<?php
// $Id$

/*
 * @file
 * Drupal Module: GoogleAnalytics
 * Adds the required Javascript to the bottom of all your Drupal pages
 * to allow tracking by the Google Analytics statistics package.
 *
 * @author: Mike Carter <www.ixis.co.uk/contact>
 */

define('GA_TRACKFILES_EXTENSIONS', '7z|aac|avi|csv|doc|exe|flv|gif|gz|jpe?g|js|mp(3|4|e?g)|mov|pdf|phps|png|ppt|rar|sit|tar|torrent|txt|wma|wmv|xls|xml|zip');

function googleanalytics_help($path, $arg) {
  switch ($path) {
    case 'admin/settings/googleanalytics':
      return t('<a href="@ga_url">Google Analytics</a> is a free statistics package based on the excellent Urchin system. This module provides services to better integrate Drupal with Google Analytics.', array('@ga_url' => 'http://www.google.com/analytics/'));
  }
}

function googleanalytics_perm() {
  return array('administer google analytics', 'opt-in or out of tracking', 'use PHP for tracking visibility');
}

function googleanalytics_menu() {
  $items['admin/settings/googleanalytics'] = array(
    'title' => 'Google Analytics',
    'description' => 'Configure the settings used to generate your Google Analytics tracking code.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('googleanalytics_admin_settings_form'),
    'access arguments' => array('administer google analytics'),
    'file' => 'googleanalytics.admin.inc',
    'type' => MENU_NORMAL_ITEM,
  );

  return $items;
}

function googleanalytics_init() {
  global $user;

  $id = variable_get('googleanalytics_account', '');

  // 1. Check if the GA account number has a value.
  // 2. Track page views based on visibility value.
  // 3. Check if we should track the currently active user's role.
  if (!empty($id) && _googleanalytics_visibility_pages() && _googleanalytics_visibility_user($user)) {
    $scope = variable_get('googleanalytics_js_scope', 'footer');

    // Should a local cached copy of ga.js be used?
    $js_file = 'ga.js';
    $url = 'http://www.google-analytics.com/'. $js_file;

    if (variable_get('googleanalytics_cache', 0) && (variable_get('file_downloads', FILE_DOWNLOADS_PUBLIC) == FILE_DOWNLOADS_PUBLIC) && $source = _googleanalytics_cache($url)) {
      drupal_add_js($source, 'module', $scope);
    }
    else {
      $script = 'var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");';
      $script .= 'document.write(unescape("%3Cscript src=\'" + gaJsHost + "google-analytics.com/'. $js_file .'\' type=\'text/javascript\'%3E%3C/script%3E"));';
      drupal_add_js($script, 'inline', $scope);
    }

    // Add link tracking.
    $link_settings = array();
    if ($track_outgoing = variable_get('googleanalytics_trackoutgoing', 1)) {
      $link_settings['trackOutgoing'] = $track_outgoing;
    }
    if ($track_mailto = variable_get('googleanalytics_trackmailto', 1)) {
      $link_settings['trackMailto'] = $track_mailto;
    }
    if (($track_download = variable_get('googleanalytics_trackfiles', 1)) && ($trackfiles_extensions = variable_get('googleanalytics_trackfiles_extensions', GA_TRACKFILES_EXTENSIONS))) {
      $link_settings['trackDownload'] = $track_download;
      $link_settings['trackDownloadExtensions'] = $trackfiles_extensions;
    }
    if (!empty($link_settings)) {
      drupal_add_js(array('googleanalytics' => $link_settings), 'setting', 'header');
      drupal_add_js(drupal_get_path('module', 'googleanalytics') .'/googleanalytics.js', 'module', $scope);
    }

    // Custom tracking.
    if (variable_get('googleanalytics_trackadsense', FALSE)) {
      drupal_add_js('window.google_analytics_uacct = ' . drupal_to_js($id) . ';', 'inline', 'header');
    }
  }
}

/**
 * Implementation of hook_footer() to insert Javascript at the end of the page.
 */
function googleanalytics_footer($main = 0) {
  global $user;

  $id = variable_get('googleanalytics_account', '');

  if (!empty($id) && _googleanalytics_visibility_pages() && _googleanalytics_visibility_user($user)) {

    // Add User profile segmentation values.
    if (is_array($profile_fields = variable_get('googleanalytics_segmentation', '')) && ($user->uid > 0)) {

      $p = module_invoke('profile', 'load_profile', $user);

      $fields = array();
      foreach ($profile_fields as $field => $title) {
        $value = $user->$field;

        if (is_array($value)) {
          $value = implode(',', $value);
        }

        $fields[$field] = $value;
      }

      // Only show segmentation variable if there are specified fields.
      $segmentation = '';
      if (count($fields) > 0) {
        $segmentation = 'pageTracker._setVar('. drupal_to_js(implode(':', $fields)) .');';
      }
    }

    // Site search tracking support.
    $url_custom = '';
    if (module_exists('search') && variable_get('googleanalytics_site_search', FALSE) && arg(0) == 'search' && $keys = search_get_keys()) {
      $url_custom = drupal_to_js(url('search/'. arg(1), array('query' => 'search='. $keys)));
    }

    // If this node is a translation of another node, pass the original
    // node instead.
    if (module_exists('translation') && variable_get('googleanalytics_translation_set', 0)) {
      // Check we have a node object, it supports translation, and its
      // translated node ID (tnid) doesn't match its own node ID.
      $node = menu_get_object();
      if ($node && translation_supported_type($node->type) && isset($node->tnid) && ($node->tnid != $node->nid)) {
        $source_node = node_load($node->tnid);
        $languages = language_list();
        $url_custom = drupal_to_js(url('node/'. $source_node->nid, array('language' => $languages[$source_node->language])));
      }
    }

    // Track access denied (403) and file not found (404) pages.
    if (function_exists('drupal_get_headers')) {
      $headers = drupal_get_headers();
      if (strstr($headers, 'HTTP/1.1 403 Forbidden')) {
        // See http://www.google.com/support/analytics/bin/answer.py?answer=86927
        $url_custom = '"/403.html?page=" + document.location.pathname + document.location.search + "&from=" + document.referrer';
      }
      elseif (strstr($headers, 'HTTP/1.1 404 Not Found')) {
        $url_custom = '"/404.html?page=" + document.location.pathname + document.location.search + "&from=" + document.referrer';
      }
    }

    // Add any custom code snippets if specified.
    $codesnippet_before = variable_get('googleanalytics_codesnippet_before', '');
    $codesnippet_after = variable_get('googleanalytics_codesnippet_after', '');

    // Build tracker code for footer.
    $script = 'try{';
    $script .= 'var pageTracker = _gat._getTracker('. drupal_to_js($id) .');';
    if (!empty($segmentation)) {
      $script .= $segmentation;
    }
    if (!empty($codesnippet_before)) {
      $script .= $codesnippet_before;
    }
    $script .= 'pageTracker._trackPageview('. $url_custom .');';
    if (!empty($codesnippet_after)) {
      $script .= $codesnippet_after;
    }
    $script .= '} catch(err) {}';

    drupal_add_js($script, 'inline', 'footer');
  }
}

/**
 * Implementation of hook_user().
 *
 * Allow users to decide if tracking code will be added to pages or not.
 */
function googleanalytics_user($type, $edit, &$account, $category = NULL) {
  switch ($type) {
    case 'form':
      if ($category == 'account' && user_access('opt-in or out of tracking') && ($custom = variable_get('googleanalytics_custom', 0)) != 0 && _googleanalytics_visibility_roles($account)) {
        $form['googleanalytics'] = array(
          '#type' => 'fieldset',
          '#title' => t('Google Analytics configuration'),
          '#weight' => 3,
          '#collapsible' => TRUE,
          '#tree' => TRUE
        );
        $form['googleanalytics']['custom'] = array(
          '#type' => 'checkbox',
          '#title' => t('User tracking'),
          '#default_value' => isset($account->googleanalytics['custom']) ? $account->googleanalytics['custom'] : ($custom == 1)
        );

        return $form;
      }
      break;

  }
}

/**
 * Implementation of hook_requirements().
 */
function googleanalytics_requirements($phase) {
  $requirements = array();

  if ($phase == 'runtime') {
    // Raise warning if Google user account has not been set yet.
    if (!preg_match('/^UA-\d{4,}-\d+$/', variable_get('googleanalytics_account', 'UA-'))) {
      $requirements['googleanalytics'] = array(
        'title' => t('Google Analytics module'),
        'description' => t('Google Analytics module has not been configured yet. Please configure its settings from the <a href="@url">Google Analytics settings page</a>.', array('@url' => url('admin/settings/googleanalytics'))),
        'severity' => REQUIREMENT_ERROR,
        'value' => t('Not configured'),
      );
    }
  }

  return $requirements;
}

/**
 * Implementation of hook_cron().
 */
function googleanalytics_cron() {
  // Regenerate the google analytics ga.js every day.
  if (time() - variable_get('googleanalytics_last_cache', 0) >= 86400) {
    // New google analytics version.
    file_delete(file_directory_path() .'/googleanalytics/ga.js');

    // Clear aggregated JS files.
    if (variable_get('preprocess_js', 0)) {
      drupal_clear_js_cache();
    }

    variable_set('googleanalytics_last_cache', time());
  }
}

/**
 * Download and cache the ga.js file locally.
 * @param $location
 *   The full URL to the external javascript file.
 * @return mixed
 *   The path to the local javascript file on success, boolean FALSE on failure.
 */
function _googleanalytics_cache($location) {
  $directory = file_directory_path() .'/googleanalytics';
  $file_destination = $directory .'/'. basename($location);
  if (!file_exists($file_destination)) {
    $result = drupal_http_request($location);
    if ($result->code == 200) {
      // Check that the files directory is writable
      if (file_check_directory($directory, FILE_CREATE_DIRECTORY)) {
        return file_save_data($result->data, $directory .'/'. basename($location), FILE_EXISTS_REPLACE);
      }
    }
  }
  else {
    return $file_destination;
  }
}

/**
 * Tracking visibility check for an user object.
 *
 * @param $account
 *   A user object containing an array of roles to check.
 * @return boolean
 *   A decision on if the current user is being tracked by Google Analytics.
 */
function _googleanalytics_visibility_user($account) {

  $enabled = FALSE;

  // Is current user a member of a role that should be tracked?
  if (_googleanalytics_visibility_roles($account)) {

    // Use the user's block visibility setting, if necessary.
    if (($custom = variable_get('googleanalytics_custom', 0)) != 0) {
      if ($account->uid && isset($account->googleanalytics['custom'])) {
        $enabled = $account->googleanalytics['custom'];
      }
      else {
        $enabled = ($custom == 1);
      }
    }
    else {
      $enabled = TRUE;
    }

  }

  return $enabled;
}

/**
 * Based on visibility setting this function returns TRUE if GA code should
 * be added for the current role and otherwise FALSE.
 */
function _googleanalytics_visibility_roles($account) {

  $enabled = FALSE;
  $roles = variable_get('googleanalytics_roles', array());

  if (array_sum($roles) > 0) {
    // One or more roles are selected for tracking.
    foreach (array_keys($account->roles) as $rid) {
      // Is the current user a member of one role enabled for tracking?
      if (isset($roles[$rid]) && $rid == $roles[$rid]) {
        // Current user is a member of a role that should be tracked.
        $enabled = TRUE;
        break;
      }
    }
  }
  else {
    // No role is selected for tracking, therefor all roles should be tracked.
    $enabled = TRUE;
  }

  return $enabled;
}

/**
 * Based on visibility setting this function returns TRUE if GA code should
 * be added to the current page and otherwise FALSE.
 */
function _googleanalytics_visibility_pages() {
  static $page_match;

  // Cache visibility setting in hook_init for hook_footer.
  if (!isset($page_match)) {

    $visibility = variable_get('googleanalytics_visibility', 0);
    $pages = variable_get('googleanalytics_pages', '');

    // Match path if necessary.
    if (!empty($pages)) {
      if ($visibility < 2) {
        $path = drupal_get_path_alias($_GET['q']);
        // Compare with the internal and path alias (if any).
        $page_match = drupal_match_path($path, $pages);
        if ($path != $_GET['q']) {
          $page_match = $page_match || drupal_match_path($_GET['q'], $pages);
        }
        // When $visibility has a value of 0, the block is displayed on
        // all pages except those listed in $pages. When set to 1, it
        // is displayed only on those pages listed in $pages.
        $page_match = !($visibility xor $page_match);
      }
      else {
        $page_match = drupal_eval($pages);
      }
    }
    else {
      $page_match = TRUE;
    }

  }
  return $page_match;
}