link.module

<?php

/**
 * @file
 * Defines simple link field types.
 */

define('LINK_EXTERNAL', 'external');
define('LINK_INTERNAL', 'internal');
define('LINK_FRONT', 'front');
define('LINK_EMAIL', 'email');
define('LINK_NEWS', 'news');
define('LINK_DOMAINS', 'aero|arpa|asia|biz|com|cat|coop|edu|gov|info|int|jobs|mil|museum|name|nato|net|org|pro|travel|mobi|local');

define('LINK_TARGET_DEFAULT', 'default');
define('LINK_TARGET_NEW_WINDOW', '_blank');
define('LINK_TARGET_TOP', '_top');
define('LINK_TARGET_USER', 'user');

/**
 * Maximum URLs length - needs to match value in link.install.
 */
define('LINK_URL_MAX_LENGTH', 2048);

/**
 * Implements hook_field_info().
 */
function link_field_info() {
  return array(
    'link_field' => array(
      'label' => t('Link'),
      'description' => t('Store a title, href, and attributes in the database to assemble a link.'),
      'settings' => array(
        'attributes' => _link_default_attributes(),
        'url' => 0,
        'title' => 'optional',
        'title_value' => '',
        'title_maxlength' => 128, //patch #1307788 from nmc
        'enable_tokens' => 1,
        'display' => array(
          'url_cutoff' => 80,
        ),
      ),
      'instance_settings' => array(
        'attributes' => _link_default_attributes(),
        'url' => 0,
        'title' => 'optional',
        'title_value' => '',
        'title_maxlength' => 128, // patch #1307788 from nmc
        'enable_tokens' => 1,
        'display' => array(
          'url_cutoff' => 80,
        ),
        'validate_url' => 1,
      ),
      'default_widget' => 'link_field',
      'default_formatter' => 'link_default',
      // Support hook_entity_property_info() from contrib "Entity API".
      'property_type' => 'field_item_link',
      'property_callbacks' => array('link_field_property_info_callback'),
    ),
  );
}

/**
 * Implements hook_field_instance_settings_form().
 */
function link_field_instance_settings_form($field, $instance) {
  $form = array(
    '#element_validate' => array('link_field_settings_form_validate'),
  );

  $form['validate_url'] = array(
    '#type' => 'checkbox',
    '#title' => t('Validate URL'),
    '#default_value' => isset($instance['settings']['validate_url']) && ($instance['settings']['validate_url'] !== '') ? $instance['settings']['validate_url'] : TRUE,
    '#description' => t('If checked, the URL field will be verified as a valid URL during validation.'),
  );

  $form['url'] = array(
    '#type' => 'checkbox',
    '#title' => t('Optional URL'),
    '#default_value' => isset($instance['settings']['url']) ? $instance['settings']['url'] : '',
    '#return_value' => 'optional',
    '#description' => t('If checked, the URL field is optional and submitting a title alone will be acceptable. If the URL is omitted, the title will be displayed as plain text.'),
  );

  $title_options = array(
    'optional' => t('Optional Title'),
    'required' => t('Required Title'),
    'value' => t('Static Title'),
    'none' => t('No Title'),
  );

  $form['title'] = array(
    '#type' => 'radios',
    '#title' => t('Link Title'),
    '#default_value' => isset($instance['settings']['title']) ? $instance['settings']['title'] : 'optional',
    '#options' => $title_options,
    '#description' => t('If the link title is optional or required, a field will be displayed to the end user. If the link title is static, the link will always use the same title. If <a href="http://drupal.org/project/token">token module</a> is installed, the static title value may use any other node field as its value. Static and token-based titles may include most inline XHTML tags such as <em>strong</em>, <em>em</em>, <em>img</em>, <em>span</em>, etc.'),
  );

  $form['title_value'] = array(
    '#type' => 'textfield',
    '#title' => t('Static title'),
    '#default_value' => isset($instance['settings']['title_value']) ? $instance['settings']['title_value'] : '',
    '#description' => t('This title will always be used if &ldquo;Static Title&rdquo; is selected above.'),
  );

  $form['title_maxlength'] = array( // patch #1307788 from nmc
    '#type' => 'textfield',
    '#title' => t('Max length of title field'),
    '#default_value' => isset($instance['settings']['title_maxlength']) ? $instance['settings']['title_maxlength'] : '128',
    '#description' => t('Set a maximum length on the title field (applies only if Link Title is optional or required).  The maximum limit is 255 characters.'),
    '#maxlength' => 3,
    '#size' => 3,
    );

  if (module_exists('token')) {
    // Add token module replacements fields
    $form['tokens'] = array(
      '#type' => 'fieldset',
      '#collapsible' => TRUE,
      '#collapsed' => TRUE,
      '#title' => t('Placeholder tokens'),
      '#description' => t("The following placeholder tokens can be used in both paths and titles. When used in a path or title, they will be replaced with the appropriate values."),
    );
    $token_type = array(
      'theme' => 'token_tree',
      'token_types' => array($instance['entity_type']),
      'global_types' => TRUE,
      'click_insert' => TRUE,
      'recursion_limit' => 2,
    );
    $form['tokens']['help'] = array(
      '#type' => 'markup',
      '#markup' => theme('token_tree', $token_type),
    );

    $form['enable_tokens'] = array(
      '#type' => 'checkbox',
      '#title' => t('Allow user-entered tokens'),
      '#default_value' => isset($instance['settings']['enable_tokens']) ? $instance['settings']['enable_tokens'] : 1,
      '#description' => t('Checking will allow users to enter tokens in URLs and Titles on the node edit form. This does not affect the field settings on this page.'),
    );
  }

  $form['display'] = array(
    '#tree' => TRUE,
  );
  $form['display']['url_cutoff'] = array(
    '#type' => 'textfield',
    '#title' => t('URL Display Cutoff'),
    '#default_value' => isset($instance['settings']['display']['url_cutoff']) ? $instance['settings']['display']['url_cutoff'] : '80',
    '#description' => t('If the user does not include a title for this link, the URL will be used as the title. When should the link title be trimmed and finished with an elipsis (&hellip;)? Leave blank for no limit.'),
    '#maxlength' => 3,
   '#size' => 3,
  );

  $target_options = array(
    LINK_TARGET_DEFAULT => t('Default (no target attribute)'),
    LINK_TARGET_TOP => t('Open link in window root'),
    LINK_TARGET_NEW_WINDOW => t('Open link in new window'),
    LINK_TARGET_USER => t('Allow the user to choose'),
  );
  $form['attributes'] = array(
    '#tree' => TRUE,
  );
  $form['attributes']['target'] = array(
    '#type' => 'radios',
    '#title' => t('Link Target'),
    '#default_value' => empty($instance['settings']['attributes']['target']) ? LINK_TARGET_DEFAULT : $instance['settings']['attributes']['target'],
    '#options' => $target_options,
  );
  $form['attributes']['rel'] = array(
    '#type' => 'textfield',
    '#title' => t('Rel Attribute'),
    '#description' => t('When output, this link will have this rel attribute. The most common usage is <a href="http://en.wikipedia.org/wiki/Nofollow">rel=&quot;nofollow&quot;</a> which prevents some search engines from spidering entered links.'),
    '#default_value' => empty($instance['settings']['attributes']['rel']) ? '' : $instance['settings']['attributes']['rel'],
    '#field_prefix' => 'rel = "',
    '#field_suffix' => '"',
    '#size' => 20,
  );
  $rel_remove_options = array(
    'default' => t('Keep rel as set up above (untouched/default)'),
    'rel_remove_external' => t('Remove rel if given link is external'),
    'rel_remove_internal' => t('Remove rel if given link is internal'),
  );
  $form['rel_remove'] = array(
    '#type' => 'radios',
    '#title' => t('Remove rel attribute automaticly'),
    '#default_value' => !isset($instance['settings']['rel_remove']) ? 'default' : $instance['settings']['rel_remove'],
    '#description' => t('Turn on/off if rel attribute should be removed automaticly, if user given link is internal/external'),
    '#options' => $rel_remove_options,
  );
  $form['attributes']['class'] = array(
    '#type' => 'textfield',
    '#title' => t('Additional CSS Class'),
    '#description' => t('When output, this link will have this class attribute. Multiple classes should be separated by spaces.'),
    '#default_value' => empty($instance['settings']['attributes']['class']) ? '' : $instance['settings']['attributes']['class'],
  );
  $form['attributes']['configurable_title'] = array(
    '#title' => t("Allow the user to enter a link 'title' attribute"),
    '#type' => 'checkbox',
    '#default_value' => empty($instance['settings']['attributes']['configurable_title']) ? '' : $instance['settings']['attributes']['configurable_title'],
  );
  $form['attributes']['title'] = array(
    '#title' => t("Default link 'title' Attribute"),
    '#type' => 'textfield',
    '#description' => t('When output, links will use this "title" attribute if the user does not provide one and when different from the link text. Read <a href="http://www.w3.org/TR/WCAG10-HTML-TECHS/#links">WCAG 1.0 Guidelines</a> for links comformances. Tokens values will be evaluated.'),
    '#default_value' => empty($instance['settings']['attributes']['title']) ? '' : $instance['settings']['attributes']['title'],
    '#field_prefix' => 'title = "',
    '#field_suffix' => '"',
    '#size' => 20,
  );
  return $form;
}

/**
 * Validate the field settings form.
 */
function link_field_settings_form_validate($element, &$form_state, $complete_form) {
  if ($form_state['values']['instance']['settings']['title'] === 'value'
      && empty($form_state['values']['instance']['settings']['title_value'])) {
    form_set_error('title_value', t('A default title must be provided if the title is a static value.'));
  }
  if (!empty($form_state['values']['instance']['settings']['display']['url_cutoff'])  // patch #1307788 from nmc
      && !is_numeric($form_state['values']['instance']['settings']['display']['url_cutoff'])) {
    form_set_error('display', t('URL Display Cutoff value must be numeric.'));
  }
  if (empty($form_state['values']['instance']['settings']['title_maxlength'])) {     // patch #1307788 from nmc
    form_set_value($element['title_maxlength'], '128', $form_state);
  } elseif (!is_numeric($form_state['values']['instance']['settings']['title_maxlength'])) {
    form_set_error('title_maxlength', t('The max length of the link title must be numeric.'));
  } elseif ($form_state['values']['instance']['settings']['title_maxlength'] > 255) {
    form_set_error('title_maxlength', t('The max length of the link title cannot be greater than 255 characters.'));
  }

}

/**
 * Implement hook_field_is_empty().
 */
function link_field_is_empty($item, $field) {
  return empty($item['title']) && empty($item['url']);
}

/**
 * Implements hook_field_load().
 */
function link_field_load($entity_type, $entities, $field, $instances, $langcode, &$items, $age) {
  foreach ($entities as $id => $entity) {
    foreach ($items[$id] as $delta => $item) {
      $items[$id][$delta]['attributes'] = _link_load($field, $item, $instances[$id]);
    }
  }
}

/**
 * Implements hook_field_validate().
 */
function link_field_validate($entity_type, $entity, $field, $instance, $langcode, $items, &$errors) {
  $optional_field_found = FALSE;
  if ($instance['settings']['validate_url'] !== 0 || is_null($instance['settings']['validate_url']) || !isset($instance['settings']['validate_url'])) {
    foreach ($items as $delta => $value) {
      _link_validate($items[$delta], $delta, $field, $entity, $instance, $langcode, $optional_field_found);
    }
  }

  if ($instance['settings']['url'] === 'optional' && $instance['settings']['title'] === 'optional' && $instance['required'] && !$optional_field_found) {
    form_set_error($field['field_name'] . '][' . $langcode . '][0][title', t('At least one title or URL must be entered.'));
  }
}

/**
 * Implements hook_field_presave().
 */
function link_field_presave($entity_type, $entity, $field, $instance, $langcode, &$items) {
  foreach ($items as $delta => $value) {
    _link_process($items[$delta], $delta, $field, $entity);
  }
}

/**
 * Implements hook_field_prepare_view().
 */
function link_field_prepare_view($entity_type, $entities, $field, $instances, $langcode, &$items) {
  foreach ($items as $entity_id => $entity_items) {
    foreach ($entity_items as $delta => $value) {
      _link_sanitize($items[$entity_id][$delta], $delta, $field, $instances[$entity_id], $entities[$entity_id]);
    }
  }
}

/**
 * Implements hook_field_widget_info().
 */
function link_field_widget_info() {
  return array(
    'link_field' => array(
      'label' => 'Link',
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
  );
}

/**
 * Implements hook_field_widget_form().
 */
function link_field_widget_form(&$form, &$form_state, $field, $instance, $langcode, $items, $delta, $element) {
  $element += array(
    '#type' => $instance['widget']['type'],
    '#default_value' => isset($items[$delta]) ? $items[$delta] : '',
  );
  return $element;
}

/**
 * Unpacks the item attributes for use.
 */
function _link_load($field, $item, $instance) {
  /*return $item['attributes'] = isset($item['attributes']) ?
                                unserialize($item['attributes']) :
                                $instance['settings']['attributes'];*/
  if (isset($item['attributes'])) {
    if (!is_array($item['attributes'])) {
      $item['attributes'] = unserialize($item['attributes']);
    }
    return $item['attributes'];
  }
  else if (isset($instance['settings']['attributes'])) {
    return $instance['settings']['attributes'];
  }
  else {
    return $field['settings']['attributes'];
  }
}

/**
 * Prepares the item attributes and url for storage.
 */
function _link_process(&$item, $delta = 0, $field, $entity) {
  // Trim whitespace from URL.
  $item['url'] = trim($item['url']);

  // if no attributes are set then make sure $item['attributes'] is an empty array - this lets $field['attributes'] override it.
  if (empty($item['attributes'])) {
    $item['attributes'] = array();
  }

  // Serialize the attributes array.
  if (!is_string($item['attributes'])) {
    $item['attributes'] = serialize($item['attributes']);
  }

  // Don't save an invalid default value (e.g. 'http://').
  if ((isset($field['widget']['default_value'][$delta]['url']) && $item['url'] == $field['widget']['default_value'][$delta]['url'])
      && is_object($node)) {
    if (!link_validate_url($item['url'])) {
      unset($item['url']);
    }
  }
  
  // token from the patch http://drupal.org/files/link_query_fragment.patch @ Issue #1321482
  if (!empty($item['query'])) {
    $item['url'] .= '?' . http_build_query($item['query']);
  }
  if (!empty($item['fragment'])) {
    $item['url'] .= '#' . $item['fragment'];
  }
}

/**
 * Validates that the link field has been entered properly.
 */
function _link_validate(&$item, $delta, $field, $node, $instance, $langcode, &$optional_field_found) {
  if ($item['url']
      && !(isset($instance['default_value'][$delta]['url'])
      && $item['url'] === $instance['default_value'][$delta]['url']
      && !$instance['required'])) {
    // Validate the link.
    if (link_validate_url(trim($item['url'])) == FALSE) {
      form_set_error($field['field_name'] . '][' . $langcode . ']['. $delta .'][url', t('Not a valid URL.'));
    }
    // Require a title for the link if necessary.
    if ($instance['settings']['title'] == 'required' && strlen(trim($item['title'])) == 0) {
      form_set_error($field['field_name'] . '][' . $langcode . ']['. $delta .'][title', t('Titles are required for all links.'));
    }
  }
  // Require a link if we have a title.
  if ($instance['settings']['url'] !== 'optional'
      && strlen(isset($item['title']) ? $item['title'] : NULL) > 0
      && strlen(trim($item['url'])) == 0) {
    form_set_error($field['field_name'] . '][' . $langcode . ']['. $delta .'][url', t('You cannot enter a title without a link url.'));
  }
  // In a totally bizzaro case, where URLs and titles are optional but the field is required, ensure there is at least one link.
  if ($instance['settings']['url'] === 'optional'
      && $instance['settings']['title'] === 'optional'
      && (strlen(trim($item['url'])) !== 0 || strlen(trim($item['title'])) !== 0)) {
    $optional_field_found = TRUE;
  }
  // Require entire field
  if ($instance['settings']['url'] === 'optional'
    && $instance['settings']['title'] === 'optional'
    && $instance['required'] == 1
    && !$optional_field_found
    && isset($instance['id'])) {
    form_set_error($instance['field_name'] . '][' . $langcode . '][0][title',
                   t('At least one title or URL must be entered.'));
  }
}

/**
 * Cleanup user-entered values for a link field according to field settings.
 *
 * @param $item
 *   A single link item, usually containing url, title, and attributes.
 * @param $delta
 *   The delta value if this field is one of multiple fields.
 * @param $field
 *   The CCK field definition.
 * @param $node
 *   The node containing this link.
 */
function _link_sanitize(&$item, $delta, &$field, $instance, &$node) {
  // Don't try to process empty links.
  if (empty($item['url']) && empty($item['title'])) {
    return;
  }

  // Replace URL tokens.
  if (isset($instance['settings']['enable_tokens']) && $instance['settings']['enable_tokens']) {
    global $user;
    // Load the node if necessary for nodes in views.
    $token_node = isset($node->nid) ? node_load($node->nid) : $node;
    $item['url'] = token_replace($item['url'], array('node' => $token_node));
  }

  $type = link_validate_url($item['url']);
  // If we can't determine the type of url, and we've been told not to validate it,
  // then we assume it's a LINK_EXTERNAL type for later processing. #357604
  if ($type == FALSE && $instance['settings']['validate_url'] === 0) {
    $type = LINK_EXTERNAL;
  }
  $url = link_cleanup_url($item['url']);

  // Separate out the anchor if any.
  if (strpos($url, '#') !== FALSE) {
    $item['fragment'] = substr($url, strpos($url, '#') + 1);
    $url = substr($url, 0, strpos($url, '#'));
  }
  // Separate out the query string if any.
  if (strpos($url, '?') !== FALSE) {
    $query = substr($url, strpos($url, '?') + 1);
    parse_str($query, $query_array);
    $item['query'] = $query_array;
    $url = substr($url, 0, strpos($url, '?'));
  }

  $item['url'] = check_plain($url);

  // Create a shortened URL for display.
  $display_url = $type == LINK_EMAIL ?
                  str_replace('mailto:', '', $url) :
                  url($url, array('query' => isset($item['query']) ?
                                              $item['query'] :
                                              NULL,
                                  'fragment' => isset($item['fragment']) ?
                                                $item['fragment'] :
                                                NULL,
                                  'absolute' => TRUE));
  if ($instance['settings']['display']['url_cutoff'] && strlen($display_url) > $instance['settings']['display']['url_cutoff']) {
    $display_url = substr($display_url, 0, $instance['settings']['display']['url_cutoff']) ."...";
  }
  $item['display_url'] = $display_url;

  // Use the title defined at the instance level.
  if ($instance['settings']['title'] == 'value' && strlen(trim($instance['settings']['title_value']))) {
    $title = $instance['settings']['title_value'];
  }
  // Use the title defined by the user at the widget level.
  else if (isset($item['title'])) {
    $title = $item['title'];
  }
  else {
    $title = '';
  }

  // Replace tokens.
  if ($title && ($instance['settings']['title'] == 'value' || $instance['settings']['enable_tokens'])) {
    // Load the node if necessary for nodes in views.
    $token_node = isset($node->nid) ? node_load($node->nid) : $node;
    $title = filter_xss(token_replace($title, array('node' => $token_node)),
                        array('b', 'br', 'code', 'em', 'i', 'img', 'span', 'strong', 'sub', 'sup', 'tt', 'u'));
    $item['html'] = TRUE;
  }
  $item['title'] = empty($title) ? $item['display_url'] : $title;

  if (!isset($item['attributes'])) {
    $item['attributes'] = array();
  }

  // Unserialize attributtes array if it has not been unserialized yet.
  if (!is_array($item['attributes'])) {
    $item['attributes'] = (array)unserialize($item['attributes']);
  }

  // Add default attributes.
  if (!is_array($instance['settings']['attributes'])){
    $instance['settings']['attributes'] = _link_default_attributes();
  }
  else {
    $instance['settings']['attributes'] += _link_default_attributes();
  }

  // Merge item attributes with attributes defined at the field level.
  $item['attributes'] += $instance['settings']['attributes'];

  // If user is not allowed to choose target attribute, use default defined at
  // field level.
  if ($instance['settings']['attributes']['target'] != LINK_TARGET_USER) {
    $item['attributes']['target'] = $instance['settings']['attributes']['target'];
  }

  // Remove the target attribute if the default (no target) is selected.
  if (empty($item['attributes']) || $item['attributes']['target'] == LINK_TARGET_DEFAULT) {
    unset($item['attributes']['target']);
  }

  // Remove rel attribute for internal or external links if selected.
  if (isset($item['attributes']['rel']) && isset($instance['settings']['rel_remove']) && $instance['settings']['rel_remove'] != 'default') {
    if (($instance['settings']['rel_remove'] != 'rel_remove_internal' && $type != LINK_INTERNAL) ||
            ($instance['settings']['rel_remove'] != 'rel_remove_external' && $type != LINK_EXTERNAL)) {
    unset($item['attributes']['rel']);
    }
  }

  // Handle "title" link attribute.
  if (!empty($item['attributes']['title']) && module_exists('token')) {
    // Load the node (necessary for nodes in views).
    $token_node = isset($node->nid) ? node_load($node->nid) : $node;
    $item['attributes']['title'] = filter_xss(token_replace($item['attributes']['title'], array('node' => $token_node)),
                        array('b', 'br', 'code', 'em', 'i', 'img', 'span', 'strong', 'sub', 'sup', 'tt', 'u'));
  }
  // Remove title attribute if it's equal to link text.
  if (isset($item['attributes']['title']) && $item['attributes']['title'] == $item['title']) {
    unset($item['attributes']['title']);
  }
  unset($item['attributes']['configurable_title']);

  // Remove empty attributes.
  $item['attributes'] = array_filter($item['attributes']);

  // Sets title to trimmed url if one exists
  // @TODO: Do we need this?  It seems not.
  /*if(!empty($item['display_url']) && empty($item['title'])) {
    $item['title'] = $item['display_url'];
  }
  elseif(!isset($item['title'])) {
    $item['title'] = $item['url'];
  }*/

}

/**
 * Implements hook_theme().
 */
function link_theme() {
  return array(
    /*'link_field_settings' => array(
      'variables' => array('element' => NULL),
    ),*/
    'link_formatter_link_default' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_plain' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_absolute' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_title_plain' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_url' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_short' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_label' => array(
      'variables' => array('element' => NULL),
    ),
    'link_formatter_link_separate' => array(
      'variables' => array('element' => NULL),
    ),
    'link_field' => array(
      'render element' => 'element',
    ),
  );
}

/**
 * FAPI theme for an individual text elements.
 */
function theme_link_field($vars) {
  drupal_add_css(drupal_get_path('module', 'link') .'/link.css');

  $element = $vars['element'];
  // Prefix single value link fields with the name of the field.
  if (empty($element['#field']['multiple'])) {
    if (isset($element['url']) && !isset($element['title'])) {
      unset($element['url']['#title']);
    }
  }

  $output = '';
  $output .= '<div class="link-field-subrow clearfix">';
  if (isset($element['title'])) {
    $output .= '<div class="link-field-title link-field-column">'. drupal_render($element['title']) .'</div>';
  }
  $output .= '<div class="link-field-url'. (isset($element['title']) ? ' link-field-column' : '') .'">'. drupal_render($element['url']) .'</div>';
  $output .= '</div>';
  if (!empty($element['attributes']['target'])) {
    $output .= '<div class="link-attributes">'. drupal_render($element['attributes']['target']) .'</div>';
  }
  if (!empty($element['attributes']['title'])) {
    $output .= '<div class="link-attributes">'. drupal_render($element['attributes']['title']) .'</div>';
  }
  return $output;
}

/**
 * Implements hook_element_info().
 */
function link_element_info() {
  $elements = array();
  $elements['link_field'] =  array(
    '#input' => TRUE,
    '#process' => array('link_field_process'),
    '#theme' => 'link_field',
    '#theme_wrappers' => array('form_element'),
  );
  return $elements;
}

function _link_default_attributes() {
  return array(
    'target' => LINK_TARGET_DEFAULT,
    'class' => '',
    'rel' => '',
  );
}

/**
 * Process the link type element before displaying the field.
 *
 * Build the form element. When creating a form using FAPI #process,
 * note that $element['#value'] is already set.
 *
 * The $fields array is in $complete_form['#field_info'][$element['#field_name']].
 */
function link_field_process($element, $form_state, $complete_form) {
  $instance = field_widget_instance($element, $form_state);
  $settings = $instance['settings'];
  $element['url'] = array(
    '#type' => 'textfield',
    '#maxlength' => LINK_URL_MAX_LENGTH,
    '#title' => t('URL'),
    '#required' => ($element['#delta'] == 0 && $settings['url'] !== 'optional') ? $element['#required'] : FALSE,
    '#default_value' => isset($element['#value']['url']) ? $element['#value']['url'] : NULL,
  );
  if ($settings['title'] !== 'none' && $settings['title'] !== 'value') {
    $element['title'] = array(
      '#type' => 'textfield',
      '#maxlength' => $settings['title_maxlength'],  // patch #1307788 from nmc
      '#title' => t('Title'),
      '#description' => t('The link title is limited to @maxlength characters maximum.', array('@maxlength' => $settings['title_maxlength'])),
      '#required' => ($settings['title'] == 'required' && (($element['#delta'] == 0 && $element['#required']) || !empty($element['#value']['url']))) ? TRUE : FALSE, // davereids patch from jan 2011
      '#default_value' => isset($element['#value']['title']) ? $element['#value']['title'] : NULL,
    );
  }

  // Initialize field attributes as an array if it is not an array yet.
  if (!is_array($settings['attributes'])) {
    $settings['attributes'] = array();
  }
  // Add default attributes.
  $settings['attributes'] += _link_default_attributes();
  $attributes = isset($element['#value']['attributes']) ? $element['#value']['attributes'] : $settings['attributes'];
  if (!empty($settings['attributes']['target']) && $settings['attributes']['target'] == LINK_TARGET_USER) {
    $element['attributes']['target'] = array(
      '#type' => 'checkbox',
      '#title' => t('Open URL in a New Window'),
      '#return_value' => LINK_TARGET_NEW_WINDOW,
      '#default_value' => isset($attributes['target']) ? $attributes['target'] : FALSE,
    );
  }
  if (!empty($settings['attributes']['configurable_title']) && $settings['attributes']['configurable_title'] == 1) {
    $element['attributes']['title'] = array(
      '#type' => 'textfield',
      '#title' => t('Link "title" attribute'),
      '#default_value' => isset($attributes['title']) ? $attributes['title'] : '',
      '#field_prefix' => 'title = "',
      '#field_suffix' => '"',
    );
  }

  // To prevent an extra required indicator, disable the required flag on the
  // base element since all the sub-fields are already required if desired.
  $element['#required'] = FALSE; // davereids patch from jan 2011

  return $element;
}

/**
 * Implementation of hook_field_formatter_info().
 */
function link_field_formatter_info() {
  return array(
    'link_default' => array(
      'label' => t('Title, as link (default)'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_title_plain' => array(
      'label' => t('Title, as plain text'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_url' => array(
      'label' => t('URL, as link'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_plain' => array(
      'label' => t('URL, as plain text'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_absolute' => array(
      'label' => t('URL, absolute'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_short' => array(
      'label' => t('Short, as link with title "Link"'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_label' => array(
      'label' => t('Label, as link with label as title'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
    'link_separate' => array(
      'label' => t('Separate title and URL'),
      'field types' => array('link_field'),
      'multiple values' => FIELD_BEHAVIOR_DEFAULT,
    ),
  );
}

/**
 * Implements hook_field_formatter_view().
 */
function link_field_formatter_view($entity_type, $entity, $field, $instance, $langcode, $items, $display) {
  $elements = array();
  foreach ($items as $delta => $item) {
    $elements[$delta] = array(
      '#markup' => theme('link_formatter_'. $display['type'], array('element' => $item, 'field' => $instance)),
    );
  }
  return $elements;
}

/**
 * Theme function for 'default' text field formatter.
 */
function theme_link_formatter_link_default($vars) {
  $link_options = $vars['element'];
  unset($link_options['element']['title']);
  unset($link_options['element']['url']);

  // Issue #1199806 by ss81: Fixes fatal error when the link URl is equal to page URL
  if (isset($link_options['attributes']['class'])) {
    $link_options['attributes']['class'] = array($link_options['attributes']['class']);
  }

  // Display a normal link if both title and URL are available.
  if (!empty($vars['element']['title']) && !empty($vars['element']['url'])) {
    return l($vars['element']['title'], $vars['element']['url'], $link_options);
  }
  // If only a title, display the title.
  elseif (!empty($vars['element']['title'])) {
    return check_plain($vars['element']['title']);
  }
  elseif (!empty($vars['element']['url'])) {
    return l($vars['element']['title'], $vars['element']['url'], $link_options);
  }
}

/**
 * Theme function for 'plain' text field formatter.
 */
function theme_link_formatter_link_plain($vars) {
  $link_options = $vars['element'];
  unset($link_options['element']['title']);
  unset($link_options['element']['url']);
  return empty($vars['element']['url']) ?
    check_plain($vars['element']['title']) :
    url($vars['element']['url'], $link_options);
}

/**
 * Theme function for 'absolute' text field formatter.
 */
function theme_link_formatter_link_absolute($vars) {
  $absolute = array('absolute' => TRUE);
  return empty($vars['element']['url']) ? '' : url($vars['element']['url'], $absolute + $vars['element']);
}

/**
 * Theme function for 'title_plain' text field formatter.
 */
function theme_link_formatter_link_title_plain($vars) {
  return empty($vars['element']['title']) ? '' : check_plain($vars['element']['title']);
}

/**
 * Theme function for 'url' text field formatter.
 */
function theme_link_formatter_link_url($vars) {
  $link_options = $vars['element'];
  unset($link_options['element']['title']);
  unset($link_options['element']['url']);
  return $vars['element']['url'] ? l($vars['element']['display_url'], $vars['element']['url'], $link_options) : '';
}

/**
 * Theme function for 'short' text field formatter.
 */
function theme_link_formatter_link_short($vars) {
  $link_options = $vars['element'];
  unset($link_options['element']['title']);
  unset($link_options['element']['url']);
  return $vars['element']['url'] ? l(t('Link'), $vars['element']['url'], $link_options) : '';
}

/**
 * Theme function for 'label' text field formatter.
 */
function theme_link_formatter_link_label($vars) {
  $link_options = $vars['element'];
  unset($link_options['element']['title']);
  unset($link_options['element']['url']);
  return $vars['element']['url'] ? l($vars['field']['label'], $vars['element']['url'], $link_options) : '';
}

/**
 * Theme function for 'separate' text field formatter.
 */

function theme_link_formatter_link_separate($vars) {
  $class = empty($vars['element']['attributes']['class']) ? '' : ' '. $vars['element']['attributes']['class'];
  unset($vars['element']['attributes']['class']);
  $link_options = $vars['element'];
  unset($link_options['element']['title']);
  unset($link_options['element']['url']);
  $title = empty($vars['element']['title']) ? '' : check_plain($vars['element']['title']);

  /**
   * @TODO static html markup looks not very elegant
   * needs smarter output solution and an optional title/url seperator
   */
  $output = '';
  $output .= '<div class="link-item '. $class .'">';
  if (!empty($title)) {
    $output .= '<div class="link-title">'. $title .'</div>';
  }
  $output .= '<div class="link-url">'. l($vars['element']['url'], $vars['element']['url'], $link_options) .'</div>';
  $output .= '</div>';
  return $output;
}


function link_token_list($type = 'all') {
  if ($type === 'field' || $type === 'all') {
    $tokens = array();

    $tokens['link']['url'] = t("Link URL");
    $tokens['link']['title'] = t("Link title");
    $tokens['link']['view'] = t("Formatted html link");

    return $tokens;
  }
}

function link_token_values($type, $object = NULL) {
  if ($type === 'field') {
    $item = $object[0];

    $tokens['url'] = $item['url'];
    $tokens['title'] = $item['title'];
    $tokens['view'] = isset($item['view']) ? $item['view'] : '';

    return $tokens;
  }
}

/**
 * Implements hook_views_api().
 */
function link_views_api() {
  return array(
    'api' => 2,
    'path' => drupal_get_path('module', 'link') .'/views',
  );
}

/**
 * Implements hook_migrate_api().
 */
function link_migrate_api() {
  return array('api' => 2);
}

/**
 * Forms a valid URL if possible from an entered address.
 * Trims whitespace and automatically adds an http:// to addresses without a protocol specified
 *
 * @param string $url
 * @param string $protocol The protocol to be prepended to the url if one is not specified
 */
function link_cleanup_url($url, $protocol = "http") {
  $url = trim($url);