Admin order item manual restocking

// Admin Order Items Table Header
add_action( 'woocommerce_admin_order_item_headers', function( $order ) {

	?>
	<th class="manage-column column-cb check-column">
		<input id="cb-select-all-1" type="checkbox">
	</th>
	<?php

} );

// Admin Order Item Checkbox
add_action( 'woocommerce_admin_order_item_values',
	function( $product, $item, $item_id ) {

	// For Products Only
	if( ! method_exists( $product, 'get_type' ) ) {
		return;
	}

	// Get Any Status - Good, Damage
	$status = wc_get_order_item_meta( $item_id, '_rstatus', true );
	if( ! $status ) {
		$status = 'None';
	}

	// Output Checkbox And Status
	?>
	<td class="check-column">
		<input class="order_item_status" type="checkbox"
			name="order_item_status[]" value="<?php echo $item_id; ?>" />
	</td>
	<?php
}, 10, 3 );

// Add Order Items Table Buttons
add_action( 'woocommerce_order_item_add_action_buttons', function( $order ) {

	?>
	<button class="button" type="button" id="order-items-restock">
		Restock
	</button>
	<?php

} );

// JavaScript
add_action( 'admin_print_footer_scripts', function() {

	?>
	<script type="text/javascript">

	// Triggers
	jQuery( document ).ready( function( $ ) {
		$( '#order-items-restock' ).click( function() {
			ccom_order_item_status( $, 'Restock' );
		} );
	} );

	// Send Requests
	function ccom_order_item_status( $, status ) {
		var inputs = '';
		$( 'input.order_item_status:checked' ).each( function() {
			var order_item_id = $( this ).val();
			inputs += '<input type="hidden" name="order_item_status['
				+ order_item_id + ']" value="' + status + '" />';
		} );
		var form = $( '<form action="" method="POST">' + inputs + '</form>' );
		$( 'body' ).append( form );
		form.submit();
	}

	</script>
	<?php

} );

// Save Submissions
add_action( 'admin_notices', function() {

	// Submissions Only
	if( empty( $_POST['order_item_status'] ) ) {
		return;
	}

	// Loop Order items
	$notes = [];
	foreach( $_POST['order_item_status'] as $order_item_id => $return_status ) {

		// Get Order Item Product
		$product_id = wc_get_order_item_meta( $order_item_id, '_product_id' );
		$product = wc_get_product( $product_id );

		// Process Returns
		switch( $return_status ) {

			// Restocking
			case 'Restock':

				// Get Order Item Quantity
				$order_item = new WC_Order_Item_Product( $order_item_id );
				$order_item_quantity = (int) $order_item->get_quantity();

				// Get Product Stock
				$product_stock = (int) $product->get_stock_quantity();

				// Update Stock
				$new_quantity = $product_stock + $order_item_quantity;
				wc_update_product_stock( $product, $new_quantity );
				$notes[] = sprintf(
					'%s (%s) %d->%d',
					$product->get_title(), $product->get_sku(), $product_stock, $new_quantity
				);
				break;
		}

	}

	// Add Order Note
	$order = wc_get_order( $_GET['post'] );
	$message = 'Order items updated: ' . implode( ', ', $notes );
	$order->add_order_note( $message, false, true );

} );