#!/bin/bash
#
# squeezesync
#	-- watch a local itunes installation for changes and sync them to a 
#	   remote squeezeboxserver using rsync.
#
# author: <greg@automagick.us>
#
# Requires: ssh, rsync, curl

#### LOCAL ITUNES CONFIGURATION ####

USER=greg
ITUNES_DIR=/Users/${USER}/Music/iTunes
MUSIC_DIR=${ITUNES_DIR}/iTunes\ Music
ITUNES_XML=${ITUNES_DIR}/iTunes\ Music\ Library.xml


#### REMOTE SQUEEZEBOXSERVER CONFIGURATION ####

# Note: configure SSH to allow a login by this user without a password.
REMOTE_USER=greg
REMOTE_HOST=garrett

# where should the tracks be synced to?
REMOTE_MUSIC=/usr/local/music/music

# where should the iTunes Library XML file be synced to?
REMOTE_LIBRARY=/usr/local/music/itunesdb

# the URL for the squeezeboxserver (needed to force a rescan)
SQZBOX_URL=http://garrett:9000

# How long the script should wait before checking for changes, in seconds.
SLEEP_INTERVAL=30


#### MAIN LOOP (THE WORKIN' OVERTIME PART) ####

cd "${MUSIC_DIR}"
while true; do 

	# Create a string representing the state of the iTunes library. 
	# We do this by tracking total disk usage and a checksum of the
	# directory listing.  This ensures we notice any change to the
	# directory structure, even ones (like renames) that don't change
	# total disk usage, as well as solving a race condition for files
	# being modified while the sync runs.  Finally, we checksum the
	# iTunes XML file to detect changes to playlists and other metadata.
	#
	i="`du |tail -1|cut -f1` `find . |cksum` `cksum \"${ITUNES_XML}\"|cut -f1 -d\ `" 

	# Compare the current state of the iTunes library ($i) to the previous state ($j).
	if [[ $i != $j ]]; then 

		# changes were detected, so use rsync to update the squeezebox library
		rsync -av --delete "${MUSIC_DIR}/" "${REMOTE_USER}@${REMOTE_HOST}:${REMOTE_MUSIC}"

		# copy the iTunes Music Library.xml file so playlists and such are preserved.
		rsync -qav "${ITUNES_XML}" "${REMOTE_USER}@${REMOTE_HOST}:${REMOTE_LIBRARY}"

		# request a rescan of the squeezecenter library
		curl -so /dev/null "${SQZBOX_URL}/status.html?p0=rescan"
	fi

	# remember the current state of the library for the next check, and wait 30 seconds.
	j="$i"
	sleep ${SLEEP_INTERVAL}
done