Importing data into WordPress using the strategy pattern

CSVCustomerDataConverter.php

<?php

class CSVCustomerDataConverter implements CustomerDataConverterInterface
{
    /**
     * Convert the given CSV data array into an array of customers. The returned
     * array should use the following format:
     *
     * @param array $data
     *
     * @return array
     */
    public function convert(array $data)
    {
        $customers = array();

        foreach ($data as $row) {
            $row = str_getcsv($row);
            $customers[] = array(
                'name' => $row[0],
                'email' => $row[1],
                'details' => $row[2],
            );
        }

        return $customers;
    }
}

CustomerDataConverterInterface.php

<?php

interface CustomerDataConverterInterface
{
    /**
     * Convert the given data array into an array of customers. The returned
     * array should use the following format:
     *
     * array(
     *     array(
     *         'name'    => (string) Name of the customer.
     *         'email'   => (string) Email address of the customer.
     *         'details' => (string) The customer details.
     *     )
     * )
     *
     * @param array $data
     *
     * @return array
     */
    public function convert(array $data);
}

CustomerImporter.php

<?php

class CustomerImporter
{
    /**
     * The customer data converter used by the importer.
     *
     * @var CustomerDataConverterInterface
     */
    private $converter;

    /**
     * Constructor.
     *
     * @param CustomerDataConverterInterface $converter
     */
    public function __construct(CustomerDataConverterInterface $converter)
    {
        $this->converter = $converter;
    }

    /**
     * Import a customer data file.
     *
     * @param string $filename
     *
     * @return bool|WP_Error
     */
    public function import_from_file($filename)
    {
        if (!is_readable($filename)) {
            return new WP_Error('file_unreadable', sprintf('Unable to read "%" customer data file.', $filename));
        }

        $customer_data = file($filename, FILE_IGNORE_NEW_LINES);

        if (!is_array($customer_data)) {
            return new WP_Error('parse_error', sprintf('Failed to parse the "%" customer data file.', $filename));
        }

        $customers = $this->converter->convert($customer_data);

        foreach ($customers as $customer) {
            $this->add_customer($customer['name'], $customer['email'], $customer['details']);
        }

        return true;
    }

    /**
     * Add a new customer into the WordPress database.
     *
     * @param string $name
     * @param string $email
     * @param string $details
     *
     * @return int|WP_Error
     */
    private function add_customer($name, $email, $details = '')
    {
        $customer_id = wp_insert_post(array(
            'post_title' => $name,
            'post_content' => $details,
            'post_status' => 'publish',
            'post_type' => 'customer'
        ), true);

        if ($customer_id instanceof WP_Error) {
            return $customer_id;
        }

        update_post_meta($customer_id, 'email', $email);

        return $customer_id;
    }
}