#!/bin/bash
set -e

SINK='@DEFAULT_SINK@'
TMP_FILE='/tmp/set-vol'

for _ in 1 2 3; do
    [ -f "$TMP_FILE" ] || break
    sleep 0.03
done
touch "$TMP_FILE"

VOL="$(pactl get-sink-volume "$SINK")"
VOL="$(grep -Po '\d+(?=%)' <<< "$VOL" | head -n 1)"
VOL="$((VOL - VOL % "$1"))"

case "${1:0:1}" in
    '')
        exit 1
        ;;
    '+'|'-')
        VOL="$((VOL + "$1"))"
        ;;
    *)
        VOL="$1"
        ;;
esac

[ "$VOL" -lt 0   ] && VOL=0
[ "$VOL" -gt 100 ] && VOL=100

pactl set-sink-volume "$SINK" "$VOL%"
pactl set-sink-mute   "$SINK" 0

rm "$TMP_FILE"

if [ -t 1 ]; then
    echo "$VOL"
fi