#!/usr/bin/env sh
# change Volume in an easy and unified way

direction=$1
step=${2:-5dB}

# amixer channel to target
amixer_quiet() {
    amixer -c 0 "$@" >/dev/null
}
amixer_noisy="amixer -c 0 "

# Query amixer for the current volume
get_volume() {
    $amixer_noisy get Master | tail -1 | awk '{print $4}' | sed 's/[^0-9]*//g'
}

# query amixer for mute state (off=muted)
get_mute() {
    $amixer_noisy get Master | tail -1 | awk '{print $6}' | sed 's/[^a-z]*//g'
}

set_volume() {
    # Change the volume using alsa(might differ if you use pulseaudio)
    amixer_quiet set Master "$@" >/dev/null

    # Play the volume changed sound
    # -- this is *extremely* laggy (>8s) on my system, no idea why and no time to find out
    # canberra-gtk-play -i audio-volume-change -d "changeVolume"
}

# set mute state (off=mute)
set_mute() {
    [ "$(get_mute)" = "on" ] && toggleto=off || toggleto=on
    if [ "$1" = 'off' ]; then
        amixer_quiet set Master mute
    elif [ "$1" = 'on' ]; then
        amixer_quiet set Master unmute
        # the following is needed, see https://superuser.com/questions/805525/why-is-unmute-not-working-with-amixer-command
        amixer_quiet set Speaker unmute
        amixer_quiet set Headphone unmute
    else
        amixer_quiet set Master "$toggleto"
        amixer_quiet set Speaker "$toggleto"
        amixer_quiet set Headphone "$toggleto"
    fi
}

usage() {
    echo "control-volume up|down [step], with step any int value
or:     control-brightness set [target], with target any int value 0-100"
}

send_notification() {
    if type dunstify 1>/dev/null 2>/dev/null; then
        notcmd="dunstify -h string:x-dunst-stack-tag:brightness"
    else
        notcmd="notify-send -h string:x-dunst-stack-tag:brightness"
    fi

    vol="$(get_volume)"

    if [ "$vol" -eq 0 ] || [ "$(get_mute)" = "off" ]; then
        # Show the sound muted notification
        $notcmd -a "changeVolume" -u low -i audio-volume-muted "Volume muted"
    else
        # Show the volume notification
        $notcmd -a "changeVolume" -u low -i audio-volume-high \
            -h int:value:"$vol" "Volume: $vol%"
    fi
}

case $direction in
up)
    set_volume "${step}+"
    ;;
down)
    set_volume "${step}-"
    ;;
mute)
    set_mute "$step"
    ;;
mutetoggle)
    set_mute
    ;;
set)
    if [ -z "$step" ]; then
        echo "set option requires target brightness to be specified."
        return 1
    fi
    set_volume "$step"
    ;;
*)
    usage
    ;;
esac
send_notification