<?php

/**
 * @file
 * Provides native meta tag integration with Views.
 */

// This is used to join the view name and the display name when building the
// context string.
define('METATAG_VIEWS_CONTEXT_SEPARATOR', '__');

/**
 * Implements hook_views_api().
 */
function metatag_views_views_api() {
  return array('api' => 3.0);
}

/**
 * Implements hook_ctools_plugin_api().
 */
function metatag_views_ctools_plugin_api($owner, $api) {
  if ($owner == 'metatag' && $api == 'metatag') {
    return array('version' => 1);
  }
}

/**
 * Implements hook_view_preview_info_alter().
 */
function metatag_views_views_preview_info_alter(&$rows, $view) {
  $metatags = $view->display_handler->get_option('metatags');
  if (!is_array($metatags) || empty($metatags)) {
    return;
  }

  // If meta tags were found but they're not nested for the language, fix it.
  // This leaves some possibility for future versions to support translation.
  if (!empty($metatags) && !isset($metatags[LANGUAGE_NONE])) {
    $metatags = array(LANGUAGE_NONE => $metatags);
  }

  // Set the page title to be the previewed views title before fetching meta
  // tag values.
  $title = drupal_set_title();
  if ($view_title = $view->get_title()) {
    drupal_set_title($view_title);
  }

  $instance = 'view:' . $view->name;
  $options['token data']['view'] = $view;
  $values = metatag_metatags_values($instance, $metatags, $options);
  $use_views_tokens = $view->display_handler->get_option('metatags_tokenize');
  foreach ($values as $metatag => $value) {
    $metatag_info = metatag_get_info('tags', $metatag);
    // If enabled, use replacement tokens from the first Views result row.
    if ($value && $use_views_tokens) {
      $value = $view->style_plugin->tokenize_value($value, 0);
    }
    $values[$metatag] = check_plain($metatag_info['label']) . ': ' . check_plain($value);
  }
  if (!empty($values)) {
    $rows['query'][] = array(
      '<strong>' . t('Meta tags') . '</strong>',
      implode('<br />', $values),
    );
  }

  // Restore the page title.
  drupal_set_title($title);
}

/**
 * Implements hook_page_alter().
 */
function metatag_views_page_alter(&$page) {
  // By default do not add meta tags to admin pages. To enable meta tags on
  // admin pages set the 'metatag_tag_admin_pages' variable to TRUE.
  if (path_is_admin(current_path()) && !variable_get('metatag_tag_admin_pages', FALSE)) {
    return;
  }

  $view = views_get_page_view();

  // Check if Views metatags are enabled.
  if (!empty($view) && metatag_config_is_enabled('view')) {
    global $language;

    // The following is taken from views_get_page_view().
    // If a module is still putting in the display like we used to, catch that.
    if (is_subclass_of($view, 'views_plugin_display')) {
      $view = $view->view;
    }

    // Prevent Views settings from overwriting global:frontpage.
    if (drupal_is_front_page() && metatag_config_is_enabled('global:frontpage')) {
      return;
    }

    // Include only view name by default.
    $instance = 'view:' . $view->name;

    // Include display name if option is overridden.
    if (!$view->display_handler->is_defaulted('metatags')) {
      $instance = 'view:' . $view->name . ':' . $view->current_display;
    }

    // Load the meta tags for this view.
    $metatags = $view->display_handler->get_option('metatags');

    // Only proceed if there's something to work with.
    if (!empty($metatags) && is_array($metatags)) {
      // If meta tags were found but they're not nested for the language, fix
      // it. This leaves some possibility for future versions to support
      // translation.
      if (!isset($metatags[LANGUAGE_NONE])) {
        $metatags = array(LANGUAGE_NONE => $metatags);
      }

      // Translate all of the meta tags using i18n, but don't update the
      // strings.
      metatag_translate_metatags($metatags[LANGUAGE_NONE], 'metatag_views:' . $view->name . METATAG_VIEWS_CONTEXT_SEPARATOR . $view->current_display, NULL, FALSE);

      // If enabled, use replacement tokens from the first Views result row.
      if ($view->display_handler->get_option('metatags_tokenize')) {
        // If the Views output was loaded from the Views output cache, the
        // fields won't have been rendered and thus the first row tokens would
        // be empty. Therefore, in this case, we manually trigger rendering of
        // the first row.
        _metatag_views_render_first_row($view);

        foreach ($metatags as $langcode => $values) {
          foreach ($values as $metatag => $config) {
            if (!empty($config['value']) && is_scalar($config['value'])) {
              $metatags[$langcode][$metatag]['value'] = $view->style_plugin->tokenize_value($config['value'], 0);
            }
          }
        }
      }

      // Build options for meta tag rendering.
      $options = array();
      $options['token data']['view'] = $view;
      $options['language'] = $language->language;

      // The page region can be changed.
      $region = variable_get('metatag_page_region', 'content');

      // Add the metatags.
      $page[$region]['metatags'][$instance] = metatag_metatags_view($instance, $metatags, $options);
    }
  }
}

/**
 * Triggers rendering of the first row of the Views result set.
 *
 * This is used as a helper function in metatag_views_page_alter() to have the
 * necessary field tokens available.
 *
 * @param view $view
 *   The view for which result fields should be rendered.
 */
function _metatag_views_render_first_row(view $view) {
  $result = $view->result;
  if (!$result) {
    return;
  }
  // We only need the first row of the results.
  $result = array_intersect_key($result, array(0 => TRUE));
  $view->style_plugin->render_fields($result);
}