Unable to export the output data as csv / excel from ShinyApp using rpivotTable

[sid]

Hi guys,
I'm using rpivotTables Shinyapp to export the pivottable data as csv, excel, pdf using buttons (I don't want to export the actual data). However i'm unable to do so, can't figure out the reason due to my limited knowledge. I'm pasting my codes as well. I shall be really thankful for the help 
Kind regards

...
library(rpivotTable)

library(dplyr)

library(readr)

library(shiny)

library(openxlsx)

#ui

ui = fluidPage(

  radioButtons(inputId="format", label="Enter the format to download", 

               choices=c("none", "csv", "excel", "pdf", "copy"), inline = FALSE, selected="none"),

  fluidRow( rpivotTableOutput("pivot")))

#server

server = function(input, output, session) { 

  output$pivot <- renderRpivotTable( rpivotTable::rpivotTable( rows = c( 

    "vs"),cols=c("carb"),vals =  "mpg", aggregatorName = "Sum",rendererName =  

      "Table",width="50%", height="550px",

    {

      data <- mtcars

     

      if(input$format =="csv") {

        write_csv( data, 'data.csv')

        

      } 

      if (input$format=="excel") {

        write.xlsx(data, "data.xlsx")

      } 

     

      data

     

    }))

}

shinyApp(ui = ui, server = server)

[Omar Giorgetti]

rpivotTabletocsv