#!/bin/bash
#
# ---------------------------
# Snapshot - Rollback - Btrfs
# ---------------------------
#
# readonly-Snapshot + inkrementelles Backup von /home auf eine externe verschlüsselte USB-Backup-Festplatte
#
declare -i fertig=0
user=xxxx
MAXBACKUPFILES=23
RemoteCryptPartition='/dev/disk/by-id/usb-WD_My_Passport_25EA_595832314131384C4A527034-0:0-part1'
RemoteCryptDeviceTarget=backupdrive
RemoteBackupDrive="/dev/disk/by-id/dm-uuid-CRYPT-LUKS2-8bcd8784c8c04d294d6e064268723d3a-${RemoteCryptDeviceTarget}"
RemoteBackupMountpoint=/backup
remoteSubvolume=@LENOVO_T61_xxxx
#
ZuSicherndesVerzeichnis=/home
RemoteBackupFolder=${RemoteBackupMountpoint}/home_backups
RemotehomeBackupName=home_backup_RO
remotehomebackup=${RemoteBackupFolder}/${RemotehomeBackupName}
remoteNEWhomebackup=${RemoteBackupFolder}/NEW_${RemotehomeBackupName}
LocalhomeBackupName=${RemotehomeBackupName}
localhomebackup=/home/.home_snapshots/${LocalhomeBackupName}
localNEWhomebackup=/home/.home_snapshots/NEW_${LocalhomeBackupName}
ScriptName=`basename $0`
#
#
#==== Funktionen ================================================================================================================================================
function UnmountCryptedDevice {
    umount ${RemoteBackupDrive}
    cryptsetup luksClose ${RemoteCryptDeviceTarget}
}
#
[ -f /root/${ScriptName}.tmp ] && rm /root/${ScriptName}.tmp
touch /root/${ScriptName}.tmp
if [ ! -f /root/${ScriptName}.tmp ] ; then
    echo ""
    echo "Abbruch, keine root-rechte !"
    echo 'Bitte dieses Script mit "sudo" oder als user "root" ausführen !'
    exit 1
fi
rm /root/${ScriptName}.tmp
#
if [ ! -e ${RemoteCryptPartition} ] ; then
    echo ""
    echo "Abbruch, keine USB-Backup-Festplatte angeschlossen !"
    exit 1
fi
#
if [ ! -e /dev/mapper/${RemoteCryptDeviceTarget} ]
    then
        cryptsetup luksOpen ${RemoteCryptPartition} ${RemoteCryptDeviceTarget}
        mount -o rw,noatime,compress=lzo,space_cache=v2,subvol=${remoteSubvolume} ${RemoteBackupDrive} ${RemoteBackupMountpoint}
    elif grep "/dev/mapper/${RemoteCryptDeviceTarget} ${RemoteBackupMountpoint} btrfs rw" /proc/mounts
        then
            sleep 0
        else
            mount -o rw,noatime,compress=lzo,space_cache=v2,subvol=${remoteSubvolume} ${RemoteBackupDrive} ${RemoteBackupMountpoint}
fi
#
if [ -f /tmp/timestamp.txt ]
    then
        TIMESTAMP=`cat /tmp/timestamp.txt`
    else
        TIMESTAMP=`ls -l --time-style=+%Y-%m-%d-%H%M ${RemoteBackupFolder} | grep -w "NEW_${RemotehomeBackupName}" | awk {'print $6'}`
fi
#
mountstate=`grep "/dev/mapper/${RemoteCryptDeviceTarget} ${RemoteBackupMountpoint} btrfs rw" /proc/mounts`
if [[ -z "${mountstate}" ]]
    then
        echo ""
        echo $mountstate
        echo "BTRFS-Backup-Datentraeger ist nicht eingebunden !"
        echo "ENDE !"
        UnmountCryptedDevice
        exit 1
    else
        # echo "mountstate: $mountstate"
        if [ ! -d $localhomebackup ] && [ $fertig -eq 0 ]
           then
            echo "localhomebackup fehlt - vollständiges Backup wird ausgeführt !"
            btrfs subvolume snapshot -r ${ZuSicherndesVerzeichnis} $localhomebackup
            if [ -d $remotehomebackup ] ; then
                [ -d ${RemoteBackupFolder}/${TIMESTAMP}_${RemotehomeBackupName} ] && btrfs subvolume delete ${RemoteBackupFolder}/${TIMESTAMP}_${RemotehomeBackupName}
                mv $remotehomebackup ${RemoteBackupFolder}/${TIMESTAMP}_${RemotehomeBackupName}
            fi
            [ -d $localNEWhomebackup ] && btrfs subvolume delete $localNEWhomebackup
            [ -d $remoteNEWhomebackup ] && btrfs subvolume delete $remoteNEWhomebackup
            btrfs send $localhomebackup | btrfs receive ${RemoteBackupFolder}
            btrfs subvolume snapshot -r ${ZuSicherndesVerzeichnis} $localNEWhomebackup
            fertig=1
           elif [ ! -d $remotehomebackup ] && [ $fertig -eq 0 ]
               then
                echo "remotehomebackup fehlt - vollständiges Backup wird ausgeführt !"
                [ -d $localhomebackup ] && btrfs subvolume delete $localhomebackup
                btrfs subvolume snapshot -r ${ZuSicherndesVerzeichnis} $localhomebackup
                [ -d $localNEWhomebackup ] && btrfs subvolume delete $localNEWhomebackup
                [ -d $remoteNEWhomebackup ] && btrfs subvolume delete $remoteNEWhomebackup
                btrfs send $localhomebackup | btrfs receive ${RemoteBackupFolder}
                btrfs subvolume snapshot -r ${ZuSicherndesVerzeichnis} $localNEWhomebackup
                fertig=1
           elif [ ! -d $localNEWhomebackup ] && [ $fertig -eq 0 ]
               then
                echo "localNEWhomebackup fehlt und wird erneuert - inkrementelles Backup wird versucht !"
                [ -d $remoteNEWhomebackup ] && btrfs subvolume delete $remoteNEWhomebackup
                btrfs subvolume snapshot -r ${ZuSicherndesVerzeichnis} $localNEWhomebackup
                fertig=1
           elif [ -d $localhomebackup ] && [ -d $localNEWhomebackup ] && [ -d $remotehomebackup ] && [ ! -d $remoteNEWhomebackup ] && [ $fertig -eq 0 ]
               then
                echo "remoteNEWhomebackup fehlt - inkrementelles Backup wird versucht !"
                btrfs send -p $localhomebackup $localNEWhomebackup | btrfs receive ${RemoteBackupFolder}
                if [ "$?" = "0" ]
                  then
                    fertig=2
                  else
                echo "inkrementelles Backup fehlgeschlagen - vollständiges Backup wird ausgeführt !"
                    [ -d $localhomebackup ] && btrfs subvolume delete $localhomebackup
                    btrfs subvolume snapshot -r ${ZuSicherndesVerzeichnis} $localhomebackup
                    if [ -d $remotehomebackup ] ; then
                        [ -d ${RemoteBackupFolder}/${TIMESTAMP}_${RemotehomeBackupName} ] && btrfs subvolume delete ${RemoteBackupFolder}/${TIMESTAMP}_${RemotehomeBackupName}
                        mv $remotehomebackup ${RemoteBackupFolder}/${TIMESTAMP}_${RemotehomeBackupName}
                    fi
                    [ -d $localNEWhomebackup ] && btrfs subvolume delete $localNEWhomebackup
                    [ -d $remoteNEWhomebackup ] && btrfs subvolume delete $remoteNEWhomebackup
                    btrfs send $localhomebackup | btrfs receive ${RemoteBackupFolder}
                    btrfs subvolume snapshot -r ${ZuSicherndesVerzeichnis} $localNEWhomebackup
                    fertig=1
                fi
           elif [ -d $localhomebackup ] && [ -d $localNEWhomebackup ] && [ -d $remotehomebackup ] && [ -d $remoteNEWhomebackup ] && [ $fertig -eq 0 ]
               then
                echo "normales inkrementelles Backup"
                btrfs subvolume delete $localhomebackup
                mv $localNEWhomebackup $localhomebackup
                [ -d ${RemoteBackupFolder}/${TIMESTAMP}_${RemotehomeBackupName} ] && btrfs subvolume delete ${RemoteBackupFolder}/${TIMESTAMP}_${RemotehomeBackupName}
                mv $remotehomebackup ${RemoteBackupFolder}/${TIMESTAMP}_${RemotehomeBackupName}
                mv $remoteNEWhomebackup $remotehomebackup
                btrfs subvolume snapshot -r ${ZuSicherndesVerzeichnis} $localNEWhomebackup
                fertig=1
        fi
fi
#
[ $fertig -ne 2 ] && btrfs send -p $localhomebackup $localNEWhomebackup | btrfs receive ${RemoteBackupFolder}
sync
#
typeset -i FILECOUNT
FILECOUNT=0
for file in `ls -r ${RemoteBackupFolder}` ; do
    FILECOUNT=$FILECOUNT+1
    [ $FILECOUNT -le $MAXBACKUPFILES ] && continue
    [ "$file" = "${RemotehomeBackupName}" ] && continue
    [ "$file" = "NEW_${RemotehomeBackupName}" ] && continue
    btrfs subvolume delete ${RemoteBackupFolder}/${file}
    echo  "deleting snapshot ${RemoteBackupFolder}/${file}"
done
#
btrfs balance start -dusage=5 /btrfs
btrfs balance start -dusage=5 ${RemoteBackupMountpoint}