<?php

class user_selector extends user_selector_base
{

    public function find_users($search)
    {
        global $DB;

        // Define the fields you want to select.
        $fields = 'id, firstname, lastname, email';

        // Create an SQL query to find users based on the search criteria.
        $sql = "SELECT $fields
                  FROM {user}
                 WHERE CONCAT(firstname, ' ', lastname) LIKE ? OR email LIKE ?";

        // Execute the SQL query and retrieve the users.
        $users = $DB->get_records_sql($sql, array('%' . $search . '%', '%' . $search . '%'));

        // Format the users into a format expected by the user selector.
        $options = [];
        foreach ($users as $user) {
            $options[$user->id] = $user->firstname . ' ' . $user->lastname . ' (' . $user->email . ')';
        }

        return array(get_string('users') => $options);
    }
}