# -*- mode: sh; sh-basic-offset: 3; indent-tabs-mode: nil; -*-
# vim: set filetype=sh sw=3 sts=3 expandtab autoindent:
#
# backupninja handler to do incremental backups using
# wget and hardlinks, based on rsync handler
#
# feedback: rhatto at riseup.net | gpl
#
# Config file options
# -------------------
#
#   [general]
#   log = wget log file
#   partition = partition where the backup lives
#   fscheck = set to 1 if fsck should run on $partition after the backup is made
#   read_only = set to 1 if $partition is mounted read-only
#   mountpoint = backup partition mountpoint or backup main folder
#   backupdir = folder relative do $mountpoint where the backup should be stored
#   days = number of backup increments (min = 5)
#   lockfile = lockfile to be kept during backup execution
#   nicelevel = wget command nice level
#   ionicelevel = ionice best-effort level applied to wget command
#   enable_mv_timestamp_bug = set to "yes" if your system isnt handling timestamps correctly
#   tmp = temp folder
#
#   [source]
#   wget = wget program
#   wget_options = wget command options
#   url = remote data url
#   bandwidthlimit = set a bandwidth limit in kbps (remote source only)
#
#   [destination]
#   folder = local folder
#
# You can also specify some system comands if you don't want the default system values:
#
#   [system]
#   rm = rm command
#   cp = cp command
#   touch = touch command
#   mv = mv command
#   fsck = fsck command
#
# TODO: Daily, weekly and monthly snapshot rotation (like the one present on maildir handler).
#

# config file evaluation

setsection system
getconf rm rm
getconf cp cp
getconf touch touch
getconf mv mv
getconf fsck fsck

setsection general
getconf log /var/log/backup/wget.log
getconf partition
getconf fscheck
getconf read_only
getconf mountpoint
getconf backupdir
getconf rotate
getconf days
getconf lockfile
getconf nicelevel 0
getconf ionicelevel
getconf enable_mv_timestamp_bug no
getconf tmp /tmp

setsection source
getconf wget wget
getconf wget_options
getconf url
getconf bandwidthlimit

setsection destination
getconf folder

# function definitions

function rotate {

   if [[ "$2" < 4 ]]; then
      error "Rotate: minimum of 4 rotations"
      exit 1
   fi

   if [ -d $1.$2 ]; then
      $nice $mv /$1.$2 /$1.tmp
   fi

   for ((n=$[$2 - 1]; n >= 0; n--)); do
      if [ -d $1.$n ]; then
         dest=$[$n + 1]
         $nice $mv /$1.$n /$1.$dest
         $touch /$1.$dest
      fi
   done

   if [ -d $1.tmp ]; then
      $nice $mv /$1.tmp /$1.0
   fi

   if [ -d $1.1 ]; then
      $nice $cp -alf /$1.1/. /$1.0
   fi

}

function move_files {
   ref=$tmp/makesnapshot-mymv-$$;
   $touch -r $1 $ref;
   $mv $1 $2;
   $touch -r $ref $2;
   $rm $ref;
}

backupdir="$mountpoint/$backupdir"

# does $backupdir exists?

if [ ! -d "$backupdir" ]; then
   error "Backupdir $backupdir does not exist"
   exit 1
fi

# setup number of increments

if [ -z "$days" ]; then
   keep="4"
else
   keep=$[$days - 1]
fi

# lockfile setup

if [ ! -z "$lockfile" ]; then
   $touch $lockfile || warning "Could not create lockfile $lockfile"
fi

# nicelevel setup

if [ ! -z "$nicelevel" ]; then
   nice="nice -n $nicelevel"
else
   nice=""
fi

if [ -n "$ionicelevel" ]; then
   nice="ionice -c2 -n $ionicelevel $nice"
fi

# set mv procedure

if [ $enable_mv_timestamp_bug == "yes" ]; then
   mv=move_files
fi

# set excludes

for path in $exclude; do
   EXCLUDES="$EXCLUDES --exclude=$path"
done

echo "Starting backup at `date`" >> $log

# mount backup destination folder as read-write

if [ "$read_only" == "1" ] || [ "$read_only" == "yes" ]; then
   if [ -d "$mountpoint" ]; then
      mount -o remount,rw $mountpoint
      if (($?)); then
         error "Could not mount $mountpoint"
         exit 1
      fi
   fi
fi

# the backup procedure

if [ ! -d "$backupdir/$folder/$folder.0" ]; then
   mkdir -p $backupdir/$folder/$folder.0
fi

info "Rotating $backupdir/$folder/$folder..."
echo "Rotating $backupdir/$folder/$folder..." >> $log
rotate $backupdir/$folder/$folder $keep
info "Wget'ing $SECTION on $backupdir/$folder/$folder.0..."

if [ ! -z "$bandwidth" ]; then
   limit_rate="--limit-rate=$bandwidth""k"
fi

cd $backupdir/$folder/$folder.0
wget $wget_options $limit-rate -r -c -N -e robots=off $url
cd -

$touch $backupdir/$folder/$folder.0

# remount backup destination as read-only

if [ "$read_only" == "1" ] || [ "$read_only" == "yes" ]; then
   mount -o remount,ro $mountpoint
fi

# check partition for errors

if [ "$fscheck" == "1" ] || [ "$fscheck" == "yes" ]; then
   umount $mountpoint
   if (($?)); then
      warning "Could not umount $mountpoint to run fsck"
   else
      $nice $fsck -v -y $partition >> $log
      mount $mountpoint
   fi
fi

# removes the lockfile

if [ ! -z "$lockfile" ]; then
   $rm $lockfile || warning "Could not remove lockfile $lockfile"
fi

echo "Finnishing backup at `date`" >> $log