#!/bin/bash

set -euo pipefail

current_volume=$(pactl get-sink-volume @DEFAULT_SINK@ | grep Volume | sed -e 's/.* \([0-9][0-9]*\)%.*/\1/')
case $1 in
    up)
        increment=$(( 5 - ( current_volume % 5 ) ))
        newvol=$(( current_volume + increment ))
        if [ $newvol -gt 100 ]; then
            newvol=100
        fi
        pactl set-sink-volume @DEFAULT_SINK@ $newvol%
        echo $newvol;;
    down)
        increment=$(( ( ( current_volume - 1 ) % 5 ) + 1 ))
        newvol=$(( current_volume - increment ))
        if [ $newvol -lt 0 ]; then
            newvol=0
        fi
        pactl set-sink-volume @DEFAULT_SINK@ $newvol%
        echo $newvol;;
esac