#!/bin/sh

id="${1?}" \
instance="$3" \
class="$2";

case "$class" in
    (foo)
        bar;;
    ("")
        unset -v _NET_WM_PID;
        . /dev/fd/0 2>/dev/null <<IN
        : \"\${$(
            xprop \
                -id "$id" \
                -notype \
                -f _NET_WM_PID 32c '=$0' \
                _NET_WM_PID;
        )}\";
IN
        case "$(ps -p "${_NET_WM_PID:?}" -o comm= 2>/dev/null)" in
            (spotify)
                echo desktop=7 follow=on focus=on;;
        esac;;
esac;