module.R

plotUI <- function(id) {
  ns <- NS(id)
  fluidRow(
    column(width = 10,
           echarts4r::echarts4rOutput(ns("plot")) %>%
             shinycssloaders::withSpinner()
    ),
    column(width = 2,
           actionButton(
             inputId = ns("bar"),
             label = "",
             icon = icon("chart-bar")
           ),
           actionButton(
             inputId = ns("pie"),
             label = "",
             icon = icon("chart-pie")
           )
    )
  )
  
}

plotServer <- function(id, df) {
  moduleServer(
    id,
    function(input, output, session) {
      
      # Setting reactiveValues for changing plot types
      rv <- reactiveValues(
        plot_type = "bar",
        plot = NULL
      )

      # Observer and main calculation
      observeEvent(c(df(), rv$plot_type),{
        
        # Timeout to show NO asyncronity
        Sys.sleep(5)
        
        if (rv$plot_type == "bar") {
          rv$plot <- df() %>%
            plot_bar()
        } else {
          rv$plot <- df() %>%
            plot_pie()
        }
      })
      
      # Observers for actionButtion clicks
      observeEvent(input$bar, {
        rv$plot_type <- "bar"
      })
      
      observeEvent(input$pie,{
        rv$plot_type <- "pie"
      })
      
      # Render Plots
      output$plot <- echarts4r::renderEcharts4r({
        req(rv$plot)
      })
    }
  )
}