<?php

/**
 * @file
 * Adds Google Analytics Javascript to the checkout completion page.
 *
 * Adds the required Javascript to the checkout completion page to allow
 * e-commerce statistics tracking through Google Analytics.
 *
 * Refer to http://code.google.com/apis/analytics/docs/gaTrackingEcommerce.html
 * for documentation on the functions used to submit e-commerce statistics to
 * Google Analytics.
 */

/**
 * Check which version of google analytics code is used on the site.
 */
function uc_googleanalytics_flush_caches() {
  $info = system_get_info('module', 'googleanalytics');
  if (preg_match('|7\.x\-[2-9]\.[0-9x]+|', $info['version'])) {
    variable_set('uc_googleanalytics_version', 'analytics.js');
  }
  else {
    variable_set('uc_googleanalytics_version', 'ga.js');
  }
}

/**
 * Implements hook_page_alter().
 */
function uc_googleanalytics_page_alter(&$page) {
  // Check to see if we are at the order completion page.
  if (uc_googleanalytics_display()) {
    // If so, then if we can load the order...
    if (!empty($_SESSION['ucga_order_id']) && $order = uc_order_load($_SESSION['ucga_order_id'])) {
      // Build the GA tracking code.
      $script = uc_googleanalytics_ecommerce_js($order);

      // Add the code to the footer.
      drupal_add_js($script, array('type' => 'inline', 'scope' => 'footer', 'preprocess' => FALSE));
    }

    // Clean out the session variable.
    if (isset($_SESSION['ucga_order_id'])) {
      unset($_SESSION['ucga_order_id']);
    }
  }
}

/**
 * Implements hook_uc_order().
 */
function uc_googleanalytics_uc_order($op, $order, $arg2) {
  // If a new order is created during the checkout process...
  if ($op == 'new') {
    // Store the order ID for later use.
    $_SESSION['ucga_order_id'] = $order->order_id;
  }
}

/**
 * Determine whether or not to display the e-commerce related JS through GA.
 *
 * @return bool
 *   TRUE or FALSE indicating whether or not to display the GA e-commerce JS.
 */
function uc_googleanalytics_display() {
  // Display the GA e-commerce JS if the URL is cart/checkout/complete...
  if (arg(0) == 'cart' && arg(1) == 'checkout' && arg(2) == 'complete') {
    return TRUE;
  }

  // Or if the URL is the custom completion page.
  $completion_page = variable_get('uc_cart_checkout_complete_page', '');

  if (!empty($completion_page) && $completion_page == drupal_get_path_alias($_GET['q'])) {
    return TRUE;
  }

  // Or if another module says this is the page through hook_ucga_display().
  foreach (module_invoke_all('ucga_display') as $result) {
    if ($result === TRUE) {
      return TRUE;
    }
  }

  // Otherwise return FALSE.
  return FALSE;
}

/**
 * Build the e-commerce JS passed to Google Analytics for order tracking.
 *
 * @param $order
 *   The fully loaded order object to convert into GA JS.
 *
 * @return string
 *   The JS that should be added to the page footer.
 */
function uc_googleanalytics_ecommerce_js($order) {
  $analytics_version = variable_get('uc_googleanalytics_version', 'ga.js');
  if ($analytics_version == 'analytics.js') {
    $script = 'ga("require", "ecommerce", "ecommerce.js");';
  }
  else {
    $script = '';
  }

  // Lookup the name of the country or default to the ID if it can't be found
  // for some reason.
  if ($country_data = uc_get_country_data(array('country_id' => $order->billing_country))) {
    $order->billing_country_name = $country_data[0]['country_name'];
  }
  else {
    $order->billing_country_name = $order->billing_country;
  }

  // Lookup the name of the zone.
  $order->billing_zone_name = uc_zone_get_by_id($order->billing_zone);

  // Calculate order tax and shipping totals.
  $order->tax_total = 0;
  $order->shipping_total = 0;

  foreach ($order->line_items as $line_item) {
    if ($line_item['type'] == 'tax') {
      $order->tax_total += $line_item['amount'];
    }
    elseif ($line_item['type'] == 'shipping') {
      $order->shipping_total += $line_item['amount'];
    }
  }

  // Build the transaction arguments.
  $trans = array(
    'order_id' => $order->order_id,
    'store' => uc_store_name(),
    'total' => $order->order_total,
    'tax' => $order->tax_total,
    'shipping' => $order->shipping_total,
    'city' => $order->billing_city,
    'state' => $order->billing_zone_name,
    'country' => $order->billing_country_name,
  );

  // Allow modules to alter the transaction arguments.
  drupal_alter('ucga_trans', $trans, $order);

  // Create GA-friendly associative array.
  $script_args = array(
    'id' => $trans['order_id'],
    'affiliation' => $trans['store'],
    'revenue' => $trans['total'],
    'tax' => $trans['tax'],
    'shipping' => $trans['shipping'],
    'city' => $trans['city'],
    'region' => $trans['state'],
    'country' => $trans['country'],
  );

  // Add the transaction line to the JS.
  if ($analytics_version == 'analytics.js') {
    $script .= 'ga("ecommerce:addTransaction", ' . drupal_json_encode($script_args) . ');';
  }
  else {
    foreach ($script_args as &$arg) {
      $arg = drupal_json_encode($arg);
    }
    $script .= '_gaq.push(["_addTrans", ' . implode(', ', $script_args) . ']);';
  }

  // Loop through the products on the order.
  foreach ($order->products as $product) {
    $product->category = '';

    // Try to find a category (term) for the product. Since products most often
    // only have one category, the first one returned (in the
    // $node->taxonomy_catalog) is chosen.
    if (module_exists('taxonomy')) {
      $node = node_load($product->nid);
      if (isset($node->taxonomy_catalog[LANGUAGE_NONE][0]['tid'])) {
        $term = taxonomy_term_load($node->taxonomy_catalog[LANGUAGE_NONE][0]['tid']);
        $product->category = $term->name;
      }
    }
    if (empty($product->category)) {
      $product->category = t('No category');
    }

    // Build the item arguments.
    $item = array(
      'order_id' => $order->order_id,
      'sku' => $product->model,
      'name' => $product->title,
      'category' => $product->category,
      'price' => $product->price,
      'qty' => $product->qty,
    );

    // Allow modules to alter the item arguments.
    drupal_alter('ucga_item', $item, $product, $trans, $order);

    // Create GA-friendly associative array.
    $script_args = array(
      'id' => $item['order_id'],
      'sku' => $item['sku'],
      'name' => $item['name'],
      'category' => (string) $item['category'],
      'price' => $item['price'],
      'quantity' => $item['qty'],
    );

    // Add the item line to the JS.
    if ($analytics_version == 'analytics.js') {
      $script .= 'ga("ecommerce:addItem", ' . drupal_json_encode($script_args) . ');';
    }
    else {
      foreach ($script_args as &$arg) {
        $arg = drupal_json_encode($arg);
      }
      $script .= '_gaq.push(["_addItem", ' . implode(', ', $script_args) . ']);';
    }
  }

  // Add the function to submit the transaction to GA.
  if ($analytics_version == 'analytics.js') {
    $script .= 'ga("ecommerce:send");';
  }
  else {
    $script .= '_gaq.push(["_trackTrans"]);';
  }

  return $script;
}