Drag and drop data into shiny app

How can I drag and drop data into a shiny app? I can drag and drop into an area and read it with javascript, but I'm not sure how to have shiny register it so I can process it on the server. Here is an example setup -- it's kinda long b/c I don't think there is a javascript function builtin to deal with drag-n-drop.

It currently should look like the following when run and a dataset "dat.csv" is dragged in. The goal is register the data that has been drag-n-dropped into a variable in input so it can be processed in R.

ui.R

library(shiny)

ui <- shinyUI(
  fluidPage(
    tags$head(tags$link(rel="stylesheet", href="css/styles.css", type="text/css"),
      tags$script(src="getdata.js")),
    h3(id="data-title", "Drop Datasets"),
    div(class="col-xs-12", id="drop-area", ondragover="dragOver(event)", 
      ondrop="dropData(event)"),
    tableOutput('table'),  # doesn't do anything now

    ## debug
    div(class="col-xs-12",
      tags$hr(style="border:1px solid grey;width:150%"),
      tags$button(id="showData", "Show", class="btn btn-info", 
        onclick="printData('dat.csv')")),
    div(id="data-output")  # print the data
  )
)

server.R

## Make a sample dataset
# write.csv(data.frame(a=1:10, b=letters[1:10]), "dat.csv", row.names=FALSE)
server <- function(input, output, session) {
  output$table <- renderTable(input$data)  # this variable doesn't exist
}

www/getdata.js

var datasets = {};
var dragOver = function(e) { e.preventDefault(); };
var dropData = function(e) {
    e.preventDefault();
    handleDrop(e.dataTransfer.files);
};
var handleDrop = function(files) {
    for (var i = 0, f; f = files[i]; i++) {
    var reader = new FileReader();

    reader.onload = (function(file) {
        return function(e) {
        datasets[file.name.toLowerCase()] = e.target.result;
        var div = document.createElement("div");
        var src = "https://cdn0.iconfinder.com/data/icons/office/512/e42-512.png";
        div.id = "datasets";
        div.innerHTML = [
            "<img class='thumb' src='", src, "' title='", encodeURI(file.name),
            "'/>", "<br>", file.name, "<br>"].join('');
        document.getElementById("drop-area").appendChild(div);
        };
    })(f);
    reader.readAsText(f);
    }
};
// debug
var printData = function(data) {
    var div = document.createElement("div");
    div.innerHTML = datasets[data];
    document.getElementById("data-output").appendChild(div);
};

www/css/styles.css

#data-title {
    text-align:center;
}

#drop-area {
    background-color:#BCED91;
    border:2px solid #46523C;
    border-radius:25px;
    height:90px;
    overflow:auto;
    padding:12px;
}

#drop-area #datasets {
    display:inline-block;
    font-size:small;
    margin-right:8px;
    text-align:center;
    vertical-align:top;
}

.thumb {
    height:45px;
}