Use email address as Woocommerce coupon code - php

Question

I am trying to create a function to use email address as woocommerce coupon code. My code works perfect before but suddenly it stopped working. I use this woocommerce_get_shop_coupon_data filter to get the coupon data. Please help me.
<?php
add_filter ( 'woocommerce_get_shop_coupon_data', 'firefog_create_coupon', 10, 2 );
function firefog_create_coupon($data, $code) {
global $wpdb;
//getting the coupon input value
$coupon_code = $_POST['coupon_code'] ;
//check user input is like email
if (filter_var($coupon_code, FILTER_VALIDATE_EMAIL)) {
$code = $coupon_code ;
}
// Check if the coupon has already been created in the database
$sql = $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE post_title = %s AND post_type = 'shop_coupon' AND post_status = 'publish' ORDER BY post_date DESC LIMIT 1;", $code );
$coupon_id = $wpdb->get_var( $sql );
if ( empty( $coupon_id ) ) {
// Create a coupon with the properties you need
$data = array(
'discount_type' => 'percent',
'coupon_amount' => 15, // value
'individual_use' => 'false',
'product_ids' => array(),
'exclude_product_ids' => array(),
'usage_limit' => '',
'usage_limit_per_user' => '',//Limit
'limit_usage_to_x_items' => '',
'usage_count' => '',
'expiry_date' => '2020-12-31', // YYYY-MM-DD
'free_shipping' => 'false',
'product_categories' => array(),
'exclude_product_categories' => array(),
'exclude_sale_items' => 'false',
'minimum_amount' => '',
'maximum_amount' => '',
'customer_email' => array()
);
// Save the coupon in the database
$coupon = array(
'post_title' => $code,
'post_content' => '',
'post_status' => 'publish',
'post_author' => 1,
'post_type' => 'shop_coupon'
);
$new_coupon_id = wp_insert_post( $coupon );
// Write the $data values into postmeta table
foreach ($data as $key => $value) {
update_post_meta( $new_coupon_id, $key, $value );
}
return $data;
}
}