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<?php
// $Id$

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

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

/**
 * Implementation of hook_field_info().
 */
function link_field_info() {
  return array(
    'link' => array(
      'label' => t('Link'),
      'description' => t('Store a title, href, and attributes in the database to assemble a link.'),
    ),
  );
}

/**
 * Implementation of hook_field_settings().
 */
function link_field_settings($op, $field) {
  switch ($op) {
    case 'form':
      $form = array(
        '#theme' => 'link_field_settings',
      );

      $form['url'] = array(
        '#type' => 'checkbox',
        '#title' => t('Optional URL'),
        '#default_value' => $field['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 ommitted, 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'),
      );

      $form['title'] = array(
        '#type' => 'radios',
        '#title' => t('Link Title'),
        '#default_value' => isset($field['title']) ? $field['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',
        '#default_value' => $field['title_value'],
        '#size' => '46',
      );

      // Add token module replacements if available
      if (module_exists('token')) {
        $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."),
        );
        $form['tokens']['help'] = array(
          '#value' => theme('token_help', 'node'),
        );

        $form['enable_tokens'] = array(
          '#type' => 'checkbox',
          '#title' => t('Allow user-entered tokens'),
          '#default_value' => isset($field['enable_tokens']) ? $field['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,
      );
      $form['display']['url_cutoff'] = array(
        '#type' => 'textfield',
        '#title' => t('URL Display Cutoff'),
        '#default_value' => isset($field['display']['url_cutoff']) ? $field['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(
        'default' => t('Default (no target attribute)'),
        '_top' => t('Open link in window root'),
        '_blank' => t('Open link in new window'),
        'user' => t('Allow the user to choose'),
      );
      $form['attributes'] = array(
        '#tree' => true,
      );
      $form['attributes']['target'] = array(
        '#type' => 'radios',
        '#title' => t('Link Target'),
        '#default_value' => $field['attributes']['target'] ? $field['attributes']['target'] : 'default',
        '#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' => $field['attributes']['rel'] ? $field['attributes']['rel'] : '',
        '#field_prefix' => 'rel = "',
        '#field_suffix' => '"',
        '#size' => 20,
      );
      $form['attributes']['class'] = array(
        '#type' => 'textfield',
        '#title' => t('Additional CSS Class'),
        '#description' => t('When output, this link will have have this class attribute. Multiple classes should be seperated by spaces.'),
        '#default_value' => isset($field['attributes']['class']) ? $field['attributes']['class'] : '',
      );
      return $form;

    case 'validate':
      if ($field['title'] == 'value' && empty($field['title_value'])) {
        form_set_error('title_value', t('A default title must be provided if the title is a static value'));
      }
      break;

    case 'save':
      return array('attributes', 'display', 'url', 'title', 'title_value', 'enable_tokens');

    case 'database columns':
      return array(
        'url' => array('type' => 'varchar', 'length' => 255, 'not null' => FALSE, 'sortable' => TRUE),
        'title' => array('type' => 'varchar', 'length' => 255, 'not null' => FALSE, 'sortable' => TRUE),
        'attributes' => array('type' => 'text', 'size' => 'medium', 'not null' => FALSE),
      );

    case 'views data':
      if (!empty($field)) {
        $data = link_views_data($field);
      }
      return isset($data) ? $data : NULL;
  }
}

/**
 * Theme the settings form for the link field.
 */
function theme_link_field_settings($form) {
  $title_value = drupal_render($form['title_value']);
  $title_checkbox = drupal_render($form['title']['value']);

  // Set Static Title radio option to include the title_value textfield.
  $form['title']['value'] = array('#value' => '<div class="container-inline">'. $title_checkbox . $title_value .'</div>');

  // Reprint the title radio options with the included textfield.
  return drupal_render($form);
}

/**
 * Implementation of hook_content_is_empty().
 */
function link_content_is_empty($item, $field) {
  if (empty($item['title']) && empty($item['url'])) {
    return TRUE;
  }
  return FALSE;
}

/**
 * Implementation of hook_field().
 */
function link_field($op, &$node, $field, &$items, $teaser, $page) {
  switch ($op) {
    case 'load':
      foreach ($items as $delta => $item) {
        _link_load($items[$delta], $delta);
      }
      return $items;
      break;

    case 'validate':
      $optional_field_found = FALSE;
      foreach($items as $delta => $value) {
        _link_validate($items[$delta],$delta, $field, $node, $optional_field_found);
      }

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

    case 'process form values':
      foreach($items as $delta => $value) {
        _link_process($items[$delta],$delta, $field, $node);
      }
      break;

    case 'sanitize':
      foreach ($items as $delta => $value) {
        _link_sanitize($items[$delta], $delta, $field, $node);
      }
      break;
  }
}

/**
 * Implementation of hook_widget_info().
 */
function link_widget_info() {
  return array(
    'link' => array(
      'label' => 'Text Fields for Title and URL',
      'field types' => array('link'),
      'multiple values' => CONTENT_HANDLE_CORE,
    ),
  );
}

/**
 * Implementation of hook_widget().
 */
function link_widget(&$form, &$form_state, $field, $items, $delta = 0) {
  $element = array(
    '#type' => $field['widget']['type'],
    '#default_value' => isset($items[$delta]) ? $items[$delta] : '',
    '#title' => $field['widget']['label'],
    '#weight' => $field['widget']['weight'],
    '#description' => $field['widget']['description'],
    '#required' => $field['required'],
    '#field' => $field,
  );
  return $element;
}

function _link_load(&$item, $delta = 0) {
  // Unserialize the attributes array.
  $item['attributes'] = unserialize($item['attributes']);
}

function _link_process(&$item, $delta = 0, $field, $node) {
  // Remove the target attribute if not selected.
  if (!$item['attributes']['target'] || $item['attributes']['target'] == "default") {
    unset($item['attributes']['target']);
  }
  // Trim whitespace from URL.
  $item['url'] = trim($item['url']);
  // Serialize the attributes array.
  $item['attributes'] = serialize($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']);
    }
  }
}

function _link_validate(&$item, $delta, $field, $node, &$optional_field_found) {
  if ($item['url'] && !(isset($field['widget']['default_value'][$delta]['url']) && $item['url'] == $field['widget']['default_value'][$delta]['url'] && !$field['required'])) {
    // Validate the link.
    if (link_validate_url(trim($item['url'])) == FALSE) {
      form_set_error($field['field_name'] .']['. $delta. '][url', t('Not a valid URL.'));
    }
    // Require a title for the link if necessary.
    if ($field['title'] == 'required' && strlen(trim($item['title'])) == 0) {
      form_set_error($field['field_name'] .']['. $delta. '][title', t('Titles are required for all links.'));
    }
  }
  // Require a link if we have a title.
  if ($field['url'] !== 'optional' && strlen($item['title']) > 0 && strlen(trim($item['url'])) == 0) {
    form_set_error($field['field_name'] .']['. $delta. '][url', t('You cannot enter a title without a link url.'));
  }
  // In a totally bizzaro case, where URLs and titles are optional but the field is required, ensure there is at least one link.
  if ($field['url'] == 'optional' && $field['title'] == 'optional' && (strlen(trim($item['url'])) != 0 || strlen(trim($item['title'])) != 0)) {
    $optional_field_found = TRUE;
  }
}

/**
 * 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, &$node) {
  // Don't try to process empty links.
  if (empty($item['url']) && empty($item['title'])) {
    return;
  }

  // Replace URL tokens.
  if (module_exists('token') && $field['enable_tokens']) {
    $token_node = node_load($node->nid); // Necessary for nodes in views.
    $item['url'] = token_replace($item['url'], 'node', $token_node);
  }

  $type = link_validate_url($item['url']);
  $url = link_cleanup_url($item['url']);

  // Seperate out the anchor if any.
  if (strpos($url, '#') !== FALSE) {
    $item['fragment'] = substr($url, strpos($url, '#') + 1);
    $url = substr($url, 0, strpos($url, '#'));
  }
  // Seperate out the query string if any.
  if (strpos($url, '?') !== FALSE) {
    $item['query'] = substr($url, strpos($url, '?') + 1);
    $url = substr($url, 0, strpos($url, '?'));
  }
  // Save the new URL without the anchor or query.
  $item['url'] = $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']) ? $item['fragment'] : NULL, 'absolute' => TRUE));
  if ($field['display']['url_cutoff'] && strlen($display_url) > $field['display']['url_cutoff']) {
    $display_url = substr($display_url, 0, $field['display']['url_cutoff']) . "...";
  }
  $item['display_url'] = $display_url;

  // Use the title defined at the field level.
  if ($field['title'] == 'value' && strlen(trim($field['title_value']))) {
    $title = $field['title_value'];
  }
  // Use the title defined by the user at the widget level.
  else {
    $title = $item['title'];
  }
  // Replace tokens.
  if (module_exists('token') && ($field['title'] == 'value' || $field['enable_tokens'])) {
    $token_node = node_load($node->nid); // Necessary for nodes in views.
    $title = filter_xss(token_replace($title, 'node', $token_node), array('b', 'br', 'code', 'em', 'i', 'img', 'span', 'strong', 'sub', 'sup', 'tt', 'u'));
    $item['html'] = TRUE;
  }
  $item['display_title'] = empty($title) ? $item['display_url'] : $title;

  // Add attributes defined at the widget level
  $attributes = array();
  if (is_array($item['attributes'])) {
    foreach($item['attributes'] as $attribute => $attbvalue) {
      if (isset($item['attributes'][$attribute]) && $field['attributes'][$attribute] == 'user') {
        $attributes[$attribute] = $attbvalue;
       }
     }
   }
  // Add attributes defined at the field level
  if (is_array($field['attributes'])) {
    foreach($field['attributes'] as $attribute => $attbvalue) {
      if (!empty($attbvalue) && $attbvalue != 'default' && $attbvalue != 'user') {
        $attributes[$attribute] = $attbvalue;
      }
    }
  }
  // Remove the rel=nofollow for internal links.
  if ($type != LINK_EXTERNAL && isset($attributes['rel']) && strpos($attributes['rel'], 'nofollow') !== FALSE) {
    $attributes['rel'] = str_replace('nofollow', '', $attributes['rel']);
    if (empty($attributes['rel'])) {
      unset($attributes['rel']);
    }
  }
  $item['attributes'] = $attributes;

  // Add the widget label.
  $item['label'] = $field['widget']['label'];
}

/**
 * Implementation of hook_theme().
 */
function link_theme() {
  return array(
    'link_field_settings' => array(
      'arguments' => array('element' => NULL),
    ),
    'link_formatter_default' => array(
      'arguments' => array('element' => NULL),
    ),
    'link_formatter_plain' => array(
      'arguments' => array('element' => NULL),
    ),
    'link_formatter_url' => array(
      'arguments' => array('element' => NULL),
    ),
    'link_formatter_short' => array(
      'arguments' => array('element' => NULL),
    ),
    'link_formatter_label' => array(
      'arguments' => array('element' => NULL),
    ),
    'link_formatter_separate' => array(
      'arguments' => array('element' => NULL),
    ),
    'link' => array(
      'arguments' => array('element' => NULL),
    ),
  );
}

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

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

  $output = '';
  $output .= '<div class="link-field-subrow clear-block">';
  if (isset($element['title'])) {
    $output .= '<div class="link-field-title link-field-column">' . theme('textfield', $element['title']) . '</div>';
  }
  $output .= '<div class="link-field-url' . (isset($element['title']) ? ' link-field-column' : '') . '">' . theme('textfield', $element['url']) . '</div>';
  $output .= '</div>';
  if (!empty($element['attributes'])) {
    $output .= '<div class="link-attributes">' . theme('form_element', $element['attributes'], $element['attributes']['#value']) . '</div>';
  }
  return $output;
}

/**
 * Implementation of hook_elements().
 */
function link_elements() {
  $elements = array();
  $elements['link'] =  array(
    '#input' => TRUE,
    '#columns' => array('url', 'title'),
    '#process' => array('link_process'),
  );
  return $elements;
}

/**
 * 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 $form['#field_info'][$element['#field_name']].
 */
function link_process($element, $edit, $form_state, $form) {
   $field = $form['#field_info'][$element['#field_name']];
   $delta = $element['#delta'];
   $element['url'] = array(
     '#type' => 'textfield',
     '#maxlength' => '255',
     '#title' => t('URL'),
     '#description' => $element['#description'],
     '#required' => ($delta == 0 && $field['url'] !== 'optional') ? $element['#required'] : FALSE,
     '#default_value' => isset($element['#value']['url']) ? $element['#value']['url'] : NULL,
   );
   if ($field['title'] != 'none' && $field['title'] != 'value') {
     $element['title'] = array(
       '#type' => 'textfield',
       '#maxlength' => '255',
       '#title' => t('Title'),
       '#required' => ($delta == 0 && $field['title'] == 'required') ? $field['required'] : FALSE,
       '#default_value' => isset($element['#value']['title']) ? $element['#value']['title'] : NULL,
     );
   }
   if ($field['attributes']['target'] == 'user') {
     $element['attributes']['target'] = array(
       '#type' => 'checkbox',
       '#title' => t('Open URL in a New Window'),
       '#return_value' => "_blank",
     );
   }
   return $element;
}

/**
 * Implementation of hook_field_formatter_info().
 */
function link_field_formatter_info() {
  return array(
    'default' => array(
      'label' => t('Title, as link (default)'),
      'field types' => array('link'),
      'multiple values' => CONTENT_HANDLE_CORE,
    ),
    'url' => array(
      'label' => t('URL, as link'),
      'field types' => array('link'),
      'multiple values' => CONTENT_HANDLE_CORE,
    ),
    'plain' => array(
      'label' => t('URL, as plain text'),
      'field types' => array('link'),
      'multiple values' => CONTENT_HANDLE_CORE,
    ),
    'short' => array(
      'label' => t('Short, as link with title "Link"'),
      'field types' => array('link'),
      'multiple values' => CONTENT_HANDLE_CORE,
    ),
    'label' => array(
      'label' => t('Label, as link with label as title'),
      'field types' => array('link'),
      'multiple values' => CONTENT_HANDLE_CORE,
    ),
    'separate' => array(
      'label' => t('Separate title and URL'),
      'field types' => array('link'),
      'multiple values' => CONTENT_HANDLE_CORE,
    ),
  );
}

/**
 * Theme function for 'default' text field formatter.
 */
function theme_link_formatter_default($element) {
  // Display a normal link if both title and URL are available.
  if (!empty($element['#item']['display_title']) && !empty($element['#item']['url'])) {
    return l($element['#item']['display_title'], $element['#item']['url'], $element['#item']);
  }
  // If only a title, display the title.
  elseif (!empty($element['#item']['display_title'])) {
    return check_plain($element['#item']['display_title']);
  }
}

/**
 * Theme function for 'plain' text field formatter.
 */
function theme_link_formatter_plain($element) {
  return empty($element['#item']['url']) ? check_plain($element['#item']['title']) : check_plain($element['#item']['url']);
}

/**
 * Theme function for 'url' text field formatter.
 */
function theme_link_formatter_url($element) {
  return $element['#item']['url'] ? l($element['#item']['display_url'], $element['#item']['url'], $element['#item']) : '';
}

/**
 * Theme function for 'short' text field formatter.
 */
function theme_link_formatter_short($element) {
  return $element['#item']['url'] ? l(t('Link'), $element['#item']['url'], $element['#item']) : '';
}

/**
 * Theme function for 'label' text field formatter.
 */
function theme_link_formatter_label($element) {
  return $element['#item']['url'] ? l($element['#item']['label'], $element['#item']['url'], $element['#item']) : '';
}

/**
 * Theme function for 'separate' text field formatter.
 */
function theme_link_formatter_separate($element) {
  $output = '';
  $output .= '<div class="link-item">';
  $output .= '<div class="link-title">'. $element['#item']['display_title'] .'</div>';
  $output .= '<div class="link-url">'. l($element['#item']['display_url'], $element['#item']['url'], $element['#item']) .'</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'] = $item['view'];

    return $tokens;
  }
}

/**
 * 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);
  $type = link_validate_url($url);

  if ($type == LINK_EXTERNAL) {
    // Check if there is no protocol specified.
    $protocol_match = preg_match("/^([a-z0-9][a-z0-9\.\-_]*:\/\/)/i",$url);
    if (empty($protocol_match)) {
      // But should there be? Add an automatic http:// if it starts with a domain name.
      $domain_match = preg_match('/^(([a-z0-9]([a-z0-9\-_]*\.)+)('. LINK_DOMAINS .'|[a-z]{2}))/i',$url);
      if (!empty($domain_match)) {
        $url = $protocol."://".$url;
      }
    }
  }

  return $url;
}

/**
 * A lenient verification for URLs. Accepts all URLs following RFC 1738 standard
 * for URL formation and all email addresses following the RFC 2368 standard for
 * mailto address formation.
 *
 * @param string $text
 * @return mixed Returns boolean FALSE if the URL is not valid. On success, returns an object with
 * the following attributes: protocol, hostname, ip, and port.
 */
function link_validate_url($text) {

  $allowed_protocols = variable_get('filter_allowed_protocols', array('http', 'https', 'ftp', 'news', 'nntp', 'telnet', 'mailto', 'irc', 'ssh', 'sftp', 'webcal'));

  $protocol = '((' . implode("|", $allowed_protocols) . '):\/\/)';
  $authentication = '([a-z0-9]+(:[a-z0-9]+)?@)';
  $domain = '((([a-z0-9]([a-z0-9\-_\[\]]*\.))+)('. LINK_DOMAINS .'|[a-z]{2}))';
  $ipv4 = '([0-9]{1,3}(\.[0-9]{1,3}){3})'; 
  $ipv6 = '([0-9a-fA-F]{1,4}(\:[0-9a-fA-F]{1,4}){7})'; 
  $port = '(:([0-9]{1,5}))';

  // Pattern specific to eternal links.
  $external_pattern = '/^' . $protocol . '?'. $authentication . '?' . '(' . $domain . '|' . $ipv4 . '|' . $ipv6 . ' |localhost)' . $port . '?';

  // Pattern specific to internal links.
  $internal_pattern = "/^([a-z0-9_\-+\[\]]+)";

  $directories = "(\/[a-z0-9_\-\.~+%=&,$'():;*@\[\]]*)*";
  $query = "(\/?\?([?a-z0-9+_\-\.\/%=&,$'():;*@\[\]]*))";
  $anchor = "(#[a-z0-9_\-\.~+%=&,$'():;*@\[\]]*)";

  // The rest of the path for a standard URL.
  $end = $directories . '?' . $query . '?' .  $anchor . '?' . '$/i';

  $user = '[a-zA-Z0-9_\-\.\+\^!#\$%&*+\/\=\?\`\|\{\}~\'\[\]]+';
  $email_pattern = '/^mailto:' . $user . '@' . '(' . $domain . '|' . $ipv4 .'|'. $ipv6 . '|localhost)' . $query . '$/';

  if (preg_match($external_pattern . $end, $text)) {
    return LINK_EXTERNAL;
  }
  elseif (preg_match($internal_pattern . $end, $text)) {
    return LINK_INTERNAL;
  }
  elseif (in_array('mailto', $allowed_protocols) && preg_match($email_pattern, $text)) {
    return LINK_EMAIL;
  }
  elseif (strpos($text, '<front>') === 0) {
    return LINK_FRONT;
  }
  return FALSE;
}