# Generated by DropToApp
library(shiny)
library(bslib)

# Daily air quality in New York, May to September 1973 (built into R)
aq <- airquality
aq$Date <- as.Date(paste(1973, aq$Month, aq$Day, sep = "-"))

# Average of x, rounded, or "-" when there is nothing to average
avg <- function(x, unit = "") {
  if (length(x) == 0 || all(is.na(x))) return("-")
  paste0(round(mean(x, na.rm = TRUE), 1), unit)
}

ui <- page_sidebar(
  title = "Air quality dashboard",
  sidebar = sidebar(
    title = "Filters",
    checkboxGroupInput(
      "months",
      "Months",
      choices = c("May", "June", "July", "August", "September"),
      selected = c("May", "June", "July", "August", "September")
    ),
    sliderInput(
      "min_temp",
      "Minimum temperature (F)",
      min = 56,
      max = 97,
      value = 56
    )
  ),
  theme = bs_theme(bootswatch = "flatly"),
  layout_columns(
    value_box(
      title = "Days",
      value = textOutput("n_days"),
      theme = "primary"
    ),
    value_box(
      title = "Average temperature",
      value = textOutput("avg_temp"),
      theme = "warning"
    ),
    value_box(
      title = "Average ozone (ppb)",
      value = textOutput("avg_ozone"),
      theme = "success"
    )
  ),
  card(
    full_screen = TRUE,
    card_header("Daily maximum temperature"),
    plotOutput("temp_plot", height = "300px")
  ),
  card(card_header("Hottest days"), tableOutput("hottest"))
)

server <- function(input, output, session) {
  # Inputs: input$months, input$min_temp

  filtered <- reactive({
    keep <- aq$Month %in% match(input$months, month.name) & aq$Temp >= input$min_temp
    aq[keep, ]
  })

  output$n_days <- renderText(nrow(filtered()))
  output$avg_temp <- renderText(avg(filtered()$Temp, " F"))
  output$avg_ozone <- renderText(avg(filtered()$Ozone))

  output$temp_plot <- renderPlot({
    d <- filtered()
    validate(need(nrow(d) > 0, "No days match the filters."))
    plot(d$Date, d$Temp, type = "h", lwd = 3, col = "#2c3e50",
         xlab = "", ylab = "Temperature (F)")
  })

  output$hottest <- renderTable({
    d <- filtered()
    d <- d[order(-d$Temp), c("Date", "Temp", "Ozone", "Wind")]
    d$Date <- format(d$Date, "%d %B")
    head(d, 5)
  })
}

shinyApp(ui, server)