WhatsApp order notifications for WooCommerce

<?php
// In a small custom plugin, or your theme's functions.php.
// Define OXTRO_API_KEY and OXTRO_CONNECTION_ID in wp-config.php.

add_action('woocommerce_order_status_changed', function ($order_id, $from, $to, $order) {
    // Order status => name of a template saved in Oxtro.
    $templates = [
        'processing' => 'order_confirmed',
        'completed'  => 'order_completed',
        'cancelled'  => 'order_cancelled',
    ];

    $phone = $order->get_billing_phone(); // must include the country code
    if (!isset($templates[$to]) || !$phone) {
        return;
    }

    wp_remote_post('https://api.getoxtro.com/v1/messages', [
        'blocking' => false, // never hold up checkout or the admin screen
        'timeout'  => 5,
        'headers'  => [
            'Authorization'   => 'Bearer ' . OXTRO_API_KEY,
            'Content-Type'    => 'application/json',
            // The same order and status never sends twice, even if the hook fires again.
            'Idempotency-Key' => "wc-order-{$order_id}-{$to}",
        ],
        'body' => wp_json_encode([
            'connection_id' => OXTRO_CONNECTION_ID,
            'to'            => $phone,
            'template'      => [
                'name'      => $templates[$to],
                'variables' => [
                    'customer_name' => $order->get_billing_first_name(),
                    'order_number'  => $order->get_order_number(),
                    'total'         => $order->get_total() . ' ' . $order->get_currency(),
                ],
            ],
        ]),
    ]);
}, 10, 4);