library(shinydashboard)
library(shiny)
library(ggplot2)
library(gridExtra)
library(dplyr)
library(tidyverse)
library(lubridate)

ui <- dashboardPage(
  dashboardHeader(title = "T"),
  dashboardSidebar(),
  dashboardBody(

fluidRow(

  box(
    title = "Controls",
    selectInput("User",
                "User:",
                c("All",
                  unique(as.character(df$User))))

  ),
  box(
    dateRangeInput("dates",
                   "Date range",
                   start = "01-01-2018",
                   end = "06-25-2018")
  ),

  mainPanel(

    tabsetPanel(type = "tabs",
                tabPanel("Plot", plotOutput("plot")

          )
        )
      )
    )
  )
)
  server <- function(input, output){
    df <- read.csv(file = "c:/T/T/T.csv", header = TRUE, sep = ",")
      df$Date <- as.Date(df$Date)


      begin<- reactive({input$dates[1]})
      finish<- reactive({input$dates[2]})

      output$plot <- renderPlot({
        df.filtered<-df %>%
          filter(df$User == input$User) %>%
          filter(Date >= begin(), Date <= finish())
        req(df.filtered)
       df.filtered
      })
    }

    shinyApp(ui, server)