feat: Notification on new messages in conversation (#1204)

fixes: #895
fixes: #1118
fixes: #1075

Co-authored-by: Pranav Raj S <pranav@thoughtwoot.com>

app/mailers/agent_notifications/conversation_notifications_mailer.rb

@@ -19,6 +19,18 @@ class AgentNotifications::ConversationNotificationsMailer < ApplicationMailer
     send_mail_with_liquid(to: @agent.email, subject: subject) and return
   end
 
+  def assigned_conversation_new_message(conversation, agent)
+    return unless smtp_config_set_or_development?
+    # Don't spam with email notifications if agent is online
+    return if ::OnlineStatusTracker.get_presence(conversation.account.id, 'User', agent.id)
+
+    @agent = agent
+    @conversation = conversation
+    subject = "#{@agent.available_name}, New message in your assigned conversation [ID - #{@conversation.display_id}]."
+    @action_url = app_account_conversation_url(account_id: @conversation.account_id, id: @conversation.display_id)
+    send_mail_with_liquid(to: @agent.email, subject: subject) and return
+  end
+
   private
 
   def liquid_droppables