<?php

/**
 * @file
 * Printer-friendly pages User Interface module.
 *
 * This module handles the display of the printer-friendly sub-module links.
 *
 * @ingroup print
 */

define('PRINT_UI_LINK_POS_DEFAULT', '{ "link": "link", "block": "block", "help": "help" }');
define('PRINT_UI_LINK_TEASER_DEFAULT', 0);
define('PRINT_UI_SHOW_LINK_DEFAULT', 1);
define('PRINT_UI_SYS_LINK_VISIBILITY_DEFAULT', 1);
define('PRINT_UI_SYS_LINK_PAGES_DEFAULT', '');
define('PRINT_UI_LINK_USE_ALIAS_DEFAULT', 0);
define('PRINT_UI_BOOK_LINK_DEFAULT', 1);

define('PRINT_UI_ALLOW_NORMAL_LINK', 1);
define('PRINT_UI_ALLOW_BOOK_LINK', 2);
define('PRINT_UI_TYPE_FIELDS_WEIGHT', 30);

define('PRINT_UI_TYPE_SHOW_LINK_DEFAULT', 1);
define('PRINT_UI_TYPE_COMMENT_LINK_DEFAULT', 0);

/**
 * Implements hook_permission().
 */
function print_ui_permission() {
  return array(
    'node-specific print configuration' => array(
      'title' => t('Node-specific configuration'),
      'description' => t('Enable access to the per-node settings.'),
    ),
  );
}

/**
 * Implements hook_theme().
 */
function print_ui_theme() {
  return array(
    'print_ui_format_link' => array(
      'variables' => array('format' => '', 'location' => ''),
    ),
    'print_ui_settings' => array(
      'render element' => 'form',
      'file' => 'print_ui.admin.inc',
    ),
  );
}

/**
 * Implements hook_menu().
 */
function print_ui_menu() {
  $items = array();
  $items['admin/config/user-interface/print/ui'] = array(
    'title' => 'Links',
    'description' => 'Configure the print module links.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('print_ui_settings'),
    'access arguments'  => array('administer print'),
    'weight' => 9,
    'type' => MENU_LOCAL_TASK,
    'file' => 'print_ui.admin.inc',
  );

  return $items;
}

/**
 * Implements hook_block_info().
 */
function print_ui_block_info() {
  $block['print-links']['info'] = t('Printer, email and PDF versions');
  $block['print-links']['cache'] = DRUPAL_CACHE_PER_PAGE;
  return $block;
}

/**
 * Implements hook_block_view().
 */
function print_ui_block_view($delta = '') {
  $block = array();

  switch ($delta) {
    case 'print-links':
      $nid = preg_replace('!^node/!', '', $_GET['q']);
      if (ctype_digit($nid)) {
        $node = node_load($nid);
        if (!node_access('view', $node)) {
          // If the user doesn't have access to the node, don't show any links.
          $block['content'] = '';
          return array();
        }
      }
      else {
        $node = NULL;
      }

      $block['content'] = '';
      foreach (module_implements('print_link') as $module) {
        $function = $module . '_print_link';
        if (function_exists($function)) {
          $link = call_user_func_array($function, array());

          $link_pos = variable_get('print_' . $link['format'] . '_link_pos', drupal_json_decode(PRINT_UI_LINK_POS_DEFAULT));

          if (!(empty($link_pos['block']))) {
            $links = print_ui_insert_link($link, array('node' => $node, 'location' => 'block'));
            if (!empty($links)) {
              $block['content'] .= $links;
            }
          }
        }
      }
      break;
  }
  return $block;
}

/**
 * Implements hook_help().
 */
function print_ui_help($path, $arg) {
  $links = '';

  if (($path !== 'node/%') && ($path !== 'node/%/revisions/%/view')) {
    static $output = FALSE;

    if ($output === FALSE) {
      $output = TRUE;

      foreach (module_implements('print_link') as $module) {
        $function = $module . '_print_link';
        if (function_exists($function)) {
          $link = call_user_func_array($function, array());

          $link_pos = variable_get('print_' . $link['format'] . '_link_pos', drupal_json_decode(PRINT_UI_LINK_POS_DEFAULT));

          if (!empty($link_pos['help'])) {
            $links .= print_ui_insert_link($link, array('location' => 'help'));
          }
        }
      }
      if ($links) {
        return "<span class='print-syslink'>$links</span>";
      }
    }
  }
  return '';
}

/**
 * Implements hook_node_view_alter().
 */
function print_ui_node_view_alter(&$build) {
  if (isset($build['links']['book']['#links']['book_printer'])) {
    $book_link = variable_get('print_html_book_link', PRINT_UI_BOOK_LINK_DEFAULT);

    if ($book_link) {
      $link = print_print_link();
      $link_pos = variable_get('print_html_link_pos', drupal_json_decode(PRINT_UI_LINK_POS_DEFAULT));

      if (!empty($link_pos['link'])) {
        $format = theme('print_ui_format_link', array('format' => 'html', 'location' => 'link'));

        $path = '';
        switch ($book_link) {
          case 1:
            $path = $build['links']['book']['#links']['book_printer']['href'];
            break;

          case 2:
            $link_use_alias = variable_get('print_html_link_use_alias', PRINT_UI_LINK_USE_ALIAS_DEFAULT);
            $path = ($link_use_alias && ($alias = drupal_lookup_path('alias', 'node/' . $build['#node']->nid))) ? $alias : $build['#node']->nid;
            break;
        }

        $build['links']['book']['#links']['book_printer'] = array(
          'href' => $link['path'] . '/' . $path,
          'title' => $format['text'],
          'attributes' => $format['attributes'],
          'html' => $format['html'],
        );
      }
      else {
        unset($build['links']['book']['#links']['book_printer']);
      }
    }
  }
}

/**
 * Implements hook_node_view().
 */
function print_ui_node_view($node, $view_mode) {
  $corner_markup = '';

  foreach (module_implements('print_link') as $module) {
    $function = $module . '_print_link';
    if (function_exists($function)) {
      $link = call_user_func_array($function, array());

      $link_pos = variable_get('print_' . $link['format'] . '_link_pos', drupal_json_decode(PRINT_UI_LINK_POS_DEFAULT));
      $link_use_alias = variable_get('print_' . $link['format'] . '_link_use_alias', PRINT_UI_LINK_USE_ALIAS_DEFAULT);

      if (!preg_match('!^node/[\d]*/revisions/[\d]*/view$!', $_GET['q'])) {
        // Not a revision, use node->nid to build the path.
        $path = (($link_use_alias) && ($alias = drupal_lookup_path('alias', 'node/' . $node->nid))) ? $alias : $node->nid;
      }
      else {
        // This is a node revision, replace only the node component.
        $path = preg_replace('!^node/!', '', $_GET['q']);
      }
      $path = $link['path'] . '/' . $path;

      foreach (array('node', 'comment') as $type) {
        $allowed_type = print_ui_link_allowed($link, array(
          'type' => $type,
          'node' => $node,
          'view_mode' => $view_mode,
        ));
        if ($allowed_type) {
          drupal_add_css(drupal_get_path('module', 'print_ui') . '/css/print_ui.theme.css');
          $links = array();
          $format = theme('print_ui_format_link', array('format' => $link['format'], 'location' => 'link'));

          // Show book link.
          if ($allowed_type === PRINT_UI_ALLOW_BOOK_LINK) {
            $path = $link['path'] . '/book/export/html/' . $node->nid;

            $links['book_' . $link['format']] = array(
              'href' => $path,
              'title' => $format['text'],
              'attributes' => $format['attributes'],
              'html' => $format['html'],
            );
          }
          elseif ($allowed_type === PRINT_UI_ALLOW_NORMAL_LINK) {
            $links['print_' . $link['format']] = array(
              'href' => $path,
              'title' => $format['text'],
              'attributes' => $format['attributes'],
              'html' => $format['html'],
              'query' => _print_ui_query_string_encode($_GET, array('q')),
            );
          }

          $link_content = array(
            '#theme' => 'links',
            '#links' => $links,
            '#attributes' => array('class' => array('links', 'inline')),
          );

          // If it's a node, and configured to show the link, but it's not the
          // html version of a book then show it.
          if (($type == 'node') && !empty($link_pos['link']) && !(isset($node->book) && ($link['format'] == 'html'))) {
            $node->content['links']['print_' . $link['format']] = $link_content;
          }
          elseif (($type == 'comment') && isset($node->content['comments']['comments'])) {
            foreach ($node->content['comments']['comments'] as $cid => $comment) {
              if (is_numeric($cid)) {
                $link_content['#links']['print_' . $link['format']]['query']['comment'] = $cid;
                $node->content['comments']['comments'][$cid]['links']['print_' . $link['format']] = $link_content;
              }
            }
          }
        }
      }

      if (!empty($link_pos['corner'])) {
        $corner_markup .= print_ui_insert_link($link, array(
          'node' => $node,
          'path' => $path,
          'location' => 'corner',
        ));
      }
    }
  }

  if (($view_mode == 'full') && (!empty($corner_markup))) {
    // Insert content corner links.
    $node->content['print_links'] = array(
      '#prefix' => '<span class="print-link">',
      '#markup' => $corner_markup,
      '#suffix' => '</span>',
      '#weight' => -101,
    );
  }
}

/**
 * Implements hook_node_load().
 */
function print_ui_node_load($nodes, $types) {
  $ids = array();
  foreach ($nodes as $node) {
    $ids[] = $node->nid;
  }

  foreach (module_implements('print_link') as $module) {
    $function = $module . '_print_link';
    if (function_exists($function)) {
      $link = call_user_func_array($function, array());

      $display = 'print_' . $link['format'] . '_display';
      $display_comment = 'print_' . $link['format'] . '_display_comment';
      $display_urllist = 'print_' . $link['format'] . '_display_urllist';

      $result = db_query('SELECT nid, link, comments, url_list FROM {' . $module . '_node_conf} WHERE nid IN (:nids)', array(':nids' => $ids))->fetchAllAssoc('nid');

      foreach ($nodes as $node) {
        $node->{$display} = isset($result[$node->nid]) ? intval($result[$node->nid]->link) : variable_get($display . '_' . $node->type, PRINT_UI_TYPE_SHOW_LINK_DEFAULT);
        $node->{$display_comment} = isset($result[$node->nid]) ? intval($result[$node->nid]->comments) : variable_get($display_comment . '_' . $node->type, PRINT_UI_TYPE_COMMENT_LINK_DEFAULT);
        $node->{$display_urllist} = isset($result[$node->nid]) ? intval($result[$node->nid]->url_list) : variable_get($display_urllist . '_' . $node->type, PRINT_TYPE_URLLIST_DEFAULT);
      }
    }
  }
}

/**
 * Implements hook_node_insert().
 */
function print_ui_node_insert($node) {
  print_ui_node_update($node);
}

/**
 * Implements hook_node_update().
 */
function print_ui_node_update($node) {
  if (user_access('administer print') || user_access('node-specific print configuration')) {
    foreach (module_implements('print_link') as $module) {
      $function = $module . '_print_link';
      if (function_exists($function)) {
        $link = call_user_func_array($function, array());

        $display = 'print_' . $link['format'] . '_display';
        $display_comment = 'print_' . $link['format'] . '_display_comment';
        $display_urllist = 'print_' . $link['format'] . '_display_urllist';

        if (!isset($node->{$display}) || $node->{$display} === NULL) {
          $node->{$display} = variable_get($display . '_' . $node->type, PRINT_UI_TYPE_SHOW_LINK_DEFAULT);
        }
        if (!isset($node->{$display_comment}) || $node->{$display_comment} === NULL) {
          $node->{$display_comment} = variable_get($display_comment . '_' . $node->type, PRINT_UI_TYPE_COMMENT_LINK_DEFAULT);
        }
        if (!isset($node->{$display_urllist}) || $node->{$display_urllist} === NULL) {
          $node->{$display_urllist} = variable_get($display_urllist . '_' . $node->type, PRINT_TYPE_URLLIST_DEFAULT);
        }

        db_merge($module . '_node_conf')
          ->key(array('nid' => $node->nid))
          ->fields(array(
            'link' => $node->{$display},
            'comments' => $node->{$display_comment},
            'url_list' => $node->{$display_urllist},
          ))
          ->execute();
      }
    }
  }
}

/**
 * Implements hook_node_delete().
 */
function print_ui_node_delete($node) {
  foreach (module_implements('print_link') as $module) {
    $function = $module . '_print_link';
    if (function_exists($function)) {
      call_user_func_array($function, array());

      db_delete($module . '_node_conf')
        ->condition('nid', $node->nid)
        ->execute();
    }
  }
}

/**
 * Implements hook_form_alter().
 */
function print_ui_form_alter(&$form, &$form_state, $form_id) {
  // Add the node-type settings option to activate the printer-friendly
  // version link.
  if ((user_access('administer print') || user_access('node-specific print configuration')) &&
      (($form_id == 'node_type_form') || !empty($form['#node_edit_form']))) {
    $form['print'] = array(
      '#type' => 'fieldset',
      '#title' => t('Printer, email and PDF versions'),
      '#collapsible' => TRUE,
      '#collapsed' => TRUE,
      '#weight' => PRINT_UI_TYPE_FIELDS_WEIGHT,
      '#group' => 'additional_settings',
    );

    foreach (module_implements('print_link') as $module) {
      $function = $module . '_print_link';
      if (function_exists($function)) {
        $link = call_user_func_array($function, array());

        $form['print']['print_' . $link['format']] = array(
          '#type' => 'fieldset',
          '#title' => check_plain($link['text']),
          '#collapsible' => TRUE,
        );

        $display = 'print_' . $link['format'] . '_display';
        $display_comment = 'print_' . $link['format'] . '_display_comment';
        $display_urllist = 'print_' . $link['format'] . '_display_urllist';

        $form['print']['print_' . $link['format']][$display] = array(
          '#type' => 'checkbox',
          '#title' => t('Show link'),
        );
        $form['print']['print_' . $link['format']][$display_comment] = array(
          '#type' => 'checkbox',
          '#title' => t('Show link in individual comments'),
        );
        $form['print']['print_' . $link['format']][$display_urllist] = array(
          '#type' => 'checkbox',
          '#title' => t('Show Printer-friendly URLs list'),
        );

        if ($form_id == 'node_type_form') {
          $form['print']['print_' . $link['format']][$display]['#default_value'] = variable_get($display . '_' . $form['#node_type']->type, PRINT_UI_TYPE_SHOW_LINK_DEFAULT);
          $form['print']['print_' . $link['format']][$display_comment]['#default_value'] = variable_get($display_comment . '_' . $form['#node_type']->type, PRINT_UI_TYPE_COMMENT_LINK_DEFAULT);
          $form['print']['print_' . $link['format']][$display_urllist]['#default_value'] = variable_get($display_urllist . '_' . $form['#node_type']->type, PRINT_TYPE_URLLIST_DEFAULT);
        }
        else {
          $node = $form['#node'];
          $form['print']['print_' . $link['format']][$display]['#default_value'] = isset($node->{$display}) ? $node->{$display} : variable_get($display . '_' . $node->type, PRINT_UI_TYPE_SHOW_LINK_DEFAULT);
          $form['print']['print_' . $link['format']][$display_comment]['#default_value'] = isset($node->{$display_comment}) ? $node->{$display_comment} : variable_get($display_comment . '_' . $node->type, PRINT_UI_TYPE_COMMENT_LINK_DEFAULT);
          $form['print']['print_' . $link['format']][$display_urllist]['#default_value'] = isset($node->{$display_urllist}) ? $node->{$display_urllist} : variable_get($display_urllist . '_' . $node->type, PRINT_TYPE_URLLIST_DEFAULT);
        }
      }
    }
  }
}

/**
 * Auxiliary function to fill the Printer-friendly link attributes.
 *
 * @param string $title
 *   Text to displayed by the link when hovering over it with the mouse.
 * @param string $class
 *   Class attribute to be used in the link.
 * @param bool $new_window
 *   If TRUE opens the target page in a new window.
 *
 * @return array
 *   An associative array containing:
 *   - title: text to be used when hovering over the link.
 *   - class: CSS class of the link tag.
 *   - target: used for opening a new window with the non-javascript method
 *   - onclick: open a new window, with the javascript method
 *   - rel: SEO-related attribute indicating that the printer-friendly version
 *     should not be indexed by search engine robots.
 */
function _print_ui_fill_attributes($title = '', $class = '', $new_window = FALSE) {
  $print_newwindow = variable_get('print_newwindow', PRINT_NEWWINDOW_DEFAULT);
  $print_robots_noindex = variable_get('print_robots_noindex', PRINT_ROBOTS_NOINDEX_DEFAULT);

  $attributes = array();
  $attributes['title'] = $title;
  if (!empty($class)) {
    $attributes['class'] = array($class);
  }

  if ($new_window) {
    switch ($print_newwindow) {
      case 0:
        $attributes['target'] = '_blank';
        break;

      case 1:
        $attributes['onclick'] = 'window.open(this.href); return false';
        break;
    }
  }
  if (!empty($print_robots_noindex)) {
    $attributes['rel'] = 'nofollow';
  }
  return $attributes;
}

/**
 * Format the Printer-friendly link.
 *
 * @return array
 *   An associative array containing:
 *   - text: The content of the link
 *   - html: TRUE if the text contains HTML tags, FALSE if it's plain text
 *   - attributes: several attributes of the link tag (title, class, target,
 *     onclick, rel)
 *
 * @see _print_ui_fill_attributes()
 * @ingroup themeable
 * @ingroup print_themeable
 */
function theme_print_ui_format_link($vars) {
  $format = $vars['format'];

  foreach (module_implements('print_link') as $module) {
    $function = $module . '_print_link';
    if (function_exists($function)) {
      $link = call_user_func_array($function, array());

      if ($link['format'] == $format) {
        $link_class = variable_get('print_' . $link['format'] . '_link_class', $link['class']);

        $new_window = FALSE;
        $func = $module . '_print_new_window_alter';
        if (function_exists($func)) {
          $func($new_window, $link['format']);
        }

        $show_link = variable_get('print_' . $link['format'] . '_show_link', PRINT_UI_SHOW_LINK_DEFAULT);
        $link_text = filter_xss(variable_get('print_' . $link['format'] . '_link_text', $link['text']));

        $text = '';
        if ($show_link >= 2) {
          $img = drupal_get_path('module', $module) . '/icons/' . $link['icon'];
          switch ($show_link) {
            case 2:
              $text = theme('image', array(
                'path' => $img,
                'width' => '16px',
                'height' => '16px',
                'alt' => $link_text,
                'title' => $link_text,
                'attributes' => array('class' => array('print-icon')),
              ));
              break;

            case 3:
              $text = theme('image', array(
                'path' => $img,
                'width' => '16px',
                'height' => '16px',
                'alt' => $link_text,
                'title' => $link_text,
                'attributes' => array('class' => array('print-icon', 'print-icon-margin')),
              )) . $link_text;
              break;
          }
          $html = TRUE;
        }
        else {
          $text = $link_text;
          $html = FALSE;
        }

        return array(
          'text' => $text,
          'html' => $html,
          'attributes' => _print_ui_fill_attributes($link['description'], strip_tags($link_class), $new_window),
        );
      }
    }
  }
  return array();
}

/**
 * Auxiliary function to display a formatted Printer-friendly link.
 *
 * Function made available so that developers may call this function from
 * their defined pages/blocks.
 *
 * @param array $link
 *    Array returned by the hook_print_link() call.
 * @param array $args
 *   Array of optional arguments:
 *   - node: node object, to be used in checking node access. If the path
 *     argument is not provided, the path used will be node/nid.
 *   - path: path to be used in the link. If not specified, the current URL
 *     is used.
 *   - location: the location in the page where the link is being inserted
 *     ('link', 'corner', 'block', 'help').
 *
 * @return string
 *   string with the HTML link to the printer-friendly page
 */
function print_ui_insert_link($link, $args = array()) {
  $node = isset($args['node']) ? $args['node'] : NULL;
  $path = isset($args['path']) ? $args['path'] : NULL;
  $location = isset($args['location']) ? $args['location'] : '';

  if ($node !== NULL) {
    $nid = $node->nid;
    if ($path === NULL) {
      $path = 'node/' . $nid;
    }
    $allowed_type = print_ui_link_allowed($link, array('node' => $node));
  }
  else {
    if ($path === NULL) {
      $nid = preg_replace('!^node/([\d]+)!', '$1', $_GET['q']);
      $path = $_GET['q'];
    }
    else {
      $nid = NULL;
    }
    $allowed_type = print_ui_link_allowed($link, array('path' => $path));
  }

  if ($allowed_type) {
    if ($nid !== NULL) {
      if ($allowed_type === PRINT_UI_ALLOW_BOOK_LINK) {
        $path = 'book/export/html/' . $nid;
      }
      else {
        if (variable_get('print_' . $link['format'] . '_link_use_alias', PRINT_UI_LINK_USE_ALIAS_DEFAULT) && ($alias = drupal_lookup_path('alias', $path))) {
          $path = $alias;
        }
        else {
          $path = $nid;
        }
      }
      $path = $link['path'] . '/' . $path;
      $query = _print_ui_query_string_encode($_GET, array('q'));
    }
    else {
      $query = NULL;
    }
    drupal_add_css(drupal_get_path('module', 'print_ui') . '/css/print_ui.theme.css');
    $format = theme('print_ui_format_link', array('format' => $link['format'], 'location' => $location));
    return '<span class="print_' . $link['format'] . '">' . l($format['text'], $path, array(
      'attributes' => $format['attributes'],
      'query' => $query,
      'absolute' => TRUE,
      'html' => $format['html'],
    )) . '</span>';
  }
  else {
    return FALSE;
  }
}

/**
 * Check if the link to the PF version is allowed depending on the settings.
 *
 * @param array $link
 *   Array returned by the hook_print_link() call.
 * @param array $args
 *   Array containing the possible parameters:
 *    view_mode, node, type, path.
 *
 * @return int
 *   FALSE if not allowed
 *   PRINT_UI_ALLOW_NORMAL_LINK if a normal link is allowed
 *   PRINT_UI_ALLOW_BOOK_LINK if a link is allowed in a book node
 */
function print_ui_link_allowed($link, $args) {
  if (isset($args['view_mode'])) {
    $view_mode = $args['view_mode'];
    if ((($view_mode == 'teaser') && !variable_get('print_' . $link['format'] . '_link_teaser', PRINT_UI_LINK_TEASER_DEFAULT))
      || !in_array($view_mode, array('full', 'teaser'))) {
      // If the teaser link is disabled.
      return FALSE;
    }
  }
  $link_allowed_func = $link['module'] . '_link_allowed';
  if (function_exists($link_allowed_func)) {
    if (!$link_allowed_func($args)) {
      // If the format-specific function disallows the link.
      return FALSE;
    }
  }
  if (!empty($args['path'])) {
    $nid = preg_replace('!^node/!', '', drupal_get_normal_path($args['path']));
    if (ctype_digit($nid)) {
      $args['node'] = node_load($nid);
    }
  }
  if (!empty($args['node'])) {
    static $node_type = '';

    $node = $args['node'];
    if (isset($node->type)) {
      $node_type = $node->type;
    }
    // Node.
    if (isset($args['type']) && ($args['type'] == 'comment') && isset($node_type)) {
      // Link is for a comment, return the configured setting
      // Cache this statically to avoid duplicate queries for every comment.
      static $res = array();
      if (!isset($res[$link['format']][$node->nid])) {
        $res[$link['format']][$node->nid] = db_query("SELECT comments FROM {" . $link['module'] . "_node_conf} WHERE nid = :nid", array(':nid' => $node->nid))->fetchField();
      }
      $display_comment = ($res && ($res[$link['format']][$node->nid] !== FALSE)) ? $res[$link['format']][$node->nid] : variable_get('print_' . $link['format'] . '_display_comment_' . $node_type, PRINT_UI_TYPE_COMMENT_LINK_DEFAULT);
      if ($display_comment) {
        return PRINT_UI_ALLOW_NORMAL_LINK;
      }
    }
    else {
      // Node link.
      $display = 'print_' . $link['format'] . '_display';
      if (isset($node->{$display}) && !$node->{$display}) {
        // Link for this node is disabled.
        return FALSE;
      }
      elseif (isset($node->book)) {
        // Node is a book.
        $book_link = variable_get('print_' . $link['format'] . '_book_link', PRINT_UI_BOOK_LINK_DEFAULT);
        switch ($book_link) {
          case 1:
            if (user_access('access printer-friendly version')) {
              return PRINT_UI_ALLOW_BOOK_LINK;
            }
            break;

          case 2:
            return PRINT_UI_ALLOW_NORMAL_LINK;
        }
      }
      else {
        return PRINT_UI_ALLOW_NORMAL_LINK;
      }
    }
  }
  else {
    // 'System' page.
    $sys_link_visibility = variable_get('print_' . $link['format'] . '_sys_link_visibility', PRINT_UI_SYS_LINK_VISIBILITY_DEFAULT);
    $sys_link_pages = variable_get('print_' . $link['format'] . '_sys_link_pages', PRINT_UI_SYS_LINK_PAGES_DEFAULT);

    return _print_ui_page_match($sys_link_visibility, $_GET['q'], $sys_link_pages);
  }
  return FALSE;
}

/**
 * Check if the provided page is enabled according to the visibility settings.
 *
 * @param int $visibility
 *   Current visibility settings:
 *    0 for show on every page except the listed pages
 *    1 for show on only the listed pages.
 * @param string $path
 *   Current path.
 * @param string $pages
 *   List of pages.
 *
 * @return bool
 *   TRUE if it is enabled, FALSE otherwise
 */
function _print_ui_page_match($visibility, $path, $pages) {
  if ($pages) {
    if ($visibility == 2) {
      if (module_exists('php')) {
        return php_eval($pages);
      }
      else {
        return FALSE;
      }
    }
    $alias = drupal_get_path_alias($path);
    $page_match = drupal_match_path($path, $pages);
    if ($alias != $path) {
      $page_match = $page_match || drupal_match_path($alias, $pages);
    }

    return !($visibility xor $page_match);
  }
  else {
    return !$visibility;
  }
}

/**
 * Parse an array into a valid urlencoded query string.
 *
 * Modified from drupal_query_string_encode to prevent re-encoding of
 * encoded original. (see #301192)
 *
 * @param array $query
 *   The array to be processed e.g. $_GET.
 * @param array $exclude
 *   The array filled with keys to be excluded.
 * @param string $parent
 *   The be used in recursive calls.
 *
 * @return array
 *   urlencoded string which can be appended to/as the URL query string
 */
function _print_ui_query_string_encode($query, $exclude = array(), $parent = '') {
  $params = array();
  foreach ($query as $key => $value) {
    if (in_array($key, $exclude, TRUE)) {
      continue;
    }

    if (is_array($value)) {
      $params[$key] = _print_ui_query_string_encode($value, $exclude, $key);
    }
    else {
      $params[$key] = $value;
    }
  }

  return empty($params) ? NULL : $params;
}