function api_general(method, data, callback, checked, additional_data) {
  $.ajax({
    type: 'POST',
    url: '/api/' + method,
    data: data,
    success: function (data) {
      if (checked && data.error !== undefined)
        popup('danger', 'Error: ' + data.error);
      else callback(data, additional_data);
    },
    processData: !(data instanceof FormData),
    contentType: data instanceof FormData? false: 'application/x-www-form-urlencoded',
    dataType: 'json'
  });
}

function api(method, data, callback) {
  var additional_data = Array.prototype.slice.call(arguments, 3);

  api_general(method, data, callback, true, additional_data);
}

function api_unchecked(method, data, callback) {
  var additional_data = Array.prototype.slice.call(arguments, 3);

  api_general(method, data, callback, false, additional_data);
}