library(shiny)
library(bslib)
library(dplyr)
library(ggplot2)

df <- readr::read_csv("penguins.csv")
# Find subset of columns that are suitable for scatter plot
df_num <- df |> select(where(is.numeric), -Year)

ui <- page_fillable(
  theme = bs_theme(bootswatch = "minty"),
  layout_sidebar(
    sidebar(
      varSelectInput("xvar", "X variables", df_num, selected = "Bill Length (mm)"),
      varSelectInput("yvar", "Y variables", df_num, selected = "Bill Depth (mm)"),
      checkboxGroupInput("species", "Filter by species",
        choices = unique(df$Species), selected = unique(df$Species)
      )
    ),
    plotOutput("scatter")
  )
)

server <- function(input, output, session) {
  
  subsetted <- reactive({
    req(input$species)
    df |> filter(Species %in% input$species)
  })
  
  output$scatter <- renderPlot({
    p <- ggplot(subsetted(), aes(.data[[input$xvar]], .data[[input$yvar]])) + 
      theme(legend.position = "bottom")    
    p
  })
  
}

shinyApp(ui, server)