move-wc-related-items-to-product-tab.php

<?php // only copy if needed

/**
 * If there are upsells or related items for the product, add them in a new tab.
 * @See https://www.skyverge.com/?p=4242
 *
 * @param string[] $tabs the product tabs
 * @return string[] maybe updated tabs array
 */
function sv_wc_maybe_add_upsell_tab( $tabs ) {
	global $product;

	// compatibility check for pre / post WC 3.0
	$upsells = is_callable( array( $product, 'get_upsell_ids' ) )     ? $product->get_upsell_ids()     : $product->get_upsells();
	$related = is_callable( array( $product, 'get_cross_sell_ids' ) ) ? $product->get_cross_sell_ids() : $product->get_cross_sells();

	// if we have no related items, don't add a new tab
	if ( empty( $upsells ) && empty( $related ) ) {
		return $tabs;
	}

	// green light! remove the current upsells
	remove_action( 'woocommerce_after_single_product_summary', 'woocommerce_upsell_display', 15 );
	remove_action( 'woocommerce_after_single_product_summary', 'woocommerce_output_related_products', 20 );

	// first, make sure that we're dealing with an array rather than null
	$new_tabs = is_null( $tabs ) ? array() : $tabs;

	// now add the upsells back in tabulated formation
	$new_tabs['upsells'] = array(
		'title'    => __( 'Related Items', 'woocommerce-upsells-tab' ),
		'priority' => 25,
		'callback' => 'sv_wc_output_upsells_related_items',
	);

	return $new_tabs;
}
add_filter( 'woocommerce_product_tabs', 'sv_wc_maybe_add_upsell_tab' );


// Callback to output related products and upsells.
function sv_wc_output_upsells_related_items() {
	woocommerce_upsell_display();
	woocommerce_output_related_products();
}