# Here are a few pieces for the CLT GUI that demonstrate some
# of the other input widgets, e.g. spin boxes and option menus

myCLT = function(stats = c("Mean", "Median", "Min"),
         dists = c("Normal", "Poisson", "Uniform"))
{
 library(RGtk)
 library(gtkDevice)

# Variables needed for the simulation
 sampleSize = 100
 replicate  = 1000

 selectedStat = stats[1]
# The possible values for stats -- when the option menu changes
# this function is called. Notice that it has two arguments, 
# w will contain the widget and stat will contain one of the Mean, Median, etc 
# When this function is called, it resets the value of selectedStat in the
# parent environment.

 setStat <- function(stat, w){
     selectedStat <<- stat
 }

# selectDist is a similar function 


# The runsimulation function is called when the Start button is pushed
 runSimulation <- function(w) {

     # here we get the value of the spin box only when the start button
     # is clicked, not when the value is changed in the spin box

  sampleSize <<- ssSB$GetValueAsInt()
  N = replicate * sampleSize

  samples = switch(selectedDist, "Normal" = rnorm(N),
                                 "Poisson" = rpois(N, 1),
                                 "Uniform" = runif(N))

  samples = matrix(samples, nrow = replicate)

  statistic = get(tolower(selectedStat), mode = "function")
  sampleStats = apply(samples, 1, statistic)

  plot(density(sampleStats), main=paste("Sampling Distribution of", selectedStat, "for", sampleSize, "Observations from the", selectedDist, sep=' '))
 }


  win = gtkWindow()

  vbox = gtkVBox()
  win$Add(vbox)

# Create a graphics device to put in the GUI

# Plot to the device 
# You may need to resize the window to see it

# Like in the layout function we create button to start the simulation
# The other controls are placed in an hbox
# We can nest boxes within boxes to control the layout
  hbox = gtkHBox()
  vbox$PackEnd(hbox, FALSE, FALSE)

# Here we create a spin button for selecting the sample size
# It has two pieces, the adjustment and the button
sampSLab = gtkLabel("Sample Size: ")
ssADJ <- gtkAdjustment(1,1,400,1,1,1)
ssSB <- gtkSpinButton(ssADJ,0,0)
ssSB$SetUsize(80,20)

hbox$PackStart(sampSLab,expand=FALSE)
hbox$PackStart(ssSB,expand=FALSE)

# Here we create a choice menu to select the statistic
# As with the spin button there are two parts, the option menu 
# and the information that goes in it, which itself contains
# menu items.
# Also note that the function call to AddCallBack has an extra argument
# This argument contains either "Mean" or "Median" or "Min" -- which is
# the value of stat vector

statsOMenu <- gtkOptionMenu()
statsMenu <- gtkMenu()
for (i in 1:length(stats)) {
       item <- gtkMenuItem(stats[i])
       item$AddCallback("activate",setStat,stats[i])
       statsMenu$Append(item)
       }
statsOMenu$SetMenu(statsMenu)
statLab = gtkLabel("Choose a Statistic: ")
hbox$PackStart(statLab,expand=FALSE)
hbox$PackStart(statsOMenu,expand=FALSE)

# Here we create a set of radio buttons to choose the distr
# The unusual thing about radio buttons is that they need to be grouped
# in order to limit one button at a time being pushed.
# To do this, each subsequent button is linked to the first button 
# when it is created. 
  distLab<-gtkLabel("Distribution:   ")
  hbox$PackStart(distLab,expand=FALSE)

  firstButton <- NULL
  for (i in dists) {
    distBtn <- gtkRadioButton(firstButton, i)
    if (is.null(firstButton)) {
       firstButton <- distBtn
       selectDist(i)
    }
    distBtn$AddCallback("clicked",selectDist, i)
    hbox$PackStart(distBtn,expand=FALSE)
  }

}