<?php

/**
 * @file
 * Provides two extra widgets for the Field API.
 *
 * Provides two extra widgets:
 *
 * - Hidden: this widget doesn't show anything on the edit form, and as a
 *   consequence prevents the user from modifying the content of the widget.
 *   This is useful in some situations where using hook_field_access() is not 
 *   suitable (for example when you want to have different edit forms for
 *   different users).
 * - Read-only: this widget shows the content of the field on the edit form,
 *   but doesn't allow the user to edit it. The content is rendered using one
 *   of the formatter of the field.
 */

/**
 * Implements hook_field_widget_info().
 */
function field_extrawidgets_field_widget_info() {
  $widgets['field_extrawidgets_hidden'] = array(
    'label' => t('Hidden'),
    'description' => t('A widget that is completely hidden.'),
    'field types' => array_keys(field_info_field_types()),
    'settings' => array(),
    'behaviors' => array(
      'multiple values' => FIELD_BEHAVIOR_CUSTOM,
    ),
    'weight' => 10,
  );

  $widgets['field_extrawidgets_read_only'] = array(
    'label' => t('Read-only'),
    'description' => t('A widget that is read-only.'),
    'field types' => array_keys(field_info_field_types()),
    'settings' => array(
      'formatter' => '',
      'formatter_settings' => array(),
      'display_empty' => 0,
    ),
    'behaviors' => array(
      'multiple values' => FIELD_BEHAVIOR_CUSTOM,
    ),
    'weight' => 11,
  );

  return $widgets;
}

/**
 * Get settings for a widget, merging in default values.
 */
function field_extrawidgets_widget_settings($field, $instance) {
  $settings = isset($instance['widget']['settings']) ? $instance['widget']['settings'] : array();
  
  if (empty($settings['formatter'])) {
    $field_type = field_info_field_types($field['type']);
    $settings['formatter'] = $field_type['default_formatter'];
    $settings['formatter_settings'] = field_info_formatter_settings($settings['formatter']);
  }
  return $settings;
}

/**
 * Implements hook_field_widget_settings_form().
 */
function field_extrawidgets_field_widget_settings_form($field, $instance) {
  // The Hidden widget doesn't have any settings.
  if ($instance['widget']['type'] != 'field_extrawidgets_read_only') {
    return array();
  }

  $settings = field_extrawidgets_widget_settings($field, $instance);

  // Include the field_ui admin form.
  module_load_include('inc', 'field_ui', 'field_ui.admin');

  // Get the list of formatters for this field type, and remove our own.
  $formatters = field_ui_formatter_options($field['type']);

  $element['formatter'] = array(
    '#type' => 'select',
    '#title' => t('Formatter'),
    '#options' => $formatters,
    '#default_value' => $settings['formatter'],

    // AJAX refresh the settings area when the formatter is changed.
    '#ajax' => array(
      'callback' => 'field_extrawidgets_field_widget_settings_ajax',
      'wrapper' => 'field_extrawidgets-formatter-settings',
    ),
    '#limit_validation_errors' => array(),
  );

  // Get the settings form.
  $element['formatter_settings'] = array(
    '#type' => 'container',
    '#id' => 'field_extrawidgets-formatter-settings',
    '#process' => array('field_extrawidgets_field_widget_render_settings'),
    '#tree' => TRUE,
    '#field' => $field,
    '#instance' => $instance,
  );

  $element['display_empty'] = array(
    '#type' => 'checkbox',
    '#title' => t('Display %text if empty', array('%text' => t('Not defined'))),
    '#default_value' => $settings['display_empty'],
  );

  return $element;
}

/**
 * Form #process callback: generates the formatter settings form.
 */
function field_extrawidgets_field_widget_render_settings($element, $form_state, $form) {
  $parents = $element['#parents'];
  array_pop($parents);
  $parents[] = 'formatter';
  $formatter_type = drupal_array_get_nested_value($form_state['values'], $parents);

  $field = $element['#field'];
  $instance = $element['#instance'];

  $formatter = field_info_formatter_types($formatter_type);
  $formatter_settings = array();
  if (isset($form_state['values']['instance']['widget']['settings']['formatter_settings'])) {
    $formatter_settings += $form_state['values']['instance']['widget']['settings']['formatter_settings'];
  }
  elseif (isset($instance['widget']['settings']['formatter_settings'])) {
    $formatter_settings += $instance['widget']['settings']['formatter_settings'];
  }
  $formatter_settings += field_info_formatter_settings($formatter_type);

  $settings_form = array('#value' => array());
  $function = $formatter['module'] . '_field_formatter_settings_form';
  $instance['display']['_dummy'] = array(
    'type' => $formatter_type,
    'settings' => $formatter_settings,
  );
  if (function_exists($function)) {
    $element += $function($field, $instance, '_dummy', $form, $form_state);
  }

  return $element;
}

/**
 * Form AJAX callback: refresh the formatter settings form.
 */
function field_extrawidgets_field_widget_settings_ajax($form, $form_state) {
  $trigger = $form_state['triggering_element'];
  $parents = $trigger['#array_parents'];
  // Pop the container.
  array_pop($parents);
  $parents[] = 'formatter_settings';

  $element = drupal_array_get_nested_value($form, $parents);
  return $element;
}

/**
 * Implements hook_field_widget_form().
 */
function field_extrawidgets_field_widget_form(&$form, &$form_state, $field, $instance, $langcode, $items, $delta, $element) {
  $widget_type = $instance['widget']['type'];
  $widget_settings = field_extrawidgets_widget_settings($field, $instance);

  if ($widget_type == 'field_extrawidgets_hidden') {
    return array();
  }

  if ($widget_type == 'field_extrawidgets_read_only') {
    // Clone the entity to avoid messing with it.
    $entity_type = $element['#entity_type'];
    if (!isset($form_state[$entity_type])) {
      return array();
    }
    $cloned_entity = clone $form_state[$entity_type];

    if (!field_access('view', $field, $entity_type, $cloned_entity)) {
      // The current user doesn't have access to view this field.
      return array();
    }

    // Set the fallback formatter.
    $display['type'] = $widget_settings['formatter'];
    $display['settings'] = $widget_settings['formatter_settings'];
    $formatter_type = field_info_formatter_types($display['type']);
    $display['module'] = $formatter_type['module'];

    $element += field_view_field($entity_type, $cloned_entity, $field['field_name'], $display, $langcode);

    // If asked to display a placeholder text, detect if the result is empty.
    if (!isset($element[0]) && !empty($widget_settings['display_empty'])) {
      $display = _field_info_prepare_instance_display($field, $display);
      // Generate the field structure as done in field_default_view().
      $element += array(
        '#theme' => 'field',
        '#weight' => $display['weight'],
        '#title' => $instance['label'],
        '#access' => TRUE,
        '#label_display' => $display['label'],
        '#view_mode' => '_custom_display',
        '#language' => $langcode,
        '#field_name' => $field['field_name'],
        '#field_type' => $field['type'],
        '#field_translatable' => $field['translatable'],
        '#entity_type' => $entity_type,
        '#bundle' => '',
        '#object' => $cloned_entity,
        '#items' => array(0 => ''),
        '#formatter' => $display['type']
      );
      $element[0] = array(
        '#markup' => t('Not defined'),
      );
    }

    return $element;
  }
}