Add extra product info to WooCommerce details table - Use a custom metabox for extra product information that will be added to the details table. https://www.damiencarbery.com/2024/05/add-extra-product-info-to-woocommerce-details-table/

wc-add-custom-product-note-to-details-table.php

<?php
/*
Plugin Name: WooCommerce - Add extra product info to details table
Plugin URI: https://www.damiencarbery.com/2024/05/add-extra-product-info-to-woocommerce-details-table/
Description: Use a custom metabox for extra product information that will be added to the details table.
Author: Damien Carbery
Author URI: https://www.damiencarbery.com
Version: 0.1.20240524
WC tested to: 8.9.1
Requires Plugins: woocommerce
*/

defined( 'ABSPATH' ) || exit;


use Automattic\WooCommerce\Utilities\OrderUtil;


// Declare that this plugin supports WooCommerce HPOS.
add_action( 'before_woocommerce_init', function() {
	if ( class_exists( \Automattic\WooCommerce\Utilities\FeaturesUtil::class ) ) {
	\Automattic\WooCommerce\Utilities\FeaturesUtil::declare_compatibility( 'custom_order_tables', __FILE__, true );
	}
} );


class AdditionalProductInfoToDetailsTable {
	public function __construct() {
		$this->init(); 
	}


	private function init() {
		add_action( 'woocommerce_loaded', array( $this, 'load_product_meta_box_hooks' ) );
		add_action( 'woocommerce_email_before_order_table', array( $this, 'check_for_order_completed_email' ), 10, 4 );
		add_action( 'woocommerce_order_details_before_order_table', array( $this, 'check_for_my_account_area' ) );
	}


	private function get_meta_key() {
		return 'extra_info';
	}


	private function get_nonce_name() {
		return 'dcwd_extra_info_nonce';
	}


	private function get_textarea_name() {
		return 'product_info';
	}


	// Verify the nonce and that this is not a post revision or autosave.
	private function user_can_save( $post_id, $nonce ) {
		$is_autosave = wp_is_post_autosave( $post_id );
		$is_revision = wp_is_post_revision( $post_id );
		$is_valid_nonce = ( isset( $_POST[ $nonce ] ) && wp_verify_nonce( $_POST[ $nonce ], plugin_basename( __FILE__ ) ) );

		return ! ( $is_autosave || $is_revision ) && $is_valid_nonce;
	}


	public function load_product_meta_box_hooks() {
		add_action( 'add_meta_boxes', array( $this, 'add_product_info_meta_box' ) );
		add_action( 'save_post', array( $this, 'save_product_info_meta_box_data' ) );
	}


	public function add_product_info_meta_box() {
		add_meta_box( 'dcwd_additional_info_meta_box', 'Information for order email', array( $this, 'display_product_info_meta_box' ), 'product', 'normal', 'default' );
	}


	// Render custom meta box.
	public function display_product_info_meta_box( $post ) {
		wp_nonce_field( plugin_basename(__FILE__), $this->get_nonce_name() );

		$product_id = $post->ID;
		$product_info = get_post_meta( $product_id, $this->get_meta_key(), true );
	?>
	<style>
	.dcwd-product-info label { font-weight: bold; padding-bottom: 0.5em; }
	.dcwd-product-info textarea { width: 100%; margin-bottom: 1em; margin-top: 1em; }
	</style>
	<div class="dcwd-product-info">
	  <label for="<?php echo $this->get_textarea_name(); ?>">Additional info for order emails</label>
	  <textarea name="<?php echo $this->get_textarea_name(); ?>" rows="4" cols="80"><?php esc_attr_e( $product_info ); ?></textarea>
	</div>
	<?php
	}


	// Sanitize and store the updated info.
	public function save_product_info_meta_box_data( $product_id ) {
		if ( $this->user_can_save( $product_id, $this->get_nonce_name() ) ) {
			if ( isset( $_POST[ $this->get_textarea_name() ] ) && 0 < strlen( trim( $_POST[ $this->get_textarea_name() ] ) ) ) {
				// This strips out tags so html links will be removed (but not bare urls).
				$product_info = sanitize_textarea_field( trim( $_POST[ $this->get_textarea_name() ] ) );
				update_post_meta( $product_id, $this->get_meta_key(), $product_info );
			}
		}
	}


	// Check for Completed Order email before hooking in function to echo the info.
	public function check_for_order_completed_email( $order, $sent_to_admin, $plain_text, $email ) {
		if ( 'customer_completed_order' == $email->id ) {
			add_action( 'woocommerce_order_item_meta_end', array( $this, 'add_product_info_after_product_details' ), 10, 4 );
		}
	}

	public function check_for_my_account_area( $order ) {
		// This function is called when in My Account/Orders/View Order so can now run the function to add the product info.
		// Maybe check if order is complete.
		add_action( 'woocommerce_order_item_meta_end', array( $this, 'add_product_info_after_product_details' ), 10, 4 );
	}


	public function add_product_info_after_product_details( $item_id, $item, $order, $plain_text ) {
		$product_id = $item->get_variation_id() ? $item->get_variation_id() : $item->get_product_id();
		
		$product_info = get_post_meta( $product_id, $this->get_meta_key(), true );
		if ( ! empty( $product_info ) ) {
			echo '<br>', nl2br( esc_html( $product_info ) );
		}
	}
}

$AdditionalProductInfoToDetailsTable = new AdditionalProductInfoToDetailsTable();