#!/bin/bash

# Author: Alan Pippin
# Description: This script "restores" or sends a local filesystem to a remote zfs pool.
# Usage: zfs-restore <src pool> <src filesystem> <dst pool> <dst filesystem> <dst hostname>

# source our configuration
config="${0%/*}/zfs-scripts.conf"
[ -e "${config}.dist" ] && . ${config}.dist
[ -e "${config}" ] && . ${config}

# command line arg parsing
src_pool=$1
src_fs=$2
dst_pool=$3
dst_fs=$4
dst_hostname=$5

if [[ -z "$SCRIPT_UNDER_TEST" ]]; then
    exec >> $logdir/zfs-restore.log 2>&1
fi

fatal_and_exit() {
  echo -e 2>&1 "$1"
  exit 1
}
trap fatal_and_exit INT

# Make sure we have valid arguments
if [[ -z "$src_pool" ]] || [[ -z "$src_fs" ]] || [[ -z "$dst_pool" ]] || [[ -z "$dst_fs" ]] || [[ -z "$dst_hostname" ]]; then
  fatal_and_exit "Usage: $0 <src pool> <src filesystem> <dst pool> <dst filesystem> <dst hostname>"
fi

date=`date`
echo "$date ZFS restore started: $src_pool/$src_fs -> $dst_hostname:$dst_pool/$dst_fs"

# Make sure the src pool and src filesystem exist, or print some errors
zpool list -H "$src_pool" >/dev/null 2>&1
if [ $? != 0 ]; then
  fatal_and_exit "-E- The src pool, '$src_pool' doesn't seem to exist."
fi
zfs list "$src_pool/$src_fs" >/dev/null 2>&1
if [ $? != 0 ]; then
  fatal_and_exit "-E- The src filesystem for the src pool, '$src_pool/$src_fs' doesn't seem to exist."
fi

# Obtain the zpool guid for the src pool
src_pool_guid=`zpool get guid $src_pool 2>&1 | grep $src_pool | awk '{ print $3 }'`
zpool get guid $src_pool > /dev/null 2>&1
if [ $? != 0 ]; then
  fatal_and_exit "-E- Unable to extract the guid for the src pool: $src_pool" $mailto
fi

# Setup our backup marker names
last_backup_marker=${src_fs}@previous-backup-${src_pool_guid}

# Check to make sure the src fs exists
$zfs list -t snapshot "$src_pool/$last_backup_marker" > /dev/null 2>&1
if [ $? != 0 ]; then
  fatal_and_exit "-E- The src snapshot '$src_pool/$last_backup_marker' does not exist. Unable to continue."
fi

# Check to make sure the dst pool exists
ssh $dst_hostname "$zfs list ${dst_pool}" > /dev/null 2>&1
if [ $? != 0 ]; then
  fatal_and_exit "-E- The destination pool '$dst_pool' does not exist. Create the pool '$dst_pool' and try again."
fi

# Check to make sure the dst filesystem does not exist
ssh $dst_hostname "$zfs list ${dst_pool}/${dst_fs}" > /dev/null 2>&1
if [ $? == 0 ]; then
  fatal_and_exit "-E- The destination pool/filesystem '$dst_pool/$dst_fs' already exists. Destroy the filesystem '$dst_fs' and try again."
fi 

# Now send the src filesystem
if [[ -n "$SCRIPT_UNDER_TEST" ]]; then
  echo "$zfs send -R $src_pool/$last_backup_marker | ssh $dst_hostname $zfs recv -dv $dst_pool"
else 
   if [[ $throttle_enable == 1 && -e $throttle ]]; then
     $zfs send -R "$src_pool/$last_backup_marker" | $throttle $throttle_opt | ssh $dst_hostname "$zfs recv -dv $dst_pool"
   else 
     $zfs send -R "$src_pool/$last_backup_marker" | ssh $dst_hostname "$zfs recv -dv $dst_pool"
   fi 
fi

# Now rename the dst filesystem (move it into place)
if [[ -n "$SCRIPT_UNDER_TEST" ]]; then
  echo "$dst_hostname $zfs rename $dst_pool/$src_fs $dst_pool/$dst_fs"
else
  ssh $dst_hostname "$zfs rename $dst_pool/$src_fs $dst_pool/$dst_fs"
fi

# All done!
date=`date`
echo "$date ZFS restore completed: $src_pool/$src_fs -> $dst_hostname:$dst_pool/$dst_fs"