<?php

/**
 * @file
 * Logs and displays content statistics for a site.
 */

use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Entity\Display\EntityViewDisplayInterface;
use Drupal\node\NodeInterface;

/**
 * Implements hook_help().
 */
function statistics_help($path, $arg) {
  switch ($path) {
    case 'admin/help#statistics':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The Statistics module shows you how often content is viewed. This is useful in determining which pages of your site are most popular. For more information, see <a href="!statistics_do">the online documentation for the Statistics module</a>.', array('!statistics_do' => 'https://drupal.org/documentation/modules/statistics/')) . '</p>';
      $output .= '<h3>' . t('Uses') . '</h3>';
      $output .= '<dl>';
      $output .= '<dt>' . t('Displaying popular content') . '</dt>';
      $output .= '<dd>' . t('The module includes a <em>Popular content</em> block that displays the most viewed pages today and for all time, and the last content viewed. To use the block, enable <em>Count content views</em> on the <a href="!statistics-settings">statistics settings page</a>, and then you can enable and configure the block on the <a href="!blocks">Block layout page</a>.', array('!statistics-settings' => \Drupal::url('statistics.settings'), '!blocks' => \Drupal::url('block.admin_display'))) . '</dd>';
      $output .= '<dt>' . t('Page view counter') . '</dt>';
      $output .= '<dd>' . t('The Statistics module includes a counter for each page that increases whenever the page is viewed. To use the counter, enable <em>Count content views</em> on the <a href="!statistics-settings">statistics settings page</a>, and set the necessary <a href="!permissions">permissions</a> (<em>View content hits</em>) so that the counter is visible to the users.', array('!statistics-settings' => \Drupal::url('statistics.settings'), '!permissions' => \Drupal::url('user.admin_permissions', array(), array('fragment' => 'module-statistics')))) . '</dd>';
      $output .= '</dl>';
      return $output;
    case 'admin/config/system/statistics':
      return '<p>' . t('Settings for the statistical information that Drupal will keep about the site.') . '</p>';
  }
}

/**
 * Implements hook_permission().
 */
function statistics_permission() {
  return array(
    'administer statistics' => array(
      'title' => t('Administer statistics'),
    ),
    'view post access counter' => array(
      'title' => t('View content hits'),
    ),
  );
}

/**
 * Implements hook_node_view().
 */
function statistics_node_view(EntityInterface $node, EntityViewDisplayInterface $display, $view_mode) {
  if (!$node->isNew() && $view_mode == 'full' && node_is_page($node) && empty($node->in_preview)) {
    $node->content['statistics_content_counter']['#attached']['library'][] = array('statistics', 'drupal.statistics');
    $settings = array('data' => array('nid' => $node->id()), 'url' => url(drupal_get_path('module', 'statistics') . '/statistics.php'));
    $node->content['statistics_content_counter']['#attached']['js'][] = array(
      'data' => array('statistics' => $settings),
      'type' => 'setting',
    );
  }
}

/**
 * Implements hook_node_links_alter().
 */
function statistics_node_links_alter(array &$node_links, NodeInterface $entity, array &$context) {
  if ($context['view_mode'] != 'rss') {
    if (\Drupal::currentUser()->hasPermission('view post access counter')) {
      $statistics = statistics_get($entity->id());
      if ($statistics) {
        $links['statistics_counter']['title'] = format_plural($statistics['totalcount'], '1 view', '@count views');
        $node_links['statistics'] = array(
          '#theme' => 'links__node__statistics',
          '#links' => $links,
          '#attributes' => array('class' => array('links', 'inline')),
        );
      }
    }
  }
}

/**
 * Implements hook_menu_link_defaults().
 */
function statistics_menu_link_defaults() {
  $links['statistics.admin.config.system.statistics'] = array(
    'link_title' => 'Statistics',
    'description' => 'Control details about what and how your site logs content statistics.',
    'route_name' => 'statistics.settings',
    'parent' => 'system.admin.config.system',
    'weight' => -15,
  );
  return $links;
}

/**
 * Implements hook_cron().
 */
function statistics_cron() {
  $statistics_timestamp = \Drupal::state()->get('statistics.day_timestamp') ?: 0;

  if ((REQUEST_TIME - $statistics_timestamp) >= 86400) {
    // Reset day counts.
    db_update('node_counter')
      ->fields(array('daycount' => 0))
      ->execute();
    \Drupal::state()->set('statistics.day_timestamp', REQUEST_TIME);
  }

  // Calculate the maximum of node views, for node search ranking.
  \Drupal::state()->set('statistics.node_counter_scale', 1.0 / max(1.0, db_query('SELECT MAX(totalcount) FROM {node_counter}')->fetchField()));
}

/**
 * Returns the most viewed content of all time, today, or the last-viewed node.
 *
 * @param string $dbfield
 *   The database field to use, one of:
 *   - 'totalcount': Integer that shows the top viewed content of all time.
 *   - 'daycount': Integer that shows the top viewed content for today.
 *   - 'timestamp': Integer that shows only the last viewed node.
 * @param int $dbrows
 *   The number of rows to be returned.
 *
 * @return SelectQuery|FALSE
 *   A query result containing the node ID, title, user ID that owns the node,
 *   and the username for the selected node(s), or FALSE if the query could not
 *   be executed correctly.
 */
function statistics_title_list($dbfield, $dbrows) {
  if (in_array($dbfield, array('totalcount', 'daycount', 'timestamp'))) {
    $query = db_select('node_field_data', 'n');
    $query->addTag('node_access');
    $query->join('node_counter', 's', 'n.nid = s.nid');
    $query->join('users', 'u', 'n.uid = u.uid');

    return $query
      ->fields('n', array('nid', 'title'))
      ->fields('u', array('uid', 'name'))
      ->condition($dbfield, 0, '<>')
      ->condition('n.status', 1)
      // @todo This should be actually filtering on the desired node status
      //   field language and just fall back to the default language.
      ->condition('n.default_langcode', 1)
      ->orderBy($dbfield, 'DESC')
      ->range(0, $dbrows)
      ->execute();
  }
  return FALSE;
}


/**
 * Retrieves a node's "view statistics".
 *
 * @param $nid
 *   The node ID.
 *
 * @return
 *   An associative array containing:
 *   - totalcount: Integer for the total number of times the node has been
 *     viewed.
 *   - daycount: Integer for the total number of times the node has been viewed
 *     "today". For the daycount to be reset, cron must be enabled.
 *   - timestamp: Integer for the timestamp of when the node was last viewed.
 */
function statistics_get($nid) {

  if ($nid > 0) {
    // Retrieve an array with both totalcount and daycount.
    return db_query('SELECT totalcount, daycount, timestamp FROM {node_counter} WHERE nid = :nid', array(':nid' => $nid), array('target' => 'slave'))->fetchAssoc();
  }
}

/**
 * Generates a link to a path, truncating the displayed text to a given width.
 *
 * @param string $path
 *   The path to generate the link for.
 * @param int $width
 *   The width to set the displayed text of the path.
 *
 * @return string
 *   A string as a link, truncated to the width, linked to the given $path.
 */
function _statistics_link($path, $width = 35) {
  $title = \Drupal::service('path.alias_manager')->getPathAlias($path);
  $title = truncate_utf8($title, $width, FALSE, TRUE);
  return l($title, $path);
}

/**
 * Formats an item for display, including both the item title and the link.
 *
 * @param string $title
 *   The text to link to a path; will be truncated to a maximum width of 35.
 * @param string $path
 *   The path to link to; will default to '/'.
 *
 * @return string
 *   An HTML string with $title linked to the $path.
 */
function _statistics_format_item($title, $path) {
  $path = ($path ? $path : '/');
  $output  = ($title ? "$title<br />" : '');
  $output .= _statistics_link($path);
  return $output;
}

/**
 * Implements hook_node_predelete().
 */
function statistics_node_predelete(EntityInterface $node) {
  // clean up statistics table when node is deleted
  db_delete('node_counter')
    ->condition('nid', $node->id())
    ->execute();
}

/**
 * Implements hook_ranking().
 */
function statistics_ranking() {
  if (\Drupal::config('statistics.settings')->get('count_content_views')) {
    return array(
      'views' => array(
        'title' => t('Number of views'),
        'join' => array(
          'type' => 'LEFT',
          'table' => 'node_counter',
          'alias' => 'node_counter',
          'on' => 'node_counter.nid = i.sid',
        ),
        // Inverse law that maps the highest view count on the site to 1 and 0
        // to 0. Note that the CAST here is necessary for PostgreSQL, because
        // the PostgreSQL PDO driver sometimes puts values in as strings
        // instead of numbers in complex expressions like this.
        'score' => '2.0 - 2.0 / (1.0 + node_counter.totalcount * (CAST (:statistics_scale AS DECIMAL(10,4))))',
        'arguments' => array(':statistics_scale' => \Drupal::state()->get('statistics.node_counter_scale') ?: 0),
      ),
    );
  }
}

/**
 * Implements hook_preprocess_HOOK() for block templates.
 */
function statistics_preprocess_block(&$variables) {
  if ($variables['configuration']['module'] == 'statistics') {
    $variables['attributes']['role'] = 'navigation';
  }
}

/**
 * Implements hook_block_alter().
 *
 * Removes the "popular" block from display if the module is not configured
 * to count content views.
 */
function statistics_block_alter(&$definitions) {
  $statistics_count_content_views = \Drupal::config('statistics.settings')->get('count_content_views');
  if (empty($statistics_count_content_views)) {
    unset($definitions['statistics_popular_block']);
  }
}