Dependent observeEvents cause problems in complex applications - r

Question

I prepared rather simple shiny application which resembles the problem in my much more complex application.
The three necessary components of my application are:
The number, i.e. year, can be changed in two different ways: by 1) adding a value in the textInput or 2) by clicking the action button
When the year is changed by the actionButtion, it must automatically change current value in the textInput box
When the year is changed by the textInput, reactive value for the
action button must reset to zero.
I have two observeEvents which both target two reactive values. The problem is, if I click the actionButton several times too quickly, this creates a loop of switching between those two events.
Is there any efficient tool available in Shiny which help in such situations? E.g. to prevent users to click on the button prior the execution of task.
# import libraries
library(shiny)
library(ggplot2)
library(dplyr)
ui <- shinyUI(fluidPage(
sidebarLayout(
sidebarPanel(
uiOutput("ui_year"),
uiOutput("ui_plus")
),
mainPanel(
plotOutput("plot1")
)
)))
server <- shinyServer(function(input, output) {
# Generate random data
data <- data.frame(
year = seq(1900, 2000),
value = runif(n = 101, min = -3, max = 3)
)
# Define two reactive values: add and year
rv <- reactiveValues()
rv$add <- 0
rv$year <- 2000
# render actionButton
output$ui_plus <- renderUI({
actionButton(inputId = "add",
label = paste0(""),
icon = icon("plus"))
})
# render textInput
output$ui_year <- renderUI({
textInput(inputId = "year_1", label = NULL,
value = eval(parse( text = rv$year)),
width = "100%",
placeholder = NULL)
})
# Define two observe events, based on A) action button and B) textInput
observeEvent(input$year_1, {
rv$year <- input$year_1
rv$add <- 0
})
observeEvent(input$add, {
rv$add <- rv$add + 1
rv$year <- as.numeric(rv$year) + 1
})
# Render output
output$plot1 <- renderPlot({
sumValue <- as.numeric(rv$year) + as.numeric(rv$add)
ggplot(data, aes(x = year, y = value)) + geom_line()+ annotate("text", x = -Inf, y = Inf, hjust = -0.2, vjust = 1, label = sumValue )
})
})
shinyApp(ui = ui, server = server)