Fixes #208 - Notify / Mention other agents / Subscribe to Tickets.

app/assets/javascripts/app/controllers/_plugin/keyboard_shortcuts.coffee

@@ -399,16 +399,22 @@ App.Config.set(
           shortcuts: [
             {
               key: '::'
-              hotkeys: false,
+              hotkeys: false
               description: 'Inserts Text module'
               globalEvent: 'richtext-insert-text-module'
             }
             {
               key: '??'
-              hotkeys: false,
+              hotkeys: false
               description: 'Inserts Knowledge Base answer'
               globalEvent: 'richtext-insert-kb-answer'
             }
+            {
+              key: '@@'
+              hotkeys: false
+              description: 'Inserts a mention for a user'
+              globalEvent: 'richtext-insert-mention-user'
+            }
           ]
         }
 

app/assets/javascripts/app/controllers/_profile/notification.coffee

@@ -50,18 +50,19 @@ class ProfileNotification extends App.ControllerSubContent
 
   render: =>
 
-    # matrix
+    matrix =
+      create:
+        name: 'New Ticket'
+      update:
+        name: 'Ticket update'
+      reminder_reached:
+        name: 'Ticket reminder reached'
+      escalation:
+        name: 'Ticket escalation'
+
     config =
       group_ids: []
-      matrix:
+      matrix: {}
-        create:
-          name: 'New Ticket'
-        update:
-          name: 'Ticket update'
-        reminder_reached:
-          name: 'Ticket reminder reached'
-        escalation:
-          name: 'Ticket escalation'
 
     user_config = @Session.get('preferences').notification_config
     if user_config
@@ -89,6 +90,7 @@ class ProfileNotification extends App.ControllerSubContent
       sound.selected = sound.file is App.OnlineNotification.soundFile() ? true : false
 
     @html App.view('profile/notification')
+      matrix: matrix
       groups: groups
       config: config
       sounds: @sounds
@@ -102,6 +104,7 @@ class ProfileNotification extends App.ControllerSubContent
     params.notification_config = {}
 
     form_params = @formParam(e.target)
+
     for key, value of form_params
       if key is 'group_ids'
         if typeof value isnt 'object'
@@ -118,11 +121,12 @@ class ProfileNotification extends App.ControllerSubContent
             if !params.notification_config[area[0]][area[1]]
               params.notification_config[area[0]][area[1]] = {}
             if !params.notification_config[area[0]][area[1]][area[2]]
-              params.notification_config[area[0]][area[1]][area[2]] = {
+              params.notification_config[area[0]][area[1]][area[2]] = {}
-                owned_by_me:     false
+
-                owned_by_nobody: false
+            for recipientKey in ['owned_by_me', 'owned_by_nobody', 'mentioned', 'no']
-                no:              false
+              if params.notification_config[area[0]][area[1]][area[2]][recipientKey] == undefined
-              }
+                params.notification_config[area[0]][area[1]][area[2]][recipientKey] = false
+
             params.notification_config[area[0]][area[1]][area[2]][area[3]] = value
           if area[2] is 'channel'
             if !params.notification_config[area[0]]

app/assets/javascripts/app/controllers/_ui_element/ticket_selector.coffee

@@ -118,6 +118,15 @@ class App.UiElement.ticket_selector
         translate: true
         operator: ['is', 'is not']
 
+    elements['ticket.mention_user_ids'] =
+      name: 'mention_user_ids'
+      display: 'Mention'
+      tag: 'autocompletion_ajax'
+      relation: 'User'
+      null: false
+      translate: true
+      operator: ['is', 'is not']
+
     [defaults, groups, elements]
 
   @rowContainer: (groups, elements, attribute) ->

app/assets/javascripts/app/controllers/ticket_zoom.coffee

@@ -158,6 +158,10 @@ class App.TicketZoom extends App.Controller
     else
       @ticketUpdatedAtLastCall = newTicketRaw.updated_at
 
+    # make sure to load assets for mentions if cache is not up to date
+    if !_.isEqual(data.mentions, @mentions)
+      loadAssets = true
+
     # load assets
     if loadAssets
 
@@ -180,6 +184,9 @@ class App.TicketZoom extends App.Controller
       # remember tags
       @tags = data.tags
 
+      # remember mentions
+      @mentions = data.mentions
+
       App.Collection.loadAssets(data.assets, targetModel: 'Ticket')
 
     # get ticket
@@ -515,6 +522,7 @@ class App.TicketZoom extends App.Controller
         formMeta:     @formMeta
         markForm:     @markForm
         tags:         @tags
+        mentions:     @mentions
         links:        @links
       )
 
@@ -550,8 +558,9 @@ class App.TicketZoom extends App.Controller
 
     if @sidebarWidget
       @sidebarWidget.reload(
-        tags: @tags
+        tags:     @tags
-        links: @links
+        mentions: @mentions
+        links:    @links
       )
 
     if !@initDone
@@ -891,8 +900,15 @@ class App.TicketZoom extends App.Controller
       return
 
     # verify if time accounting is active for ticket
-    selector = ticket.clone()
+    selector                 = ticket.clone()
-    selector.tags = @tags
+    selector.tags            = @tags
+    # always have a empy value to make sure that the condition gets checked
+    selector.mentions        = ['']
+    for id in @mentions
+      mention = App.Mention.find(id)
+      continue if !mention
+      selector.mentions.push(mention.user_id)
+
     time_accounting_selector = @Config.get('time_accounting_selector')
     if !App.Ticket.selector(selector, time_accounting_selector['condition'])
       @submitPost(e, ticket, macro)

app/assets/javascripts/app/controllers/ticket_zoom/sidebar.coffee

@@ -34,6 +34,7 @@ class App.TicketZoomSidebar extends App.ControllerObserver
           formMeta: @formMeta
           markForm: @markForm
           tags:     @tags
+          mentions: @mentions
           links:    @links
         )
       else
@@ -43,6 +44,7 @@ class App.TicketZoomSidebar extends App.ControllerObserver
           formMeta: @formMeta
           markForm: @markForm
           tags:     @tags
+          mentions: @mentions
           links:    @links
         )
       @sidebarItems.push @sidebarBackends[key]

app/assets/javascripts/app/controllers/ticket_zoom/sidebar_ticket.coffee

@@ -102,6 +102,8 @@ class SidebarTicket extends App.Controller
     if @tagWidget
       if args.tags
         @tagWidget.reload(args.tags)
+      if args.mentions
+        @mentionWidget.reload(args.mentions)
       if args.tagAdd
         @tagWidget.add(args.tagAdd, args.source)
       if args.tagRemove
@@ -128,6 +130,11 @@ class SidebarTicket extends App.Controller
     )
 
     if @ticket.currentView() is 'agent'
+      @mentionWidget = new App.WidgetMention(
+        el:       localEl.filter('.mentions')
+        object:   @ticket
+        mentions: @mentions
+      )
       @tagWidget = new App.WidgetTag(
         el:          localEl.filter('.tags')
         object_type: 'Ticket'

app/assets/javascripts/app/controllers/widget/mention.coffee

@@ -0,0 +1,102 @@
+class App.WidgetMention extends App.Controller
+  events:
+    'click .js-subscribe': 'subscribe'
+    'click .js-unsubscribe': 'unsubscribe'
+  elements:
+    '.js-subscribe input[type=button]': 'subscribeButton'
+    '.js-unsubscribe input[type=button]': 'unsubscribeButton'
+
+  constructor: ->
+    super
+
+    @mentions = []
+    App.Event.bind('Mention:create Mention:destroy',
+      (data) =>
+        return if !data
+        return if data.mentionable_type isnt 'Ticket'
+        return if data.mentionable_id isnt @object.id
+        @fetch()
+    )
+    @render()
+
+  fetch: =>
+    App.Mention.fetchMentionable(
+      'Ticket',
+      @object.id,
+      (data) =>
+        @mentions = data.record_ids
+        App.Collection.loadAssets(data.assets)
+        @render()
+    )
+
+  reload: (mentions) =>
+    @mentions = mentions
+    @render()
+
+  render: =>
+    subscribed = false
+    mentions   = []
+    counter    = 1
+    for id in @mentions
+      mention = App.Mention.find(id)
+      continue if !mention
+
+      user = App.User.find(mention.user_id)
+      continue if !user
+
+      if mention.user_id is App.Session.get().id
+        subscribed = true
+
+      # no break because we need to check if user is subscribed
+      continue if counter > 10
+
+      mention.avatar = user.avatar('30', '', '')
+
+      mentions.push(mention)
+      counter++
+
+    @html App.view('widget/mention')(
+      subscribed: subscribed
+      mentions: mentions
+    )
+
+  subscribe: (e) =>
+    e.preventDefault()
+    e.stopPropagation()
+    @subscribeButton.prop('readonly', true)
+    @subscribeButton.prop('disabled', true)
+
+    mention = new App.Mention
+    mention.load(
+      mentionable_type: 'Ticket'
+      mentionable_id: @object.id
+      user_id: App.Session.get().id
+    )
+    mention.save(
+      done: =>
+        @subscribeButton.prop('readonly', false)
+        @subscribeButton.prop('disabled', false)
+        $(e.currentTarget).addClass('hidden')
+        $(e.currentTarget).closest('form').find('.js-unsubscribe').removeClass('hidden')
+    )
+
+  unsubscribe: (e) =>
+    e.preventDefault()
+    e.stopPropagation()
+    @unsubscribeButton.prop('readonly', true)
+    @unsubscribeButton.prop('disabled', true)
+
+    for id in @mentions
+      mention = App.Mention.find(id)
+      continue if !mention
+      continue if mention.user_id isnt App.Session.get().id
+
+      mention.destroy(
+        done: =>
+          @unsubscribeButton.prop('readonly', false)
+          @unsubscribeButton.prop('disabled', false)
+          $(e.currentTarget).addClass('hidden')
+          $(e.currentTarget).closest('form').find('.js-subscribe').removeClass('hidden')
+      )
+
+      break

app/assets/javascripts/app/lib/base/jquery.textmodule.js

@@ -609,6 +609,82 @@
 
   KbAnswer.trigger = '??'
 
-  Plugin.prototype.helpers = [Collection, KbAnswer]
+  function Mention() {}
+
+  Mention.renderValue = function(textmodule, elem, callback) {
+    textmodule.emptyResultsContainer()
+
+    var element = $('<li>').text(App.i18n.translateInline('Please wait...'))
+    textmodule.appendResults(element)
+
+    var form_id = textmodule.$element.closest('form').find('[name=form_id]').val()
+
+    var user_id = $(elem).data('id')
+    var user    = App.User.find(user_id)
+    if (!user) {
+      callback('')
+    }
+
+    fqdn      = App.Config.get('fqdn')
+    http_type = App.Config.get('http_type')
+
+    $replace = $('<a></a>', {
+      href: http_type + '://' + fqdn + '/' + user.uiUrl(),
+      'data-mention-user-id': user_id,
+      text: user.firstname + ' ' + user.lastname
+    })
+
+    callback($replace[0].outerHTML)
+  }
+
+  Mention.renderResults = function(textmodule, term) {
+    textmodule.emptyResultsContainer()
+
+    if(!term) {
+      var element = $('<li>').text(App.i18n.translateInline('Start typing to search for users...'))
+      textmodule.appendResults(element)
+
+      return
+    }
+
+    var element = $('<li>').text(App.i18n.translateInline('Loading...'))
+    textmodule.appendResults(element)
+
+    App.Delay.set(function() {
+      items = []
+
+      App.Mention.searchUser(term, function(data) {
+        textmodule.emptyResultsContainer()
+
+        activeSet = false
+        $.each(data.user_ids, function(index, user_id) {
+          user = App.User.find(user_id)
+          if (!user) return true
+          if (!user.active) return true
+
+          item = $('<li>', {
+            'data-id': user_id,
+            text: user.firstname + ' ' + user.lastname + ' <' + user.email + '>'
+          })
+          if (!activeSet) {
+            activeSet = true
+            item.addClass('is-active')
+          }
+
+          items.push(item)
+        })
+
+        if(items.length == 0) {
+          items.push($('<li>').text(App.i18n.translateInline('No results found')))
+        }
+
+        textmodule.appendResults(items)
+      })
+    }, 200, 'textmoduleMentionDelay', 'textmodule')
+  }
+
+  Mention.trigger = '@@'
+
+  Plugin.prototype.helpers = [Collection, KbAnswer, Mention]
 
 }(jQuery, window));

app/assets/javascripts/app/models/mention.coffee

@@ -0,0 +1,41 @@
+class App.Mention extends App.Model
+  @configure 'Mention', 'mentionable_id', 'mentionable_type'
+  @extend Spine.Model.Ajax
+  @url: @apiPath + '/mentions'
+  @configure_attributes = [
+    { name: 'user_id', display: 'User', tag: 'select',   multiple: false, limit: 100, null: true, relation: 'User', width: '12%', edit: true },
+  ]
+
+  @fetchMentionable: (mentionable_type, mentionable_id, callback) ->
+    App.Ajax.request(
+      type: 'GET'
+      url:  "#{@apiPath}/mentions"
+      data:
+        mentionable_type: mentionable_type
+        mentionable_id: mentionable_id
+        full: true
+      processData: true
+      success: (data, status, xhr) ->
+        if data.assets
+          App.Collection.loadAssets(data.assets, targetModel: @className)
+        callback(data)
+    )
+
+  @searchUser: (query, callback) ->
+    roles    = App.Role.withPermissions('ticket.agent')
+    role_ids = roles.map (role) -> role.id
+
+    App.Ajax.request(
+      type: 'GET'
+      url:  "#{@apiPath}/users/search"
+      data:
+        limit: 10
+        query: query
+        role_ids: role_ids
+        full: true
+      processData: true
+      success: (data, status, xhr) ->
+        if data.assets
+          App.Collection.loadAssets(data.assets, targetModel: @className)
+        callback(data)
+    )

app/assets/javascripts/app/models/role.coffee

@@ -35,3 +35,21 @@ class App.Role extends App.Model
           data['permissions'].push permission
 
     data
+
+  @withPermissions: (permissions) ->
+    if !_.isArray(permissions)
+      permissions = [permissions]
+
+    roles = []
+    for role in App.Role.all()
+      found = false
+      for permission in permissions
+        id = App.Permission.findByAttribute('name', permission)?.id
+        continue if !id
+        continue if !_.contains(role.permission_ids, id)
+        found = true
+        break
+      continue if !found
+      roles.push(role)
+    roles
+

app/assets/javascripts/app/models/ticket.coffee

@@ -196,6 +196,15 @@ class App.Ticket extends App.Model
         objectName    = 'ticket'
         attributeName = 'title'
 
+      if objectAttribute == 'ticket.mention_user_ids'
+        if condition['pre_condition'] isnt 'not_set'
+          if condition['pre_condition'] is 'specific'
+            condition.value = parseInt(condition.value)
+          if condition.operator is 'is'
+            condition.operator = 'contains one'
+          else if condition.operator is 'is not'
+            condition.operator = 'contains all not'
+
       # for new articles there is no created_by_id so we set the current user
       # if no id is given
       if objectAttribute == 'article.created_by_id' && !ticket['article']['created_by_id']

app/assets/javascripts/app/views/profile/notification.jst.eco

@@ -9,38 +9,47 @@
       <thead>
         <tr>
           <th>
-          <th width="18%" style="text-align: center;"><%- @T('My Tickets') %>
+          <th width="16%" style="text-align: center;"><%- @T('My Tickets') %>
-          <th width="18%" style="text-align: center;"><%- @T('Not Assigned') %>*
+          <th width="16%" style="text-align: center;"><%- @T('Not Assigned') %>*
-          <th width="18%" style="text-align: center;"><%- @T('All Tickets') %>*
+          <th width="16%" style="text-align: center;"><%- @T('Mentioned Tickets') %>
+          <th width="16%" style="text-align: center;"><%- @T('All Tickets') %>*
           <th width="120px" class="settings-list-separator" style="text-align: center;"><%- @T('Also notify via email') %>
       </thead>
       <tbody>
-      <% if @config.matrix: %>
+      <% if @matrix: %>
-        <% for key, value of @config.matrix: %>
+        <% for key, value of @matrix: %>
         <tr>
           <td>
             <%- @T(value.name) %>
+            <% criteria = @config.matrix[key]?.criteria %>
+            <% channel = @config.matrix[key]?.channel %>
           <td class="u-positionOrigin">
             <label class="checkbox-replacement checkbox-replacement--fullscreen">
-              <input type="checkbox" name="matrix.<%= key %>.criteria.owned_by_me" value="true" <% if value.criteria && value.criteria.owned_by_me: %>checked<% end %>/>
+              <input type="checkbox" name="matrix.<%= key %>.criteria.owned_by_me" value="true"<% if criteria && criteria.owned_by_me: %> checked<% end %> />
               <%- @Icon('checkbox', 'icon-unchecked') %>
               <%- @Icon('checkbox-checked', 'icon-checked') %>
             </label>
           <td class="u-positionOrigin">
             <label class="checkbox-replacement checkbox-replacement--fullscreen">
-              <input type="checkbox" name="matrix.<%= key %>.criteria.owned_by_nobody" value="true"  <% if value.criteria && value.criteria.owned_by_nobody: %>checked<% end %>/>
+              <input type="checkbox" name="matrix.<%= key %>.criteria.owned_by_nobody" value="true"<% if criteria && criteria.owned_by_nobody: %> checked<% end %> />
               <%- @Icon('checkbox', 'icon-unchecked') %>
               <%- @Icon('checkbox-checked', 'icon-checked') %>
             </label>
           <td class="u-positionOrigin">
             <label class="checkbox-replacement checkbox-replacement--fullscreen">
-              <input type="checkbox" name="matrix.<%= key %>.criteria.no" value="true"  <% if  value.criteria && value.criteria.no: %>checked<% end %>/>
+              <input type="checkbox" name="matrix.<%= key %>.criteria.mentioned" value="true"<% if criteria && criteria.mentioned: %> checked<% end %> />
+              <%- @Icon('checkbox', 'icon-unchecked') %>
+              <%- @Icon('checkbox-checked', 'icon-checked') %>
+            </label>
+          <td class="u-positionOrigin">
+            <label class="checkbox-replacement checkbox-replacement--fullscreen">
+              <input type="checkbox" name="matrix.<%= key %>.criteria.no" value="true"<% if criteria && criteria.no: %> checked<% end %> />
               <%- @Icon('checkbox', 'icon-unchecked') %>
               <%- @Icon('checkbox-checked', 'icon-checked') %>
             </label>
           <td class="u-positionOrigin settings-list-separator">
             <label class="checkbox-replacement checkbox-replacement--fullscreen">
-              <input type="checkbox" name="matrix.<%= key %>.channel" value="email" <% if value.channel && value.channel.email: %>checked<% end %>/>
+              <input type="checkbox" name="matrix.<%= key %>.channel" value="email"<% if channel && channel.email: %> checked<% end %> />
               <%- @Icon('checkbox', 'icon-unchecked') %>
               <%- @Icon('checkbox-checked', 'icon-checked') %>
             </label>
@@ -51,7 +60,7 @@
   </div>
 
   <% if @groups: %>
-  <h2>* <%- @T( 'Limit Groups' ) %></h2>
+  <h2>* <%- @T('Limit Groups') %></h2>
   <div class="settings-entry">
     <table class="settings-list">
       <thead>

app/assets/javascripts/app/views/ticket_zoom/sidebar_ticket.jst.eco

@@ -5,3 +5,4 @@
 <div class="links"></div>
 <div class="link_kb_answers"></div>
 <div class="js-timeUnit"></div>
+<div class="mentions"></div>

app/assets/javascripts/app/views/widget/mention.jst.eco

@@ -0,0 +1,14 @@
+<label><%- @T('Mentions') %></label>
+<form class="ui-front mentionWidget">
+  <div class="js-subscribe<% if @subscribed: %> hidden<% end %>">
+    <input type="button" class="btn btn--fullWidth" name="subscribe" value="<%- @T('Subscribe') %>">
+  </div>
+  <div class="js-unsubscribe<% if !@subscribed: %> hidden<% end %>">
+    <input type="button" class="btn btn--fullWidth" name="unsubscribe" value="<%- @T('Unsubscribe') %>">
+  </div>
+</form>
+<div class="controls-label">
+<% for mention in @mentions: %>
+  <a href="#user/profile/<%= mention.user_id %>"><%- mention.avatar %></a>
+<% end %>
+</div>

app/assets/stylesheets/zammad.scss

@@ -5613,6 +5613,10 @@ footer {
       cursor: help;
     }
 
+    .notification-icon-help {
+      opacity: .2;
+    }
+
     .stat-label {
       color: #444a4f;
       @extend .u-textTruncate;

app/controllers/mentions_controller.rb

@@ -0,0 +1,100 @@
+# Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
+
+class MentionsController < ApplicationController
+  prepend_before_action -> { authorize! }
+  prepend_before_action { authentication_check }
+
+  # GET /api/v1/mentions
+  def list
+    list = Mention.where(condition).order(created_at: :desc)
+
+    if response_full?
+      assets = {}
+      item_ids = []
+      list.each do |item|
+        item_ids.push item.id
+        assets = item.assets(assets)
+      end
+      render json: {
+        record_ids: item_ids,
+        assets:     assets,
+      }, status: :ok
+      return
+    end
+
+    # return result
+    render json: {
+      mentions: list,
+    }
+  end
+
+  # POST /api/v1/mentions
+  def create
+    success = Mention.create!(
+      mentionable: mentionable!,
+      user:        current_user,
+    )
+    if success
+      render json: success, status: :created
+    else
+      render json: success.errors, status: :unprocessable_entity
+    end
+  end
+
+  # DELETE /api/v1/mentions
+  def destroy
+    success = Mention.find_by(user: current_user, id: params[:id]).destroy
+    if success
+      render json: success, status: :ok
+    else
+      render json: success.errors, status: :unprocessable_entity
+    end
+  end
+
+  private
+
+  def ensure_mentionable_type!
+    return if ['Ticket'].include?(params[:mentionable_type])
+
+    raise 'Invalid mentionable_type!'
+  end
+
+  def mentionable!
+    ensure_mentionable_type!
+
+    object = params[:mentionable_type].constantize.find(params[:mentionable_id])
+    authorize!(object, :update?)
+    object
+  end
+
+  def fill_condition_mentionable(condition)
+    condition[:mentionable_type] = params[:mentionable_type]
+    return if params[:mentionable_id].blank?
+
+    condition[:mentionable_id] = params[:mentionable_id]
+  end
+
+  def fill_condition_id(condition)
+    return if params[:id].blank?
+
+    condition[:id] = params[:id]
+  end
+
+  def fill_condition_user(condition)
+    return if params[:user_id].blank?
+
+    condition[:user] = User.find(params[:user_id])
+  end
+
+  def condition
+    condition = {}
+    fill_condition_id(condition)
+    fill_condition_user(condition)
+
+    return condition if params[:mentionable_type].blank?
+
+    mentionable!
+    fill_condition_mentionable(condition)
+    condition
+  end
+end

app/controllers/tickets_controller.rb

@@ -163,6 +163,14 @@ class TicketsController < ApplicationController
         end
       end
 
+      # create mentions if given
+      if params[:mentions].present?
+        authorize!(Mention.new, :create?)
+        Array(params[:mentions]).each do |user_id|
+          Mention.where(mentionable: ticket, user_id: user_id).first_or_create(mentionable: ticket, user_id: user_id)
+        end
+      end
+
       # create article if given
       if params[:article]
         article_create(ticket, params[:article])
@@ -702,6 +710,12 @@ class TicketsController < ApplicationController
     # get tags
     tags = ticket.tag_list
 
+    # get mentions
+    mentions = Mention.where(mentionable: ticket).order(created_at: :desc)
+    mentions.each do |mention|
+      assets = mention.assets(assets)
+    end
+
     # return result
     {
       ticket_id:          ticket.id,
@@ -709,6 +723,7 @@ class TicketsController < ApplicationController
       assets:             assets,
       links:              links,
       tags:               tags,
+      mentions:           mentions.pluck(:id),
       form_meta:          attributes_to_change[:form_meta],
     }
   end

app/models/concerns/checks_client_notification.rb

@@ -17,12 +17,19 @@ module ChecksClientNotification
     {
       message: {
         event: "#{class_name}:#{event}",
-        data:  { id: id, updated_at: updated_at }
+        data:  notify_clients_data_attributes
       },
       type:    'authenticated',
     }
   end
 
+  def notify_clients_data_attributes
+    {
+      id:         id,
+      updated_at: updated_at
+    }
+  end
+
   def notify_clients_send(data)
     return notify_clients_send_to(data[:message]) if client_notification_send_to.present?
 
@@ -104,38 +111,28 @@ module ChecksClientNotification
   # methods defined here are going to extend the class, not the instance of it
   class_methods do
 
-=begin
+    # serve method to ignore events
-
+    #
-serve method to ignore events
+    # @example
-
+    #   class Model < ApplicationModel
-class Model < ApplicationModel
+    #     include ChecksClientNotification
-  include ChecksClientNotification
+    #     client_notification_events_ignored :create, :update, :touch
-  client_notification_events_ignored :create, :update, :touch
+    #   end
-end
-
-=end
-
     def client_notification_events_ignored(*attributes)
       @client_notification_events_ignored ||= []
       @client_notification_events_ignored |= attributes
     end
 
-=begin
+    # serve method to define recipient user ids
-
+    #
-serve method to define recipient user ids
+    # @example
-
+    #   class Model < ApplicationModel
-class Model < ApplicationModel
+    #     include ChecksClientNotification
-  include ChecksClientNotification
+    #     client_notification_send_to :user_id
-  client_notification_send_to :user_id
+    #   end
-end
-
-=end
-
     def client_notification_send_to(*attributes)
       @client_notification_send_to ||= []
       @client_notification_send_to |= attributes
     end
-
   end
-
 end

app/models/concerns/has_history.rb

@@ -204,7 +204,7 @@ returns
 =end
 
   def history_get(fulldata = false)
-    relation_object = self.class.instance_variable_get(:@history_relation_object) || nil
+    relation_object = history_relation_object
 
     if !fulldata
       return History.list(self.class.name, self['id'], relation_object)
@@ -213,12 +213,16 @@ returns
     # get related objects
     history = History.list(self.class.name, self['id'], relation_object, true)
     history[:list].each do |item|
-      record = item['object'].constantize.find(item['o_id'])
+      record = item['object'].constantize.lookup(id: item['o_id'])
 
-      history[:assets] = record.assets(history[:assets])
+      if record.present?
+        history[:assets] = record.assets(history[:assets])
+      end
 
-      if item['related_object']
+      next if !item['related_object']
-        record = item['related_object'].constantize.find(item['related_o_id'])
+
+      record = item['related_object'].constantize.lookup(id: item['related_o_id'])
+      if record.present?
         history[:assets] = record.assets(history[:assets])
       end
     end
@@ -228,6 +232,10 @@ returns
     }
   end
 
+  def history_relation_object
+    @history_relation_object ||= self.class.instance_variable_get(:@history_relation_object) || []
+  end
+
   # methods defined here are going to extend the class, not the instance of it
   class_methods do
 =begin
@@ -256,8 +264,9 @@ end
 
 =end
 
-    def history_relation_object(attribute)
+    def history_relation_object(*attributes)
-      @history_relation_object = attribute
+      @history_relation_object ||= []
+      @history_relation_object |= attributes
     end
 
   end

app/models/history.rb

@@ -124,7 +124,7 @@ returns
 
 return all history entries of an object and it's related history objects
 
-  history_list = History.list('Ticket', 123, true)
+  history_list = History.list('Ticket', 123, 'Ticket::Article')
 
 returns
 
@@ -137,7 +137,7 @@ returns
 
 return all history entries of an object and it's assets
 
-  history = History.list('Ticket', 123, nil, true)
+  history = History.list('Ticket', 123, nil, ['Ticket::Article'])
 
 returns
 
@@ -148,16 +148,21 @@ returns
 
 =end
 
-  def self.list(requested_object, requested_object_id, related_history_object = nil, assets = nil)
+  def self.list(requested_object, requested_object_id, related_history_object = [], assets = nil)
     histories = History.where(
       history_object_id: object_lookup(requested_object).id,
       o_id:              requested_object_id
     )
 
     if related_history_object.present?
+      object_ids = []
+      Array(related_history_object).each do |object|
+        object_ids << object_lookup(object).id
+      end
+
       histories = histories.or(
         History.where(
-          history_object_id: object_lookup(related_history_object).id,
+          history_object_id: object_ids,
           related_o_id:      requested_object_id
         )
       )

app/models/mention.rb

@@ -0,0 +1,54 @@
+# Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
+
+class Mention < ApplicationModel
+  include ChecksClientNotification
+  include HasHistory
+
+  include Mention::Assets
+
+  after_create :update_mentionable
+  after_destroy :update_mentionable
+
+  belongs_to :created_by, class_name: 'User'
+  belongs_to :updated_by, class_name: 'User'
+  belongs_to :user, class_name: 'User'
+  belongs_to :mentionable, polymorphic: true
+
+  association_attributes_ignored :created_by, :updated_by
+  client_notification_events_ignored :update, :touch
+
+  validates_with Mention::Validation
+
+  def notify_clients_data_attributes
+    super.merge(
+      'mentionable_id'   => mentionable_id,
+      'mentionable_type' => mentionable_type,
+    )
+  end
+
+  def history_log_attributes
+    {
+      related_o_id:           mentionable_id,
+      related_history_object: mentionable_type,
+    }
+  end
+
+  def history_destroy
+    history_log('removed', created_by_id)
+  end
+
+  def self.duplicates(mentionable1, mentionable2)
+    Mention.joins(', mentions as mentionsb').where('
+      mentions.user_id = mentionsb.user_id
+      AND mentions.mentionable_type = ?
+      AND mentions.mentionable_id = ?
+      AND mentionsb.mentionable_type = ?
+      AND mentionsb.mentionable_id = ?
+    ', mentionable1.class.to_s, mentionable1.id, mentionable2.class.to_s, mentionable2.id)
+  end
+
+  def update_mentionable
+    mentionable.update(updated_by: updated_by)
+    mentionable.touch # rubocop:disable Rails/SkipsModelValidations
+  end
+end

app/models/mention/assets.rb

@@ -0,0 +1,28 @@
+# Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
+
+class Mention
+  module Assets
+    extend ActiveSupport::Concern
+
+    def assets_attributes(data)
+      app_model = self.class.to_app_model
+
+      data[ app_model ] ||= {}
+      return data if data[ app_model ][ id ]
+
+      data[ app_model ][ id ] = attributes_with_association_ids
+
+      data
+    end
+
+    def assets(data)
+      assets_attributes(data)
+
+      if mentionable.present?
+        data = mentionable.assets(data)
+      end
+
+      user.assets(data)
+    end
+  end
+end

app/models/mention/validation.rb

@@ -0,0 +1,21 @@
+# Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
+class Mention::Validation < ActiveModel::Validator
+  attr_reader :record
+
+  def validate(record)
+    @record = record
+    check_user_permission
+  end
+
+  private
+
+  def check_user_permission
+    return if MentionPolicy.new(record.user, record).create?
+
+    invalid_because(:user, 'has no ticket.agent permissions')
+  end
+
+  def invalid_because(attribute, message)
+    record.errors.add attribute, message
+  end
+end

app/models/ticket.rb

@@ -66,7 +66,7 @@ class Ticket < ApplicationModel
                              :article_count,
                              :preferences
 
-  history_relation_object 'Ticket::Article'
+  history_relation_object 'Ticket::Article', 'Mention'
 
   sanitized_html :note
 
@@ -75,6 +75,7 @@ class Ticket < ApplicationModel
   has_many      :articles,               class_name: 'Ticket::Article', after_add: :cache_update, after_remove: :cache_update, dependent: :destroy, inverse_of: :ticket
   has_many      :ticket_time_accounting, class_name: 'Ticket::TimeAccounting', dependent: :destroy, inverse_of: :ticket
   has_many      :flags,                  class_name: 'Ticket::Flag', dependent: :destroy
+  has_many      :mentions,               as: :mentionable, dependent: :destroy
   belongs_to    :state,                  class_name: 'Ticket::State', optional: true
   belongs_to    :priority,               class_name: 'Ticket::Priority', optional: true
   belongs_to    :owner,                  class_name: 'User', optional: true
@@ -84,7 +85,7 @@ class Ticket < ApplicationModel
   belongs_to    :create_article_type,    class_name: 'Ticket::Article::Type', optional: true
   belongs_to    :create_article_sender,  class_name: 'Ticket::Article::Sender', optional: true
 
-  association_attributes_ignored :flags
+  association_attributes_ignored :flags, :mentions
 
   self.inheritance_column = nil
 
@@ -364,6 +365,10 @@ returns
         updated_by_id: data[:user_id],
       )
 
+      # search for mention duplicates and destroy them before moving mentions
+      Mention.duplicates(self, target_ticket).destroy_all
+      Mention.where(mentionable: self).update_all(mentionable_id: target_ticket.id) # rubocop:disable Rails/SkipsModelValidations
+
       # reassign links to the new ticket
       # rubocop:disable Rails/SkipsModelValidations
       ticket_source_id = Link::Object.find_by(name: 'Ticket').id
@@ -574,17 +579,19 @@ condition example
 
     # get tables to join
     tables = ''
-    selectors.each_key do |attribute|
+    selectors.each do |attribute, selector_raw|
-      selector = attribute.split('.')
+      attributes = attribute.split('.')
-      next if !selector[1]
+      selector = selector_raw.stringify_keys
-      next if selector[0] == 'ticket'
+      next if !attributes[1]
-      next if selector[0] == 'execution_time'
+      next if attributes[0] == 'execution_time'
-      next if tables.include?(selector[0])
+      next if tables.include?(attributes[0])
+      next if attributes[0] == 'ticket' && attributes[1] != 'mention_user_ids'
+      next if attributes[0] == 'ticket' && attributes[1] == 'mention_user_ids' && selector['pre_condition'] == 'not_set'
 
       if query != ''
         query += ' AND '
       end
-      case selector[0]
+      case attributes[0]
       when 'customer'
         tables += ', users customers'
         query += 'tickets.customer_id = customers.id'
@@ -600,8 +607,13 @@ condition example
       when 'ticket_state'
         tables += ', ticket_states'
         query += 'tickets.state_id = ticket_states.id'
+      when 'ticket'
+        if attributes[1] == 'mention_user_ids'
+          tables += ', mentions'
+          query += "tickets.id = mentions.mentionable_id AND mentions.mentionable_type = 'Ticket'"
+        end
       else
-        raise "invalid selector #{attribute.inspect}->#{selector.inspect}"
+        raise "invalid selector #{attribute.inspect}->#{attributes.inspect}"
       end
     end
 
@@ -662,6 +674,29 @@ condition example
         query += ' AND '
       end
 
+      # because of no grouping support we select not_set by sub select for mentions
+      if attributes[0] == 'ticket' && attributes[1] == 'mention_user_ids'
+        if selector['pre_condition'] == 'not_set'
+          query += if selector['operator'] == 'is'
+                     "(SELECT 1 FROM mentions mentions_sub WHERE mentions_sub.mentionable_type = 'Ticket' AND mentions_sub.mentionable_id = tickets.id) IS NULL"
+                   else
+                     "1 = (SELECT 1 FROM mentions mentions_sub WHERE mentions_sub.mentionable_type = 'Ticket' AND mentions_sub.mentionable_id = tickets.id)"
+                   end
+        else
+          query += if selector['operator'] == 'is'
+                     'mentions.user_id IN (?)'
+                   else
+                     'mentions.user_id NOT IN (?)'
+                   end
+          if selector['pre_condition'] == 'current_user.id'
+            bind_params.push current_user_id
+          else
+            bind_params.push selector['value']
+          end
+        end
+        next
+      end
+
       if selector['operator'] == 'is'
         if selector['pre_condition'] == 'not_set'
           if attributes[1].match?(/^(created_by|updated_by|owner|customer|user)_id/)

app/models/ticket/article.rb

@@ -31,7 +31,8 @@ class Ticket::Article < ApplicationModel
   belongs_to :updated_by, class_name: 'User', optional: true
   belongs_to :origin_by,  class_name: 'User', optional: true
 
-  before_save   :touch_ticket_if_needed
+  before_validation :check_mentions, on: :create
+  before_save :touch_ticket_if_needed
   before_create :check_subject, :check_body, :check_message_id_md5
   before_update :check_subject, :check_body, :check_message_id_md5
   after_destroy :store_delete, :update_time_units
@@ -323,6 +324,26 @@ returns
     self.body = body[0, limit]
   end
 
+  def check_mentions
+    begin
+      mention_user_ids = Nokogiri::HTML(body).css('a[data-mention-user-id]').map do |link|
+        link['data-mention-user-id']
+      end
+    rescue => e
+      Rails.logger.error "Can't parse body '#{body}' as HTML for extracting Mentions."
+      Rails.logger.error e
+      return
+    end
+
+    return if mention_user_ids.blank?
+    raise "User #{updated_by_id} has no permission to mention other Users!" if !MentionPolicy.new(updated_by, Mention.new).create?
+
+    user_ids = User.where(id: mention_user_ids).pluck(:id)
+    user_ids.each do |user_id|
+      Mention.where(mentionable: ticket, user_id: user_id).first_or_create(mentionable: ticket, user_id: user_id)
+    end
+  end
+
   def history_log_attributes
     {
       related_o_id:           self['ticket_id'],

app/models/ticket/search_index.rb

@@ -8,10 +8,10 @@ module Ticket::SearchIndex
 
     # collect article data
     # add tags
-    tags = tag_list
+    attributes['tags'] = tag_list
-    if tags.present?
+
-      attributes[:tags] = tags
+    # mentions
-    end
+    attributes['mention_user_ids'] = mentions.pluck(:user_id)
 
     # current payload size
     total_size_current = 0

app/models/transaction/notification.rb

@@ -50,9 +50,22 @@ class Transaction::Notification
     recipients_and_channels = []
     recipients_reason = {}
 
-    # loop through all users
+    # loop through all group users
     possible_recipients = possible_recipients_of_group(ticket.group_id)
 
+    # loop through all mention users
+    mention_users = Mention.where(mentionable_type: @item[:object], mentionable_id: @item[:object_id]).map(&:user)
+    if mention_users.present?
+
+      # only notify if read permission on group are given
+      mention_users.each do |mention_user|
+        next if !mention_user.group_access?(ticket.group_id, 'read')
+
+        possible_recipients.push mention_user
+        recipients_reason[mention_user.id] = 'are mentioned'
+      end
+    end
+
     # apply owner
     if ticket.owner_id != 1
       possible_recipients.push ticket.owner

app/models/user.rb

@@ -34,6 +34,7 @@ class User < ApplicationModel
   has_one                 :chat_agent_updated_by,  class_name: 'Chat::Agent', foreign_key: :updated_by_id, dependent: :destroy, inverse_of: :updated_by
   has_many                :chat_sessions,          class_name: 'Chat::Session', dependent: :destroy
   has_many                :karma_user,             class_name: 'Karma::User', dependent: :destroy
+  has_many                :mentions,               dependent: :destroy
   has_many                :karma_activity_logs,    class_name: 'Karma::ActivityLog', dependent: :destroy
   has_many                :cti_caller_ids,         class_name: 'Cti::CallerId', dependent: :destroy
   has_many                :customer_tickets,       class_name: 'Ticket', foreign_key: :customer_id, dependent: :destroy, inverse_of: :customer
@@ -54,7 +55,7 @@ class User < ApplicationModel
 
   store :preferences
 
-  association_attributes_ignored :online_notifications, :templates, :taskbars, :user_devices, :chat_sessions, :karma_activity_logs, :cti_caller_ids, :text_modules, :customer_tickets, :owner_tickets, :created_recent_views, :chat_agents, :data_privacy_tasks, :overviews
+  association_attributes_ignored :online_notifications, :templates, :taskbars, :user_devices, :chat_sessions, :karma_activity_logs, :cti_caller_ids, :text_modules, :customer_tickets, :owner_tickets, :created_recent_views, :chat_agents, :data_privacy_tasks, :overviews, :mentions
 
   activity_stream_permission 'admin.user'
 

app/policies/controllers/mentions_controller_policy.rb

@@ -0,0 +1,3 @@
+class Controllers::MentionsControllerPolicy < Controllers::ApplicationControllerPolicy
+  default_permit!('ticket.agent')
+end

app/policies/mention_policy.rb

@@ -0,0 +1,5 @@
+class MentionPolicy < ApplicationPolicy
+  def create?
+    user.permissions?('ticket.agent')
+  end
+end

app/views/mailer/ticket_update/cs.html.erb

@@ -25,5 +25,5 @@ Ticket (#{ticket.title}) byl aktualizován uživatelem "<b>#{current_user.longna
 <% end %>
 <br>
 <div>
-  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}" target="zammad_app">#{t('View this in Zammad')}</a>
+  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}<% if @objects[:article] %>/#{article.id}<% end %>" target="zammad_app">#{t('View this in Zammad')}</a>
 </div>

app/views/mailer/ticket_update/de.html.erb

@@ -25,5 +25,5 @@ Ticket (#{ticket.title}) wurde von "<b>#{current_user.longname}</b>" aktualisier
 <% end %>
 <br>
 <div>
-  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}" target="zammad_app">#{t('View this in Zammad')}</a>
+  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}<% if @objects[:article] %>/#{article.id}<% end %>" target="zammad_app">#{t('View this in Zammad')}</a>
 </div>

app/views/mailer/ticket_update/en.html.erb

@@ -25,5 +25,5 @@ Ticket (#{ticket.title}) has been updated by "<b>#{current_user.longname}</b>".
 <% end %>
 <br>
 <div>
-  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}" target="zammad_app">#{t('View this in Zammad')}</a>
+  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}<% if @objects[:article] %>/#{article.id}<% end %>" target="zammad_app">#{t('View this in Zammad')}</a>
 </div>

app/views/mailer/ticket_update/es.html.erb

@@ -25,5 +25,5 @@ Ticket (#{ticket.title}) ha sido actualizado por "<b>#{current_user.longname}</b
 <% end %>
 <br>
 <div>
-  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}" target="zammad_app">#{t('View this in Zammad')}</a>
+  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}<% if @objects[:article] %>/#{article.id}<% end %>" target="zammad_app">#{t('View this in Zammad')}</a>
 </div>

app/views/mailer/ticket_update/fr.html.erb

@@ -25,5 +25,5 @@ Le ticket (#{ticket.title}) a été mis à jour par "<b>#{current_user.longname}
 <% end %>
 <br>
 <div>
-  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}" target="zammad_app">#{t('View this in Zammad')}</a>
+  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}<% if @objects[:article] %>/#{article.id}<% end %>" target="zammad_app">#{t('View this in Zammad')}</a>
 </div>

app/views/mailer/ticket_update/it.html.erb

@@ -25,5 +25,5 @@ Il ticket (#{ticket.title}) è stato aggiornato da "<b>#{current_user.longname}<
 <% end %>
 <br>
 <div>
-  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}" target="zammad_app">#{t('View this in Zammad')}</a>
+  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}<% if @objects[:article] %>/#{article.id}<% end %>" target="zammad_app">#{t('View this in Zammad')}</a>
 </div>

app/views/mailer/ticket_update/pt-br.html.erb

@@ -25,5 +25,5 @@ O chamado (#{ticket.title}) foi atualizado por "<b>#{current_user.longname}</b>"
 <% end %>
 <br>
 <div>
-  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}" target="zammad_app">#{t('Veja mais informações no Zammad')}</a>
+  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}<% if @objects[:article] %>/#{article.id}<% end %>" target="zammad_app">#{t('Veja mais informações no Zammad')}</a>
 </div>

app/views/mailer/ticket_update/zh-cn.html.erb

@@ -25,5 +25,5 @@
 <% end %>
 <br>
 <div>
-  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}" target="zammad_app">#{t('View this in Zammad')}</a>
+  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}<% if @objects[:article] %>/#{article.id}<% end %>" target="zammad_app">#{t('View this in Zammad')}</a>
 </div>

app/views/mailer/ticket_update/zh-tw.html.erb

@@ -25,5 +25,5 @@
 <% end %>
 <br>
 <div>
-  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}" target="zammad_app">#{t('View this in Zammad')}</a>
+  <a href="#{config.http_type}://#{config.fqdn}/#ticket/zoom/#{ticket.id}<% if @objects[:article] %>/#{article.id}<% end %>" target="zammad_app">#{t('View this in Zammad')}</a>
 </div>

config/application.rb

@@ -49,6 +49,7 @@ module Zammad
               criteria: {
                 owned_by_me:     true,
                 owned_by_nobody: true,
+                mentioned:       true,
                 no:              false,
               },
               channel:  {
@@ -60,6 +61,7 @@ module Zammad
               criteria: {
                 owned_by_me:     true,
                 owned_by_nobody: true,
+                mentioned:       true,
                 no:              false,
               },
               channel:  {
@@ -71,6 +73,7 @@ module Zammad
               criteria: {
                 owned_by_me:     true,
                 owned_by_nobody: false,
+                mentioned:       false,
                 no:              false,
               },
               channel:  {
@@ -82,6 +85,7 @@ module Zammad
               criteria: {
                 owned_by_me:     true,
                 owned_by_nobody: false,
+                mentioned:       false,
                 no:              false,
               },
               channel:  {

config/initializers/html_sanitizer.rb

@@ -26,7 +26,7 @@ Rails.application.config.html_sanitizer_tags_whitelist = %w[
 # attributes allowed for tags
 Rails.application.config.html_sanitizer_attributes_whitelist = {
   :all         => %w[class dir lang title translate data-signature data-signature-id],
-  'a'          => %w[href hreflang name rel data-target-id data-target-type],
+  'a'          => %w[href hreflang name rel data-target-id data-target-type data-mention-user-id],
   'abbr'       => %w[title],
   'blockquote' => %w[type cite],
   'col'        => %w[span width],

config/routes/mention.rb

@@ -0,0 +1,7 @@
+Zammad::Application.routes.draw do
+  api_path = Rails.configuration.api_path
+
+  match api_path + '/mentions',           to: 'mentions#list',         via: :get
+  match api_path + '/mentions',           to: 'mentions#create',       via: :post
+  match api_path + '/mentions/:id',       to: 'mentions#destroy',      via: :delete
+end

db/migrate/20120101000001_create_base.rb

@@ -747,5 +747,17 @@ class CreateBase < ActiveRecord::Migration[4.2]
       t.timestamps limit: 3, null: false
     end
     add_index :data_privacy_tasks, [:state]
+
+    create_table :mentions do |t|
+      t.references :mentionable,      polymorphic: true, null: false
+      t.column :user_id,              :integer, null: false
+      t.column :updated_by_id,        :integer, null: false
+      t.column :created_by_id,        :integer, null: false
+      t.timestamps limit: 3, null: false
+    end
+    add_index :mentions, %i[mentionable_id mentionable_type user_id], unique: true, name: 'index_mentions_mentionable_user'
+    add_foreign_key :mentions, :users, column: :created_by_id
+    add_foreign_key :mentions, :users, column: :updated_by_id
+    add_foreign_key :mentions, :users, column: :user_id
   end
 end

db/migrate/20201110000001_mention_init.rb

@@ -0,0 +1,66 @@
+class MentionInit < ActiveRecord::Migration[5.2]
+  def change
+
+    # return if it's a new setup
+    return if !Setting.exists?(name: 'system_init_done')
+
+    create_table :mentions do |t|
+      t.references :mentionable,      polymorphic: true, null: false
+      t.column :user_id,              :integer, null: false
+      t.column :updated_by_id,        :integer, null: false
+      t.column :created_by_id,        :integer, null: false
+      t.timestamps limit: 3, null: false
+    end
+    add_index :mentions, %i[mentionable_id mentionable_type user_id], unique: true, name: 'index_mentions_mentionable_user'
+    add_foreign_key :mentions, :users, column: :created_by_id
+    add_foreign_key :mentions, :users, column: :updated_by_id
+    add_foreign_key :mentions, :users, column: :user_id
+
+    Mention.reset_column_information
+    create_overview
+    update_user_matrix
+  end
+
+  def create_overview
+    Overview.create_if_not_exists(
+      name:          'My mentioned Tickets',
+      link:          'my_mentioned_tickets',
+      prio:          1025,
+      role_ids:      Role.with_permissions('ticket.agent').pluck(:id),
+      condition:     { 'ticket.mention_user_ids'=>{ 'operator' => 'is', 'pre_condition' => 'current_user.id', 'value' => '', 'value_completion' => '' } },
+      order:         {
+        by:        'created_at',
+        direction: 'ASC',
+      },
+      view:          {
+        d:                 %w[title customer group created_at],
+        s:                 %w[title customer group created_at],
+        m:                 %w[number title customer group created_at],
+        view_mode_default: 's',
+      },
+      created_by_id: 1,
+      updated_by_id: 1,
+    )
+  end
+
+  def update_user_matrix
+    User.with_permissions('ticket.agent').each do |user|
+      next if user.preferences.blank?
+      next if user.preferences['notification_config'].blank?
+      next if user.preferences['notification_config']['matrix'].blank?
+
+      update_user_matrix_by_user(user)
+    end
+  end
+
+  def update_user_matrix_by_user(user)
+    %w[create update].each do |type|
+      user.preferences['notification_config']['matrix'][type]['criteria']['mentioned'] = true
+    end
+
+    %w[reminder_reached escalation].each do |type|
+      user.preferences['notification_config']['matrix'][type]['criteria']['mentioned'] = false
+    end
+    user.save!
+  end
+end

db/seeds/overviews.rb

@@ -85,6 +85,24 @@ Overview.create_if_not_exists(
   },
 )
 
+Overview.create_if_not_exists(
+  name:      'My mentioned Tickets',
+  link:      'my_mentioned_tickets',
+  prio:      1025,
+  role_ids:  [overview_role.id],
+  condition: { 'ticket.mention_user_ids'=>{ 'operator' => 'is', 'pre_condition' => 'current_user.id', 'value' => '', 'value_completion' => '' } },
+  order:     {
+    by:        'created_at',
+    direction: 'ASC',
+  },
+  view:      {
+    d:                 %w[title customer group created_at],
+    s:                 %w[title customer group created_at],
+    m:                 %w[number title customer group created_at],
+    view_mode_default: 's',
+  },
+)
+
 Overview.create_if_not_exists(
   name:      'Open',
   link:      'all_open',

lib/html_sanitizer.rb

@@ -13,7 +13,9 @@ satinize html string based on whiltelist
 
   def self.strict(string, external = false, timeout: true)
     Timeout.timeout(timeout ? PROCESSING_TIMEOUT : nil) do
-      @fqdn = Setting.get('fqdn')
+      @fqdn              = Setting.get('fqdn')
+      http_type          = Setting.get('http_type')
+      web_app_url_prefix = "#{http_type}://#{@fqdn}/\#".downcase
 
       # config
       tags_remove_content = Rails.configuration.html_sanitizer_tags_remove_content
@@ -179,7 +181,11 @@ satinize html string based on whiltelist
 
           node.set_attribute('href', href)
           node.set_attribute('rel', 'nofollow noreferrer noopener')
-          node.set_attribute('target', '_blank')
+
+          # do not "target=_blank" WebApp URLs (e.g. mentions)
+          if !href.downcase.start_with?(web_app_url_prefix)
+            node.set_attribute('target', '_blank')
+          end
         end
 
         if node.name == 'a' && node['href'].blank?

lib/notification_factory/mailer.rb

@@ -48,6 +48,7 @@ returns
 
     owned_by_nobody = false
     owned_by_me = false
+    mentioned = false
     case ticket.owner_id
     when 1
       owned_by_nobody = true
@@ -69,6 +70,11 @@ returns
       end
     end
 
+    # always trigger notifications for user if he is mentioned
+    if owned_by_me == false && ticket.mentions.exists?(user: user)
+      mentioned = true
+    end
+
     # check if group is in selected groups
     if !owned_by_me
       selected_group_ids = user_preferences['notification_config']['group_ids']
@@ -109,6 +115,12 @@ returns
         channels: channels
       }
     end
+    if data['criteria']['mentioned'] && mentioned
+      return {
+        user:     user,
+        channels: channels
+      }
+    end
     return if !data['criteria']['no']
 
     {

lib/search_index_backend.rb

@@ -489,7 +489,10 @@ example for aggregations within one year
       minute: 'm',
     }
     if selector.present?
+      operators_is_isnot = ['is', 'is not']
+
       selector.each do |key, data|
+
         data = data.clone
         table, key_tmp = key.split('.')
         if key_tmp.blank?
@@ -510,8 +513,6 @@ example for aggregations within one year
           when 'not_set'
             data['value'] = if key_tmp.match?(/^(created_by|updated_by|owner|customer|user)_id/)
                               1
-                            else
-                              'NULL'
                             end
           when 'current_user.id'
             raise "Use current_user.id in selector, but no current_user is set #{data.inspect}" if !current_user_id
@@ -562,6 +563,22 @@ example for aggregations within one year
           end
         end
 
+        # for pre condition not_set we want to check if values are defined for the object by exists
+        if data['pre_condition'] == 'not_set' && operators_is_isnot.include?(data['operator']) && data['value'].nil?
+          t['exists'] = {
+            field: key_tmp,
+          }
+
+          case data['operator']
+          when 'is'
+            query_must_not.push t
+          when 'is not'
+            query_must.push t
+          end
+          next
+
+        end
+
         if table != 'ticket'
           key_tmp = "#{table}.#{key_tmp}"
         end

public/assets/tests/ticket_selector.js

@@ -131,6 +131,7 @@ window.onload = function() {
         "id": 434
       },
       "tags": ["tag a", "tag b"],
+      "mention_user_ids": [1,3,5,6],
       "escalation_at": "2017-02-09T09:16:56.192Z",
       "last_contact_agent_at": "2017-02-09T09:16:56.192Z",
       "last_contact_agent_at": "2017-02-09T09:16:56.192Z",
@@ -1106,4 +1107,12 @@ window.onload = function() {
 
     testContains('organization.domain', 'cool', ticket);
   });
+
+  test("ticket mention user_id", function() {
+    ticket = new App.Ticket();
+    ticket.load(ticketData);
+
+    testPreConditionUser('ticket.mention_user_ids', '6', ticket, sessionData);
+  });
+
 }

spec/factories/mention.rb

@@ -0,0 +1,8 @@
+FactoryBot.define do
+  factory :mention do
+    mentionable { create(:ticket) }
+    user_id { 1 }
+    created_by_id { 1 }
+    updated_by_id { 1 }
+  end
+end

spec/lib/search_index_backend_spec.rb

@@ -193,6 +193,7 @@ RSpec.describe SearchIndexBackend, searchindex: true do
 
     before do
       Ticket.destroy_all # needed to remove not created tickets
+      create(:mention, mentionable: ticket1, user: agent1)
       ticket1.search_index_update_backend
       travel 1.second
       ticket2.search_index_update_backend
@@ -631,5 +632,99 @@ RSpec.describe SearchIndexBackend, searchindex: true do
       end
 
     end
+
+    context 'mentions' do
+      it 'finds records with pre_condition is not_set' do
+        result = described_class.selectors('Ticket',
+                                           {
+                                             'ticket.mention_user_ids' => {
+                                               'pre_condition' => 'not_set',
+                                               'operator'      => 'is',
+                                             },
+                                           },
+                                           { current_user: agent1 },
+                                           {
+                                             field: 'created_at', # sort to verify result
+                                           })
+        expect(result).to eq({ count: 7, ticket_ids: [ticket8.id.to_s, ticket7.id.to_s, ticket6.id.to_s, ticket5.id.to_s, ticket4.id.to_s, ticket3.id.to_s, ticket2.id.to_s] })
+      end
+
+      it 'finds records with pre_condition is not not_set' do
+        result = described_class.selectors('Ticket',
+                                           {
+                                             'ticket.mention_user_ids' => {
+                                               'pre_condition' => 'not_set',
+                                               'operator'      => 'is not',
+                                             },
+                                           },
+                                           { current_user: agent1 },
+                                           {
+                                             field: 'created_at', # sort to verify result
+                                           })
+        expect(result).to eq({ count: 1, ticket_ids: [ticket1.id.to_s] })
+      end
+
+      it 'finds records with pre_condition is current_user.id' do
+        result = described_class.selectors('Ticket',
+                                           {
+                                             'ticket.mention_user_ids' => {
+                                               'pre_condition' => 'current_user.id',
+                                               'operator'      => 'is',
+                                             },
+                                           },
+                                           { current_user: agent1 },
+                                           {
+                                             field: 'created_at', # sort to verify result
+                                           })
+        expect(result).to eq({ count: 1, ticket_ids: [ticket1.id.to_s] })
+      end
+
+      it 'finds records with pre_condition is not current_user.id' do
+        result = described_class.selectors('Ticket',
+                                           {
+                                             'ticket.mention_user_ids' => {
+                                               'pre_condition' => 'current_user.id',
+                                               'operator'      => 'is not',
+                                             },
+                                           },
+                                           { current_user: agent1 },
+                                           {
+                                             field: 'created_at', # sort to verify result
+                                           })
+        expect(result).to eq({ count: 7, ticket_ids: [ticket8.id.to_s, ticket7.id.to_s, ticket6.id.to_s, ticket5.id.to_s, ticket4.id.to_s, ticket3.id.to_s, ticket2.id.to_s] })
+      end
+
+      it 'finds records with pre_condition is specific' do
+        result = described_class.selectors('Ticket',
+                                           {
+                                             'ticket.mention_user_ids' => {
+                                               'pre_condition' => 'specific',
+                                               'operator'      => 'is',
+                                               'value'         => agent1.id,
+                                             },
+                                           },
+                                           {},
+                                           {
+                                             field: 'created_at', # sort to verify result
+                                           })
+        expect(result).to eq({ count: 1, ticket_ids: [ticket1.id.to_s] })
+      end
+
+      it 'finds records with pre_condition is not specific' do
+        result = described_class.selectors('Ticket',
+                                           {
+                                             'ticket.mention_user_ids' => {
+                                               'pre_condition' => 'specific',
+                                               'operator'      => 'is not',
+                                               'value'         => agent1.id,
+                                             },
+                                           },
+                                           {},
+                                           {
+                                             field: 'created_at', # sort to verify result
+                                           })
+        expect(result).to eq({ count: 7, ticket_ids: [ticket8.id.to_s, ticket7.id.to_s, ticket6.id.to_s, ticket5.id.to_s, ticket4.id.to_s, ticket3.id.to_s, ticket2.id.to_s] })
+      end
+    end
   end
 end

spec/models/concerns/has_history_examples.rb

@@ -1,4 +1,4 @@
-RSpec.shared_examples 'HasHistory' do |history_relation_object: nil|
+RSpec.shared_examples 'HasHistory' do |history_relation_object: []|
   describe 'auto-creation of history records' do
     let(:histories) { History.where(history_object_id: History::Object.find_by(name: described_class.name)) }
 

spec/models/mention_spec.rb

@@ -0,0 +1,11 @@
+require 'rails_helper'
+
+RSpec.describe Mention, type: :model do
+  let(:ticket) { create(:ticket) }
+
+  describe 'validation' do
+    it 'does not allow mentions for customers' do
+      expect { create(:mention, mentionable: ticket, user: create(:customer)) }.to raise_error(ActiveRecord::RecordInvalid, 'Validation failed: User has no ticket.agent permissions')
+    end
+  end
+end

spec/models/ticket_spec.rb

@@ -21,7 +21,7 @@ RSpec.describe Ticket, type: :model do
   it_behaves_like 'ApplicationModel'
   it_behaves_like 'CanBeImported'
   it_behaves_like 'CanCsvImport'
-  it_behaves_like 'HasHistory', history_relation_object: 'Ticket::Article'
+  it_behaves_like 'HasHistory', history_relation_object: ['Ticket::Article', 'Mention']
   it_behaves_like 'HasTags'
   it_behaves_like 'TagWritesToTicketHistory'
   it_behaves_like 'HasTaskbars'
@@ -196,6 +196,20 @@ RSpec.describe Ticket, type: :model do
         end
       end
 
+      context 'when both tickets having mentions to the same user' do
+        let(:watcher) { create(:agent) }
+
+        before do
+          create(:mention, mentionable: ticket, user: watcher)
+          create(:mention, mentionable: target_ticket, user: watcher)
+          ticket.merge_to(ticket_id: target_ticket.id, user_id: 1)
+        end
+
+        it 'does remove the link from the merged ticket' do
+          expect(target_ticket.mentions.count).to eq(1) # one mention to watcher user
+        end
+      end
+
       context 'when merging' do
         let(:merge_user) { create(:user) }
 
@@ -1509,6 +1523,210 @@ RSpec.describe Ticket, type: :model do
     end
   end
 
+  describe 'Mentions:', sends_notification_emails: true do
+    context 'when notifications' do
+      let(:prefs_matrix_no_mentions) do
+        { 'notification_config' =>
+                                   { 'matrix' =>
+                                                 { 'create'           => { 'criteria' => { 'owned_by_me' => true, 'owned_by_nobody' => true, 'mentioned' => false, 'no' => true }, 'channel' => { 'email' => true, 'online' => true } },
+                                                   'update'           => { 'criteria' => { 'owned_by_me' => true, 'owned_by_nobody' => true, 'mentioned' => false, 'no' => true }, 'channel' => { 'email' => true, 'online' => true } },
+                                                   'reminder_reached' => { 'criteria' => { 'owned_by_me' => false, 'owned_by_nobody' => false, 'mentioned' => false, 'no' => false }, 'channel' => { 'email' => false, 'online' => false } },
+                                                   'escalation'       => { 'criteria' => { 'owned_by_me' => false, 'owned_by_nobody' => false, 'mentioned' => false, 'no' => false }, 'channel' => { 'email' => false, 'online' => false } } } } }
+      end
+
+      let(:prefs_matrix_only_mentions) do
+        { 'notification_config' =>
+                                   { 'matrix' =>
+                                                 { 'create'           => { 'criteria' => { 'owned_by_me' => false, 'owned_by_nobody' => false, 'mentioned' => true, 'no' => false }, 'channel' => { 'email' => true, 'online' => true } },
+                                                   'update'           => { 'criteria' => { 'owned_by_me' => false, 'owned_by_nobody' => false, 'mentioned' => true, 'no' => false }, 'channel' => { 'email' => true, 'online' => true } },
+                                                   'reminder_reached' => { 'criteria' => { 'owned_by_me' => false, 'owned_by_nobody' => false, 'mentioned' => true, 'no' => false }, 'channel' => { 'email' => false, 'online' => false } },
+                                                   'escalation'       => { 'criteria' => { 'owned_by_me' => false, 'owned_by_nobody' => false, 'mentioned' => true, 'no' => false }, 'channel' => { 'email' => false, 'online' => false } } } } }
+      end
+
+      let(:mention_group) { create(:group) }
+      let(:no_access_group) { create(:group) }
+      let(:user_only_mentions) { create(:agent, groups: [mention_group], preferences: prefs_matrix_only_mentions) }
+      let(:user_no_mentions) { create(:agent, groups: [mention_group], preferences: prefs_matrix_no_mentions) }
+      let(:ticket) { create(:ticket, group: mention_group, owner: user_no_mentions) }
+
+      it 'does inform mention user about the ticket update' do
+        create(:mention, mentionable: ticket, user: user_only_mentions)
+        create(:mention, mentionable: ticket, user: user_no_mentions)
+        Observer::Transaction.commit
+        Scheduler.worker(true)
+
+        check_notification do
+          ticket.update(priority: Ticket::Priority.find_by(name: '3 high'))
+          Observer::Transaction.commit
+          Scheduler.worker(true)
+          sent(
+            template: 'ticket_update',
+            user:     user_no_mentions,
+          )
+          sent(
+            template: 'ticket_update',
+            user:     user_only_mentions,
+          )
+        end
+      end
+
+      it 'does not inform mention user about the ticket update' do
+        ticket
+        Observer::Transaction.commit
+        Scheduler.worker(true)
+
+        check_notification do
+          ticket.update(priority: Ticket::Priority.find_by(name: '3 high'))
+          Observer::Transaction.commit
+          Scheduler.worker(true)
+          sent(
+            template: 'ticket_update',
+            user:     user_no_mentions,
+          )
+          not_sent(
+            template: 'ticket_update',
+            user:     user_only_mentions,
+          )
+        end
+      end
+
+      it 'does inform mention user about ticket creation' do
+        check_notification do
+          ticket = create(:ticket, owner: user_no_mentions, group: mention_group)
+          create(:mention, mentionable: ticket, user: user_only_mentions)
+          Observer::Transaction.commit
+          Scheduler.worker(true)
+          sent(
+            template: 'ticket_create',
+            user:     user_no_mentions,
+          )
+          sent(
+            template: 'ticket_create',
+            user:     user_only_mentions,
+          )
+        end
+      end
+
+      it 'does not inform mention user about ticket creation' do
+        check_notification do
+          create(:ticket, owner: user_no_mentions, group: mention_group)
+          Observer::Transaction.commit
+          Scheduler.worker(true)
+          sent(
+            template: 'ticket_create',
+            user:     user_no_mentions,
+          )
+          not_sent(
+            template: 'ticket_create',
+            user:     user_only_mentions,
+          )
+        end
+      end
+
+      it 'does not inform mention user about ticket creation because of no permissions' do
+        check_notification do
+          ticket = create(:ticket, group: no_access_group)
+          create(:mention, mentionable: ticket, user: user_only_mentions)
+          Observer::Transaction.commit
+          Scheduler.worker(true)
+          not_sent(
+            template: 'ticket_create',
+            user:     user_only_mentions,
+          )
+        end
+      end
+    end
+
+    context 'selectors' do
+      let(:mention_group) { create(:group) }
+      let(:ticket_mentions) { create(:ticket, group: mention_group) }
+      let(:ticket_normal) { create(:ticket, group: mention_group) }
+      let(:user_mentions) { create(:agent, groups: [mention_group]) }
+      let(:user_no_mentions) { create(:agent, groups: [mention_group]) }
+
+      before do
+        described_class.destroy_all
+        ticket_normal
+        user_no_mentions
+        create(:mention, mentionable: ticket_mentions, user: user_mentions)
+      end
+
+      it 'pre condition is not_set' do
+        condition = {
+          'ticket.mention_user_ids' => {
+            pre_condition: 'not_set',
+            operator:      'is',
+          },
+        }
+
+        expect(described_class.selectors(condition, limit: 100, access: 'full'))
+          .to match_array([1, [ticket_normal].to_a])
+      end
+
+      it 'pre condition is not not_set' do
+        condition = {
+          'ticket.mention_user_ids' => {
+            pre_condition: 'not_set',
+            operator:      'is not',
+          },
+        }
+
+        expect(described_class.selectors(condition, limit: 100, access: 'full'))
+          .to match_array([1, [ticket_mentions].to_a])
+      end
+
+      it 'pre condition is current_user.id' do
+        condition = {
+          'ticket.mention_user_ids' => {
+            pre_condition: 'current_user.id',
+            operator:      'is',
+          },
+        }
+
+        expect(described_class.selectors(condition, limit: 100, access: 'full', current_user: user_mentions))
+          .to match_array([1, [ticket_mentions].to_a])
+      end
+
+      it 'pre condition is not current_user.id' do
+        condition = {
+          'ticket.mention_user_ids' => {
+            pre_condition: 'current_user.id',
+            operator:      'is not',
+          },
+        }
+
+        expect(described_class.selectors(condition, limit: 100, access: 'full', current_user: user_mentions))
+          .to match_array([0, []])
+      end
+
+      it 'pre condition is specific' do
+        condition = {
+          'ticket.mention_user_ids' => {
+            pre_condition: 'specific',
+            operator:      'is',
+            value:         user_mentions.id
+          },
+        }
+
+        expect(described_class.selectors(condition, limit: 100, access: 'full'))
+          .to match_array([1, [ticket_mentions].to_a])
+      end
+
+      it 'pre condition is not specific' do
+        condition = {
+          'ticket.mention_user_ids' => {
+            pre_condition: 'specific',
+            operator:      'is not',
+            value:         user_mentions.id
+          },
+        }
+
+        expect(described_class.selectors(condition, limit: 100, access: 'full'))
+          .to match_array([0, []])
+      end
+    end
+  end
+
   describe '.search_index_attribute_lookup_oversized?' do
     subject!(:ticket) { create(:ticket) }
 

spec/models/user_spec.rb

@@ -869,9 +869,10 @@ RSpec.describe User, type: :model do
                      'User'                               => { 'created_by_id' => 0, 'updated_by_id' => 0 },
                      'Organization'                       => { 'created_by_id' => 0, 'updated_by_id' => 0 },
                      'Macro'                              => { 'created_by_id' => 0, 'updated_by_id' => 0 },
+                     'Mention'                            => { 'created_by_id' => 1, 'updated_by_id' => 0, 'user_id' => 1 },
                      'Channel'                            => { 'created_by_id' => 0, 'updated_by_id' => 0 },
                      'Role'                               => { 'created_by_id' => 0, 'updated_by_id' => 0 },
-                     'History'                            => { 'created_by_id' => 2 },
+                     'History'                            => { 'created_by_id' => 3 },
                      'Webhook'                            => { 'created_by_id' => 0, 'updated_by_id' => 0 },
                      'Overview'                           => { 'created_by_id' => 1, 'updated_by_id' => 0 },
                      'ActivityStream'                     => { 'created_by_id' => 0 },
@@ -893,6 +894,8 @@ RSpec.describe User, type: :model do
       recent_view         = create(:recent_view, created_by: user)
       avatar              = create(:avatar, o_id: user.id)
       overview            = create(:overview, created_by_id: user.id, user_ids: [user.id])
+      mention             = create(:mention, mentionable: create(:ticket), user: user)
+      mention_created_by  = create(:mention, mentionable: create(:ticket), user: create(:agent), created_by: user)
       expect(overview.reload.user_ids).to eq([user.id])
 
       # create a chat agent for admin user (id=1) before agent user
@@ -930,6 +933,8 @@ RSpec.describe User, type: :model do
       expect { customer_ticket2.reload }.to raise_exception(ActiveRecord::RecordNotFound)
       expect { customer_ticket3.reload }.to raise_exception(ActiveRecord::RecordNotFound)
       expect { chat_agent_user.reload }.to raise_exception(ActiveRecord::RecordNotFound)
+      expect { mention.reload }.to raise_exception(ActiveRecord::RecordNotFound)
+      expect(mention_created_by.reload.created_by_id).not_to eq(user.id)
       expect(overview.reload.user_ids).to eq([])
 
       # move ownership objects

spec/requests/mention_spec.rb

@@ -0,0 +1,72 @@
+require 'rails_helper'
+
+RSpec.describe 'Mention', type: :request, authenticated_as: -> { user } do
+  let(:group) { create(:group) }
+  let(:ticket1) { create(:ticket, group: group) }
+  let(:ticket2) { create(:ticket, group: group) }
+  let(:ticket3) { create(:ticket, group: group) }
+  let(:ticket4) { create(:ticket, group: group) }
+  let(:user) { create(:agent, groups: [group]) }
+
+  describe 'GET /api/v1/mentions' do
+    before do
+      create(:mention, mentionable: ticket1, user: user)
+      create(:mention, mentionable: ticket2, user: user)
+      create(:mention, mentionable: ticket3, user: user)
+    end
+
+    it 'returns good status code' do
+      get '/api/v1/mentions', params: {}, as: :json
+      expect(response).to have_http_status(:ok)
+    end
+
+    it 'returns mentions by user' do
+      get '/api/v1/mentions', params: {}, as: :json
+      expect(json_response['mentions'].count).to eq(3)
+    end
+
+    it 'returns mentions by mentionable' do
+      get '/api/v1/mentions', params: { mentionable_type: 'Ticket', mentionable_id: ticket3.id }, as: :json
+      expect(json_response['mentions'].count).to eq(1)
+    end
+
+    it 'returns mentions by id' do
+      mention = create(:mention, mentionable: ticket4, user: user)
+      get '/api/v1/mentions', params: { id: mention.id }, as: :json
+      expect(json_response['mentions'].count).to eq(1)
+    end
+  end
+
+  describe 'POST /api/v1/mentions' do
+
+    let(:params) do
+      {
+        mentionable_type: 'Ticket',
+        mentionable_id:   ticket1.id
+      }
+    end
+
+    it 'returns good status code for subscribe' do
+      post '/api/v1/mentions', params: params, as: :json
+      expect(response).to have_http_status(:created)
+    end
+
+    it 'updates mention count' do
+      expect { post '/api/v1/mentions', params: params, as: :json }.to change(Mention, :count).from(0).to(1)
+    end
+  end
+
+  describe 'DELETE /api/v1/mentions/:id' do
+
+    let!(:mention) { create(:mention, user: user) }
+
+    it 'returns good status code' do
+      delete "/api/v1/mentions/#{mention.id}", params: {}, as: :json
+      expect(response).to have_http_status(:ok)
+    end
+
+    it 'clears mention count' do
+      expect { delete "/api/v1/mentions/#{mention.id}", params: {}, as: :json }.to change(Mention, :count).from(1).to(0)
+    end
+  end
+end

spec/requests/ticket/article_spec.rb

@@ -486,6 +486,36 @@ AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO
       expect(json_response['attachments']).to be_truthy
       expect(json_response['attachments'].count).to eq(0)
     end
+
+    it 'does ticket create with mentions' do
+      params = {
+        title:       'a new ticket #1',
+        group:       'Users',
+        customer_id: customer.id,
+        article:     {
+          body: "some body <a data-mention-user-id=\"#{agent.id}\">agent</a>",
+        }
+      }
+      authenticated_as(agent)
+      post '/api/v1/tickets', params: params, as: :json
+      expect(response).to have_http_status(:created)
+      expect(Mention.where(mentionable: Ticket.last).count).to eq(1)
+    end
+
+    it 'does not ticket create with mentions when customer' do
+      params = {
+        title:       'a new ticket #1',
+        group:       'Users',
+        customer_id: customer.id,
+        article:     {
+          body: "some body <a data-mention-user-id=\"#{agent.id}\">agent</a>",
+        }
+      }
+      authenticated_as(customer)
+      post '/api/v1/tickets', params: params, as: :json
+      expect(response).to have_http_status(:internal_server_error)
+      expect(Mention.count).to eq(0)
+    end
   end
 
   describe 'DELETE /api/v1/ticket_articles/:id', authenticated_as: -> { user } do

spec/requests/ticket_spec.rb

@@ -2200,6 +2200,47 @@ RSpec.describe 'Ticket', type: :request do
 
   end
 
+  describe 'mentions' do
+    let(:user1) { create(:agent, groups: [ticket_group]) }
+    let(:user2) { create(:agent, groups: [ticket_group]) }
+    let(:user3) { create(:agent, groups: [ticket_group]) }
+
+    def new_ticket_with_mentions
+      params = {
+        title:    'a new ticket #11',
+        group:    ticket_group.name,
+        customer: {
+          firstname: 'some firstname',
+          lastname:  'some lastname',
+          email:     'some_new_customer@example.com',
+        },
+        article:  {
+          body: 'some test 123',
+        },
+        mentions: [user1.id, user2.id, user3.id]
+      }
+      authenticated_as(agent)
+      post '/api/v1/tickets', params: params, as: :json
+      expect(response).to have_http_status(:created)
+
+      json_response
+    end
+
+    it 'create ticket with mentions' do
+      new_ticket_with_mentions
+      expect(Mention.all.count).to eq(3)
+    end
+
+    it 'check ticket get' do
+      ticket = new_ticket_with_mentions
+
+      get "/api/v1/tickets/#{ticket['id']}?all=true", params: {}, as: :json
+      expect(response).to have_http_status(:ok)
+      expect(json_response['mentions'].count).to eq(3)
+      expect(json_response['assets']['Mention'].count).to eq(3)
+    end
+  end
+
   describe 'stats' do
     let(:ticket1) { create(:ticket, customer: customer, organization: organization, group: ticket_group) }
     let(:ticket2) { create(:ticket, customer: customer, organization: organization, group: ticket_group) }

spec/system/ticket/zoom_spec.rb

@@ -1277,6 +1277,36 @@ RSpec.describe 'Ticket zoom', type: :system do
     end
   end
 
+  describe 'mentions' do
+    context 'when logged in as agent' do
+      let(:ticket) { create(:ticket, group: Group.find_by(name: 'Users')) }
+      let!(:other_agent) { create(:agent, groups: [Group.find_by(name: 'Users')]) }
+
+      it 'can subscribe and unsubscribe' do
+        ensure_websocket do
+          visit "ticket/zoom/#{ticket.id}"
+
+          click '.mentions .js-subscribe input'
+          expect(page).to have_selector('.mentions .js-unsubscribe input', wait: 10)
+          expect(page).to have_selector('.mentions span.avatar', wait: 10)
+
+          click '.mentions .js-unsubscribe input'
+          expect(page).to have_selector('.mentions .js-subscribe input', wait: 10)
+          expect(page).to have_no_selector('.mentions span.avatar', wait: 10)
+
+          create(:mention, mentionable: ticket, user: other_agent)
+          expect(page).to have_selector('.mentions span.avatar', wait: 10)
+
+          # check history for mention entries
+          click 'h2.sidebar-header-headline.js-headline'
+          click 'li[data-type=ticket-history] a'
+          expect(page).to have_text('created Mention', wait: 10)
+          expect(page).to have_text('removed Mention', wait: 10)
+        end
+      end
+    end
+  end
+
   # https://github.com/zammad/zammad/issues/2671
   describe 'Pending time field in ticket sidebar', authenticated_as: :customer do
     let(:customer) { create(:customer) }