Order tracking information on note emails

add_action( 'woocommerce_email_header', function( $email_heading, $email ) {

	// Limit To Specific Email
	if(
		empty( $email->id )
		|| ! in_array( $email->id, [ 'customer_note' ] )
	) {
		return;
	}

	// Get Order
	$order = $email->object;
	if( ! $order ) {
		return;
	}

	// Translate Email Copy
	add_filter( 'gettext', function( $text ) use( $order ) {

		// Specific Line
		if( $text != 'As a reminder, here are your order details:' ) {
			return $text;
		}

		// Loop Customer Order Notes
		$notes = wc_get_order_notes(
			[
				'order_id' => $order->get_id(),
				'type' => 'customer',
			]
		);
		foreach( $notes as $note ) {

			// Match ShipStation Formatted Note
			if( stristr( $note->content, ' shipped via ' ) === false ) {
				continue;
			}

			// Get USPS Tracking Number
			if( preg_match( '/\b(\d{20,22})\b/', $note->content, $matches ) ) {
				$tracking_num = $matches[1];
				$note->content = str_replace( 'USPS', '<strong>USPS</strong>', $note->content );
				$tracking_link = 'https://tools.usps.com/go/TrackConfirmAction?qtc_tLabels1';
			}

			// Detect UPS
			if( preg_match( '/\b1Z[A-Z0-9]{16}\b/i', $note->content, $matches ) ) {
				$tracking_num = $matches[1];
				$note->content = str_replace( 'UPS', '<strong>UPS</strong>', $note->content );
				$tracking_link = 'https://www.ups.com/track?loc=en_US&tracknum';
			}

			// Detect FedEx
			if( stristr( $note->content, 'FedEx' ) ) {
				$words = preg_replace( "/[^A-Za-z0-9 ]/", '', $note->content);
				$words = explode( ' ', $words );
				$last_index = sizeof( $words ) - 1;
				$tracking_num = $words[$last_index];
				$note->content = str_replace( 'FedEx', '<strong>FedEx</strong>', $note->content );
				$tracking_link = 'https://www.fedex.com/fedextrack/?trknbr';
			}

			// Missing Tracking Link
			if( empty( $tracking_link ) ) {
				continue;
			}

			// Get Tracking Link
			$tracking_link = sprintf(
				'<a target="_blank" href="%s=%s">%s</a>',
				$tracking_link,
				$tracking_num,
				$tracking_num
			);

			// Output Tracking Link
			printf(
				'<p><strong>Track your package: %s</strong></p>',
				$tracking_link
			);

			// Partial Shipment Text
			if( preg_match_all( '/ x (?<qty>\d+)/', $note->content, $matches ) ) {
				$shipment_qty = array_sum( $matches['qty'] );
				if( $shipment_qty != $order->get_item_count() ) {
					printf(
						'
							<p>
								<strong style="color:IndianRed;">
									** Partial shipment quantity %d of %d. **
								</strong>
							</p>
						',
						$shipment_qty,
						$order->get_item_count()
					);
				}
			}

		} // End Customer Notes Loop

		// Preserve Original Translation
		return $text;

	} ); // End Translate Email Copy

}, 10, 2 ); // End Email Header