<?php
// $Id$

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

/**
 * Implementation of hook_help().
 */
function link_help($section) {
  switch ($section) {
    case 'admin/modules#description':
      return t('Defines simple link field types. <em>Note: Requires content.module.</em>');
  }
}

/**
 * Implementation of hook_field_info().
 */
function link_field_info() {
  return array(
    'link' => array('label' => 'Link'),
  );
}

/**
 * Implementation of hook_field_settings().
 */
function link_field_settings($op, $field) {
  switch ($op) {
    case 'form':
      $form = array();
      
      $options = array (
        'optional' => t('Optional Title'),
        'required' => t('Required Title'),
        'none' => t('No Title'),
      );
      
      $form['title'] = array(
        '#type' => 'radios',
        '#title' => t('Link Title'),
        '#default_value' => isset($field['title']) ? $field['title'] : 'optional',
        '#options' => $options,
      );
      
      $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' => $options,
      );
      $form['attributes']['rel'] = array(
        '#type' => 'checkbox',
        '#return_value' => 'nofollow',
        '#prefix' => '<div class="form-item"><label>Nofollow Value: </label>',
        '#suffix' => '</div>',
        '#title' => t('Add rel=&quot;nofollow&quot; Attribute'),
        '#description' => t('The <a href="http://en.wikipedia.org/wiki/Nofollow#rel.3Dnofollow">rel=&quot;nofollow&quot; attribute</a> prevents some search engines from spidering entered links.'),
        '#default_value' => isset($field['attributes']['rel']) ? $field['attributes']['rel'] : false,
      );
      return $form;

    case 'save':
      return array('attributes', 'title');

    case 'database columns':
      return array(
        'url' => array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => "''"),
        'title' => array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => "''"),
        'attributes' => array('type' => 'mediumtext', 'not null' => TRUE, 'default' => "''"),
      );

    case 'filters':
      return array(
        'default' => array(
          'operator' => 'views_handler_operator_like',
          'handler' => 'views_handler_filter_like',
        ),
      );

  }
}

/**
 * Implementation of hook_field().
 */
function link_field($op, &$node, $field, &$items, $teaser, $page) {
  switch ($op) {
    case 'view':
      foreach ($items as $delta => $item) {
        $items[$delta]['attributes'] = unserialize($item['attributes']);
        $items[$delta]['view'] = content_format($field, $items[$delta], 'default', $node);
      }
      return theme('field', $node, $field, $items, $teaser, $page);
      break;
    case 'submit':
      foreach ($items as $delta => $item) {
        $items[$delta]['attributes'] = serialize($item['attributes']);
      }
      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'),
    ),
  );
}

/**
 * Implementation of hook_widget().
 */
function link_widget($op, &$node, $field, &$node_field) {
  switch ($op) {
    case 'form':
      $form = array();

      $form[$field['field_name']] = array('#tree' => TRUE);

      if ($field['multiple']) {
        // Generate more fields if necessary on preview
        if ($_POST['edit'][$field['field_name']]) {
          $node_field = $_POST['edit'][$field['field_name']];
        }
        $delta = 0;
        // Render link fields for all the entered values
        foreach ($node_field as $data) {
        if ($data['url']) {
            _link_widget_form($form[$field['field_name']][$delta], $field, $data, $delta);
            $delta++;
          }
        }
        // Render two additional new link fields
        foreach (range($delta, $delta + 1) as $delta) {
          _link_widget_form($form[$field['field_name']][$delta], $field, $node_field, $delta);
        }
      } // end if multiple
      else {
        _link_widget_form($form[$field['field_name']][0], $field, $node_field[0]);
      }
      return $form;

    case 'validate':
      foreach($node_field as $delta => $value) {
        if ($value['url']) {
          // Validate the link
          if (link_validate_url(trim($value['url'])) == FALSE) {
            form_set_error($field['field_name'] .']['. $delta. '][url', t('Not a valid URL.'));
          }
          // Require a title for the link if necessary
          elseif ($field['title'] == 'required' && strlen(trim($value['title'])) == 0) {
            form_set_error($field['field_name'] .']['. $delta. '][title', t('Titles are required for all links.'));
          }
        }
        // Require a link if we have a title
        elseif (strlen($value['title']) > 0) {
          form_set_error($field['field_name'] .']['. $delta. '][link', t('You cannot enter a title without a link.'));
        }
      }
      return;
      
    case 'process form values':
      foreach($node_field as $delta => $value) {
        _link_widget_process($node_field[$delta],$delta);
      }
      return;
    
    case 'submit':
      return;
  }
}

/**
 * Helper function renders the link widget in both single and multiple value cases.
 */

function _link_widget_form (&$form_item, $field, $node_field, $delta = 0) {
  
  $form_item = array(
    '#tree' => true,
    // Add a microweight to keep fields in first-in first-out order
    '#weight' => $field['widget']['weight'].".00".$delta,
  );
  $form_item['url'] = array(
    '#type' => 'textfield',
    '#maxlength' => '255',
    '#title' => $field['title'] == 'none' ? t($field['widget']['label']) : t($field['widget']['label'])." ".t('URL'),
    '#default_value' => $node_field['url'],
    '#required' => ($delta == 0) ? $field['required'] : FALSE,
    '#description' => $field['widget']['description'],
  );
  if ($field['title'] != 'none') {
    $form_item['title'] = array(
      '#type' => 'textfield',
      '#maxlength' => '255',
      '#title' => t($field['widget']['label'])." ".t('Title'),
      '#default_value' => $node_field['title'],
      '#required' => ($delta == 0 && $field['title'] == 'required') ? $field['required'] : FALSE,
    );
  }
  if ($field['attributes']['target'] == 'user') {
    $form_item['attributes']['target'] = array(
      '#type' => 'checkbox',
      '#title' => t('Open URL in a New Window'),
      '#default_value' => $node_field['attributes']['target'],
      '#return_value' => "_blank",
    );
  }
}

function _link_widget_process (&$node_field, $delta = 0) {
  // Remove the target attribute if not selected
  if (!$node_field['attributes']['target'] || $node_field['attributes']['target'] == "default") {
    unset($node_field['attributes']['target']);
  }
  // Trim whitespace from URL
  $node_field['url'] = trim($node_field['url']);
}

/**
 * Implementation of hook_field_formatter_info().
 */
function link_field_formatter_info() {
  return array(
    'default' => array(
      'label' => 'Default, as link',
      'field types' => array('link'),
    ),
    'plain' => array(
      'label' => 'Plain, no link',
      'field types' => array('link'),
    ),
  );
}

/**
 * Implementation of hook_field_formatter().
 *
 */
function link_field_formatter($field, $item, $formatter) {
  if (empty($item['url'])) {
    return '';
  }
  
  if ($formatter == 'plain') {
    return check_plain($item['url']);
  }
  
  $attributes = array();
  // Add attributes defined at the widget level
  if (is_array($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;
      }
    }
  }
  
  $url = link_cleanup_url($item['url']);
      
  if (strpos($url, '#') !== FALSE) {
    $fragment = substr($url, strpos($url, '#') + 1);
    $url = substr($url, 0, strpos($url, '#'));
  }
  if (strpos($url, '?') !== FALSE) {
    $query = substr($url, strpos($url, '?') + 1);
    $url = substr($url, 0, strpos($url, '?'));
  }
  
  // Build the link with a title
  if (strlen(trim($item['title']))) {
    $output = l($item['title'], $url, $attributes, $query, $fragment);
  }
  // Build the link with the URL as the title (max 80 characters)
  else {
    $display_url = url($url, $query, $fragment, TRUE);
    $output = l(strlen($display_url) > 80 ? substr($display_url,0,80)."..." : $display_url, $url, $attributes, $query, $fragment);
  }
  return $output;
}

/**
 * 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 == 1) {
    // 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 it be? Add an automatic http:// if it starts with a domain name
      $domain_match = preg_match('/^(([a-z0-9]([a-z0-9\-_]*\.)+)(aero|arpa|biz|com|coop|edu|gov|info|int|jobs|mil|museum|name|nato|net|org|pro|travel|[a-z]{2}))/i',$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.  
 *
 * @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) {
  static $allowed_protocols;
  if (!isset($allowed_protocols)) {
    $allowed_protocols = implode("|",variable_get('filter_allowed_protocols', array('http', 'https', 'ftp', 'news', 'nntp', 'telnet', 'mailto', 'irc', 'ssh', 'sftp', 'webcal')));
  } 
  
  $external_pattern = 
  // protocol
  '/^((' . $allowed_protocols . '):\/\/)?'.
  '('.
    // domains
    '(([a-z0-9]([a-z0-9\-_]*\.)+)(aero|arpa|biz|com|coop|edu|gov|info|int|jobs|mil|museum|name|nato|net|org|pro|travel|mobi|[a-z]{2}))'.
    // OR ip addresses
    '|(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})'.
  ')'.
  // port number
  '(:([0-9]{1,4}))?';
  
  // Starting path
  $internal_pattern = "/^([a-z0-9_\-+]+)";
  
  // the rest of the path
  $end = "(\/[a-z0-9_\-\.~+%=&,$'():;*@]+)*".
  // forward slash 0 or 1 times
  '(\/)?'.
  // query string
  "(\/?\?[a-z0-9+_\-\.\/%=&,$'():;*@]*)?".
  // anchors
  "(#[a-z0-9_\-\.~+%=&,$'():;*@]*)?".
  // end of the expression, case insensitive
  '$/i';
  
  if (preg_match($external_pattern . $end, $text, $m)) {
    return 1;
  }
  elseif (preg_match($internal_pattern . $end, $text, $m)) {
    return 2;
  }
  elseif (strpos($text, '<front>') === 0) {
    return 3;
  }
  return FALSE;
}