<?php
/**
 * @file
 *
 * "MultiLanguage Links" (MultiLink) module for Drupal 7.
 * Support: Commercial support and customization is available from www.netgenius.co.uk
 * Contact: www.netgenius.co.uk/contact or email drupal at netgenius.co.uk.
 */

/*
function multilink_menu() {
  // Get $mod_name, and $mod_id;
  extract(_multilink_get_ids());

  $items[$mod_config_path] = array(
    'title' => $mod_name,
    'description' => t('Configure the %name module.', array('%name' => $mod_name)),
    'page callback' => 'drupal_get_form',
    'page arguments' => array(sprintf('_%s_config_form', $mod_id)),
    'access arguments' => array('administer filters'),
  );
  return $items;
}
 */

function _multilink_config_form() {
  // Get $mod_name, $mod_id and $mod_prefix;
  extract(_multilink_get_ids());

  // Some settings should be reset to default if set blank in the form:
  $keys = array('pattern', 'short_help');
  foreach ($keys as $key) {
    if (!($$key = _multilink_setting($mod_prefix, $key))) {
      variable_del($mod_prefix . $key);
      $$key = _multilink_setting($mod_prefix, $key);
    }
  }

  // Create collapsible section for this module in the filters configuration form.
  // $section =& $form[$mod_id];
  $section =& $form;
  $fieldset =& $section;

  $key = 'absolute';
  $fieldset[$mod_prefix . $key] = array(
    '#type' => 'checkbox',
    '#title' => t('Absolute urls'),
    '#default_value' => _multilink_setting($mod_prefix, $key),
    '#description' => t('If set, links will be generated with absolute urls, i.e: http://example.com/node/1'),
  );

  $key = 'short_help';
  $fieldset[$mod_prefix . $key] = array(
    '#type' => 'textarea',
    '#title' => t('User help'),
    '#rows' => 2,
    '#default_value' => _multilink_setting($mod_prefix, $key),
    '#description' => t('Filter-help shown to the user. This text is passed through t(). Blank to reset to default value.'),
  );

  return system_settings_form($form);

}

// Get $mod_id
function _multilink_get_ids($format = FALSE) {

  static $ids;
  if (!isset($ids)) {
    $mod_id = drupal_strtolower($mod_name = 'MultiLink');

    // Define the prefix used for config values:
    $format_id = ($format)? $format->format : 'none';
    $mod_prefix = sprintf('%s_%s_', $mod_id, $format_id);
    // If set, use shared config.
    if (_multilink_setting($mod_prefix, 'shared')) {
      $mod_prefix = $mod_id . '_shared_';
    }

    $mod_config_path = sprintf('admin/config/regional/%s', $mod_id);
    $ids = compact('mod_name', 'mod_id', 'mod_prefix', 'mod_config_path');
    $GLOBALS['multilink_prefix'] = $mod_prefix;
  }
  return $ids;
}

/*
 * Build and return a url
 */
function multilink_url($path, $absolute = NULL) {
  $options['absolute'] = ($absolute !== NULL)? $absolute : $GLOBALS['multilink_absolute'];

  // We use the first of _multilink_preferred_languages()
  // to build the url (language subdomain or path-prefix).
  $pref_languages = _multilink_preferred_languages();
  $language_list = language_list();
  $options['language'] = $language_list[$pref_languages[0]];

  // If MultiLink SecurePages is installed, use it.
  if (function_exists('multilink_securepages_url')) {
    return multilink_securepages_url($path, $options);
  }
  else {
    return url($path, $options);
  }
}

/*
 * Get an array of preferred languages.
 */
function _multilink_preferred_languages() {

  // Note: multilink_filter() overrides normal language preferences while processing text.
  if (isset($GLOBALS['multilink_pref_languages'])) {
    return $GLOBALS['multilink_pref_languages'];
  }

  // Build an array of preferred languages (if not already done) ...
  static $pref_languages;
  if (!isset($pref_languages)) {

    // Get user and browser languages.
    $languages = language_list();
    $user_language_id = locale_language_from_user($languages);
    $browser_language_id = locale_language_from_browser($languages);

    // Define an array of possible languages in default order.
    // Since Drupal 7, more possibilities exist - see:
    // http://api.drupal.org/api/drupal/developer--globals.php/global/language/7
    // http://api.drupal.org/api/drupal/developer--globals.php/global/language_content/7
    // http://api.drupal.org/api/drupal/developer--globals.php/global/language_url/7
    $languages = array(
      // The most recent language chosen via a language-switcher (MultiLink-specific.)
      'selected'  => _multilink_session_language(),
      // User-preferred language, from account if available.
      'preferred' => $user_language_id,
      // Language from browser (first preference).
      'browser'   => $browser_language_id,
      // Language selected by Drupal for interface (always same as "content"?)
      'current'   => @$GLOBALS['language']->language,
      // Language selected by Drupal for content (always same as "current"?)
      'content'   => @$GLOBALS['language_content']->language,
      // Language specified in the url
      'url'       => @$GLOBALS['language_url']->language,
      // Site default language
      'default'   => @language_default()->language,
    );

    // Set order of preference - default can be changed via settings.php or variable_set().
    // @todo Consider Providing a UI to set order.
    $language_order = variable_get('multilink_language_order', FALSE);
    if ($language_order === FALSE) {
      // Use default order for preferred languages.
      $pref_languages = $languages;
    }
    else {
      // Build array of preferred languages in given order.
      $pref_languages = array();
      foreach ($language_order as $key) {
        if ($languages[$key]) {
          $pref_languages[$key] = $languages[$key];
        }
      };
    }
    //multilink_set_message('recalcuate: ' . print_r($pref_languages, 1));
    $pref_languages = array_values(array_unique($pref_languages));
    //multilink_set_message('unique: ' . print_r($pref_languages, 1));

    // Remove any blank languages;
    if (in_array('', $pref_languages)) {
      while (($n = array_search('', $pref_languages)) !== FALSE) {
        unset($pref_languages[$n]);
      }
      $pref_languages = array_values($pref_languages);
    }
    //multilink_set_message('_multilink_preferred_languages() -> ' . print_r($pref_languages, 1));
  }

  //multilink_set_message('_multilink_preferred_languages() -> ' . print_r($pref_languages, 1));
  return array_values($pref_languages);
}

/*
 * Return a $node object containing (at least) nid, language, title for translated version of $node.
 * Return original $node if no suitable translation is available.
 */
function _multilink_get_translation($node, $pref_languages) {
  global $language;

  // If the node is not 'language neutral'...
  if ($node->language) {
    // Get translations;
    drupal_load('module', 'translation');
    $translations = translation_node_get_translations($node->tnid);

    foreach ($pref_languages as $lang) {
      if (isset($translations[$lang])) {
        $node = $translations[$lang];
        break;
      }
    }
  }
  /*
  // @todo Else if Language Sections is in use...
  elseif (function_exists('language_sections_format_check')) {
    // If node uses Language Sections filtering...
    if (language_sections_format_check($node->format)) {
      // @todo: Get supported languages from LS.  Needs supporting updates in LS.
    }
  }
  */
  return $node;
}

/*
 * Cache operations.
 */
function _multilink_cache($op, $nid, $pref_languages = array(), $data = NULL) {

  // We are using our own cache table, so don't need to worry about key conflicts with other modules.
  $table = 'cache_multilink';
  $base_key = $nid? sprintf('nid:%d:', $nid) : '*';
  $full_key = sprintf('%s%08x', $base_key, crc32(implode(':', $pref_languages)));

  // Additional static cache, effective when same nodes are referenced several times per page.
  static $saved;

  switch ($op) {
    case 'get':
      // Retrieve from cache.
      if (isset($saved[$full_key])) {
        return $saved[$full_key];
      }
      else {
        $cached = cache_get($full_key, $table);
        if ($cached) {
          $saved[$full_key] = $cached->data;
          return $saved[$full_key];
        }
        else {
          return FALSE;
        }
      }
    case 'set':
      // Store in cache for 24 hours.
      cache_set($full_key, $data, $table, REQUEST_TIME + 86400);
      $saved[$full_key] = $data;
      return;
    case 'clear':
      // Clear selected cache entries.
      //drupal_set_message('clear cache for nid: ' . $nid);
      cache_clear_all($base_key, $table, TRUE);
      unset($saved);
      return;
  }
}

/*
 * Implement hook_flush_caches().
 */
function multilink_flush_caches() {
  return array('cache_multilink');
}

function _multilink_getnode($nid) {
  // Load from cache if available.
  $pref_languages = _multilink_preferred_languages();
  $result = _multilink_cache('get', $nid, $pref_languages);

  if (!$result) {
    // Build from scratch and store in cache.
    $result = _multilink_buildnode($nid, $pref_languages);
    if ($result) {
      _multilink_cache('set', $nid, $pref_languages, $result);
    }
  }
  return $result;
}

function _multilink_buildnode($nid, $pref_languages) {
  global $language;
  $result = new stdClass();

  // We need to load the node to get its language and tnid.
  drupal_load('module', 'node');
  drupal_load('module', 'user');
  drupal_load('module', 'field');
  $node = node_load($nid);
  // We may get here with with $nid of non-existant node.
  if (!$node) {
    return;
  }

  // If the node has a language but it's not the first preferred language...
  if ($node->language && $node->language != $pref_languages[0]) {
    // Try to find a suitable translation.
    $node = _multilink_get_translation($node, $pref_languages);
  }

  // Set nid and language into result.
  $result->nid = $node->nid;
  $result->language = $node->language;

  // If node language is different from interface language, show actual language in title.
  // @todo Ideally we would do this when language is different from *current content* language.
  if ($node->language && $node->language != $language->language) {
    $result->title = sprintf('[%s] %s', locale_language_name($node->language), $node->title);
  }
  else {
    $result->title = $node->title;
  }
  // Security: Store a flag indicating whether anonymous access is allowed.
  $result->access = node_access('view', $node, drupal_anonymous_user());

  return $result;
}

/*
 * Define default values for settings, get individual setting.
 * Note: Settings specific to the filter are now in _multilink_filter_default_settings().
 */
function _multilink_setting($mod_prefix, $key) {
  static $defaults;
  if (!isset($defaults)) {

    $defaults = array(
      //'key' => 'value',
    );

    // Merge settings from multilink_filter.
    if (function_exists('_multilink_filter_default_settings')) {
      $defaults += _multilink_filter_default_settings();
    }
  }
  return variable_get($mod_prefix . $key, @$defaults[$key]);
}


/*
 * Implement hook_node_insert().
 */
function multilink_node_insert($node) {
  // If we have a translation source, process translations for *that* node.
  if (isset($node->translation_source)) {
    _multilink_cache_clear_translations($node, $node->translation_source->tnid);
  }
  // Just to be safe, clear any cache entries for the new node.
  _multilink_cache('clear', $node->nid);
}

/*
 * Implement hook_node_update().
 */
function multilink_node_update($node) {
  _multilink_cache_clear_translations($node, $node->tnid);
}

/*
 * Implement hook_node_delete().
 */
function multilink_node_delete($node) {
  _multilink_cache_clear_translations($node, $node->tnid);
}

/*
 * Clear any cached entries for a node's translations.
 */
function _multilink_cache_clear_translations($node, $tnid) {
  // Get translations for this node, and clear cached entries.
  $translations = translation_node_get_translations($tnid);

  // If no translations exist, just delete cache entries for current node.
  if (empty($translations)) {
    _multilink_cache('clear', $node->nid);
  }
  else {
    // Loop through all translations deleting cache entries.
    foreach ($translations as $translation) {
      _multilink_cache('clear', $translation->nid);
    }
  }
}

/**
 * Implement hook_url_outbound_alter().
 * Add a query string to translation links - allows detection of explicit
 * language choice by user.  This works for the standard translation links
 * on node pages and standard Language Switcher block. Will also work with
 * other links which have class 'translation-link' or 'language-link'.
 */
function multilink_url_outbound_alter($path, &$options, $original_path) {
  // drupal_set_message(sprintf('url_outbound_alter - path: %s original: %s options: %s', $path, $original_path, print_r($options, 1)));
  // drupal_set_message(sprintf('url_outbound_alter - path: %s original: %s class: %s', $path, $original_path, print_r(@$options['attributes']['class'], 1)));
  if (is_array($class = @$options['attributes']['class'])) {
    if (in_array('language-link', $class) || in_array('translation-link', $class)) {
      $options['query']['multilink'] = 'switch';
    }
  }
}

/*
 * Utility function to update a link (used above.)
 */
function _multilink_update_link(&$link) {
  $link['query']['multilink'] = 'switch';
  ////multilink_set_message(print_r($link, 1), 'warning');
}

/*
 * Implement hook_init().
 * Check for ?multilink = switch in request, and process it if found.
 * If found, we redirect to the same path, inlcuding any other elements of the quiery string.
 * Note: May also be called via multilink_redirect_cached_boot in which case Drupal boot is not yet complete,
 * but in that case the caller is responsible for ensuring that required includes and modules have been loaded.
 */
function multilink_init() {
  static $done;

  if (!$done) {
    //multilink_set_message('multilink_init');
    $done = TRUE;

    // If the user arriving from a "language switcher" or similar link,
    // we will regard the chosen language as their preferred language from now on.
    // We use global $language_url as that should be correct (global $language may not be.)
    // Note: $_GET['multilink'] gets added to links via our _url_outbound_alter hook.
    if (@$_GET['multilink'] == 'switch') {
      $set_language = $GLOBALS['language_url']->language;
      _multilink_session_language($set_language);

      // For tidiness/SEO, redirect to the same url without $_GET['multilink'].
      $get = $_GET;
      unset($get['q'], $get['multilink']);
      $request = base_path() . request_path();
      // Note, we 'external' here to maintain the requested path (no alias or language conversion wanted.)
      // $url = url($request, array('query' => $get, 'external'=> 1)); drupal_set_message('url: ' . $url);
      drupal_goto($request, array('query' => $get, 'external' => 1));
    }
  }
}

/*
 * Return and optionally set the "preferred" language for current session.
 * We use cookies rather than $_SESSION so that this can work during bootstrap.
 */
function _multilink_session_language($language = FALSE) {
  $cookie = 'multilink_pl';
  if ($language) {
    // Set a cookie to expire in 24 hours.
    setcookie($cookie, $language, REQUEST_TIME + 86400, '/', $GLOBALS['cookie_domain']);
    $_COOKIE[$cookie] = $language;
  }
  ////multilink_set_message(sprintf('session_language: %s', $_COOKIE[$cookie]));
  return (isset($_COOKIE[$cookie]))? $_COOKIE[$cookie] : NULL;
}

/*
 * Utility to display or log debug messages.
 */

/***
function multilink_set_message($message = NULL, $type = 'status') {
  //return;
  if ($GLOBALS['user']->uid == 1) {
    drupal_set_message(filter_xss($message), $type);
  }
  else {
    static $log;
    $logname = '/tmp/multilink.log';
    if (!isset($log)) {
      $log = fopen($logname, 'a');
    }
    fwrite($log, sprintf("[%s][%s] %s\n", REQUEST_TIME, $type, $message));
  }
}
***/

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