<?php
// $Id$

/*
 * 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', 'pdf|zip|mp3');

function googleanalytics_help($path, $arg) {
  switch ($path) {
    case 'admin/settings/googleanalytics':
      return t('Google Analytics is a free statistics package based on the excellent Urchin system.');
  }
}

function googleanalytics_perm() {
  return array('administer google analytics');
}

function googleanalytics_menu() {

  $items['admin/settings/googleanalytics'] = array(
    'title' => 'Google Analytics',
    'description' => 'Configure the settings used to generate your Google Analytics site map.',
    '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', '');

  // Check if we should track the currently active user's role.
  $track = _googleanalytics_track($user);

  // Don't track page views in the admin sections
  if ($id && (arg(0) != 'admin') && $track == TRUE) {
    // Use the old version of Google Analytics?
    $legacy_version = variable_get('googleanalytics_legacy_version', FALSE);
    $scope = variable_get('googleanalytics_js_scope', 'footer');

    // Are we on a secure page?
    $prefix = '://www';
    if (isset($_SERVER['HTTPS']) && !empty($_SERVER['HTTPS']) && (strtolower($_SERVER['HTTPS']) != 'off')) {
      $prefix = 's://ssl';
    }

    // Should a local cached copy of urchin.js or ga.js be used?
    $js_file = ($legacy_version) ? 'urchin.js' : 'ga.js';
    $url = 'http'. $prefix .'.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 = 'document.write(unescape("%3Cscript src=\''. $url .'\' type=\'text/javascript\'%3E%3C/script%3E"));';
      drupal_add_js($script, 'inline', $scope);
    }

    // Add download tracking.
    $path = drupal_get_path('module', 'googleanalytics');
    if (variable_get('googleanalytics_trackfiles', TRUE) && $trackfiles_extensions = variable_get('googleanalytics_trackfiles_extensions', GA_TRACKFILES)) {
      drupal_add_js(array('googleanalytics' => array('trackDownload' => $trackfiles_extensions, 'LegacyVersion' => $legacy_version)), 'setting', 'header');
      drupal_add_js($path .'/downloadtracker.js', 'module', $scope);
    }
  }
}

/**
 * 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', '');

  // Check if we should track the currently active user's role.
  $track = _googleanalytics_track($user);

  // Don't track page views in the admin sections
  if ($id && (arg(0) != 'admin') && $track == TRUE) {

    // Use the old version of Google Analytics?
    $legacy_version = variable_get('googleanalytics_legacy_version', FALSE);

    // 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) {
        if ($legacy_version) {
          $segmentation = '__utmSetVar('. drupal_to_js(implode(':', $fields)) .');';
        }
        else {
          $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();
      $url_custom = drupal_to_js(url('search/'. arg(1), array('query' => 'search='. trim($keys))));
    }

    // 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')) {
        if ($legacy_version) {
          // See http://www.google.com/support/analytics/bin/answer.py?answer=86928
          $url_custom = '"/403.html?page=" + _udl.pathname + _udl.search';
        }
        else {
          // 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')) {
        if ($legacy_version) {
          $url_custom = '"/404.html?page=" + _udl.pathname + _udl.search';
        }
        else {
          $url_custom = '"/404.html?page=" + document.location.pathname + document.location.search + "&from=" + document.referrer';
        }
      }
    }

    // Add any custom code snippets if specified.
    $codesnippet = variable_get('googleanalytics_codesnippet', '');

    // Should the legacy code be used?
    $script = '';
    if ($legacy_version) {
      $script .= '_uacct = '. drupal_to_js($id) .';';
      if (!empty($segmentation)) {
        $script .= $segmentation;
      }
      if (!empty($codesnippet)) {
        $script .= $codesnippet;
      }
      $script .= 'urchinTracker('. $url_custom .');';
    }
    else {
      $script .= 'var pageTracker = _gat._getTracker('. drupal_to_js($id) .');';
      $script .= 'pageTracker._initData();';
      if (!empty($segmentation)) {
        $script .= $segmentation;
      }
      if (!empty($codesnippet)) {
        $script .= $codesnippet;
      }
      $script .= 'pageTracker._trackPageview('. $url_custom .');';
    }

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

/**
 * 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 urchin.js or ga.js every day.
  if (time() - variable_get('googleanalytics_last_cache', 0) >= 86400) {
    // Legacy google analytics version.
    file_delete(file_directory_path() .'/googleanalytics/urchin.js');

    // 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 urchin.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 = 'http://www.google-analytics.com/urchin.js') {
  $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;
  }
}

/**
 *
 * @param $account
 *   A user object containing an array of roles to check.
 * @return boolean
 *   A decision on if the current user is being tracked by GAnalytics.
 */
function _googleanalytics_track($account) {
  // By default we don't track users.
  $track = FALSE;

  foreach (array_keys($account->roles) as $role) {
    // Add the tracking code if user is member of one role that should be tracked.
    if (variable_get('googleanalytics_track_'. $role, FALSE)) {
      $track = TRUE;
    }
  }

  // Handle behavior for administrative user 1.
  if ($account->uid == 1 && variable_get('googleanalytics_track__user1', FALSE)) {
    // Enable tracking of user 1 if tracking for "authenticated user" is disabled.
    $track = TRUE;
  }
  elseif ($account->uid == 1 && !variable_get('googleanalytics_track__user1', FALSE)) {
    // User 1 is a member of "authenticated user". Disable user tracking
    // if user 1 shouldn't be tracked, but "authenticated user" should.
    $track = FALSE;
  }

  return $track;
}