#!/bin/bash

source /etc/profile >/dev/null
[ -f "$HOME/.zb-rc" ] && source "$HOME/.zb-rc"

if [[ -z "$1" || -z "$2" || -z "$3" ]] ; then
	echo "usage: $0 <remote> <remote_zfs_object> <local_zfs_object>" >&2
	echo "<remote> is either ssh-style user@hostname, or - for local operation" >&2
	exit 1
fi

timestamp () {
	t="`echo \"$1\" |sed -ne 's/^.*@zb-//p' |tr 'p_' '+ '`"
	[[ -z "$t" ]] && return 1
	date --date="$t" +%s
	return $?
}


if [ "$1" = "-" ]
then remote_cmd="sh -c"
else remote_cmd="ssh $1"
fi

remote_zfs="$2"
local_zfs="$3"

# find newest available and newest common snapshot
newest="N/A"
newest_common="N/A"

while read l ; do
	fullname=${l#* }
	snapname=${fullname#*@zb-}

	newest="$snapname"

	if zfs list -t snapshot -H "${local_zfs}@zb-${snapname}" ; then
		newest_common="$snapname"
	fi >/dev/null 2>/dev/null
done < <(
$remote_cmd "zfs list -t snapshot -r -d 1 -H \"${remote_zfs}\" " | awk '{print $1;}' | while read l ; do
	#link unix timestamps
	unixtime=`timestamp "$l"` || continue
	echo "$unixtime" "$l"
done | sort -n )

# some checks

if [ "$newest" = "N/A" ] ; then
	echo "$0: no remote snapshots available to pull" >&2
	exit 2
fi

if [ "$newest" = "$newest_common" ] ; then
	echo "$0: nothing new to pull" >&2
	exit 0
fi

ret=0

if [ "$newest_common" = "N/A" ] ; then
	#do a full send
	$remote_cmd "zfs send -R \"${remote_zfs}@zb-${newest}\"" | zfs recv -F "${local_zfs}"
	ret=$?
else
	#do incremental send
	$remote_cmd "zfs send -R -I \"${remote_zfs}@zb-${newest_common}\" \"${remote_zfs}@zb-${newest}\"" | zfs recv -F "${local_zfs}"
	ret=$?
fi

[ "$ret" != 0 ] && echo "pulling to ${local_zfs} failed" >&2

#in some cases and on some setups (Sun_SSH) when `zfs recv` fails, ssh ignores
#the SIGPIPE and the connection hangs there forever, somehow. This fixes the
#issue by killing all children that were possibly spawned by this shell.
[ "$ZB_WORKAROUND_SSH_SIGPIPE" = "yes" ] && pkill -P $$

exit $ret