<?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magento.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magento.com for more information.
 *
 * @category    Mage
 * @package     Mage_Customer
 * @copyright  Copyright (c) 2006-2016 X.commerce, Inc. and affiliates (http://www.magento.com)
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

/**
 * @var $this Mage_Catalog_Model_Resource_Setup
 * @var $conn Varien_Db_Adapter_Interface
 */
$conn = $this->getConnection();

//get all duplicated emails
$select  = $conn->select()
    ->from($this->getTable('customer/entity'), array('email', 'website_id', 'cnt' => 'COUNT(*)'))
    ->group('email')
    ->group('website_id')
    ->having('cnt > 1');
$emails = $conn->fetchAll($select);

foreach ($emails as $data) {
    $email = $data['email'];
    $websiteId = $data['website_id'];

    $select = $conn->select()
        ->from($this->getTable('customer/entity'), array('entity_id'))
        ->where('email = ?', $email)
        ->where('website_id = ?', $websiteId);
    $activeId = $conn->fetchOne($select);

    //receive all other duplicated customer ids
    $select = $conn->select()
        ->from($this->getTable('customer/entity'), array('entity_id', 'email'))
        ->where('email = ?', $email)
        ->where('website_id = ?', $websiteId)
        ->where('entity_id <> ?', $activeId);
    $result = $conn->fetchAll($select);

    //change email to unique value
    foreach ($result as $row) {
        $changedEmail = $conn->getConcatSql(array('"(duplicate"', $row['entity_id'], '")"', '"' . $row['email'] . '"'));
        $conn->update(
            $this->getTable('customer/entity'),
            array('email' => $changedEmail),
            array('entity_id =?' => $row['entity_id'])
        );
    }
}

/**
 * Add unique index for customer_entity table
 */
$conn->addIndex(
    $this->getTable('customer/entity'),
    $this->getIdxName(
        'customer/entity',
        array('email', 'website_id'),
        Varien_Db_Adapter_Interface::INDEX_TYPE_UNIQUE
    ),
    array('email', 'website_id'),
    Varien_Db_Adapter_Interface::INDEX_TYPE_UNIQUE
);