bayesAPI = function (){
  require(tcltk);
  t=seq(0,1,0.001);
  nmax <- 5000; theta=0.3;
  y <<- as.integer(runif(nmax)<theta); 

  mode <- tclVar("demo"); visu <- tclVar("dens");
  a <- tclVar(10); 
  b <- tclVar(10);
  n <- tclVar(0);
  Theta <- tclVar(50);

  base <- tktoplevel(); 
  tkwm.title(base, 'Bayesian estimation: Binomial model');
  tt <- tkframe(base, borderwidth=2)
  sliderFrame <- tkframe(tt, borderwidth=2, relief='groove');

  nFrame <- tkframe(sliderFrame, borderwidth=2);
  nLabel <- tklabel(nFrame, text="n", width=4);
  nValueLabel <- tklabel(nFrame, text="", width=6);
  
  aFrame <- tkframe(sliderFrame, borderwidth=2);
  aLabel <- tklabel(aFrame, text="a: ", width=4);
  aValueLabel <- tklabel(aFrame, text="", width=6);
  
  bFrame <- tkframe(sliderFrame, borderwidth=2);
  bLabel <- tklabel(bFrame, text="b: ", width=4);
  bValueLabel <- tklabel(bFrame, text="", width=6);
  
  thetaFrame <- tkframe(sliderFrame, borderwidth=2);
  thetaLabel <- tklabel(thetaFrame, text="theta: ", width=4);
  thetaValueLabel <- tklabel(thetaFrame, text="", width=6);
  
  init <- function(){
    th<- as.double(tclvalue(theta))/100;
    y <<- as.integer(runif(nmax)<th);
  }

  controlPlot <- function(...){
  nn <- as.integer(tclvalue(n));
  aa <- as.double(tclvalue(a))/10;
  bb <- as.double(tclvalue(b))/10;
  theta <- as.double(tclvalue(theta))/100;
  if (tclvalue(mode)=="demo"){
    plot(t, dbeta(t, aa, bb), type="l", lwd=3, col="blue")
    mu <- aa/(aa+bb);
    lines(mu*c(1,1), c(0,dbeta(mu, aa, bb)), lwd=2, col="red")
  }
  else{
    plot(t, dbeta(t, aa+ sum(y[1:nn]), bb + nn - sum(y[1:nn])), type="l", lwd=3, col="blue")
    mu <- (aa + sum(y[1:nn]))/(aa+bb+nn);
    lines(mu*c(1,1), c(0,dbeta(mu, aa+ sum(y[1:nn]), bb + nn- sum(y[1:nn]))), lwd=2, col="red")
    lines(theta, 0, type="p", pch="x", cex=3, col="red");
    if (nn>=1) {lines(mean(y[1:nn]), 0, type="p", pch="o", cex=3, col="green");}
  }
 tkconfigure(nValueLabel, text=as.character(nn));
 tkconfigure(aValueLabel, text=as.character(aa));
 tkconfigure(bValueLabel, text=as.character(bb));
 tkconfigure(thetaValueLabel, text=as.character(theta));
  }

  otherPlot <- function(...){
    init(); controlPlot();
  }
  
  nSlider <- tkscale(nFrame, from=0, to=nmax, length=600, showvalue=F, variable=n, resolution=1, orient='horizontal', command=controlPlot)
  tkpack(nFrame, nLabel, nValueLabel, nSlider, side='left');
    
  aSlider <- tkscale(aFrame, from=1, to=500, length=600, showvalue=F, variable=a, resolution=1, orient='horizontal', command=controlPlot)
  tkpack(aFrame, aLabel, aValueLabel, aSlider, side='left');

  bSlider <- tkscale(bFrame, from=1, to=500, length=600, showvalue=F, variable=b, resolution=1, orient='horizontal', command=controlPlot)
  tkpack(bFrame, bLabel, bValueLabel, bSlider, side='left');
  
  thetaSlider <- tkscale(thetaFrame, from=0, to=100, length=600, showvalue=F, variable=theta, resolution=1, orient='horizontal', command=otherPlot)
  tkpack(thetaFrame, thetaLabel, thetaValueLabel, thetaSlider, side='left');
   
  tkpack(sliderFrame, nFrame, aFrame, bFrame, thetaFrame, side='top')
  
  btfrm <- tkframe(tt, borderwidth=2,relief='groove')
  rbdemo <- tkradiobutton(btfrm, command=controlPlot, text='demo', variable=mode)
  rbexp <- tkradiobutton(btfrm, command=controlPlot, text='exp', variable=mode)
  tkconfigure(rbdemo, variable=mode, value='demo'); 
  tkconfigure(rbexp, variable=mode, value='exp');
  

  rbdens <- tkradiobutton(btfrm, command=controlPlot, text='dens', variable=visu)
  rbnorm <- tkradiobutton(btfrm, command=controlPlot, text='norm', variable=visu)
  tkconfigure(rbdens, variable=visu, value='demo'); 
  tkconfigure(rbnorm, variable=visu, value='exp');
  
  tkpack(btfrm, rbdemo, rbexp, tklabel(btfrm, text="   "), rbdens, rbnorm, side='left')
  
  btReset <- tkbutton(tt, command=otherPlot, text='Reset');
  tkpack(tt, btfrm, sliderFrame, btReset, side='top');
}


bayesAPI();