#!/bin/sh
#
# Changes the JACK sound device on the fly with minimal damage to running
# programs.  Useful for those who frequently unplug their USB sound cards, e.g.
# if you need to move your laptop to the kitchen and continue watching the
# movie with the built-in audio.
#
# The damage mostly lies in PulseAudio, which usually segfaults if jackd dies,
# and with PulseAudio dies Skype, hangs mplayer and other bad things happen.
# This script properly unloads PulseAudio modules then loads them when JACK is
# ready to be restarted; if you don't use PulseAudio, JACK is just started.
#
# For this to work with PulseAudio you will need the pactl-unload-by-name
# script, which is available at:
# <http://umonkey-tools.googlecode.com/hg/bin/pactl-unload-by-name>.
#
# @author hex@umonkey.net (Justin Forest)
# @license Public Domain

export GREP_OPTIONS=
AVAILABLE_CARDS="$(aplay -L | grep CARD= | cut -d: -f2 | cut -d, -f1 | cut -d= -f2 | sort -u | xargs echo)"
if [ -n "$1" ]; then
    CARDNAME="$1"
    if [ -z "$(aplay -L | grep CARD=$1, )" ]; then
        echo "No such card: $1, available options: $AVAILABLE_CARDS."
        exit 1
    fi
elif [ -n "$(aplay -L | grep 'CARD=USB')" ]; then
    CARDNAME="USB"
else
    CARDNAME="Intel"
fi

CONFIG="/usr/bin/jackd -dalsa -dhw:$CARDNAME -r44100 -p1024 -n2 -s -H -M"
CONFIG_NAME=$HOME/.jackdrc

if [ "$CONFIG" = "$(cat $CONFIG_NAME)" ]; then
    echo "Current card: $CARDNAME, available options: $AVAILABLE_CARDS."
    exit 0
fi

HAVE_JACK="$(pgrep -u $USER jackd)"
HAVE_PULSE="$(pgrep -u $USER pulseaudio)"

if [ -n "$HAVE_PULSE" ]; then
    if [ -z "$(which pactl-unload-by-name)" ]; then
        echo "Please install pactl-unload-by-name (copy to your \$PATH) from here:"
        echo "http://umonkey-tools.googlecode.com/hg/bin/pactl-unload-by-name"
        exit 1
    fi
    echo "Unloading PulseAudio modules."
    pactl-unload-by-name "module-jack-*"
fi

echo "Switching to $CARDNAME."
echo -n "$CONFIG" > $CONFIG_NAME

if [ -n "$HAVE_JACK" ]; then
    echo "Stopping JACK."
    pkill -9 -u $USER jackd
    sleep 1
fi

if [ -n "$HAVE_PULSE" ]; then
    echo "Loading PulseAudio JACK sink."
    pactl load-module module-jack-sink >/dev/null
    echo "Loading PulseAudio JACK source."
    pactl load-module module-jack-source >/dev/null
else
    echo "Starting the JACK daemon."
    . $CONFIG_NAME
fi

if [ -n "$(which jack.plumbing)" ]; then
    echo "Restarting jack.plumbing"
    pkill -u $USER jack.plumbing
    jack.plumbing >/dev/null 2>&1 &
fi