Async Progress Bar in R Shiny

shiny_async_progress_bar.R

library(shiny)
library(future)
library(promises)

plan(multisession, workers = 4)

ui <- fluidPage(
  tags$head(
    tags$style(
      HTML("
.progress-bar{
    background-color: #753bbd;
}

.progress-message {
    padding: 0px 3px;
    margin: 75px;
    font-weight: bold;
    font-size: 90%;
}
      
.shiny-notification {
    position:relative;
    top: -60vh;
    left: -70vw;
    width: 350px;
    font-size: 16px;
    background-color: #d1e4ff;
    color: #333;
    border: 1.5px solid #753bbd;
    border-radius: 3px;
    opacity: 1;
    padding: 10px 8px 10px 10px;
    margin: 2px;
  }")
    )
  ),
  
  actionButton("show", "Show"),
  actionButton("show2", "Show2")
)

server <- function(input, output, session) {
  
  onStop(function() cat("Session stopped\n"))
  
  observeEvent(input$show, {
    
    detail_text <- sample(
      c(
        "Use frequency keywords 'monthly', 'weekly' to get time series data",
        "More information about the platform use can be found on Info tab or website",
        "Platform is a real-time analytics platform built by the Data team",
        "You can upload your own data in csv or xlsx (first tab)",
        "Save output by downloading a csv file or interactive HTML report",
        "Use 'average' keyword when working with measures like 'Cycle Time'"
      ),
      size = 1)
    
    progress <- ipc::AsyncProgress$new(session, 
      message = "10% Starting Engine", 
      min = 0, 
      max = 100, 
      value = 10,
      detail = detail_text
    )
    
    Sys.sleep(0.5)
    
    promises::future_promise({
      for (i in 10:99) {
        
        progress$set(value = i, 
          message = dplyr::case_when(
            i < 40 ~ paste0(i, "% Retrieving Data"),
            i < 70 ~ paste0(i, "% Rendering Output"),
            i < 90 ~ paste0(i, "% Writing Narratives"),
            TRUE ~  paste0(i, "% Finalizing Search")
          )
        )
        
        Sys.sleep(5/90)
      }
      #progress$close()
    })
    cli::cat_rule("Progress Bar 1")
  })
  
  observeEvent(input$show2,{
    
    progress2 <- ipc::AsyncProgress$new(session, 
      message = "Progress Bar 2", 
      min = 0, 
      max = 100, 
      value = 10
    )
    
    future_promise({
      Sys.sleep(3)
      #progress2$close()
    })
    
    cli::cat_rule("Progress Bar 2")

  })
}

shinyApp(ui, server)