<?php

/**
 * @file
 * Creates the option of Repeating date fields and manages Date fields that use the Date Repeat API.
 *
 * The Repeating functionality is pretty tightly intermingled with other code,
 * so the process of pulling it out into this module will happen gradually.
 *
 * The current implementation adds a repeat form to the date field so the user
 * can select the repeat rules. That selection is built into an RRULE
 * which is stored in the zero position of the field values. During widget
 * validation, the rule is parsed to see what dates it will create,
 * and multiple values are added to the field, one for each repeat date.
 * That update only happens when the rule, the start date, or the end date
 * change, no need to waste processing cycles for other changes to the node
 * values.
 *
 * Lots of possible TODOs, the biggest one is figuring out the best
 * way to handle dates with no UNTIL date since we can't add an infinite
 * number of values to the field. For now, we require the UNTIL date.
 */

/**
 * Implements hook_theme().
 */
function date_repeat_field_theme() {
  $themes = array(
    'date_repeat_display' => array(
      'variables' => array(
        'field' => NULL,
        'item' => NULL,
        'entity_type' => NULL,
        'entity' => NULL,
        'dates' => NULL
      ),
      'function' => 'theme_date_repeat_display',
    ),
  );

  return $themes;
}

/**
 * Theme the human-readable description for a Date Repeat rule.
 *
 * TODO -
 * add in ways to store the description in the date so it isn't regenerated
 * over and over and find a way to allow description to be shown or hidden.
 */
function theme_date_repeat_display($vars) {
  $field = $vars['field'];
  $item = $vars['item'];
  $entity = !empty($vars['node']) ? $vars['node'] : NULL;
  $output = '';
  if (!empty($item['rrule'])) {
    $output = date_repeat_rrule_description($item['rrule']);
    $output = '<div class="date-repeat-rule">' . $output . '</div>';
  }
  return $output;
}

/**
 * Implements hook_menu().
 *
 * Add menu tabs to display pages with details about repeating date values.
 */
function date_repeat_field_menu() {
  $items = array();

  $values = date_repeat_field_bundles();
  foreach ($values as $entity_type => $bundles) {
    if (module_exists('field_collection') && $entity_type == 'field_collection_item') {
      foreach ($bundles as $bundle => $fields) {
        $field = field_info_field($bundle);
        if ($field['type'] == 'field_collection') {
          $path = field_collection_field_get_path($field);
          $count = count(explode('/', $path));
          $items[$path . '/%field_collection_item/repeats'] = array(
            'title' => 'Repeats',
            'page callback' => 'date_repeat_field_page',
            'page arguments' => array($entity_type, $count),
            'access callback' => 'date_repeat_field_show',
            'access arguments' => array($entity_type, $count),
            'type' => MENU_LOCAL_TASK,
            'context' => MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE,
          );
        }
      }
    }
    else {
      $path = $entity_type . '/%' . $entity_type;
      $items[$path . '/repeats'] = array(
        'title' => 'Repeats',
        'page callback' => 'date_repeat_field_page',
        'page arguments' => array($entity_type, 1),
        'access callback' => 'date_repeat_field_show',
        'access arguments' => array($entity_type, 1),
        'type' => MENU_LOCAL_TASK,
        'context' => MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE,
      );
    }
  }
  return $items;
}

/**
 * Implements hook_permission().
 */
function date_repeat_field_permission() {
  return array(
    'view date repeats' => array(
      'title' => t('View Repeating Dates'),
      'description' => t('Allow user to see a page with all the times a date repeats.'),
    ),
  );
}

/**
 * See if the user can access repeat date info for this entity.
 *
 * @param string $entity_type
 *   The entity type.
 * @param string $entity
 *   The specific entity to check (optional).
 *
 * @return bool
 *   Return TRUE if there is at least one date field attached to this entity,
 *   and the current user has the permission 'view date repeats'; FALSE otherwise.
 */
function date_repeat_field_show($entity_type = 'node', $entity = NULL) {
  if (!user_access('view date repeats')) {
    return FALSE;
  }

  $bundle = date_get_entity_bundle($entity_type, $entity);

  // In Drupal 7.22 the field_info_field_map() function was added, which is more
  // memory-efficient in certain cases than field_info_fields().
  // @see https://drupal.org/node/1915646
  $field_map_available = version_compare(VERSION, '7.22', '>=');
  $field_list = $field_map_available ? field_info_field_map() : field_info_fields();

  foreach ($field_list as $field_name => $data) {
    if (in_array($data['type'], array('date', 'datestamp', 'datetime'))
        && array_key_exists($entity_type, $data['bundles'])
        && in_array($bundle, $data['bundles'][$entity_type])) {
      $field_info = $field_map_available ? field_info_field($field_name) : $data;
      if (date_is_repeat_field($field_info)) {
        return TRUE;
      }
    }
  }
  return FALSE;
}

/**
 * A page to list all values for a repeating date.
 */
function date_repeat_field_page($entity_type = 'node', $entity = NULL) {
  $bundle = date_get_entity_bundle($entity_type, $entity);
  $info = entity_get_info($entity_type);
  $key = $info['entity keys']['id'];
  drupal_set_title(t('Repeats'));
  $entity->date_repeat_show_all = TRUE;
  $entity->content = array();
  $output = '';
  foreach (field_info_fields() as $field_name => $field) {
    if (in_array($field['type'], array('date', 'datestamp', 'datetime')) && date_is_repeat_field($field)) {
      foreach ($field['bundles'] as $field_entity_type => $bundles) {
        foreach ($bundles as $field_bundle) {
          if ($entity_type == $field_entity_type && $bundle == $field_bundle) {
            $data = field_view_field($entity_type, $entity, $field_name);
            $output .= drupal_render($data);
          }
        }
      }
    }
  }
  return $output;
}

/**
 * Return an array of all entity types and bundles that have repeating date fields.
 */
function date_repeat_field_bundles() {
  $values = array();
  foreach (field_info_fields() as $field_name => $field) {
    if (in_array($field['type'], array('date', 'datestamp', 'datetime')) && $field['settings']['repeat']) {
      foreach ($field['bundles'] as $entity_type => $bundles) {
        foreach ($bundles as $bundle) {
          $values[$entity_type][$bundle][] = $field_name;
        }
      }
    }
  }
  return $values;
}

/**
 * Check field is repeat.
 */
function date_is_repeat_field($field, $instance = NULL) {
  if (is_string($field)) {
    $field = field_info_field($field);
  }

  if (!isset($field['settings']['repeat'])) {
    return FALSE;
  }

  $value = $field['settings']['repeat'];

  // This might be either a field form or a real field.
  if (is_array($value)) {
    return $value['#value'];
  }
  else {
    return $value;
  }
}

/**
 * Implements hook_date_field_insert_alter().
 */
function date_repeat_field_date_field_insert_alter(&$items, $context) {

  $entity = $context['entity'];
  $field = $context['field'];
  $instance = $context['instance'];
  $langcode = $context['langcode'];

  // If an RRULE with a frequency of NONE made it this far, unset it.
  if (!empty($items[0]['rrule']) && strpos($items[0]['rrule'], 'FREQ=NONE')) {
    $items[0]['rrule'] = NULL;
  }

  // We can't use hook_devel_generate() because we need custom handling for
  // repeating date fields. So we wait until the entity is inserted, then
  // intervene here to fix it.
  if (!empty($entity->devel_generate) && !empty($field['settings']['repeat'])) {
    module_load_include('inc', 'date_repeat_field', 'date_repeat_field.devel_generate');
    date_repeat_field_date_field_insert($items, $context);
  }
}

/**
 * Implements hook_date_field_update_alter().
 */
function date_repeat_field_date_field_update_alter(&$items, $context) {

  // If an RRULE with a frequency of NONE made it this far, unset it.
  if (!empty($items[0]['rrule']) && strpos($items[0]['rrule'], 'FREQ=NONE')) {
    $items[0]['rrule'] = NULL;
  }

  // If you have a repeating date field on a user and don't check the box to repeat it,
  // we end up with $items[0]['rrule'] = array('additions' => '', 'exceptions' => ''));
  // This will clean it up by getting rid of those bogus values.
  // @TODO Figure out where that's coming from. It doesn't happen on nodes.
  if (!empty($items[0]['rrule']) && is_array($items[0]['rrule'])) {
    $items[0]['rrule'] = NULL;
  }
}

/**
 * Implements hook_field_widget_form_alter().
 */
function date_repeat_field_field_widget_form_alter(&$element, &$form_state, $context) {

  $field = $context['field'];
  $instance = $context['instance'];
  $items = $context['items'];
  $delta = $context['delta'];

  if (in_array($field['type'], array('date', 'datetime', 'datestamp'))) {
    if (!empty($field['settings']['repeat'])) {
      $element['#element_validate'][] = 'date_repeat_field_widget_validate';
      $element['show_repeat_settings'] = array(
        '#type' => 'checkbox',
        '#title' => t('Repeat'),
        '#weight' => $instance['widget']['weight'] + .3,
        '#prefix' => '<div class="date-clear">',
        '#suffix' => '</div>',
        '#default_value' => isset($items[$delta]['rrule']) && !empty($items[$delta]['rrule']) ? 1 : 0,
      );

      // Make changes if instance is set to be rendered as a regular field.
      if (!empty($instance['widget']['settings']['no_fieldset'])) {
        $element['#title'] = check_plain($instance['label']);
        $element['#description'] = field_filter_xss($instance['description']);
        $element['#theme_wrappers'] = array('date_form_element');
      }
    }
  }
}

/**
 * Validation for date repeat form element.
 *
 * Create multiple values from the RRULE results.
 * Lots more work needed here.
 */
function date_repeat_field_widget_validate($element, &$form_state) {
  $field = field_widget_field($element, $form_state);
  if (empty($field['settings']['repeat'])) {
    return;
  }

  $field_name = $element['#field_name'];
  $delta = $element['#delta'];
  $langcode = $element['#language'];

  // If the widget has been hidden by #access, the RRULE will still be in its
  // original string form here. Nothing to process.
  if (date_hidden_element($element)) {

    // If this was a hidden repeating date, we lost all the repeating values in the widget processing.
    // Add them back here if that happened since we are skipping the re-creation of those values.
    if (!empty($form_state['storage']['date_items'][$field_name])) {
      array_pop($element['#parents']);
      form_set_value($element, $form_state['storage']['date_items'][$field_name][$langcode], $form_state);
    }
    return;
  }

  module_load_include('inc', 'date_repeat', 'date_repeat_form');
  $instance = field_widget_instance($element, $form_state);

  // Here 'values' returns an array of input values, which includes the original RRULE, as a string.
  // and 'input' returns an array of the form elements created by the repeating date widget, with
  // RRULE values as an array of the selected elements and their chosen values.
  $item = drupal_array_get_nested_value($form_state['values'], $element['#parents'], $input_exists);
  $input = drupal_array_get_nested_value($form_state['input'], $element['#parents'], $input_exists);

  $rrule_values = date_repeat_merge($input['rrule'], $element['rrule']);

  // If no repeat information was set, treat this as a normal, non-repeating value.
  if ($rrule_values['FREQ'] == 'NONE' || empty($input['show_repeat_settings'])) {
    $item['rrule'] = NULL;
    form_set_value($element, $item, $form_state);
    return;
  }

  // If no start date was set, clean up the form and return.
  if (empty($item['value'])) {
    form_set_value($element, NULL, $form_state);
    return;
  }

  // Require the UNTIL date for now.
  // The RRULE has already been created by this point, so go back
  // to the posted values to see if this was filled out.
  $error_field_base = implode('][', $element['#parents']);
  $error_field_until = $error_field_base . '][rrule][until_child][datetime][';
  if (!empty($item['rrule']) && $rrule_values['range_of_repeat'] === 'UNTIL' && empty($rrule_values['UNTIL']['datetime'])) {
    switch ($instance['widget']['type']) {
      case 'date_text':
      case 'date_popup':
        form_set_error($error_field_until . 'date', t("Missing value in 'Range of repeat'. (UNTIL).", array(), array('context' => 'Date repeat')));
        break;

      case 'date_select':
        form_set_error($error_field_until . 'year', t("Missing value in 'Range of repeat': Year (UNTIL)", array(), array('context' => 'Date repeat')));
        form_set_error($error_field_until . 'month', t("Missing value in 'Range of repeat': Month (UNTIL)", array(), array('context' => 'Date repeat')));
        form_set_error($error_field_until . 'day', t("Missing value in 'Range of repeat': Day (UNTIL)", array(), array('context' => 'Date repeat')));
        break;
    }
  }

  $error_field_count = $error_field_base . '][rrule][count_child';
  if (!empty($item['rrule']) && $rrule_values['range_of_repeat'] === 'COUNT' && empty($rrule_values['COUNT'])) {
    form_set_error($error_field_count, t("Missing value in 'Range of repeat'. (COUNT).", array(), array('context' => 'Date repeat')));
  }

  if (form_get_errors()) {
    return;
  }

  // If the rule, the start date, or the end date have changed, re-calculate
  // the repeating dates, wipe out the previous values, and populate the
  // field with the new values.

  $rrule = $item['rrule'];
  if (!empty($rrule)) {

    // Avoid undefined index problems on dates that don't have all parts.
    $possible_items = array('value', 'value2', 'timezone', 'offset', 'offset2');
    foreach ($possible_items as $key) {
      if (empty($item[$key])) {
        $item[$key] = '';
      }
    }

    // We only collect a date for UNTIL, but we need it to be inclusive,
    // so force it to a full datetime element at the last possible second of the day.
    if (!empty($rrule_values['UNTIL'])) {
      $gran = array('year', 'month', 'day', 'hour', 'minute', 'second');
      $rrule_values['UNTIL']['datetime'] .= ' 23:59:59';
      $rrule_values['UNTIL']['granularity'] = serialize(drupal_map_assoc($gran));
      $rrule_values['UNTIL']['all_day'] = 0;
    }
    $value = date_repeat_build_dates($rrule, $rrule_values, $field, $item);
    // Unset the delta value of the parents.
    array_pop($element['#parents']);
    // Set the new delta values for this item to the array of values returned by the repeat rule.
    form_set_value($element, $value, $form_state);
  }
}

/**
 * Implements the form after_build().
 *
 * Remove the 'Add more' elements from a repeating date form.
 */
function date_repeat_after_build(&$element, &$form_state) {
  foreach ($form_state['storage']['repeat_fields'] as $field_name => $parents) {
    // Remove unnecessary items in the form added by the Add more handling.
    $value = drupal_array_get_nested_value($element, $parents);
    $langcode = $value['#language'];
    unset($value[$langcode]['add_more'], $value[$langcode]['#suffix'], $value[$langcode]['#prefix'], $value[$langcode][0]['_weight']);
    $value[$langcode]['#cardinality'] = 1;
    $value[$langcode]['#max_delta'] = 1;
    drupal_array_set_nested_value($element, $parents, $value);
  }
  return $element;
}

/**
 * Helper function to build repeating dates from a $node_field.
 *
 * Pass in either the RRULE or the $form_values array for the RRULE,
 * whichever is missing will be created when needed.
 */
// @codingStandardsIgnoreStart
function date_repeat_build_dates($rrule = NULL, $rrule_values = NULL, $field, $item) {
// @codingStandardsIgnoreEnd
  include_once DRUPAL_ROOT . '/' . drupal_get_path('module', 'date_api') . '/date_api_ical.inc';
  $field_name = $field['field_name'];

  if (empty($rrule)) {
    $rrule = date_api_ical_build_rrule($rrule_values);
  }
  elseif (empty($rrule_values)) {
    $rrule_values = date_ical_parse_rrule(NULL, $rrule);
  }

  // By the time we get here, the start and end dates have been
  // adjusted back to UTC, but we want localtime dates to do
  // things like '+1 Tuesday', so adjust back to localtime.
  $timezone = date_get_timezone($field['settings']['tz_handling'], $item['timezone']);
  $timezone_db = date_get_timezone_db($field['settings']['tz_handling']);
  $start = new DateObject($item['value'], $timezone_db, date_type_format($field['type']));
  $start->limitGranularity($field['settings']['granularity']);
  if ($timezone != $timezone_db) {
    date_timezone_set($start, timezone_open($timezone));
  }
  if (!empty($item['value2']) && $item['value2'] != $item['value']) {
    $end = new DateObject($item['value2'], date_get_timezone_db($field['settings']['tz_handling']), date_type_format($field['type']));
    $end->limitGranularity($field['settings']['granularity']);
    date_timezone_set($end, timezone_open($timezone));
  }
  else {
    $end = $start;
  }
  $duration = $start->difference($end);
  $start_datetime = date_format($start, DATE_FORMAT_DATETIME);

  if (!empty($rrule_values['UNTIL']['datetime'])) {
    $end = date_ical_date($rrule_values['UNTIL'], $timezone);
    $end_datetime = date_format($end, DATE_FORMAT_DATETIME);
  }
  elseif (!empty($rrule_values['COUNT'])) {
    $end_datetime = NULL;
  }
  else {
    // No UNTIL and no COUNT?
    return array();
  }

  // Split the RRULE into RRULE, EXDATE, and RDATE parts.
  $parts = date_repeat_split_rrule($rrule);
  $parsed_exceptions = (array) $parts[1];
  $exceptions = array();
  foreach ($parsed_exceptions as $exception) {
    $date = date_ical_date($exception, $timezone);
    $exceptions[] = date_format($date, 'Y-m-d');
  }

  $parsed_rdates = (array) $parts[2];
  $additions = array();
  foreach ($parsed_rdates as $rdate) {
    $date = date_ical_date($rdate, $timezone);
    $additions[] = date_format($date, 'Y-m-d');
  }

  $dates = date_repeat_calc($rrule, $start_datetime, $end_datetime, $exceptions, $timezone, $additions);
  $value = array();
  foreach ($dates as $delta => $date) {
    // date_repeat_calc always returns DATE_DATETIME dates, which is
    // not necessarily $field['type'] dates.
    // Convert returned dates back to db timezone before storing.
    $date_start = new DateObject($date, $timezone, DATE_FORMAT_DATETIME);
    $date_start->limitGranularity($field['settings']['granularity']);
    date_timezone_set($date_start, timezone_open($timezone_db));
    $date_end = clone($date_start);
    date_modify($date_end, '+' . $duration . ' seconds');
    $value[$delta] = array(
      'value' => date_format($date_start, date_type_format($field['type'])),
      'value2' => date_format($date_end, date_type_format($field['type'])),
      'offset' => date_offset_get($date_start),
      'offset2' => date_offset_get($date_end),
      'timezone' => $timezone,
      'rrule' => $rrule,
    );
  }

  return $value;
}

/**
 * Implements hook_date_combo_process_alter().
 *
 * This hook lets us make changes to the date_combo element.
 */
function date_repeat_field_date_combo_process_alter(&$element, &$form_state, $context) {

  $field = $context['field'];
  $instance = $context['instance'];
  $field_name = $element['#field_name'];
  $delta = $element['#delta'];

  // Add a date repeat form element, if needed.
  // We delayed until this point so we don't bother adding it to hidden fields.
  if (date_is_repeat_field($field, $instance)) {

    $item = $element['#value'];
    $element['rrule'] = array(
      '#type' => 'date_repeat_rrule',
      '#theme_wrappers' => array('date_repeat_rrule'),
      '#default_value' => isset($item['rrule']) ? $item['rrule'] : '',
      '#date_timezone' => $element['#date_timezone'],
      '#date_format'      => date_limit_format(date_input_format($element, $field, $instance), $field['settings']['granularity']),
      '#date_text_parts'  => (array) $instance['widget']['settings']['text_parts'],
      '#date_increment'   => $instance['widget']['settings']['increment'],
      '#date_year_range'  => $instance['widget']['settings']['year_range'],
      '#date_label_position' => $instance['widget']['settings']['label_position'],
      '#date_repeat_widget' => str_replace('_repeat', '', $instance['widget']['type']),
      '#date_repeat_collapsed' => $instance['widget']['settings']['repeat_collapsed'],
      '#date_flexible' => 0,
      '#weight' => $instance['widget']['weight'] + .4,
    );
  }

}

/**
 * Implements hook_date_combo_pre_validate_alter().
 *
 * This hook lets us alter the element or the form_state before the rest
 * of the date_combo validation gets fired.
 */
function date_repeat_field_date_combo_pre_validate_alter(&$element, &$form_state, $context) {
  // Just a placeholder for now.
}

/**
 * Implements hook_field_info_alter().
 *
 * This Field API hook lets us add a new setting to the fields.
 */
function date_repeat_field_field_info_alter(&$info) {

  $info['date']['settings'] += array(
    'repeat' => 0,
  );
  $info['datetime']['settings'] += array(
    'repeat' => 0,
  );
  $info['datestamp']['settings'] += array(
    'repeat' => 0,
  );
}

/**
 * Implements hook_field_formatter_info_alter().
 *
 * This hook lets us add settings to the formatters.
 */
function date_repeat_field_field_formatter_info_alter(&$info) {

  if (isset($info['date_default'])) {
    $info['date_default']['settings'] += array(
      'show_repeat_rule' => 'show',
    );
  }
}

/**
 * Implements hook_field_widget_info_alter().
 *
 * This Field API hook lets us add a new setting to the widgets.
 */
function date_repeat_field_field_widget_info_alter(&$info) {

  $info['date_text']['settings'] += array(
    'repeat_collapsed' => 0,
  );
  $info['date_select']['settings'] += array(
    'repeat_collapsed' => 0,
  );
  if (module_exists('date_popup')) {
    $info['date_popup']['settings'] += array(
      'repeat_collapsed' => 0,
    );
  }
}

/**
 * Implements hook_date_field_settings_form_alter().
 *
 * This hook lets us alter the field settings form.
 */
function date_repeat_field_date_field_settings_form_alter(&$form, $context) {

  $field = $context['field'];
  $instance = $context['instance'];
  $has_data = $context['has_data'];

  $form['repeat'] = array(
    '#type' => 'select',
    '#title' => t('Repeating date'),
    '#default_value' => $field['settings']['repeat'],
    '#options' => array(0 => t('No'), 1 => t('Yes')),
    '#attributes' => array('class' => array('container-inline')),
    '#description' => t("Repeating dates use an 'Unlimited' number of values. Instead of the 'Add more' button, they include a form to select when and how often the date should repeat."),
    '#disabled' => $has_data,
  );
}

/**
 * Implements hook_form_FORM_ID_alter() for field_ui_field_edit_form().
 */
function date_repeat_field_form_field_ui_field_edit_form_alter(&$form, &$form_state, $form_id) {
  $field = $form['#field'];
  $instance = $form['#instance'];

  if (!in_array($field['type'], array('date', 'datetime', 'datestamp'))) {
    return;
  }

  // If using repeating dates, override the Field module's handling of the multiple values option.
  if (date_is_repeat_field($field, $instance)) {
    $form['field']['cardinality']['#disabled'] = TRUE;
    $form['field']['cardinality']['#value'] = FIELD_CARDINALITY_UNLIMITED;
  }
  // Repeating dates need unlimited values, confirm that in element_validate.
  $form['field']['#element_validate'] = array('date_repeat_field_set_cardinality');
}

/**
 * Ensure the cardinality gets updated if the option to make a date repeating is checked.
 */
function date_repeat_field_set_cardinality($element, &$form_state) {
  if (!empty($form_state['values']['field']['settings']['repeat'])) {
    form_set_value($element['cardinality'], FIELD_CARDINALITY_UNLIMITED, $form_state);
  }
}

/**
 * Implements hook_date_field_instance_settings_form_alter().
 *
 * This hook lets us alter the field instance settings form.
 */
function date_repeat_field_date_field_instance_settings_form_alter(&$form, $context) {
  // Just a placeholder for now.
}

/**
 * Implements hook_date_field_widget_settings_form_alter().
 *
 * This hook lets us alter the field widget settings form.
 */
function date_repeat_field_date_field_widget_settings_form_alter(&$form, $context) {

  $field = $context['field'];
  $instance = $context['instance'];

  if (date_is_repeat_field($field, $instance)) {
    $form['repeat_collapsed'] = array(
      '#type' => 'value',
      '#default_value' => 1,
      '#options' => array(
        0 => t('Expanded', array(), array('context' => 'Date repeat')),
        1 => t('Collapsed', array(), array('context' => 'Date repeat'))
      ),
      '#title' => t('Repeat display', array(), array('context' => 'Date repeat')),
      '#description' => t("Should the repeat options form start out expanded or collapsed? Set to 'Collapsed' to make those options less obtrusive.", array(), array('context' => 'Date repeat')),
      '#fieldset' => 'date_format',
    );
  }
}

/**
 * Implements hook_date_field_foramatter_settings_form_alter().
 *
 * This hook lets us alter the field formatter settings form.
 */
function date_repeat_field_date_field_formatter_settings_form_alter(&$form, &$form_state, $context) {

  $field = $context['field'];
  $instance = $context['instance'];
  $view_mode = $context['view_mode'];
  $display = $instance['display'][$view_mode];
  $formatter = $display['type'];
  $settings = $display['settings'];
  if ($formatter == 'date_default') {
    $form['show_repeat_rule'] = array(
      '#title' => t('Repeat rule:'),
      '#type' => 'select',
      '#options' => array(
        'show' => t('Show repeat rule'),
        'hide' => t('Hide repeat rule')),
      '#default_value' => $settings['show_repeat_rule'],
      '#access' => $field['settings']['repeat'],
      '#weight' => 5,
    );
  }
}

/**
 * Implements hook_date_field_foramatter_settings_summary_alter().
 *
 * This hook lets us alter the field formatter settings summary.
 */
function date_repeat_field_date_field_formatter_settings_summary_alter(&$summary, $context) {

  $field = $context['field'];
  $instance = $context['instance'];
  $view_mode = $context['view_mode'];
  $display = $instance['display'][$view_mode];
  $formatter = $display['type'];
  $settings = $display['settings'];
  if (isset($settings['show_repeat_rule']) && !empty($field['settings']['repeat'])) {
    if ($settings['show_repeat_rule'] == 'show') {
      $summary[] = t('Show repeat rule');
    }
    else {
      $summary[] = t('Hide repeat rule');
    }
  }
}