###############################################################
#
#  This handler slowly creates a backup of each user's maildir
#  to a remote server. It is designed to be run with low overhead
#  in terms of cpu and bandwidth so it runs pretty slow.
#
#  if destdir is /backup/maildir/, then it will contain the files
#    daily.1
#    daily.2
#    daily.3
#    weekly.1
#    weekly.2
#    monthly.1
#  if keepdaily is 3, keepweekly is 2, and keepmonthly is 1. 
# 
##############################################################

getconf rotate yes
getconf remove yes

getconf loadlimit 5
getconf speedlimit 0
getconf keepdaily 5
getconf keepweekly 3
getconf keepmonthly 1

getconf srcdir /var/maildir
getconf destdir
getconf desthost
getconf destport 22
getconf destuser

# strip trailing /
destdir=${destdir%/}
srcdir=${srcdir%/}

# used for testing
getconf letter
getconf user

[ -d $srcdir ] || fatal "source directory $srcdir doesn't exist"

[ ! $test ] || testflags="--dry-run -v"
rsyncflags="$testflags -e 'ssh -p $destport'"
flags_mail="$rsyncflags --archive --ignore-existing --delete --numeric-ids --size-only --bwlimit=$speedlimit"
flags_folders="$rsyncflags --archive --delete --numeric-ids"
excludes='--exclude ".Trash/*" --exclude ".Mistakes/*" --exclude ".Spam/*"'

# see if we can login
debug "ssh -o PasswordAuthentication=no $desthost -l $destuser 'echo -n 1'"
if [ ! $test ]; then
	result=`ssh -o PasswordAuthentication=no $desthost -l $destuser 'echo -n 1' 2>&1`
	if [ "$result" != "1" ]; then
		fatal "Can't connect to $desthost as $destuser."
	fi
fi

##################################################################
### FUNCTIONS

# remote run the args remotely
function rrun() {
	debug ssh -o PasswordAuthentication=no $desthost -l $destuser $@
	if [ ! $test ]; then
		debug ssh -o PasswordAuthentication=no $desthost -l $destuser $@
	fi
}

function do_letters() {
	for i in a b c d e f g h i j k l m n o p q r s t u v w x y z; do
		do_maildirs "$srcdir/$i"
	done
}

function do_maildirs() {
	local dir=$1
	[ -d $dir ] || fatal "directory $dir not found."
	for userdir in `ls -1 $dir`; do
		do_userdir $userdir
	done
}

function do_user() {
	local user=$1
	local letter=${user:0:1}
	local dir="$srcdir/$letter/$user"
	[ -d $dir ] || fatal "maildir $dir not found".

	while 1; do
		load=`uptime | sed 's/^.*load average: \\([^,]*\\).*$/\\1/'`
		if [ $load -lt $loadlimit ]; then
			info "load $load, sleeping..."
			sleep 600
		else
			break
		fi
	done
	
  	cmd="rsync $maildirrsyncflags $excludes '$dir' '$destuser@$desthost:$destdir/maildir/$letter'"
  	debug $cmd
	# ret=`rsync $maildirrsyncflags $excludes '$dir' '$destuser@$desthost:$destdir/maildir/$letter' 2>&1`
}

# remove any maildirs from backup which might have been deleted
# and add new ones which have just been created.

function do_remove() {
	local tmp1=/tmp/maildirtmpfile$$
	local tmp2=/tmp/maildirtmpfile$$
	
	for i in a b c d e f g h i j k l m n o p q r s t u v w x y z; do
		ls -1 "$srcdir/$i" | sort > $tmp1
		ssh -p $destport $desthost ls -1 '$destdir/maildir/$i' | sort > $tmp2
		for deluser in `join -v 2 $tmp1 $tmp2`; do
			cmd="ssh -p $destport $desthost rm -vr '$destdir/maildir/$i/$deluser/'"
			debug $cmd
		done
	done
	rm $tmp1
	rm $tmp2	
}

function do_rotate() {
	backuproot=$destdir

	ssh -T -o PasswordAuthentication=no $desthost -l $destuser <<EOF
##### BEGIN REMOTE SCRIPT #####
	seconds_daily=86400
	seconds_weekly=604800
	seconds_monthly=2628000
	keepdaily=$keepdaily
	keepweekly=$keepweekly
	keepmonthly=$keepmonthly
	now=\`date +%s\`

	for rottype in daily weekly monthly; do
		seconds=\$((seconds_\${rottype}))

		dir="$backuproot/\$rottype"
		if [ ! -d \$dir.1 ]; then
			echo "Info: \$dir.1 does not exist. This backup is missing, so we are skipping the rotation."
			continue 1
		elif [ ! -f \$dir.1/created ]; then
			echo "Warning: \$dir.1/created does not exist. This backup may be only partially completed. Skipping rotation."
			continue 1
		fi
		
		# Rotate the current list of backups, if we can.
		oldest=\`ls -d \$dir.* | sed 's/^.*\.//' | sort -n | tail -1\`
		[ "\$oldest" == "" ] && oldest=0
		for (( i=\$oldest; i > 0; i-- )); do
			if [ -d \$dir.\$i ]; then
				if [ -f \$dir.\$i/rotated ]; then
					rotated=\`tail -1 \$dir.\$i/rotated\`
				else
					rotated=0
				fi
				cutoff_time=\$(( now - (seconds*i) ))
				if [ \$rotated -lt \$cutoff_time ]; then
					next=\$(( i + 1 ))
					if [ ! -d \$dir.\$next ]; then
						echo "mv \$dir.\$i \$dir.\$next"
						mv \$dir.\$i \$dir.\$next
						date +%c%n%s > \$dir.\$next/rotated
					else
						echo "Info: skipping rotation of \$dir.\$i because \$dir.\$next already exists."
					fi
				else
					echo "Info: skipping rotation of \$dir.\$i because it was rotated" \$(( (now-rotated)/86400)) "days ago ("\$(( (now-cutoff_time)/86400))" needed)."
				fi
			fi
		done
	done

	max=\$((keepdaily+1))
	if [ \( \$keepweekly -gt 0 -a -d $backuproot/daily.\$max \) -a ! -d $backuproot/weekly.1 ]; then
		echo mv $backuproot/daily.\$max $backuproot/weekly.1
		mv $backuproot/daily.\$max $backuproot/weekly.1
		date +%c%n%s > $backuproot/weekly.1/rotated
	fi

	max=\$((keepweekly+1))
	if [ \( \$keepmonthly -gt 0 -a -d $backuproot/weekly.\$max \) -a ! -d $backuproot/monthly.1 ]; then
		echo mv $backuproot/weekly.\$max $backuproot/monthly.1
		mv $backuproot/weekly.\$max $backuproot/monthly.1
		date +%c%n%s > $backuproot/monthly.1/rotated
	fi

	for rottype in daily weekly monthly; do
		max=\$((keep\${rottype}+1))
		dir="$backuproot/\$rottype"
		oldest=\`ls -d \$dir.* | sed 's/^.*\.//' | sort -n | tail -1\`
		[ "\$oldest" == "" ] && oldest=0 
		# if we've rotated the last backup off the stack, remove it.
		for (( i=\$oldest; i >= \$max; i-- )); do
			if [ -d \$dir.\$i ]; then
				echo "Info: removing \$dir.\$i"
				rm -rf \$dir.\$i
			fi
		done
	done
####### END REMOTE SCRIPT #######
EOF
}


###
##################################################################

### ROTATE BACKUPS ###

if [ "$rotate" == "yes" ]; then
	do_rotate
fi

### REMOVE OLD MAILDIRS ###

if [ "$remove" == "yes" ]; then
	debug remove
fi

### ROTATE BACKUPS ###

if [ "$letter" != "" ]; then
	debug letter
fi

if [ "$user" != "" ]; then
	debug user
fi