Javascript for uploading using https://github.com/nathancolgate/s3-swf-upload-plugin

index.html.erb

<div id="swf_upload">
  <strong>New Upload:</strong>
  <div id="browse">
    <%= raw s3_swf_upload_tag(
      fileTypes: "*.csv",
      queueSizeLimit: 1,
      selectMultipleFiles: false,
      onQueueEmpty: "window.uploader.queueEmpty();",
      onFileAdd: "window.uploader.fileAdd(file);",
      onUploadingStart: "window.uploader.uploadingStart();",
      onUploadingFinish: "window.uploader.uploadingFinish();",
      onUploadProgress: "window.uploader.uploadProgress(progress_event);",
      onUploadComplete: "window.uploader.uploadComplete(upload_options, event);"
    ) %>
  </div>

  <div id="file-list">
    <ul id="queue">
    </ul>
  </div>

  <input type="submit" value="Start Uploading" id="start_upload" />
</div>

swf_s3_upload.js

(function ($) {
  var position = $("#browse").position();

  // This puts the queue on the same place as the flash button. Pure Eyecandy.
  $("#queue").css({
    "top": position.top,
    "left": position.left,
    "position": "absolute",
    "display": "none"
  });

  $("#start_upload").click(function (evt) {
    evt.preventDefault();
    s3_swf_1_object.startUploading();
    $(this).val("Please wait...");
    $(this).attr("disabled", "disabled");
  });

  var uploader = {
    // s3_swf_upload handlers
    queueEmpty: function () {
      alert("You have to select 1 file.")
    },

    fileAdd: function (file) {
      $("#queue").html(function () {
        var size_in_mb = Math.round(file.size / (1024 * 1024) * 100) / 100,
        li = $("<li>").html(file.name + " (" + size_in_mb + " mb) &nbsp;"),
        a = $("<a href='javascript:;'>").html("remove");

        $(s3_swf_1_object.obj()).css("visibility", "hidden");
        $("#queue").show();

        a.click(function (evt) {
          evt.preventDefault();
          s3_swf_1_object.clearQueue();
          $(this).parent("li").remove();
          $("#queue").hide();
          $(s3_swf_1_object.obj()).css("visibility", "visible");
        });

        li.append(a);

        return li;
      });
    },

    uploadingStart: function () {
      $("#queue li a").replaceWith(function () {
        var progress = $("<strong id='progress'>").html("Uploading: 0 %");
        return progress;
      });
    },

    uploadingFinish: function () {
      $("#queue li #progress").html(function () {
        return "Upload Done!";
      });
    },

    uploadProgress: function (progress_event) {
      $("#progress").html(function () {
        var percentage =  parseInt(progress_event.bytesLoaded) / parseInt(progress_event.bytesTotal);

        return "Uploading: " + Math.floor(percentage * 100) + " %"
      });
    },

    uploadComplete: function (upload, evt) {
      var form = $("<form action='/admin/imports' method='post'>");
      form.append("<input type='hidden' name='file_name' value='" + upload.FileName + "'>");

      $("body").append(form);
      form.submit();
    }
  }

  window.uploader = uploader;
})(jQuery);