module MessageBuilder
     def self.build_multi_messages(message, from, attendants, chat_id)
         attendants.map do |person|
             message = Jabber::Message.new(person, message)
             message.from = from
             message.add_attribute('chat_id', chat_id)
             message.add_attribute('is_simulating', true)
             message
         end
     end
 
     def self.build_message(message, from, to)
         message = Jabber::Message.new(to, message)
         message.from = from
 
         message
     end
 
     def self.ask_for_multichat_contacts(from, to, chat_id)
         message = Jabber::Message.new(to)
         message.from = from
         sync_request = REXML::Element.new('sync_contacts_request')
         sync_request.add_attributes('chat_id' => chat_id)
         message.add_element sync_request
 
         message
     end
 
     def self.send_multichat_contacts(from, to, chat_id, contacts)
         message = Jabber::Message.new(to)
         message.from = from
         sync_answer = REXML::Element.new('synced_contacts')
         collect_contacts(sync_answer, contacts)
         sync_answer.add_attributes('chat_id' => chat_id)
         message.add_element sync_answer
 
         message
     end
 
     def self.export_multichat(from, to, chat_id, contacts)
         message = Jabber::Message.new(to)
         message.from = from
         chat = REXML::Element.new('exported_chat')
         collect_contacts(chat, contacts)
         chat.add_attributes('chat_id' => chat_id)
         message.add_element chat
 
         message
     end
 

     def self.control_answer(from, to)
         message = Jabber::Message.new(to)
         message.from = from
         message.add_attributes('i_am_using_same_app' => 'true')
 
         message
     end
 
     def self.control_question(from, to)
         message = Jabber::Message.new(to)
         message.from = from
         message.add_attributes('are_you_using_my_app' => '?')
 
         message
     end
 

     def self.req_update_multichat_contacts(from, to, chat_id, changes)
         message = Jabber::Message.new(to)
         message.from = from
         message.add_attributes('req_update_contacts' => 'true')
         message.add_attributes('chat_id' => chat_id)
 
         added   = REXML::Element.new('added')
         removed = REXML::Element.new('removed')
 
         collect_contacts(added, changes[:added])
         collect_contacts(removed, changes[:removed])
 
         message.add_element added
         message.add_element removed
 
         message
     end
 
     def self.destroy_multichat(from, to, chat_id)
         message = Jabber::Message.new(to)
         message.from = from
         message.add_attributes('destroy_multichat' => 'true')
         message.add_attributes('chat_id' => chat_id)
 
         message
     end
 

     private
 
     def self.collect_contacts(to_element, contacts)

         if contacts.kind_of?(Array)
             contacts.each do |contact|
                 contact_xml = REXML::Element.new('contact')
                 contact_xml.text = contact
                 to_element.add_element contact_xml
             end

         end
     end
 end