seo_meta.module

<?php
/**
 * @file seo_meta.module
 */

define('TYPE_DEFAULTS', 0);
define('TYPE_HOMEPAGE', 1);
define('TYPE_NODE',     2);
define('TYPE_VIEW',     3);
define('TYPE_TAXONOMY', 4);
define('TAG_WEIGHT',  100);

/**
 * Implements hook_config_info().
 */
function seo_meta_config_info() {
  $prefixes['seo_meta.settings'] = array(
    'label' => t('SEO Meta Tags'),
    'group' => t('Configuration'),
  );

  return $prefixes;
}

/**
 * Implements hook_permission().
 *
 */
function seo_meta_permission() {
  return array(
    'administer seo meta settings' => array(
      'title' => t('Administer SEO Meta Tags settings')
    ),
  );
}

/**
 * Implements hook_menu().
 *
 */
function seo_meta_menu() {
  $sub_path = seo_meta_menu_sub_path();
  $items = array();

  $items['admin/config/' . $sub_path . '/seo_meta'] = array(
    'type' => MENU_NORMAL_ITEM,
    'title' => 'SEO Meta Tags',
    'page callback' => 'backdrop_get_form',
    'page arguments' => array('seo_meta_settings_form'),
    'file' => 'seo_meta.admin.inc',
    'access callback' => 'user_access',
    'access arguments' => array('administer seo meta settings'),
  );

  $items['admin/config/' . $sub_path . '/seo_meta/default'] = array(
    'title' => 'Default meta tags',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => 1,
  );

  $items['admin/config/' . $sub_path . '/seo_meta/home'] = array(
    'title' => 'Front page',
    'type' => MENU_LOCAL_TASK,
    'page arguments' => array('seo_meta_settings_homepage_form'),
    'file' => 'seo_meta.admin.inc',
    'access callback' => 'user_access',
    'access arguments' => array('administer seo meta settings'),
    'weight' => 2,
  );

  $items['admin/config/' . $sub_path . '/seo_meta/home/%'] = array(
    'title' => 'Front page meta tags edit form',
    'type' => MENU_LOCAL_TASK,
    'page arguments' => array('seo_meta_custom_item_tags_edit'),
    'file' => 'seo_meta.admin.inc',
    'access arguments' => array('administer seo meta settings'),
  );

  $items['admin/config/' . $sub_path . '/seo_meta/views'] = array(
    'title' => 'Views pages',
    'type' => MENU_LOCAL_TASK,
    'page arguments' => array('seo_meta_settings_views_form'),
    'file' => 'seo_meta.admin.inc',
    'access callback' => 'user_access',
    'access arguments' => array('administer seo meta settings'),
    'weight' => 3,
  );

  $items['admin/config/' . $sub_path . '/seo_meta/views/%'] = array(
    'title' => 'Views page meta tags edit form',
    'type' => MENU_LOCAL_TASK,
    'page arguments' => array('seo_meta_custom_item_tags_edit'),
    'file' => 'seo_meta.admin.inc',
    'access arguments' => array('administer seo meta settings'),
  );

  if (module_exists('taxonomy')) {
    $items['admin/config/' . $sub_path . '/seo_meta/taxonomy'] = array(
      'title' => 'Taxonomy pages',
      'type' => MENU_LOCAL_TASK,
      'page arguments' => array('seo_meta_settings_taxonomy_form'),
      'file' => 'seo_meta.admin.inc',
      'access callback' => 'user_access',
      'access arguments' => array('administer seo meta settings'),
      'weight' => 4,
    );

    $items['admin/config/' . $sub_path . '/seo_meta/taxonomy/%'] = array(
      'title' => 'Taxonomy page meta tags edit form',
      'type' => MENU_LOCAL_TASK,
      'page arguments' => array('seo_meta_custom_item_tags_edit'),
      'file' => 'seo_meta.admin.inc',
      'access arguments' => array('administer seo meta settings'),
    );
  }

  return $items;
}

/**
 * Implements hook_form_alter().
 *
 * Adds fieldset to the node create/edit form as vertical tab.
 *
 */
function seo_meta_form_alter(&$form, $form_state, $form_id) {
  $sub_path = seo_meta_menu_sub_path();

  if (isset($form['#node']) && $form['#node']->type . '_node_form' == $form_id) {
    $config = config('seo_meta.settings');
    $excluded_types = $config->get('excluded_types');

    foreach (array_keys($excluded_types, 0, true) as $key) {
      unset($excluded_types[$key]);
    }

    if (array_key_exists($form['#node']->type, $excluded_types)) {
      return;
    }

    $site_frontpage = config_get('system.core', 'site_frontpage');
    $use_keywords = $config->get('use_keywords');

    $form['#validate'][] = 'seo_meta_form_validate';
    // edit existing node or add new
    $nid = isset($form['nid']['#value']) ? $form['nid']['#value'] : NULL;

    $saved_tags  = isset($nid) ? seo_meta_get_saved_tags(TYPE_NODE, $nid) : NULL;

    $form['seo_meta'] = array(
      '#type' => 'fieldset',
      '#title' => t('SEO meta tags'),
      '#access' => user_access('administer seo meta settings'),
      '#collapsible' => TRUE,
      '#collapsed' => FALSE,
      '#tree' => TRUE,
      '#weight' => 99,
      '#group' => 'additional_settings',
      '#attached' => array(
        'js' => array(
          'vertical-tabs' => backdrop_get_path('module', 'seo_meta') . '/js/seo_meta.admin.js',
        ),
      ),
    );

    $form['seo_meta']['#attached']['css'] = array(
      backdrop_get_path('module', 'seo_meta') . '/css/seo_meta.admin.css',
    );

    // Inform user if currently editing node is set as site front page
    if (strpos($site_frontpage, 'node/') === 0 && $form['#node']->nid == substr($site_frontpage, 5)) {
      $form['seo_meta']['note'] = array(
        '#prefix' => '<div class="messages warning">',
        '#suffix' => '</div>',
        '#markup' => t('This node is set as site <a href="@front">front page</a>, '
            . 'so for this page <a href="@link">front page meta tags</a> will be used.',
            array('@link' => url('admin/config/' . $sub_path . '/seo_meta/home'),'@front' => url('admin/config/system/site-information'))),
      );
    }
    else {
      $form['seo_meta']['enabled'] = array(
        '#type' => 'checkbox',
        '#title' => t('Define tags for page of this node'),
        '#default_value' => !empty($saved_tags),
        '#description' => t('Optional. If not enabled, <a href="@url">default values</a> will be used', array('@url' => url('admin/config/' . $sub_path . '/seo_meta'))),
      );
      $form['seo_meta']['holder'] = array(
        '#type' => 'container',
        '#parents' => array('seo_meta'),
        '#states' => array(
          'invisible' => array(
            'input[name="seo_meta[enabled]"]' => array('checked' => FALSE),
          ),
        ),
      );
      $form['seo_meta']['holder']['page_title'] = array(
        '#type' => 'textfield',
        '#title' => t('Page title'),
        '#default_value' => isset($saved_tags['page_title']) ? $saved_tags['page_title'] : '',
        '#description' => t('Description of this page to appear in the &lt;title&gt; tag for search engines search result listings.'),
      );
      if ($use_keywords) {
        $form['seo_meta']['holder']['meta_keywords'] = array(
          '#type' => 'textfield',
          '#title' => t('Meta keywords'),
          '#default_value' => isset($saved_tags['meta_keywords']) ? $saved_tags['meta_keywords'] : '',
          '#size' => 120,
          '#maxlength' => 255,
          '#description' => t('Comma separated list of keywords (no more than 10 keyword phrases).'),
        );
      }
      $form['seo_meta']['holder']['meta_description'] = array(
        '#type' => 'textarea',
        '#title' => t('Meta description'),
        '#default_value' => isset($saved_tags['meta_description']) ? $saved_tags['meta_description'] : '',
        '#rows' => 3,
        '#description' => t('One or two sentence described this page (160-240 characters max. without any HTML markup.)'),
      );

      $form['seo_meta']['holder']['more'] = array(
        '#type' => 'fieldset',
        '#title' => t('More'),
        '#collapsible' => TRUE,
        '#collapsed' => TRUE,
      );
      $form['seo_meta']['holder']['more']['meta_robots'] = array(
        '#type' => 'checkboxes',
        '#title' => t('Meta robots'),
        '#options' => backdrop_map_assoc(array('NOINDEX', 'NOFOLLOW', 'NOARCHIVE', 'NOODP', 'NOYDIR', 'NOSNIPPET')),
        '#default_value' => isset($saved_tags['meta_robots']) ? unserialize($saved_tags['meta_robots']) : array(),
        '#description' => t('Search engines assume "INDEX" and "FOLLOW" unless these are specifically disabled above.'),
        '#attributes' => array('class' => array('seo-meta')),
      );
      $form['seo_meta']['holder']['more']['rel_canonical'] = array(
        '#type' => 'textfield',
        '#title' => t('Canonical URL'),
        '#default_value' => isset($saved_tags['rel_canonical']) ? $saved_tags['rel_canonical'] : '',
        '#description' => t("Use a relative URL without the initial slash for current default domain or full URL."
          . " By default (if no value) this will automatically use URL of this page."),
      );

      $form['seo_meta']['holder']['open_graph'] = array(
        '#type' => 'fieldset',
        '#title' => t('Open Graph'),
        '#collapsible' => TRUE,
        '#collapsed' => TRUE,
      );
      $form['seo_meta']['holder']['open_graph']['meta_og_title'] = array(
        '#type' => 'textfield',
        '#title' => t('Open Graph title'),
        '#default_value' => isset($saved_tags['meta_og_title']) ? $saved_tags['meta_og_title'] : '',
        '#description' => t('The title of this page/article as rendered on Facebook (without any branding such as your site name.)'),
      );
      $form['seo_meta']['holder']['open_graph']['meta_og_description'] = array(
        '#type' => 'textarea',
        '#title' => t('Open Graph description'),
        '#default_value' => isset($saved_tags['meta_og_description']) ? $saved_tags['meta_og_description'] : '',
        '#rows' => 3,
        '#description' => t('A brief description of the content, usually between 2 and 4 sentences (160-240 characters max. without any HTML markup). This will displayed below the title of the post on Facebook.'),
      );
      $form['seo_meta']['holder']['open_graph']['meta_og_type'] = array(
        '#title' => t('Open Graph type'),
        '#type' => 'select',
        '#options' => array(
          '' => t('Select type'),
          'website' => 'website',
          'article' => 'article',
          'product' => 'product',
          'profile' => 'profile',
        ),
        '#default_value' => isset($saved_tags['meta_og_type']) ? $saved_tags['meta_og_type'] : '',
        '#description' => t('The type of media of your content.'),
      );
      $form['seo_meta']['holder']['open_graph']['meta_og_image_fid'] = array(
        '#title' => t('Upload image that appears when someone shares the content to Facebook.'),
        '#type' => 'managed_file',
        '#upload_location' => 'public://' . $config->get('meta_og_images_dir'),
        '#default_value' => isset($saved_tags['meta_og_image_fid']) ? $saved_tags['meta_og_image_fid'] : '',
        '#upload_validators' => array(
          'file_validate_extensions' => array('gif png jpg jpeg'),
          'file_validate_size' => array(file_upload_max_size()),
        ),
      );
      $form['seo_meta']['holder']['open_graph']['meta_og_site_name'] = array(
        '#type' => 'textfield',
        '#title' => t('Site name'),
        '#default_value' => isset($saved_tags['meta_og_site_name']) ? $saved_tags['meta_og_site_name'] : '',
        '#description' => t('The name of your website (such as IMDb, not imdb.com).'),
      );

      $form['seo_meta']['holder']['twitter'] = array(
        '#type' => 'fieldset',
        '#title' => t('Twitter'),
        '#collapsible' => TRUE,
        '#collapsed' => TRUE,
      );
      $form['seo_meta']['holder']['twitter']['meta_tw_card'] = array(
        '#title' => t('Twitter Card type'),
        '#type' => 'select',
        '#options' => array(
          '' => t('Select card type'),
          'summary' => 'Summary Card',
          'summary_large_image' => 'Summary Card with Large Image',
          'photo' => 'Photo Card',
          'gallery' => 'Gallery Card',
          'product' => 'Product Card',
        ),
        '#default_value' => isset($saved_tags['meta_tw_card']) ? $saved_tags['meta_tw_card'] : '',
        '#description' => t('The card type.'),
      );
      $form['seo_meta']['holder']['twitter']['meta_tw_site'] = array(
        '#type' => 'textfield',
        '#title' => t('Site'),
        '#default_value' => isset($saved_tags['meta_tw_site']) ? $saved_tags['meta_tw_site'] : '',
        '#description' => t('@username of website.'),
      );
      $form['seo_meta']['holder']['twitter']['meta_tw_creator'] = array(
        '#type' => 'textfield',
        '#title' => t('Creator'),
        '#default_value' => isset($saved_tags['meta_tw_creator']) ? $saved_tags['meta_tw_creator'] : '',
        '#description' => t('@username of content creator.'),
      );
      $form['seo_meta']['holder']['twitter']['div'] = array(
        '#markup' => '<div class="description">' . t('Note: When the Twitter card processor looks for tags on your page,
           it first checks for the Twitter property, and if not present,
           falls back to the supported Open Graph property (for example site URL, title, description and image).
           This allows for both to be defined on the page independently, and minimizes
           the amount of duplicate markup required to describe your content and experience.') . '</div>',
      );
    }
  }
}

/**
 * Implements hook_validate() for node edit form.
 *
 * @todo per field validation.
 */

function seo_meta_form_validate($form, &$form_state) {
  if (isset($form['#node']) && is_object($form['#node'])) {
    if (isset($form_state['values']['seo_meta']['enabled']) && $form_state['values']['seo_meta']['enabled'] == 1) {
      $seo_meta_values = $form_state['values']['seo_meta'];

      $empty_tags = (
        empty($seo_meta_values['page_title']) &&
        empty($seo_meta_values['meta_keywords']) &&
        empty($seo_meta_values['meta_description'])) ? TRUE : FALSE;

      $checked_boxes = FALSE;

      foreach ($seo_meta_values['more']['meta_robots'] as $tag => $value) {
        if (is_string($value)) {
          $checked_boxes = TRUE;
        }
      }

      if ($empty_tags && !$checked_boxes) {
        form_set_error('',
          t('Please fill in some fields in the form "SEO meta tags" or uncheck checkbox "Define tags for page of this node".'));
      }

      if (backdrop_strlen($seo_meta_values['meta_description']) > 254) {
        form_set_error('seo_meta][meta_description',
          t('Text you trying fill in to field "Meta description" (under "SEO meta tags" tab) is too long!'));
      }
      if (backdrop_strlen($seo_meta_values['open_graph']['meta_og_description']) > 254) {
        form_set_error('seo_meta][open_graph][meta_og_description',
          t('Text you trying fill in to field "Open Graph description" (under "SEO meta tags" tab > "Open Graph") is too long!'));
      }
    }
  }
}

/**
 * Helper for collect data from node
 *
 * @param Node $node
 * @return array $data (key => value when insert/update)
 */
function seo_meta_get_node_data(Node $node) {
  $config   = config('seo_meta.settings');
  $keywords = $config->get('use_keywords') ? trim($node->seo_meta['meta_keywords']) : '';
  return array(
    'ce_type'             => TYPE_NODE,
    'ce_id'               => $node->nid,
    'path_alias'          => trim($node->path['alias']),
    'langcode'	          => isset($node->langcode) ? $node->langcode : LANGUAGE_NONE,
    'page_title'          => trim($node->seo_meta['page_title']),
    'meta_keywords'       => $keywords,
    'meta_description'    => trim($node->seo_meta['meta_description']),
    'meta_robots'         => serialize($node->seo_meta['more']['meta_robots']),
    'rel_canonical'       => trim($node->seo_meta['more']['rel_canonical']),
    'meta_og_title'       => trim($node->seo_meta['open_graph']['meta_og_title']),
    'meta_og_description' => trim($node->seo_meta['open_graph']['meta_og_description']),
    'meta_og_type'        => $node->seo_meta['open_graph']['meta_og_type'],
    'meta_og_image_fid'   => $node->seo_meta['open_graph']['meta_og_image_fid'],
    'meta_og_site_name'   => trim($node->seo_meta['open_graph']['meta_og_site_name']),
    'meta_tw_card'        => $node->seo_meta['twitter']['meta_tw_card'],
    'meta_tw_site'        => trim($node->seo_meta['twitter']['meta_tw_site']),
    'meta_tw_creator'     => trim($node->seo_meta['twitter']['meta_tw_creator']),
    'uid'                 => $node->uid,
    'changed'             => time(),
  );
}

/**
 * Implements hook_node_presave().
 */
function seo_meta_node_presave(Node $node) {
  if (isset($node->seo_meta['enabled']) && $node->seo_meta['enabled'] == 1) {
    // save OG image as permanent file
    if (!empty($node->seo_meta['open_graph']['meta_og_image_fid'])) {
      $file = file_load($node->seo_meta['open_graph']['meta_og_image_fid']);
      $file->status = FILE_STATUS_PERMANENT;
      file_save($file);
      file_usage_add($file, 'file', 'file', $file->fid);
    }
  }
}

/**
 * Implements hook_node_insert().
 */
function seo_meta_node_insert(Node $node) {
  if (isset($node->seo_meta['enabled']) && $node->seo_meta['enabled'] == 1) {
    $data = seo_meta_get_node_data($node);
    seo_meta_record_insert($data);
  }
}

/**
 * Implements hook_node_update().
 */
function seo_meta_node_update(Node $node) {
  $result = db_select('seo_meta', 'sm')
      ->fields('sm')
      ->condition('ce_type', TYPE_NODE, '=')
      ->condition('ce_id', $node->nid, '=')
      ->execute()
      ->fetchObject();

  $sm_id = is_object($result) ? $sm_id = $result->sm_id : NULL;

  if (isset($node->seo_meta['enabled']) && $node->seo_meta['enabled'] == 1) {
    $data = seo_meta_get_node_data($node);

    if ($sm_id) {
      seo_meta_record_update(TYPE_NODE, $node->nid, $data);
    }
    else {
      seo_meta_record_insert($data);
    }
  }
  else {
    if ($sm_id) {
      seo_meta_record_delete(TYPE_NODE, $node->nid);
    }
  }
}

/**
 * Implements hook_node_predelete().
 */
function seo_meta_node_predelete(Node $node) {
  seo_meta_record_delete(TYPE_NODE, $node->nid);
}

/**
 * Implements hook_html_head_alter().
 */
function seo_meta_html_head_alter(&$head_elements) {
  $head_elements = array_reverse($head_elements);
  $config = config('seo_meta.settings');
  $fix_favicon = $config->get('fix_favicon');
  $tmp_arr = array();

  foreach ($head_elements as $key => $element) {
    if (isset($element['#attributes']['rel']) && $element['#attributes']['rel'] == 'canonical') {
      // deduplicate system canonical
      $tmp_arr[] = $head_elements[$key];
      if (count($tmp_arr)> 1) {
        unset($head_elements[$key]);
      }
    }

    if ($fix_favicon) {
      if (isset($element['#attributes']['rel']) && $element['#attributes']['rel'] == 'shortcut icon') {
        $head_elements[$key]['#attributes']['type'] = 'image/x-icon';
        $head_elements[$key]['#attributes']['rel'] = 'icon';
      }
    }
  }
}

/**
 *
 * @global object $language
 * @return object $caller or FALSE for admin path
 */
function seo_meta_caller() {
  if (path_is_admin($_GET['q'])) {
    return FALSE;
  }

  global $language;
  $caller = new stdClass();
  $caller->langcode = $language->langcode;

  if (arg(0) == 'node' && is_numeric(arg(1))) {
    $caller->type = TYPE_NODE;
    $caller->id = arg(1);
  }

  if (arg(0) == 'taxonomy' && arg(1) == 'term' && arg(2)) {
    $term_name = taxonomy_term_load(arg(2))->name;
    $caller->type = TYPE_TAXONOMY;
    $caller->id = $term_name;
  }

  if (function_exists('views_get_page_view') && views_get_page_view()){
    $view_name = views_get_page_view()->name;
    $caller->type = TYPE_VIEW;
    $caller->id = $view_name;
  }
  // front(home)page as type should overwrite original content entry (node, view...) if it defined as FP
  if (backdrop_is_front_page()) {
    $caller->is_front = TRUE;
    $caller->type = TYPE_HOMEPAGE;
    $caller->id = $caller->langcode != 'und' ? $caller->langcode : '';
  }
  // fix for pages with undefined id and type, user login for example
  $caller->id = isset($caller->id) ? $caller->id : $caller->langcode;
  $caller->type = isset($caller->type) ? $caller->type : TYPE_DEFAULTS;

  return $caller;
}

/**
 * Get tags associated with content entry -
 * node or other page.
 *
 * @params string $ce_type -
 *   content entry type code
 * @params string $ce_id
 *   content entry type id
 * @return array of tags or false
 *
 */
function seo_meta_get_saved_tags($ce_type, $ce_id) {
  $result = db_select('seo_meta', 'sm')
      ->fields('sm', array(
        'page_title',
        'meta_keywords',
        'meta_description',
        'meta_robots',
        'rel_canonical',
        'meta_tw_card',
        'meta_tw_site',
        'meta_tw_creator',
        'meta_og_type',
        'meta_og_title',
        'meta_og_description',
        'meta_og_site_name',
        'meta_og_image_fid',
        )
      )
      ->condition('ce_type', $ce_type, '=')
      ->condition('ce_id', $ce_id, '=')
      ->execute()
      ->fetchAssoc();
  return $result;
}

/**
 * Get saved default tags
 *
 * @params string langcode
 *
 * @return array of tags or false
 *
 */
function seo_meta_get_saved_defaults($langcode) {
  $result = db_select('seo_meta', 'sm')
      ->fields('sm', array(
        'meta_keywords',
        'meta_description',
        'meta_robots',
        'meta_tw_card',
        'meta_tw_site',
        'meta_tw_creator',
        'meta_og_type',
        'meta_og_title',
        'meta_og_description',
        'meta_og_site_name',
        'meta_og_image_fid',
        )
      )
      ->condition('ce_type', TYPE_DEFAULTS, '=')
      ->condition('ce_id', $langcode, '=')                // CHECK !!!!
      ->execute()
      ->fetchAssoc();
  return $result;
}

/**
 * Insert to table new content entry tags
 *
 * @param array $data
 */
function seo_meta_record_insert($data = array()) {
  db_insert('seo_meta')
      ->fields($data)
      ->execute();
}

/**
 * Update content entry tags
 *
 * @param string $ce_type
 * @param string $ce_id
 * @param array $data
 */
function seo_meta_record_update($ce_type = '', $ce_id = '', $data = array()) {
  db_update('seo_meta')
      ->fields($data)
      ->condition('ce_type', $ce_type, '=')
      ->condition('ce_id', $ce_id, '=')
      ->execute();
}

/**
 * Remove content entry tags
 *
 * @param string $ce_type
 * @param string $ce_id
 */
function seo_meta_record_delete($ce_type = '', $ce_id = '') {
  $result = db_select('seo_meta', 'sm')
      ->fields('sm')
      ->condition('ce_type', $ce_type, '=')
      ->condition('ce_id', $ce_id, '=')
      ->execute()
      ->fetchObject();

  if (is_object($result)) {
    $sm_id = $result->sm_id;
    $sm_fid = $result->meta_og_image_fid;

    if (!empty($sm_fid)) {
      file_delete($sm_fid);
    }

    db_delete('seo_meta')
        ->condition('sm_id', $sm_id)
        ->execute();
  }
}
/**
 * Prepare and add to render saved or default meta tags
 *
 */
function seo_meta_build_page_tags() {
  $secure = config_get('system.core', 'canonical_secure') == 1 ? TRUE : FALSE;
  $caller = seo_meta_caller();
  $weight = TAG_WEIGHT;

  if (!$caller) {
    return;
  }

  $saved_tags = seo_meta_get_saved_tags($caller->type, $caller->id);

  if (!empty($saved_tags)) {
    $tags = $saved_tags;
  }
  else {
    $tags = seo_meta_get_saved_defaults($caller->langcode);
  }

  if (!empty($tags)) {
    foreach ($tags as $tag => $value) {
      if (!empty($value)) {
        $excluded_tags = array('page_title', 'rel_canonical');
        if (in_array($tag, $excluded_tags)) {
          continue;
        }

        if ($tag == 'meta_robots') {
          $array_meta_robots = unserialize($value);
          $meta_robots       = '';

          foreach ($array_meta_robots as $key => $name) {
            if ($name) {
              $meta_robots .= strtolower($key) . ', ';
            }
          }
          $value = rtrim($meta_robots, ', ');

          if ($value == '') {
            continue;
          }
        }

        if ($tag == 'meta_og_image_fid') {
          $image = file_load($value);
          $value = is_object($image) ? file_create_url($image->uri) : '';

          if (!empty($value) && $secure) {
            $value = str_replace('http://', 'https://', $value);
          }

          $attribute = 'property';
          $tag = str_replace('_fid', '', $tag);
        }

        if (strpos($tag, 'meta_og') === FALSE) {
          $attribute = 'name';
          if (strpos($tag, 'meta_tw') === FALSE) {
            $weight = $weight + 10;
            $tag = str_replace('meta_', '', $tag);
          }
          else {
            $weight = $weight + 11;
            $tag = str_replace('meta_tw_', 'twitter:', $tag);
          }
        }
        else {
          $attribute = 'property';
          $weight = $weight + 75;
          $tag = str_replace('meta_og_', 'og:', $tag);
        }

        $element = array(
          '#tag' => 'meta',
          '#attributes' => array(
            $attribute => $tag,
            'content' => $value,
          ),
          '#weight' => $weight,
        );
        backdrop_add_html_head($element, 'seo_meta_' . $tag);
      }
    }
  }
}

function seo_meta_preprocess_page(&$variables) {
  // not for admin pages
  if (path_is_admin($_GET['q'])) {
    return FALSE;
  }

  global $base_url;

  $is_node_page = arg(0) == 'node' && is_numeric(arg(1));

  $status = backdrop_get_http_header('status');
  // awoid non-custom http status errors pages
  if (in_array($status, array('404 Not Found', '403 Forbidden')) && !$is_node_page) {
    return FALSE;
  }

  $config         = config('seo_meta.settings');
  $use_og_url     = $config->get('use_og_url');
  $caller         = seo_meta_caller();
  $caller_type    = is_object($caller) ? $caller->type : NULL;
  $seo_meta_title = is_object($caller) ? seo_meta_get_tag_value('page_title', $caller->type, $caller->id) : '';
  $head_site_name = $variables['head_title_array']['name'];

  // Add page title
  if (!empty($seo_meta_title) && $seo_meta_title != 'und') {
    $page_title = $seo_meta_title;
  }
  else {
    $page_title = isset($variables['head_title_array']['title']) ? $variables['head_title_array']['title'] : '';
  }

  if (!empty($page_title)) {
    if ($config->get('append_site_name')) {
      $site_name_divider = $config->get('site_name_divider');
      $variables['head_title'] = $page_title . ' ' . $site_name_divider . ' ' . $head_site_name;
    }
    else {
      $variables['head_title'] = $page_title;
    }
  }

  // Add canonical URL to views and homepages overriding
  if ($caller_type == TYPE_VIEW) {
    $view_url = url(current_path(), array('absolute' => TRUE));
    $canonical_url =  seo_meta_canonical_url($view_url);
  }

  if ($caller_type == TYPE_HOMEPAGE) {
    $canonical_url = seo_meta_canonical_url($base_url);
  }

  if (!empty($canonical_url)) {
    backdrop_add_html_head_link(array('rel' => 'canonical', 'href' => $canonical_url));
  }

  // add og:url if selected in default settings
  if ($use_og_url) {
    $current_path = current_path();
    $secure = config_get('system.core', 'canonical_secure') == 1 ? TRUE : FALSE;

    if ($caller_type == TYPE_HOMEPAGE) {
      $current_url = url('/', array('absolute' => TRUE, 'https' => $secure));
    }
    else {
      $current_url = url($current_path, array('absolute' => TRUE, 'https' => $secure));
    }

    backdrop_add_html_head(
      array(
        '#tag' => 'meta',
        '#attributes' => array(
          'property' => 'og:url',
          'content' => $current_url,
        ),
        '#weight' => TAG_WEIGHT + 65,
      ),
      'seo_meta_url'
    );
  }
  // Add rest of meta tags
  seo_meta_build_page_tags();
}

/**
 * Redefine system canonical if needed
 *
 * @return string $canonical_url
 */
function seo_meta_canonical_url($system_canonical = '') {
  global $base_url;
  $canonical_secure   = config_get('system.core', 'canonical_secure');
  $proto              = $canonical_secure ? 'https://' : 'http://';
  $path               = parse_url($system_canonical, PHP_URL_PATH);
  $host               = parse_url($base_url, PHP_URL_HOST);
  $base_canonical_url = rtrim(config_get('seo_meta.settings', 'base_canonical_url'), '/');
  $caller             = seo_meta_caller();

  // If base canonical URL is not defined by default
  if ($base_canonical_url == '') {
    $base_canonical_url = $host;
  }

  $canonical_url = $proto . $base_canonical_url . $path;

  // Check if canonical URL redefined in content entry
  if (is_object($caller)) {

    $rel_canonical = seo_meta_get_tag_value('rel_canonical', $caller->type, $caller->id);

    if ($rel_canonical != '') {

      $canonical_url = strpos($rel_canonical, 'http') !== 0 ? $proto . $base_canonical_url . '/' . $rel_canonical : $rel_canonical;
    }
  }

  return $canonical_url;
}

/**
 * Helper for getting value of page title
 * or canonical URL for content entry
 *
 * @param string $tag_name
 * @param string $ce_type
 * @param string $ce_id
 * @return string
 */
function seo_meta_get_tag_value($tag_name = '', $ce_type = '', $ce_id = '') {
  $tag_value = '';

  $result = db_select('seo_meta', 'sm')
      ->fields('sm', array($tag_name))
      ->condition('ce_type', $ce_type, '=')
      ->condition('ce_id', $ce_id, '=')
      ->execute()
      ->fetchField();

  if (!empty($result)) {
    $tag_value = $result;
  }

  return $tag_value;
}

/**
 * Helper for BD >= 1.6.0 - menu sub-path was changed from 'search' to 'metadata;
 * @return string
 */
function seo_meta_menu_sub_path() {
  $sub_path = 'search';
  $backdrop_version = explode('.', BACKDROP_VERSION);
  if ($backdrop_version[0] == 1 && $backdrop_version[1] > 5) {
    $sub_path = 'metadata';
  }

  return $sub_path;
}