[WooCommerce] Orders - Filter by User Role

<?php

/**
 * Add filter to show WooCommerce orders from a specific user role
 */
if ( ! function_exists( 'wc_get_role_order_count' ) ) {
    // Function to get number of orders of a user role
    function wc_get_role_order_count( $role ) {
        global $wpdb;

        if ( ! isset( get_editable_roles()[ $role ] ) ) {
            return 0;
        }

        $user_ids = get_users( array( 'role' => $role, 'fields' => 'ID' ) );

        if ( ! $user_ids ) {
            return 0;
        }

        $user_ids = array_map( 'absint', $user_ids );
        $user_ids = implode( ',', $user_ids );

        $count = $wpdb->get_var( $sql = "
            SELECT COUNT(*)
            FROM {$wpdb->posts} as posts

            LEFT JOIN {$wpdb->postmeta} AS meta ON posts.ID = meta.post_id

            WHERE   meta.meta_key       = '_customer_user'
            AND     posts.post_type     IN ('" . implode( "','", wc_get_order_types( 'order-count' ) ) . "')
            AND     posts.post_status   IN ('" . implode( "','", array_keys( wc_get_order_statuses() ) )  . "')
            AND     meta.meta_value     IN ({$user_ids})
        " );

        return absint( $count );
    }
}

add_action( 'restrict_manage_posts', 'shop_order_user_role_filter' );

function shop_order_user_role_filter() {
    global $typenow;

    if ( in_array( $typenow, wc_get_order_types( 'order-meta-boxes' ) ) ) {
        $user_role = '';

        // Get all user roles
        $user_roles = array();

        foreach ( get_editable_roles() as $key => $values ) {
            // Only show the role if it has orders
            if ( wc_get_role_order_count( $key ) > 0 ) {
                $user_roles[ $key ] = $values['name'];
            }
        }

        // Set a selected user role
        if ( ! empty( $_GET['_user_role'] ) ) {
            $user_role = sanitize_text_field( $_GET['_user_role'] );
        }

        // Display drop down
        ?><select name="_user_role">
            <option value=""><?php _e( 'Select a user role', 'woocommerce' ); ?></option><?php
            foreach ( $user_roles as $key => $value ) {
                ?><option <?php selected( $user_role, $key ); ?> value="<?php echo esc_attr( $key ); ?>"><?php echo esc_html( $value ); ?></option><?php
            }
        ?></select><?php
    }
}

add_filter( 'request', 'shop_order_user_role_request_query' );

function shop_order_user_role_request_query( $vars ) {
    global $typenow;

    if ( ! empty( $_GET['_user_role'] ) && in_array( $typenow, wc_get_order_types( 'order-meta-boxes' ) ) ) {
        // Get user IDs of role
        $ids = get_users( array( 'role' => sanitize_text_field( $_GET['_user_role'] ), 'fields' => 'ID' ) );
        $ids = array_map( 'absint', $ids );

        // Make sure we have a valid array to work with
        if ( ! isset( $vars['meta_query'] ) || ! is_array( $vars['meta_query'] ) ) {
            $vars['meta_query'] = array();
        }

        // Add query to check for _customer_user
        $vars['meta_query'][] = array(
            'key'     => '_customer_user',
            'value'   => $ids,
            'compare' => 'IN',
        );
    }

    return $vars;
}