# Shiny app demo - UW Data Science Working Group
# March 23, 2022

# Notes about Shiny-

# (1) Keep track of parentheses and commas! They are the #1 issue I encounter when it comes to error messages.
# (2) Make sure all of your ID names are unique, otherwise Shiny will get confused when calling them between the user interface and the server.

#### Setup ####

# Load packages
library(tidyverse)
library(shiny)
library(shinythemes)
library(palmerpenguins)

# Load data
dat <- penguins

# Any additional data should be loaded in here.

#### User interface ####

ui <- fluidPage(
  
  theme = shinytheme("superhero"), # changes app theme
  
  titlePanel("Penguin Shiny App"), # title
  
  sidebarLayout( # creates the layout
    
    sidebarPanel("Widgets go here.", # sidebar title
                 
                 # our first widget - dropdown menu
                 selectInput(inputId = "island_select", # variable name
                             label = "Select an island.", # user instructions
                             choices = unique(dat$island) # choices displayed
                             ),
                 
                 # our second widget - multiple choice
                 radioButtons(inputId = "species_select",
                              label = "Select a species.",
                              choices = unique(dat$species))
                 
                 ),
    
    mainPanel("Outputs go here.", # main panel title
              
              # our first output - penguin plot
              p("Penguin Plot:"), # the p() command creates a new paragraph
              plotOutput(outputId = "penguin_plot"),
              
              # our second output - penguin table
              p("Penguin Bill Summary Statistics:"),
              tableOutput(outputId = "penguin_table")
              
              ) 
    
  )
  
)

#### Server ####

server <- function(input, output) {
  
  # create a new dataset based on selected island
  penguin_island <- reactive({ # reactive tells shiny to monitor user's selections
    dat %>%
      filter(island == input$island_select)
  })
  
  # create a plot
  output$penguin_plot <- renderPlot({ # render tells shiny to monitor changes
    ggplot(penguin_island(), # parentheses indicate the dataset is not static
           aes(x = species, y = body_mass_g)) +
      geom_boxplot(aes(fill = sex)) +
      labs(x = "Species",
           y = "Body Mass (g)",
           fill = "Sex") +
      theme_minimal()
  })
  
  # create another new dataset
  penguin_species <- reactive({
    dat %>%
      filter(species == input$species_select) %>%
      group_by(sex) %>%
      summarize(Length = mean(bill_length_mm, na.rm = TRUE),
                Depth = mean(bill_depth_mm, na.rm = TRUE))
  })
  
  # create a table
  output$penguin_table <- renderTable({
    penguin_species()
  })
  
}

#### Combine the user interface and server ####

shinyApp(ui = ui, server = server)