'. t('GeSHi filter is configured to use global tag settings. For separate settings per input format, enable this option in the general GeSHi filter settings.', array('!geshi_admin_url' => url('admin/settings/geshifilter'))) .'

')),
      GESHI_HEADER_DIV => t('%val: uses a @cnt wrapper, enables automatic line wrapping.',
        array('%val' => 'GESHI_HEADER_DIV', '@cnt' => '
')),
    );
    if (version_compare(GESHI_VERSION, '1.0.8', '>=')) {
      $container_options[GESHI_HEADER_PRE_VALID] = t('%val: uses @pre wrappers, ensures valid HTML with line numbering, but generates more markup.',
        array('%val' => 'GESHI_HEADER_PRE_VALID', '@pre' => '
', '@li' => '
'));
      $container_options[GESHI_HEADER_PRE_TABLE] = t('%val: uses a @table construction for adding line numbers which avoids selection/copy/paste problems.',
        array('%val' => 'GESHI_HEADER_PRE_TABLE', '@table' => ''));
    }
    if (version_compare(GESHI_VERSION, '1.0.7.2', '>=')) {
      $container_options[GESHI_HEADER_NONE] = t('%val: uses no wrapper.',
        array('%val' => 'GESHI_HEADER_NONE'));
    }

    $form['geshifilter_styling']['geshifilter_code_container'] = array(
      '#type' => 'radios',
      '#title' => t('Code container, wrapping technique'),
      '#description' => t('Define the wrapping technique to use for code blocks. (GeSHi documentation: The Code Container).',
        array('!link' => 'http://qbnz.com/highlighter/geshi-doc.html#the-code-container')
      ),
      '#options' => $container_options,
      '#default_value' => variable_get('geshifilter_code_container', GESHI_HEADER_PRE),
    );
  }
  // Make it a system settings form.
  $form  = system_settings_form($form);
  // Set custom validate/submit handlers (to be run after system_settings_form submit).
  $form['#validate'][] = 'geshifilter_admin_general_settings_validate';
  $form['#submit'][] = 'geshifilter_admin_general_settings_submit';
  return $form;
}

/**
 * After build function for admin settings
 */
function geshifilter_admin_general_settings_after_build($form, &$form_state) {
  $geshi_library = _geshifilter_check_geshi_library(FALSE, $form_state['values']['geshifilter_geshi_dir'], FALSE);
  if (!$geshi_library['success']) {
    form_set_error('geshifilter_geshi_dir', $geshi_library['message']);
  }
  return $form;
}

/**
 * Validate function for admin settings
 */
function geshifilter_admin_general_settings_validate($form, &$form_state) {
  // Check if automatically managed style sheet is posible
  if ($form_state['values']['geshifilter_css_mode'] == GESHIFILTER_CSS_CLASSES_AUTOMATIC && !_geshifilter_managed_external_stylesheet_possible()) {
    form_set_error('geshifilter_css_mode', t('GeSHi filter can not automatically manage an external CSS style sheet when the download method is private.'));
  }
}

/**
 * Submit function for admin settings
 */
function geshifilter_admin_general_settings_submit($form, &$form_state) {
  // Cache of available languages should be cleared when GeSHi library dir changes
  // _geshifilter_get_geshi_dir() returns the new value set by
  // system_settings_form_submit() which runs before
  // geshifilter_admin_general_settings_submit(),
  // $form['geshifilter_library']['geshifilter_geshi_dir']['#default_value'] is
  // the old value
  if (_geshifilter_get_geshi_dir() != $form['geshifilter_library']['geshifilter_geshi_dir']['#default_value']) {
    variable_del('geshifilter_available_languages_cache');
  }
  // Regenerate language_css
  // Note the use of variable_get('geshifilter_css_mode') which is alread set
  // to $form_state['values']['geshifilter_css_mode'] by
  // system_settings_form_submit, which is run before this submit handler.
  if (variable_get('geshifilter_css_mode', GESHIFILTER_CSS_INLINE) == GESHIFILTER_CSS_CLASSES_AUTOMATIC) {
    _geshifilter_generate_languages_css_file();
  }
  // Always clear the filter cache.
  _geshifilter_clear_filter_cache();
}

/**
 * Menu callback for per language settings
 */
function geshifilter_admin_per_language_settings($form_state, $view = 'enabled') {
  $form = array();
  // check if GeSHi library is available
  $geshi_library = _geshifilter_check_geshi_library();
  if (!$geshi_library['success']) {
    drupal_set_message($geshi_library['message'], 'error');
    return;
  }
  $add_checkbox = TRUE;
  $add_tag_option = (!geshifilter_use_format_specific_options());
  $form['language_settings'] = geshifilter_per_language_settings(NULL, $view, $add_checkbox, $add_tag_option);

  // Make it a system settings form.
  $form = system_settings_form($form);

  // set custom validate and submit handlers
  $form['#validate'][] = 'geshifilter_per_language_settings_validate';
  $form['#submit'][] = 'geshifilter_admin_per_language_settings_submit';

  return $form;
}

/**
 * Validate function for per language settings
 *
 * Check that language tags differ between languages and fro the generic tags.
 */
function geshifilter_per_language_settings_validate($form, &$form_state) {

  // if we're coming from the _geshifilter_filter_settings (sub)form, we should
  // take the input format into account
  $format = isset($form_state['values']['format']) ? $form_state['values']['format'] : NULL;
  $f = ($format === NULL) ? '' : "_$format";

  // language tags should differ from each other
  $languages = _geshifilter_get_available_languages();
  foreach ($languages as $language1 => $language_data1) {
    // iterate over the enabled languages: skip disabled ones
    $field = "geshifilter_language_enabled_{$language1}";
    if (!(isset($form_state['values'][$field]) ? $form_state['values'][$field] : variable_get($field, FALSE))) {
      continue;
    }
    // get the associated tags as $tags1
    $field = "geshifilter_language_tags_{$language1}{$f}";
    if (isset($form_state['values'][$field])) {
      $tags1 = _geshifilter_tag_split($form_state['values'][$field]);
    }
    else {
      $tags1 = _geshifilter_tag_split(geshifilter_language_tags($language1, $format));
    }
    // also include the generic tags
    $field = "geshifilter_tags{$f}";
    $generic_tags = isset($form_state['values'][$field]) ? $form_state['values'][$field] : geshifilter_tags($format);
    $tags1 = array_merge($tags1, _geshifilter_tag_split($generic_tags));

    // check that other languages do not use these tags
    foreach ($languages as $language2 => $language_data2) {
      // check these tags against the tags of other enabled languages
      $field = "geshifilter_language_enabled_{$language2}";
      if ($language1 == $language2 || !(isset($form_state['values'][$field]) ? $form_state['values'][$field] : variable_get($field, FALSE))) {
        continue;
      }
      // get tags for $language2, or skip when not in $form_state['values']
      $field = "geshifilter_language_tags_{$language2}{$f}";
      if (isset($form_state['values'][$field])) {
        $tags2 = _geshifilter_tag_split($form_state['values'][$field]);
      }
      else {
        continue;
      }
      // and now we can check tags1 against tags2
      foreach ($tags1 as $tag1) {
        foreach ($tags2 as $tag2) {
          if ($tag1 == $tag2) {
            form_set_error("geshifilter_language_tags_{$language2}{$f}",  t('The language tags should differ between languages and from the generic tags.'));
          }
        }
      }
    }
  }
}

/**
 * Submit function for per language settings
 */
function geshifilter_admin_per_language_settings_submit($form, &$form_state) {
  // regenerate language_css
  if (variable_get('geshifilter_css_mode', GESHIFILTER_CSS_INLINE) == GESHIFILTER_CSS_CLASSES_AUTOMATIC) {
    _geshifilter_generate_languages_css_file();
  }
  _geshifilter_clear_filter_cache();
}

/**
 * Helper function for some settings form fields usable as general and specific settings
 */
function _geshifilter_general_highlight_tags_settings($format=NULL) {
  $form = array();
  $f = ($format === NULL) ? '' : "_$format";
  // generic tags
  $form["geshifilter_tags$f"] = array(
    '#type' => 'textfield',
    '#title' => t('Generic syntax highlighting tags'),
    '#default_value' => geshifilter_tags($format),
    '#description' => t('Tags that should activate the GeSHi syntax highlighting. Specify a space-separated list of tagnames.'),
  );
  // Container tag styles.
  $form["geshifilter_tag_styles$f"] = array(
    '#type' => 'checkboxes',
    '#title' => t('Container tag style'),
    '#options' => array(
      GESHIFILTER_BRACKETS_ANGLE => ''. check_plain(' ... ') .'',
      GESHIFILTER_BRACKETS_SQUARE => ''. check_plain('[foo] ... [/foo]') .'',
      GESHIFILTER_BRACKETS_DOUBLESQUARE => ''. check_plain('[[foo]] ... [[/foo]]') .'',
      GESHIFILTER_BRACKETS_PHPBLOCK => t('PHP style source code blocks: !php and !percent', array(
        '!php' => ''. check_plain(''). '',
        '!percent' =>  ''. check_plain('<% ... %>'). '',
      )),
    ),
    '#default_value' => _geshifilter_tag_styles($format),
    '#description' => t('Select the container tag styles that should trigger GeSHi syntax highlighting.'),
  );
  return $form;
}

/**
 * function for generating a form table for per language settings
 */
function geshifilter_per_language_settings($format, $view, $add_checkbox, $add_tag_option) {
  $form = array(
    '#theme' => 'geshifilter_per_language_settings',
  );
  // table header
  $form['header'] = array(
    '#type' => 'value',
    '#value' => array(),
  );
  $form['header']['#value'][] = t('Language');
  $form['header']['#value'][] = t('GeSHi language code');
  if ($add_tag_option) {
    $form['header']['#value'][] = t('Tag/language attribute value');
  }
  // table body
  $form['languages'] = array();
  $languages = _geshifilter_get_available_languages();
  foreach ($languages as $language => $language_data) {
    $enabled = variable_get("geshifilter_language_enabled_{$language}", FALSE);
    // skip items to hide
    if (($view == 'enabled' && !$enabled) || ($view == 'disabled' && $enabled)) {
      continue;
    }
    // build language row
    $form['languages'][$language] = array();
    // add enable/disable checkbox
    if ($add_checkbox) {
      $form['languages'][$language]["geshifilter_language_enabled_{$language}"] = array(
        '#type' => 'checkbox',
        '#default_value' => $enabled,
        '#title' => $language_data['fullname'],
      );
    }
    else {
      $form['languages'][$language]['fullname'] = array(
        '#type' => 'markup',
        '#value' => $language_data['fullname'],
      );
    }
    // language code
    $form['languages'][$language]['name'] = array(
      '#type' => 'markup',
      '#value' => $language,
    );
    // add a textfield for tags
    if ($add_tag_option) {
      $f = ($format === NULL) ? '' : "_$format";
      $form['languages'][$language]["geshifilter_language_tags_{$language}{$f}"] = array(
        '#type' => 'textfield',
        '#default_value' => geshifilter_language_tags($language, $format),
        '#size' => 20,
      );
    }
  }
  return $form;
}

/**
 * theming function for the per language settings table
 */
function theme_geshifilter_per_language_settings($form) {
  // build table body
  $rows = array();
  foreach (element_children($form['languages']) as $language) {
    $row = array();
    foreach (element_children($form['languages'][$language]) as $key) {
      $row[] = drupal_render($form['languages'][$language][$key]);
    }
    $rows[] = $row;
  }
  // build table header
  $header = array();
  foreach ($form['header']['#value'] as $cell) {
    if ($cell == t('Enabled')) {
      // add JavaScript 'select all/select none' stuff
      $header[] = array('data' => $cell) + theme('table_select_header_cell');
    }
    else {
      $header[] = $cell;
    }
  }
  // return themed table
  return theme('table', $header, $rows);
}

/**
 * Helper function for flushing the GeSHi language definition cache
 */
function _geshifilter_flush_language_definition_cache() {
  if (GESHIFILTER_CSS_CLASSES_AUTOMATIC == variable_get('geshifilter_css_mode', GESHIFILTER_CSS_INLINE)) {
    // Forced regeneration of the CSS file
    _geshifilter_generate_languages_css_file(TRUE);
  }
  // Flush cache of available languages
  variable_del('geshifilter_available_languages_cache');
  drupal_set_message(t('Flushed the GeSHi language definition cache.'));
}

/**
 * Helper function for clearing the appropriate filter cache entries
 */
function _geshifilter_clear_filter_cache() {
  $message = FALSE;

  // Iterate over input formats and clear the ones GeSHi filter is active in.
  foreach (filter_formats() as $format => $input_format) {
    // Get the filters in this input format
    $filters = filter_list_format($format);
    // look if GeSHi is enabled in this input format
    if (isset($filters['geshifilter/0'])) {
      cache_clear_all($format .':', 'cache_filter', TRUE);
      $message = TRUE;
    }
  }

  // Clear the geshifilter entries in the cache_filter table,
  // created by geshifilter_geshi_process().
  cache_clear_all('geshifilter:', 'cache_filter', TRUE);

  // Show a message that the filter cache was cleared.
  if ($message) {
    drupal_set_message(t('GeSHi filter cleared the filter cache for the appropriate input formats.'));
  }
}

/**
 * Helper function for generating the CSS rules
 *
 * @return string with the CSS rules
 */
function _geshifilter_generate_languages_css_rules() {
  $output = '';
  $geshi_library = _geshifilter_check_geshi_library();
  if ($geshi_library['loaded']) {
    require_once drupal_get_path('module', 'geshifilter') .'/geshifilter.pages.inc';
    $languages = _geshifilter_get_enabled_languages();
    foreach ($languages as $langcode => $language_full_name) {
      // create GeSHi object
      $geshi = _geshifilter_GeSHi_factory('', $langcode);
      _geshifilter_override_geshi_defaults($geshi, $langcode);
      // add CSS rules for current language
      $output .= $geshi->get_stylesheet(FALSE) ."\n";
      // release GeSHi object
      unset($geshi);
    }
  }
  else {
    drupal_set_message(t('Error while generating CSS rules: could not load GeSHi library.'), 'error');
  }
  return $output;
}

/**
 * Function for generating the external stylesheet.
 *
 * @param $force force the regeneration of the CSS file
 */
function _geshifilter_generate_languages_css_file($force=FALSE) {
  $languages = _geshifilter_get_enabled_languages();
  // Serialize the array of enabled languages as sort of hash.
  $languages_hash = serialize($languages);

  // Check if generation of the CSS file is needed
  if ($force || $languages_hash != variable_get('geshifilter_cssfile_languages', '')) {
    // Build stylesheet.
    $stylesheet = _geshifilter_generate_languages_css_rules();
    // Save stylesheet.
    $stylesheet_filename = file_directory_path() .'/geshifilter-languages.css';
    $ret = file_save_data($stylesheet, $stylesheet_filename, FILE_EXISTS_REPLACE);
    if ($ret) {
      drupal_set_message(t('(Re)generated external CSS style sheet %file.', array('%file' => $ret)));
    }
    else {
      drupal_set_message(t('Could not generate external CSS file. Check the settings of your file system.',
        array('!filesystem' => url('admin/settings/file-system'))), 'error');
    }
    // Remember for which list of languages the CSS file was generated
    variable_set('geshifilter_cssfile_languages', $languages_hash);
  }
}