<?php

/**
 * Implementation of hook_theme.
 */
function media_multiselect_theme() {
  return array(
    'media_multiselect_empty_field' => array(
      'render element' => 'element',
    ),
  );
}

/**
 * Implements hook_field_widget_info().
 */
function media_multiselect_field_widget_info() {
  $media_widgets = media_field_widget_info();
  return array(
    'media_multiselect' => array(
      'label' => t('Media multiselect'),
      'behaviors' => array(
        'multiple values' => FIELD_BEHAVIOR_CUSTOM,
        'default value' => FIELD_BEHAVIOR_NONE,
      ),
    ) + $media_widgets['media_generic']
  );
}

/**
 * Implements hook_field_widget_settings_form().
 */
function media_multiselect_field_widget_settings_form($field, $instance) {
  return media_field_widget_settings_form($field, $instance);
}

/**
 * Implements hook_field_widget_form().
 */
function media_multiselect_field_widget_form(&$form, &$form_state, $field, $instance, $langcode, $items, $delta, $element) {
  $form['#entity'] = $element['#entity'];

  // We cheat and alter the widget-type to the normal media widget
  $instance['widget']['type'] = 'media_generic';
  $instance['widget']['module'] = 'media';

  if ($field['cardinality'] == 1) {
    return field_default_form(
      $element['#entity_type'],
      $element['#entity'],
      $field,
      $instance,
      $langcode,
      $items,
      $form,
      $form_state
    );
  }

  // Then ask the Field API to generate that widget
  $element += field_multiple_value_form($field, $instance, $langcode, $items, $form, $form_state);

  // If we have a != 1, != unlimited field, we have a fixed amount of values
  // which we can't ajaxify the 'add-more' button of, as it does not have a
  // 'add-more' button. So abort untill we've found a way around this.
  if ($field['cardinality'] != FIELD_CARDINALITY_UNLIMITED) {
    return $element;
  }

  // Copy over the media-options
  $element['#media_options'] = $element[0]['#media_options'];
  $element['#media_options']['global']['multiselect'] = TRUE;

  // Remove the last element (the empty element used to add new items)
  unset($element[$element['#max_delta']]);
  $element['#max_delta'] -= 1;

  // If we now no longer has any items, change the theme to not get the
  // empty table
  if ($element['#max_delta'] < 0) {
    $element['add_more']['#value'] = t('Select Media');
    $element['#theme'] = 'media_multiselect_empty_field';
  } else {
    $element['add_more']['#value'] = t('Add Media');
  }
  
  // Add our JS
  $element['#attached'] = array(
    'js' => array(
      drupal_get_path('module', 'media_multiselect') . '/media_multiselect.js',
    ),
  );

  // Attach the browser JS (this is normally done by the media-elements,
  // but on empty nodes, there arent any media-elements, as we unset the
  // empty placeholder)
  module_load_include('inc', 'media', 'includes/media.browser');
  media_attach_browser_js($element);

  $element['#after_build'][] = 'media_multiselect_add_js_settings';
  
  // Change the AJAX info for the add-more button.
  $element['add_more']['#ajax']['event'] = 'media_select';
  $element['add_more']['#ajax']['callback'] = 'media_multiselect_add_more_callback';
  $element['add_more']['#submit'][0] = 'media_multiselect_add_more_submit';
  
  return $element;
}

/**
 * Element-process callback. See @media_multiselect_field_widget_form
 */
function media_multiselect_add_js_settings($element) {
  static $processed = array();
  
  // Add the media-options so the add-more button has the correct options for
  // opening the dialog.
  // We use a static variable to prevent we add the settings more than once
  $id = $element['add_more']['#id'];
  if (empty($processed[$id])) {
    drupal_add_js(array(
      'media' => array(
        'multi_select' => array(
          'elements' => array(
            $id => $element['#media_options'],
          ),
        ),
      ),
    ), 'setting');
    $processed[$id] = TRUE;
  }
  
  return $element;
}

/**
 * Theme callback for empty multiselect media-fields
 */
function theme_media_multiselect_empty_field($vars) {
  $element = $vars['element'];
  
  $attributes['class'] = array('form-item');
  if (!empty($element['#type'])) {
    $attributes['class'][] = 'form-type-' . strtr($element['#type'], '_', '-');
  }
  if (!empty($element['#name'])) {
    $attributes['class'][] = 'form-item-' . strtr($element['#name'], array(' ' => '-', '_' => '-', '[' => '-', ']' => ''));
  }
  // Add a class for disabled elements to facilitate cross-browser styling.
  if (!empty($element['#attributes']['disabled'])) {
    $attributes['class'][] = 'form-disabled';
  }
  $output = '<div' . drupal_attributes($attributes) . '>' . "\n";
  $output .= theme('form_element_label', $element);
  $output .= '<div class="description">' . $element['#description'] . "</div>\n";
  $output .= '<div class="clearfix">' . drupal_render($element['add_more']) . '</div>';
  $output .= "</div>\n";
  
  return $output;
}

/**
 * AJAX callback. See @media_multiselect_field_widget_form
 */
function media_multiselect_add_more_callback($form, $form_state) {
  $button = $form_state['triggering_element'];

  // Go one level up in the form, to the widgets container.
  $elements = drupal_array_get_nested_value($form, array_slice($button['#array_parents'], 0, -1));

  // Find the fids that was just added
  $selected_fids = $form_state['input']['media_multiselect_fids'];

  // Run through the elements in the form and add the 'ajax-new-content'
  // wrapper around the new files
  $children = element_children($elements);
  foreach ($children AS $child) {
    $element = &$elements[$child];
    if (!empty($element['#value']['fid']) && in_array($element['#value']['fid'], $selected_fids)) {
      $element['#prefix'] = '<div class="ajax-new-content">';
      $element['#suffix'] = '</div>';
    }
  }
  return $elements;
}

/**
 * AJAX add-more button #submit. See @media_multiselect_field_widget_form
 */
function media_multiselect_add_more_submit($form, &$form_state) {
  $button = $form_state['triggering_element'];

  // Go one level up in the form, to the widgets container.
  $element = drupal_array_get_nested_value($form, array_slice($button['#array_parents'], 0, -1));
  $value = drupal_array_get_nested_value($form_state['values'], array_slice($button['#array_parents'], 0, -1));
  
  // Some convinient short-hand variables
  $field_name = $element['#field_name'];
  $langcode = $element['#language'];
  $parents = $element['#field_parents'];
  $field_state = field_form_get_state($parents, $field_name, $langcode, $form_state);
  
  // Remove the 'add more' value, because its not a file.
  unset($value['add_more']);
  
  // Filter the existing values so only fid > 0 remains.
  $value = array_filter($value, '_media_multiselect_filter_empty_value');
  // Sort according to weight.
  _field_sort_items($field_state['field'], $value);
  
  // Find the highest weight, so we know where to continue from.
  $max_weight = empty($value) ? -1 : end(end($value));
  
  if (!empty($form_state['input']['media_multiselect_fids'])) {
    // Add the selected fids to the list of values
    foreach ($form_state['input']['media_multiselect_fids'] AS $fid) {
      $value[] = array(
        'fid' => $fid,
        '_weight' => ++$max_weight,
        );
    }
  }

  // Update the Field State to the new amount of items
  $field_state['items_count'] = count($value);
  field_form_set_state($parents, $field_name, $langcode, $form_state, $field_state);
  
  // Update the Form State to make it seem like it received the new files as an input.
  drupal_array_set_nested_value($form_state['input'], array_slice($button['#array_parents'], 0, -1), $value);
  
  $form_state['rebuild'] = TRUE;
}

/**
 * Helper function to remove empty file values (fid=0)
 */
function _media_multiselect_filter_empty_value($value) {
  return !empty($value['fid']);
}

/**
 * Implements hook_field_validate()
 */
function media_multiselect_field_validate($entity_type, $entity, $field, $instance, $langcode, $items, &$errors) {
  media_field_validate($entity_type, $entity, $field, $instance, $langcode, $items, $errors);
}