function sandbox_field_widget_info() {
dsm('sandbox_field_widget_info');
  return array(
    'sandbox' => array(
      'behaviors' => array(
        'default value' => FIELD_BEHAVIOR_NONE,
        'multiple values' => FIELD_BEHAVIOR_DEFAULT,
      ),
      'field types' => array('file'),
      'label' => 'xxxxing sandbox',
    ),
  );
}

function sandbox_field_widget_form(&$form, &$form_state, $field, $instance, $language, $items, $delta, $element) {
dsm('sandbox_field_widget_form');

  $element_info = element_info('managed_file');
  $element += array(
    '#type' => 'managed_file',
    '#process' => array_merge($element_info['#process'], array('sandbox_field_widget_process')),
  );

dsm($element, '  element');

  // Add ajax wrapper so that the entire form can be replaced.
  // This is the only way to replace multiple fields.
//  $form['#prefix'] = '<div id="' . 'sandbox-wrapper-all' . '">';
//  $form['#suffix'] = '</div>';


  return $element;
}


function sandbox_field_widget_form_alter(&$element, &$form_state, $context) {
  $field_name = $context['field']['field_name'];
  $wrapper_id = 'sandbox-' . $field_name . '-ajax-wrapper';

  $wrapper_prefix = '<div id="' . $wrapper_id . '">';
  $wrapper_suffix = '</div>';

dsm($field_name, 'sandbox_field_widget_form_alter');
// dsm($element, '  element');

  // Adds a wrapper around each field.
  if (isset($element['#prefix'])) {
    $element['#prefix'] .= $wrapper_prefix;
  }
  else {
    $element['#prefix'] = $wrapper_prefix;
  }

  if (isset($element['#suffix'])) {
    $element['#suffix'] = $wrapper_suffix . $element['#suffix'];
  }
  else {
    $element['#suffix'] = $wrapper_suffix;
  }
}




function sandbox_field_widget_process($element, &$form_state, $form) {
dsm('sandbox_field_widget_process');

  // Replace ajax calls.
  $ajax_replacement = $element['upload_button']['#ajax'];
  $ajax_replacement['path'] = 'sandbox/ajax/' . implode('/', $element['#array_parents']) . '/' . $form['form_build_id]['#value'];
  $ajax_replacement['wrapper'] = 'sandbox-wrapper-header';

  $element['upload_button']['#ajax'] = $ajax_replacement;

  // Toggle to see some changes!!!
  if (!empty($form['field_text_widget']['und'][0]['value']['#title'])) {
    $form['field_text_widget']['und'][0]['value']['#title'] = 'xxxx';
  }
  else {
    $form['field_text_widget']['und'][0]['value']['#title'] = '';
  }

dsm($ajax_replacement);
  return $element;
}





function sandbox_ajax_callback() {
dsm('sandbox_ajax_callback');
  $args = func_get_args();

  list($form, $form_state, $form_id, $form_build_id, $commands) = ajax_get_form();

  drupal_process_form($form['#form_id'], $form, $form_state);
  $form_state['rebuild'] = TRUE;

  $ajax = array(
    '#type' => 'ajax',
    '#commands' => array(),
  );



  $commands = array();
  $commands[] = ajax_command_replace(NULL, theme('status_messages'));
  $commands[] = ajax_command_replace('#sandbox-field_sandbox_widget-ajax-wrapper', render($form['field_sandbox_widget']));
  $commands[] = ajax_command_replace('#sandbox-field_text_widget-ajax-wrapper', render($form['field_text_widget']));

  $ajax['#commands'] = array_merge($ajax['#commands'], $commands);

  return $ajax;
}




function sandbox_form_alter(&$form, &$form_state, $form_id) {
  if (!isset($form['#prefix'])) {
    $form['#prefix'] = '';
  }
  $form['#prefix'] = '<div id="sandbox-wrapper-header"></div>';
}

function sandbox_help($path, $arg) {

  switch ($path) {
    case 'admin/help#sandbox':
      $output = '';
      $output .= 'xxxx';
      return $output;
  }
}



function sandbox_menu() {
dsm('sandbox_menu');

  // Copied from file_menu
  $items = array();
  $items['sandbox/ajax'] = array(
    'page callback' => 'sandbox_ajax_callback',
//    'page callback' => 'file_ajax_upload',
    'delivery callback' => 'ajax_deliver',
    'access arguments' => array('access content'),
    'theme callback' => 'ajax_base_page_theme',
    'type' => MENU_CALLBACK,
  );

  return $items;
}