WordPress: Password protected content helpers

password-protection.php

<?php

/**
 * Helpers: Password protected content
 */

/**
 * Remove "Protected:" prefix from the title of password protected posts
 */
function dt_remove_protected_prefix_from_titles($var, $post)
{
    return '%s';
};
add_filter('protected_title_format', 'dt_remove_protected_prefix_from_titles', 10, 2);


/**
 * Get the id of closest password protected post.
 * Start with current post and work up the ancestors
 */
function dt_related_password_protected_post_id($post = null)
{

    if (!is_page()) {
        return false;
    }

    $post = get_post($post);
    $ancestors = get_ancestors($post->ID, 'page');
    $all_relevant_post_ids = array_merge([$post->ID], $ancestors);

    foreach ($all_relevant_post_ids as $post_id) {
        $current_post = get_post($post_id);
        if (!empty($current_post->post_password)) {
            return $post_id;
        }
    }

    return false;
}

/**
 * Wrapper for core function post_password_required() that also considers
 * if parents are password protected
 */
function dt_post_password_required()
{

    $pasword_protected_ancestor_id = dt_related_password_protected_post_id();
    return post_password_required($pasword_protected_ancestor_id);
}

/**
 * Wrapper for core function get_the_password_form() that also considers
 * if parents are password protected
 */
function dt_get_the_password_form()
{

    $pasword_protected_ancestor_id = dt_related_password_protected_post_id();
    return get_the_password_form($pasword_protected_ancestor_id);
}


/**
 * Get all page ids that either have a password or have an ancestor that has a password.
 */
function dt_get_all_password_protected_page_ids()
{

    $all_protected_page_ids = [];

    $password_pages_query = [
        'posts_per_page' => -1,
        'post_type' => 'page',
        'has_password' => true,
        'fields' => 'ids',
    ];

    $page_ids_with_passwords = get_posts($password_pages_query);

    if ($page_ids_with_passwords) {

        foreach ($page_ids_with_passwords as $ancestor_page_id) {

            if (!in_array($ancestor_page_id, $all_protected_page_ids)) {
                $all_protected_page_ids[] = $ancestor_page_id;
            }

            $get_pages_args = [
                'child_of' => $ancestor_page_id,
            ];

            $child_pages_array = get_pages($get_pages_args);

            if ($child_pages_array) {

                foreach ($child_pages_array as $child_page_obj) {

                    if (!in_array($child_page_obj->ID, $all_protected_page_ids)) {
                        $all_protected_page_ids[] = $child_page_obj->ID;
                    }
                }
            }
        }
    }

    return $all_protected_page_ids;
}