Block specific membership level for old and current members. Hide level from levels page. Redirect level away from checkout page. Stop checkout for level.

stop-member-from-checking-out-for-specific-level.php

<?php
/**
 * This recipe will prevent members and users who has had a membership before
 * from checking out for a specific level.
 *
 * 1. Hides level on the Membership Levels page
 * 2. Redirect back to levels page if user visits checkout page.
 * 3. Checks on checkout that user neither has nor had the level.
 *
 * This is an advanced customization recipe that may require further development
 * to suit specific needs and/or setups.
 *
 * Implementation and further customization may require developer skills.
 * If you would like, you can reach out to a Partner Developer (working independently from PMPro)
 * to get an estimate for the project.
 *
 * For more details, please see: https://www.paidmembershipspro.com/developers/
 *
 * OPTIONAL:
 * Forcing existing users to log in before checking out.
 * @link https://gist.github.com/ipokkel/5676f64f58c29719756d7c7022215332
 *
 * 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/
 */

/**
 * If a user is or was a member hide level from the levels page.
 */
function my_pmpro_hide_specific_level_from_members( $levels ) {

	if ( ! is_user_logged_in() ) {
		return $levels;
	}

	global $current_user_id;
	$user_previous_levels = my_pmpro_get_all_previous_membership_levels_for_user( $current_user_id );

	/**
	 * Set your level ID here
	 */
	$blocked_level_id = 1; // Set the level to hide here.
	// hide level
	if ( pmpro_hasMembershipLevel() || in_array( $blocked_level_id, $user_previous_levels ) ) {
		// remove if user were a member before
		unset( $levels[ $blocked_level_id ] );
	}

	return $levels;
}
add_filter( 'pmpro_levels_array', 'my_pmpro_hide_specific_level_from_members', 10 );

/**
 * If a user is or was a member redirect them from the checkout page
 * to the levels page.
 */
function my_pmpro_redirect_checkout_of_specific_level_to_levels_page_for_members() {

	// Lets only check for users who has logged in.
	if ( ! is_user_logged_in() ) {
		return;
	}

	global $pmpro_pages;
	if ( ! is_page( $pmpro_pages['checkout'] ) ) {
		return;
	}

	global $pmpro_level;
	$level = $pmpro_level;

	/**
	 * Set your level ID here
	 */
	$blocked_level_id = 1; // Set the level to hide here.

	// are we checking out for this level?
	if ( intval( $blocked_level_id ) !== intval( $level->id ) ) {
		return;
	}

	// Get all levels user had before.
	global $current_user_id;
	$user_previous_levels = my_pmpro_get_all_previous_membership_levels_for_user( $current_user_id );

	// Redirect to levels page
	if ( pmpro_hasMembershipLevel() || in_array( $blocked_level_id, $user_previous_levels ) ) {
		$levels_page_url = get_permalink( $pmpro_pages['levels'] );
		wp_safe_redirect( $levels_page_url );
		exit;
	}

}
add_action( 'template_redirect', 'my_pmpro_redirect_checkout_of_specific_level_to_levels_page_for_members' );

/**
 * If a user is or was a member stop them from checking out for the level.
 */
function my_pmpro_registration_checks_to_prevent_free_level_checkout_if_member( $okay ) {

	// Let's only check if things are OK.
	if ( ! $okay ) {
		return $okay;
	}

	global $pmpro_level;
	$level = $pmpro_level;

	/**
	 * Set your level ID here
	 */
	$blocked_level_id = 1; // Set the level to hide here.

	// are we checking out for this level?
	if ( intval( $blocked_level_id ) !== intval( $level->id ) ) {
		return $okay;
	}

	// Get all levels user had before.
	global $current_user_id;
	$user_previous_levels = my_pmpro_get_all_previous_membership_levels_for_user( $current_user_id );

	// Stop checkout for the level.
	if ( pmpro_hasMembershipLevel() || in_array( $blocked_level_id, $user_previous_levels ) ) {
		pmpro_setMessage( 'You cannot checkout for this level, please select a different level.', 'pmpro_error' );
		$okay = false;
	}

	return $okay;
}
add_action( 'pmpro_registration_checks', 'my_pmpro_registration_checks_to_prevent_free_level_checkout_if_member' );

/**
 * Get all membership levels the user belonged to.
 *
 * @param mixed $user_id, accepts integer or string.
 * @return array $member_previous_levels
 */
function my_pmpro_get_all_previous_membership_levels_for_user( $user_id = null ) {

	$member_previous_levels = 0;

	if ( empty( $user_id ) ) {
		$user_id = get_current_user_id();
	}
	$user_id = intval( $user_id );

	if ( is_user_logged_in() ) {

		global $wpdb;
		$sql_query = "SELECT DISTINCT membership_id FROM $wpdb->pmpro_memberships_users WHERE user_id = '$user_id'";

		// Check if user previously belonged to a membership level
		$member_previous_levels = $wpdb->get_results( $sql_query, ARRAY_N ); // get levels
		$member_previous_levels = array_merge( ...$member_previous_levels ); // flatten multidimensional array
	}

	return $member_previous_levels;

}