if function for fileInput and disable/enable selectInput and fileInput upon the selection of Advanced checkboxInput

[cowa]

I have a Shiny code as like this

library(datasets)
ui <-fluidPage(    
titlePanel("Telephones by region"),
sidebarLayout(      
sidebarPanel(
  selectInput("region", "Region:", 
              choices=colnames(WorldPhones)), checkboxInput(inputId = "Adv",
                                                            label = strong("Advanced"),
                                                            value = FALSE),fileInput("file1", "Choose CSV File",
            multiple = FALSE,accept = c("text/csv", "text/comma-separated-values,text/plain", ".csv")),
  hr(),
  helpText("Data from AT&T (1961) The World's Telephones.")),
mainPanel(
  plotOutput("phonePlot")   )))

server <- function(input, output) {

output$phonePlot <- renderPlot({

barplot(WorldPhones[,input$region]*1000, 
        main=input$region,
        ylab="Number of Telephones",
        xlab="Year")})}
shinyApp(ui, server)

I need to implement following modifications

1. How to use if function for fileInput from user input (Asia,Africa….ect one per line )
2. How to disable/enable selectInput and fileInput upon the selection of Advanced checkboxInput. If user choose advanced, the selectInput must be disable (vice versa)