/*****************************************************************************
       * Step 3. Handle the flows
       *----------------------------------------------------------------------------
       * (1) implicit flow (response_type = 'id_token')
       *     This case we get a 'id_token'
       * (2) hybrid flow (response_type = 'id_token code')
       *     This case we get both 'id_token' and 'code'
       * (3) authorization code flow (response_type = 'code')
       *     This case we get a 'code', we will use it to get 'access_token' and 'id_token'
       * (4) for any other request, we will ask for authorization and initialize
       *     the authorization process
       ****************************************************************************/