Magento – Magento Import product reviews from a csv

I am trying to import magento product reviews form a csv using the following script but it seem not to be working. When I run the script I get a blank page and nothing is imported into the database although the existing ratings are removed.

please what am I doing wrong ?

// Invoke the Magento environment
require_once( 'app/Mage.php' );
Mage::app();

$_read = Mage::getSingleton('core/resource')->getConnection('core_read');
$_write = Mage::getSingleton('core/resource')->getConnection('core_write');

// Remove existing ratings
$_write->query("SET FOREIGN_KEY_CHECKS = 0;");
$_write->query("TRUNCATE TABLE rating_option_vote;");
$_write->query("TRUNCATE TABLE review_detail;");
$_write->query("TRUNCATE TABLE review_entity_summary;");
$_write->query("TRUNCATE TABLE review_store;");
$_write->query("TRUNCATE TABLE review;");
$_write->query("TRUNCATE TABLE rating_option_vote_aggregated;");
$_write->query("SET FOREIGN_KEY_CHECKS = 1;");

$file_handle = fopen('reviews-data.csv', 'r');
$i = 0;
while( $csv_line = fgetcsv($file_handle) ){
  if( !is_array($csv_line) ) {
    break;
  }
  //if( $i > 50 ) break;
  $i++;
  // Define and clean variables
  $product_id = trim($csv_line[0]);
  $sku = trim($csv_line[1]);
  $product_name = ucwords( strtolower( trim( $csv_line[2] ) ) );
  $rating_value = (int)$csv_line[3];
  if( empty( $rating_value ) ){
    continue;
  }
  $details = trim( $csv_line[4] );
  $first_name = ucwords( strtolower( trim( $csv_line[5] ) ) );
  $last_name = ucwords( strtolower( trim( $csv_line[6] ) ) );
  // Create a single name
  $nickname = '';
  if( !empty($first_name) ){
    $nickname .= $first_name;
  }
  if( !empty($last_name) ){
    if( !empty($nickname) ){
      $nickname .= ' ';
    }
    $nickname .= $last_name;
  }
  if( empty($nickname) ){
    $nickname = 'Guest';
  }

  $email = strtolower( trim( $csv_line[7] ) );
  if( !$created = strtotime( trim($csv_line[8]) ) ){
    $created = time();  
  }

  $status = (int)$csv_line[9];
  if( $status == 1 ){
    $approval_status = 1;
  } else {
    $approval_status = 3;
  }

  // Customer setup;
  $_customer = Mage::helper('custom')->getCustomerByEmail($email); // You'll need to write this logic yourself

  // IMPORTANT: Set up customer session.
  // the rating/option model resource checks the customer session to get the customer ID.
  $_session = Mage::getSingleton('customer/session')->setCustomer($_customer)->setCustomerAsLoggedIn($_customer);

  $_product = _getReviewProduct($sku); // You'll need to write this logic yourself

  if(!$_product) {
    print '<p>Unmatched SKU: ' . $sku . '</p>';
    continue;
  }

  // Add the review
  $_review = Mage::getModel('review/review')
    ->setEntityPkValue($_product->getId())
    ->setStatusId($approval_status)
    // ->setCreatedAt( date('Y-m-d H:m:s', $created) ) // Has no effect
    ->setTitle($product_name)
    ->setDetail($details)
    ->setEntityId(1)
    ->setStoreId(1)
    ->setStores(array(1,0))
    ->setCustomerId($_customer->getId())
    ->setNickname($nickname)
    ->save();
  // Set the created date
  $_write->query("UPDATE review SET created_at = '" . date('Y-m-d H:m:s', $created) .  "' WHERE review_id = " . $_review->getId());
  $_review->aggregate();

  // Map your rating_id to your option_id with an array or something
  $rating_options = array(
      //1 => array(1,2,3,4,5), // <== Look at your database table `rating_option` for these vals
      //2 => array(6,7,8,9,10),
      //3 => array(11,12,13,14,15),
      4 => array(16,17,18,19,20),
  );

  // Now save the ratings
  foreach($rating_options as $rating_id => $option_ids):
    try {
      $_rating = Mage::getModel('rating/rating')
      ->setRatingId($rating_id)
      ->setReviewId($_review->getId())
      ->addOptionVote( $option_ids[$rating_value-1],$_product->getId() );
    } catch (Exception $e) {
      print_r($e);
      die($e->getMessage());
    }
  endforeach;
}

function _getReviewProduct( $sku ){
  static $cache = array();

  if( !array_key_exists($sku, $cache) ){
    $cache[$sku] = NULL;
     // You'll need to write this logic yourself
    }
  }

  return $cache[$sku];
}