on( 'woocommerce_analytics_update_customer', $customer_id );

		ReportsCache::invalidate();

		return $results;
	}

	/**
	 * Check if a user ID is a valid customer or other user role with past orders.
	 *
	 * @param int $user_id User ID.
	 * @return bool
	 */
	protected static function is_valid_customer( $user_id ) {
		$customer = new \WC_Customer( $user_id );

		if ( absint( $customer->get_id() ) !== absint( $user_id ) ) {
			return false;
		}

		$customer_roles = (array) apply_filters( 'woocommerce_analytics_customer_roles', array( 'customer' ) );
		if ( $customer->get_order_count() < 1 && ! in_array( $customer->get_role(), $customer_roles, true ) ) {
			return false;
		}

		return true;
	}

	/**
	 * Delete a customer lookup row.
	 *
	 * @param int $customer_id Customer ID.
	 */
	public static function delete_customer( $customer_id ) {
		global $wpdb;

		$customer_id = (int) $customer_id;
		$num_deleted = $wpdb->delete( self::get_db_table_name(), array( 'customer_id' => $customer_id ) );

		if ( $num_deleted ) {
			/**
			 * Fires when a customer is deleted.
			 *
			 * @param int $order_id Order ID.
			 */
			do_action( 'woocommerce_analytics_delete_customer', $customer_id );

			ReportsCache::invalidate();
		}
	}

	/**
	 * Delete a customer lookup row by WordPress User ID.
	 *
	 * @param int $user_id WordPress User ID.
	 */
	public static function delete_customer_by_user_id( $user_id ) {
		global $wpdb;

		$user_id     = (int) $user_id;
		$num_deleted = $wpdb->delete( self::get_db_table_name(), array( 'user_id' => $user_id ) );

		if ( $num_deleted ) {
			ReportsCache::invalidate();
		}
	}

	/**
	 * Initialize query objects.
	 */
	protected function initialize_queries() {
		$this->clear_all_clauses();
		$table_name     = self::get_db_table_name();
		$this->subquery = new SqlQuery( $this->context . '_subquery' );
		$this->subquery->add_sql_clause( 'from', $table_name );
		$this->subquery->add_sql_clause( 'select', "{$table_name}.customer_id" );
		$this->subquery->add_sql_clause( 'group_by', "{$table_name}.customer_id" );
	}
}