ui1 <- function(){
  tagList(h2("Hello", align = "center"),
          div(id = "login",
            wellPanel(textInput("userName", "Username"),
            passwordInput("passwd", "Password"),
            br(),actionButton("Login", "Log in"),
            actionLink("Regis","Register"),
            actionLink("FORGET","Forgot"))),
          tags$style(type="text/css", "#login {font-size:10px;   text-align: left;position:absolute;top: 45%;left: 50%;margin-top: -100px;margin-left: -150px;}")
  )}
ui2 <- function(){
  tagList(tabPanel(""),
          pageWithSidebar(
            headerPanel(
              ""
            ),
            sidebarPanel
            (
            tags$head(tags$style(type="text/css", ".well { max-width: 280px; }")),
            selectInput("CC","Please select a course", choices = c("E"=1,"M"=2)),
            selectInput("SP","Bla Bla", choices = c("AA"=1,"BB"=2,"CC"=3,"DD"=4,"EE"=5)),
            numericInput("UT",label = "Available", value = 10, min = 10),
            actionButton("RM", label = "RM",style="width:32%;"),
            actionButton("Cont", label = "Cont",style="width:32%;"),
            hidden(actionButton("strt", label = "Start",style="width:32%;")),
            actionButton("logout", "Logout",style="color: red; width:32%;")
            ),
            mainPanel(tableOutput('path'),
            shinyjs::useShinyjs(),
            hidden(actionButton("nxt", label = "Done/Next",style="color: blue;width:15%;float:right")),
            hidden(selectInput("test", "Was it easy?", list(" "="","No" = "No", "Not_sure" = "Not sure", "Yes" = "Yes"),selected = NULL))
            )
        )
    )
}
server = (function(input, output,session) {
  USER <- reactiveValues(Logged = Logged)
  observe({
    if (USER$Logged == FALSE) {
      if (!is.null(input$Login)) {
        if (input$Login > 0) {
          Username <- isolate(input$userName)
          Password <- isolate(input$passwd)
          query <- sprintf({"
            SELECT rowid
            FROM users
            WHERE username='%s' and password ='%s'"},
                           Username, Password, serialize=F)
          db   <- RSQLite::dbConnect(RSQLite::SQLite(), dbname="db.sqlite")
          user <- RSQLite::dbGetQuery(db, query)
          RSQLite::dbDisconnect(db)
          if ( length(user$rowid)==1 ) {
            USER$Logged <- TRUE
          }
          }
        }
      }
  })
observe({
    if (USER$Logged == FALSE) {
      output$page <- renderUI({div(class="outer",do.call(bootstrapPage,c("",ui1())))})
    }
    if (USER$Logged == TRUE)
    {
      output$page <- renderUI({div(class="outer",do.call(navbarPage,c(inverse=TRUE,title = paste("Welcome", isolate(input$userName)," !"),ui2())))})
      shinyjs::hide("nxt")
      shinyjs::hide("test")
      print(ui)
    }
  })
})
ui = (htmlOutput("page"))

library(shiny)
library(RSQLite)
db <- dbConnect(SQLite(), dbname="db.sqlite")
dbSendQuery(conn = db,"CREATE TABLE users (username TEXT, password TEXT, email TEXT)")
dbSendQuery(db, "INSERT INTO users ( username, password, email) VALUES ( 'ester', 'silva', 'abc@gmail.com');")