
-
         text = Group.reference_prefix + group
-        %(<a href="#{url}" #{data} class="#{link_class}">#{text}</a>)
+
+        link_tag(url, data, text)
       end
 
       def link_to_user(user, namespace)
         url = urls.user_url(user, only_path: context[:only_path])
         data = data_attribute(user: namespace.owner_id)
-
         text = User.reference_prefix + user
+
+        link_tag(url, data, text)
+      end
+
+      def link_tag(url, data, text)
         %(<a href="#{url}" #{data} class="#{link_class}">#{text}</a>)
       end
     end
diff --git a/lib/tasks/flay.rake b/lib/tasks/flay.rake
index dfb9df4772a..e9587595fef 100644
--- a/lib/tasks/flay.rake
+++ b/lib/tasks/flay.rake
@@ -1,6 +1,6 @@
 desc 'Code duplication analyze via flay'
 task :flay do
-  output = %x(bundle exec flay --mass 30 app/ lib/gitlab/)
+  output = %x(bundle exec flay --mass 35 app/ lib/gitlab/)
 
   if output.include? "Similar code found"
     puts output