Save or unsave the item.

class-toptal-save-public.php

/**
 * Save or unsave the item.
 *
 * @since    1.0.0
 */
public function save_unsave_item() {

	// Check the nonce, if ok, proceed.
	if ( ! wp_verify_nonce( $_REQUEST['nonce'], 'toptal_save_nonce' ) ) {
		die;
	}

	// Get the item ID from AJAX
	if ( isset( $_REQUEST['item_id'] ) ) {

		$item_id = intval( $_REQUEST['item_id'] );

	} else {
		
		$item_id = 0;

	}

	$is_saved = false;

	// Check if user is logged in
	if ( is_user_logged_in() ) {

		// Get all saved items for this user
		$saved_items = get_user_meta( get_current_user_id(), 'toptal_saved_items', true );

		// Check if this user doesn't have any saved items
		if ( empty( $saved_items ) ) {

			$saved_items = array();

		}

		// Check if this item is saved or not, if it is - unsave it, if it's not - save it
		if ( in_array( $item_id, $saved_items ) ) {

			$is_saved = true;

			// Remove the item
			unset( $saved_items[array_search( $item_id, $saved_items )] );

		} else {

			$is_saved = false;

			// Add the item
			array_push( $saved_items, $item_id );

		}

		// Save the changes to the user meta field
		update_user_meta( get_current_user_id(), 'toptal_saved_items', $saved_items );

	} else {

		// Get all saved items from the cookie
		$saved_items = $this->toptal_get_cookie( $this->get_unique_cookie_name() );

		// Check if this item is saved or not
		if ( in_array( $item_id, $saved_items ) ) {

			$is_saved = true;

			// Remove the item
			unset( $saved_items[array_search( $item_id, $saved_items )] );

		} else {

			$is_saved = false;

			// Add the item
			array_push( $saved_items, $item_id );

		}

		// Save the changes to the cookie
		$this->toptal_set_cookie( $this->get_unique_cookie_name(), $saved_items );

	}

	// Create an array of data that we will return back to our AJAX
	$return = array(
		'is_saved' => $is_saved
	);

	// Return the data
	return wp_send_json( $return );

}