WooCommerce: Add Billing Codes To Checkout & User Profile

We got a request to add a custom field to user profiles allowing multiple codes separated by commas and then add a select containing those codes to the checkout page. These codes were going to be used to add a cc: to pdf invoice emails being sent out separately.

• WooCommerce

<?php
/**
// Add Billing Codes user profile field. Used as a comma deliniated list
// See custom_override_checkout_fields()
**/
add_filter( 'user_contactmethods', 'modify_contact_methods' );
function modify_contact_methods( $profile_fields ) {

    // Add new fields
    $profile_fields['billing_code']  =  'Billing Codes';

    return $profile_fields;
}

/**
// Add a billing code to the checkout screen. Customzied to show different values based on the
// value of the User Field "Billing Code"|'billing_code' from modify_contact_methods()
**/
add_filter( 'woocommerce_checkout_fields', 'custom_override_checkout_fields' );
function custom_override_checkout_fields( $fields ) {

    $billing_code  =  get_user_meta ( get_current_user_id() );
    $billing_code  =  $billing_code['billing_code']['0'];
    if ( empty ( $billing_code ) ) {
        $num_billing_codes  =  0 ;
    }
    else {
        $billing_code  =  explode ( ',', $billing_code );
        $num_billing_codes  =  count ( $billing_code );
    }

    $fields['billing']['billing_code']  =  array(
            'label'          => __('Bill To', 'woocommerce'),
            'placeholder'    => _x('', 'placeholder', 'woocommerce'),
            'required'       => true,
            'clear'          => false,
            'type'           => 'select',
            'class'          => array('form-row-wide'),
    );

    $i  =  0;
    if ( $num_freshmed_billing_codes  ==  0 ) {
        $fields['billing']['billing_code']['type']  =  'text';
    }
    elseif ( $num_billing_codes == 1 ) {
        $fields['billing']['billing_code']['options']  =  array(
            $billing_code['0']  => __( $freshmed_billing_code['0'], 'woocommerce' ),  
        );
    }
    elseif ( $num_freshmed_billing_codes  >  1 ) {
        $fields['billing']['billing_code']['options'][""]  =  __("Please Select Bill To" , 'woocommerce');
        foreach ( $freshmed_billing_code as $code ) {
            $fields['billing']['billing_code']['options']["$code"]  =  __($code, 'woocommerce');
            $i++;
        }
    }

    return $fields;
}
?>