Checks if a certain discount code was used in the checkout and shows messages in multiple places.

pmpro_discount_messages.php

<?php

// Copy from below here...

/**
 * Checks if a certain discount code was used in the checkout and:
 * - Shows a special message on the Confirmation page
 * - Includes a special message in the Confirmation email
 * - Shows a message on the Invoice for that order/checkout
 * - Shows a message on the Account page if the most recent order used the code in the past week
 */

/**
 * Get the discount code message to show for a given order.
 *
 * @param MemberOrder $order The order to get the message for.
 * @return string The message to show.
 */
function pmprodiscountmessage_get_message_for_order( $order ) {
	// Make sure that we have an order.
	if ( empty( $order ) ) {
		return '';
	}

	// Get the discount code used for this order.
	$discount_code = $order->getDiscountCode();

	// Make sure that we have a discount code.
	if ( empty( $discount_code ) || empty( $discount_code->code ) ) {
		return '';
	}

	// Switch on the code property of the discount code to show a message per code.
	// Edit these cases to set messages per discount code.
	switch ( $discount_code->code ) {
		case 'my-special-code':
			return 'Thanks for using my special code!';
			break;
		case 'my-other-special-code':
			return 'Thanks for using my other special code!';
			break;
		case 'free':
			return 'Thanks for using the code on my test site!';
			break;
		case 'my-super-secret-code-1':
		case 'my-super-secret-code-2':
		case 'my-super-secret-code-3':
			return 'Thanks for using one of my super secret codes!';
			break;
	}

	return '';
}

/**
 * Show a message on the Confirmation page if a certain discount code was used at checkout.
 *
 * It would be nice to use the $order parameter for the filter, but it is only passed for
 * paid checkouts so it wouldn't work for discount codes that make the checkout free.
 *
 * @param string $message The current confirmation message.
 * @return string The new confirmation message.
 */
function pmprodiscountmessage_confirmation_message( $message ) {
	global $current_user;

	// Get the most recent order for this user.
	$order_args = array(
		'user_id' => $current_user->ID,
	);
	$order = MemberOrder::get_order( $order_args );

	// Make sure that we have an order.
	$discount_message = pmprodiscountmessage_get_message_for_order( $order );
	if ( ! empty( $discount_message ) ) {
		$message .= '<p>' . $discount_message . '</p>';
	}

	return $message;
}
add_filter( 'pmpro_confirmation_message', 'pmprodiscountmessage_confirmation_message' );

/**
 * Add a !!discount_message!! email template variable that shows a message if a certain
 * discount code was used at checkout in the Confirmation email.
 *
 * @param array      $data The email template variable data.
 * @param PPMroEmail $email The email object.
 * @return array The new email template variable data.
 */
function pmprodiscountmessage_email_data( $data, $email ) {
	// Check if the email template begins with `checkout_`.
	if ( 0 !== strpos( $email->template, 'checkout_' ) ) {
		return $data;
	}

	// Add a default !!discount_message!! email template variable just in case.
	$data['discount_message'] = '';

	// Get the user from the !!user_login!! email template variable.
	if ( empty( $data['user_login'] ) ) {
		return $data;
	}
	$user = get_user_by( 'login', $data['user_login'] );
	if ( empty( $user ) ) {
		return $data;
	}

	// Get the most recent order for this user.
	$order_args = array(
		'user_id' => $user->ID,
	);
	$order = MemberOrder::get_order( $order_args );

	$discount_message = pmprodiscountmessage_get_message_for_order( $order );
	if ( ! empty( $discount_message ) ) {
		$data['discount_message'] = $discount_message;
	}

	return $data;
}
add_filter( 'pmpro_email_data', 'pmprodiscountmessage_email_data', 10, 2 );

/**
 * Show an invoice bullet on the Invoice page if a certain discount code was used for that order.
 *
 * @param MemberOrder $order The order to show the invoice bullet for.
 */
function pmprodiscountmessage_invoice_bullets_bottom( $order ) {
	global $pmpro_pages;

	// Make sure that we are on the Invoice page. We are alredy updating the message
	// on the Confirmation page so we don't want to add a bullet there.
	if ( empty( $pmpro_pages['invoice'] ) || ! is_page( $pmpro_pages['invoice'] ) ) {
		return;
	}

	// Get the discount code message for this order.
	$discount_message = pmprodiscountmessage_get_message_for_order( $order );
	if ( empty( $discount_message ) ) {
		return;
	}

	// Show the message as an invoice bullet.
	?>
	<li>
		<?php echo esc_html( $discount_message ); ?>
	</li>
	<?php
}
add_action( 'pmpro_invoice_bullets_bottom', 'pmprodiscountmessage_invoice_bullets_bottom' );

/**
 * Show a message in account bullets if the user has used a certain discount code in the past
 * week and still has the associated membership level.
 *
 * Note: Will only show a message for the user's most recent order, so may not be the expected behavior
 * for all MMPU use-cases.
 */
function pmprodiscountmessage_account_bullets_bottom() {
	global $current_user;

	// Get the most recent order for this user.
	$order_args = array(
		'user_id' => $current_user->ID,
	);
	$order = MemberOrder::get_order( $order_args );

	// Make sure that we have an order.
	if ( empty( $order ) ) {
		return;
	}

	// Check whether the user still has this order's level.
	if ( empty( $order->membership_id ) || ! pmpro_hasMembershipLevel( $order->membership_id, $current_user->ID ) ) {
		return;
	}

	// Check whether the order was placed within the last week.
	$week_ago = time() - WEEK_IN_SECONDS;
	if ( $order->timestamp < $week_ago ) {
		return;
	}

	// Get the discount code message for this order.
	$discount_message = pmprodiscountmessage_get_message_for_order( $order );
	if ( empty( $discount_message ) ) {
		return;
	}

	// Show the message as an account bullet.
	?>
	<li>
		<?php echo esc_html( $discount_message ); ?>
	</li>
	<?php
}
add_action( 'pmpro_account_bullets_bottom', 'pmprodiscountmessage_account_bullets_bottom' );