PMPro template_redirect redirection based on discount code OR membership level

pmpro-template-redirect-after-checkout-discount-or-level.php

<?php
/**
 * This recipe will redirect users after checkout based on a Discount Code OR their Membership Level.
 * 
 * It hooks into the `template_redirect` action and is useful when the default `pmpro_confirmation_url` filter
 * does not work reliably, such as with off-site gateways like Stripe Checkout.
 * 
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method:
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function my_pmpro_redirect_after_checkout() {
	if ( ! is_admin() && is_page( pmpro_getOption( 'confirmation_page_id' ) ) && is_user_logged_in() ) {
		$user_id = get_current_user_id();

		// Get the user's current level.
		$membership_level = pmpro_getMembershipLevelForUser( $user_id );

		// Get discount code used (most recent).
		global $wpdb;
		$discount_code = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT d.code
				 FROM {$wpdb->prefix}pmpro_discount_codes_uses u
				 LEFT JOIN {$wpdb->prefix}pmpro_discount_codes d ON u.code_id = d.id
				 WHERE u.user_id = %d
				 ORDER BY u.id DESC
				 LIMIT 1",
				$user_id
			)
		);

		// Coupon-based redirect (priority).
		if ( $discount_code === 'SC916E8F9CC' ) {
			wp_redirect( 'https://example.com/page_1' );
			exit;
		} elseif ( $discount_code === 'X84HJ8F9CC' ) {
			wp_redirect( 'https://example.com/page_2' );
			exit;
		}

		// Membership-level-based redirect.
		if ( pmpro_hasMembershipLevel( 2, $user_id ) ) {
			wp_redirect( 'https://example.com/level2' );
			exit;
		} elseif ( pmpro_hasMembershipLevel( 3, $user_id ) ) {
			wp_redirect( 'https://example.com/level3' );
			exit;
		}
	}
}
add_action( 'template_redirect', 'my_pmpro_redirect_after_checkout' );