/**
 * @provides javelin-behavior-differential-feedback-preview
 * @requires javelin-lib-dev
 */

JX.behavior('differential-feedback-preview', function(config) {

  var action = JX.$(config.action);
  var content = JX.$(config.content);
  var preview = JX.$(config.preview);

  var aval = null;//action.value;
  var cval = null;//content.value;
  var defer = null;
  var min = null;
  var request = null;

  function check() {
    if (request || (min && (new Date().getTime() < min))) {
      // Waiting on an async or just got one back, rate-limit.
      return;
    }

    defer && defer.stop();

    if (action.value !== aval || content.value !== cval) {
      aval = action.value;
      cval = content.value;

      request = new JX.Request(config.uri, function(r) {
        preview && JX.DOM.setContent(preview, JX.HTML(r));
        min = new Date().getTime() + 500;
        defer && defer.stop();
        defer = JX.defer(check, 500);
      });
      request.listen('finally', function() { request = null; });
      request.setData({action : aval, content : cval});
      // If we don't get a response back soon, retry on the next action.
      request.setTimeout(2000);
      request.send();
    } else {
      defer = JX.defer(check, 2000);
    }
  }

  JX.DOM.listen(content, 'keydown', null, check);
  JX.DOM.listen(action,  'change',  null, check);

  check();
});