whatsapp chatbot navigation in sub-menus

whatsapp.php

if((int)$query == 0){
    $states = #fetch states from the session
    if(count($states) > 1){
        $count = count($states);
        $prev = $count - 2;
        $prev_state = $states[$prev];
        if($prev_state != '0'){
            //go to previous key - /menus/{$prev_state}
            //show sub-menus
            //contatenate '0. Previous Menu'
            
            //remove current state and set prev_state to current
            unset($states[$count-1]);
            //save 'states' in session
        }else{
            //show main menu
            //delete states from session
            $state_id = '0';
            $states[] = $state_id;
            #save 'states' in session
        }
    }else{
        //show main menu
        //delete states from session
        $state_id = '0';
        $states[] = $state_id;
        #save 'states' in session
    }
}