<?php

/**
 * Get Linked Member Types and User Roles.
 */
function yzc_get_linked_member_types_and_user_roles() {

    // Set Member Type Name => User Role
    return array(
        'student' => 'subscriber',
        'teacher' => 'editor'
    );

}

/**
 * Sync Member Type => User Role.
 */
function yzc_link_member_type_to_user_role( $user_id, $member_type ) {

    // Get Member Types and their Users Roles
    $user_roles = yzc_get_linked_member_types_and_user_roles();

    $user = new WP_User( $user_id );

    if ( isset( $user_roles[ $member_type ] ) ) {
        $user->set_role( $user_roles[ $member_type ] );
    }

}

add_action( 'bp_set_member_type', 'yzc_link_member_type_to_user_role', 10, 2 );

/**
 * Sync User Role => Member Type.
 */
function yzc_link_user_role_to_member_type( $user_id, $role ) {

    // Get Member Types and their Users Roles
    $member_types = yzc_get_linked_member_types_and_user_roles();

    // Switch Array Order.
    $member_types = array_flip( $member_types );

    if ( isset( $member_types[ $role ] ) ) {
        bp_set_member_type( $user_id, $member_types[ $role ] );
    }

}

add_action( 'set_user_role', 'yzc_link_user_role_to_member_type', 10, 2 );