PMPro Lock Membership Levels - Allow members to cancel their own level but not change their current level

pmpro-lock-membership-levels-allow-renewal.php

<?php

/**
 * This recipe allows members to cancel a locked membership level
 * if the level was locked with PMPro Lock Membership Levels Add On.
 *
 * This recipe expects and requires the Membership Locked page set up
 * and assigned under Memberships > Settings > Page settings.
 * @link https://www.paidmembershipspro.com/add-ons/pmpro-lock-membership-level/#install
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function my_init() {
	global $pmpro_pages;

	// Check if Lock Membership is active and required Membership Locked page is set.
	if ( function_exists( 'pmprolml_template_redirect' ) && ! empty( $pmpro_pages['membership_locked'] ) && pmpro_hasMembershipLevel() ) {
		remove_action( 'template_redirect', 'pmprolml_template_redirect' );
		add_action( 'template_redirect', 'my_pmprolml_template_redirect' );
	}
}
add_action( 'init', 'my_init' );

function my_pmprolml_template_redirect() {
	global $pmpro_pages, $current_user, $pmpro_level;

	if ( empty( $pmpro_pages ) || empty( $pmpro_pages['membership_locked'] ) ) {
		return;
	}

	$user_lock_options = pmprolml_getUserOptions( $current_user->ID );

	//Redirect away from the membership locked page if user isn't locked.
	if ( is_user_logged_in() && is_page( $pmpro_pages['membership_locked'] ) && ( empty( $user_lock_options ) || empty( $user_lock_options['locked'] ) ) ) {
		if ( pmpro_hasMembershipLevel() ) {
			wp_redirect( pmpro_url( 'account' ) );
			exit;
		} else {
			wp_redirect( home_url() );
			exit;
		}
	}

	//Redirect to the membership locked page if user is locked.
	$locked_pages = array(
		$pmpro_pages['levels'],
		$pmpro_pages['checkout'],

	);
	if ( is_user_logged_in() && is_page( $locked_pages ) ) {
		if ( ! empty( $user_lock_options ) && ! empty( $user_lock_options['locked'] ) ) {
			if ( ! empty( $pmpro_pages['membership_locked'] ) ) {
				wp_redirect( pmpro_url( 'membership_locked' ) );
				exit;
			} else {
				wp_redirect( home_url() );
				exit;
			}
		}
	}
	if ( is_user_logged_in() && is_page( $pmpro_pages['checkout'] ) ) {
		$level_id = $_REQUEST['level'];
		if ( ! empty( $level_id ) && ! pmpro_hasMembershipLevel( $level_id ) ) {
			wp_redirect( pmpro_url( 'membership_locked' ) );
			exit;
		}
	}
}