Virtual URLs to modify query

query-hooks.php

<?php

function add_custom_query_vars($vars) {
    $vars[] = "past_events";
    return $vars;

}
// hook add_query_vars function into query_vars
add_filter('query_vars', 'add_custom_query_vars');

function custom_rewrite_rule() {

    add_rewrite_rule('^past-events/?','index.php?post_type=events&past_events=1','top');

}

add_action('init', 'custom_rewrite_rule', 10, 0);

function alterQuery($query) {

    global $wp_query;

    if ( ! is_admin() and $query->is_main_query() && is_post_type('events') ) {

        /* Events */

        $pastEvents = false;

        if( isset( $wp_query->query_vars['past_events'] ) ) {

            $pastEvents = $wp_query->query_vars['past_events'];

        }

        if( $pastEvents !== false ) {

            $query->set( 'meta_query', array(

                array(

                    'key'       =>  'end_time',
                    'value'     => time(),
                    'compare'   =>  '<'

                )

            ) );

        } else {

            $query->set( 'meta_query', array(

                array(

                    'key'          => 'end_time',
                    'value'        => time(),
                    'compare'      => '>='

                )

            ) );

        }



    }

}

add_action('pre_get_posts','alterQuery');