#!/bin/bash

function log {
	conf=`basename $config | sed 's/\.conf$//'`
	[ "$dolog" = "1" ] && echo "`date` - $@" >> $logdir/${conf}.log
}

if [ -z "$1" ]; then
	echo usage: $0 configfile
	exit -1
fi

if [ ! -f $1 ]; then
	echo configfile $1 is not a file
	exit -2
fi

config=$1

host=`grep ^host $config | cut -s -d ' ' -f 2`
aliases="`grep ^aliases $config | cut -s -d ' ' -f 2-`"
user=`grep ^user $config | cut -s -d ' ' -f 2`
homedirs="` grep ^homedirs $config | cut -s -d ' ' -f 2-`"
extradirs="`grep ^extradirs $config | cut -s -d ' ' -f 2-`" 
replicas=`grep ^replicas $config | cut -s -d ' ' -f 2`
oldest=`grep ^oldest $config | cut -s -d ' ' -f 2`
data=`grep ^data $config | cut -s -d ' ' -f 2`
bandwidth=`grep ^bandwidth $config | cut -s -d ' ' -f 2`
bwconn="`grep ^bandwidth $config | cut -s -d ' ' -f 3-`"
compression=`grep ^compression $config | cut -s -d ' ' -f 2`
compconn="`grep ^compression $config | cut -s -d ' ' -f 3-`"
cipher=`grep ^cipher $config | cut -s -d ' ' -f 2`
ciconn=`grep ^cipher $config | cut -s -d ' ' -f 3-`
logdir=`grep ^logdir $config | cut -s -d ' ' -f 2`

dolog=0
if [ ! -z "$logdir" ]; then
	mkdir -p $logdir
	[ -d $logdir ] && dolog=1
fi

hit=0
for conn in $host $aliases; do
	ping -c1 $conn > /dev/null 2>&1
	ret=$?
	if [ "$ret" = "0" ]; then
		remote=$conn
		break
	fi
done
if [ -z "$remote" ]; then
	log "host $host ($aliases) unreachable ..."
	exit -3
else
	log "host $host (via $remote) is online ..."
fi

if [ ! -z "`ssh $user@$remote 'cat ~/.backup | grep ^off'`" ]; then
	log "backup rejected by client ..."
	exit 0
fi

comp=6
if [ ! -z "$compression" ]; then
	comp=$compression
	for cpair in "$compconn"; do
		ch=`echo $cpair | cut -s -d ':' -f 1`
		if [[ "$remote" == "$ch"* ]]; then
			cl=`echo $cpair | cut -s -d ':' -f 2`
			[[ "$cl" == [0-9] ]] && comp=$cl
		fi
	done
fi
rcomp="-z --compress-level $comp"
log using compression level $comp ...

bw=0
if [ ! -z "$bandwidth" ]; then
	bw=$bandwidth
	for bwpair in "$bwconn"; do
		ch=`echo $bwpair | cut -s -d ':' -f 1`
		if [[ "$remote" == "$ch"* ]]; then
			bwl=`echo $cpair | cut -s -d ':' -f 2`
			[ ! -z "$bwl" ] && bw=$bwl
		fi
	done
fi
rbw="--bwlimit=$bw"
log applying bandwidth of $bw ...

ciph=""
if [ ! -z "$cipher" ]; then
	ciph=$cipher
	for cipair in "$ciconn"; do
		ch=`echo $cipair | cut -s -d ':' -f 1`
		if [[ "$remote" == "$ch"* ]]; then
			cl=`echo $cipair | cut -s -d ':' -f 2`
			[ ! -z "$cl" ] && ciph=$cl
		fi
	done
fi
if [ ! -z "$ciph" ]; then
	log using cipher $ciph ...
fi

if [ ! -d $data ]; then
	log no data directory ...
	exit -4
fi
log backing up to $data ...

today=`date -I`
backupdir=$data/${user}_at_${host}
cbd=$backupdir/$today

ob=""
lpb=""
for pb in $backupdir/[0-9]*; do
	[ ! -d $pb ] && continue
	bdd=`basename $pb`
	if [ ! -f $backupdir/.$bdd ]; then
		if [ "$pb" != "$cbd" ]; then
			rm -rf $cbd
			mv $pb $cbd
			log continuing $pb as $cbd ...
		fi
	else
		lpb=$pb
		ob="$ob $pb"
	fi
done


if [ ! -d $cbd ]; then
	if [ ! -z "$lpb" ]; then
		cp -al $lpb $cbd
		log starting backup $today from $lpb ...
	else
		mkdir -p $cbd
		log starting backup $today from scratch ...
	fi
fi

if [ ! -f $backupdir/.$today ]; then
	rsrc=""
	for dir in $homedirs; do
		rsrc="$rsrc :/home/$user/$dir"
	done
	rsrc="`echo $rsrc | sed 's/^\ //'`"
	for dir in $extradirs; do
		rsrc="$rsrc :$dir"
	done
	[ ! -z "$homedirs" ] && \
		log backing up home directories $homedirs ...
	[ ! -z "$extradirs" ] && \
		log backing up directories $extradirs ...

	if [ -z "$ciph" ]; then
		rsync=(rsync -aR $rcomp --delete $rbw $user@$remote$rsrc $cbd)
	else
		rsync=(rsync -aR -e "ssh -c $ciph" $rcomp --delete)
		rsync+=($rbw $user@$remote$rsrc $cbd)
	fi
	res=`"${rsync[@]}" 2>&1`

	ret=$?
	if [ "$ret" != "0" ]; then
		log backup terminated before completion ...
		log reason:
		log $res
		exit -50
	fi
	
	touch $backupdir/.$today
	log "backup $today completed :)"
else
	log backup $bdd found completed ...
fi

[ -z "$replicas" ] && replicas=3
[ -z "$oldest" ] && oldest=0

cob=`echo $ob | wc -w`
if [ $cob -gt $replicas ]; then
	((numdel=cob-replicas))
	todel="`echo $ob | cut -s -d ' ' -f 1-${numdel}`"
	for dirdel in $todel; do
		past=`basename $dirdel`
		ns=`date --date="$today" +%s`
		ps=`date --date="$past" +%s`
		((delta=(ns-ps)/86400))
		if [ $delta -gt $oldest ]; then
			log "deleting $dirdel ($delta days old) ..."
			bdd=`basename $dirdel`
			rm -r $dirdel
			rm $backupdir/.$bdd
		else
			log "keeping $dirdel ($delta days old) ..."
		fi
	done
fi

exit 0