# -*- mode: sh; sh-basic-offset: 3; indent-tabs-mode: nil; -*-
# vim: set filetype=sh sw=3 sts=3 expandtab autoindent:

###############################################################
#
#  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.
#  Hardlinking is used to save storage space.
#
#  This handler expects that your maildir directory structure is
#  either one of the following:
#
#  1. /$srcdir/[a-zA-Z0-9]/$user for example:
#  /var/maildir/a/anarchist
#  /var/maildir/a/arthur
#  ...
#  /var/maildir/Z/Zaphod
#  /var/maildir/Z/Zebra
#
#  2. or the following:
#  /var/maildir/domain.org/user1
#  /var/maildir/domain.org/user2
#  ...
#  /var/maildir/anotherdomain.org/user1
#  /var/maildir/anotherdomain.org/user2
#  ...
#
#  if the configuration is setup to have keepdaily at 3,
#  keepweekly is 2, and keepmonthly is 1, then each user's
#  maildir backup snapshot directory will contain these files:
#    daily.1
#    daily.2
#    daily.3
#    weekly.1
#    weekly.2
#    monthly.1
#
#  The basic algorithm is to rsync each maildir individually,
#  and to use hard links for retaining historical data.
#
#  We handle each maildir individually because it becomes very
#  unweldy to hardlink and rsync many hundreds of thousands
#  of files at once. It is much faster to take on smaller
#  chunks at a time.
#
#  For the backup rotation to work, destuser must be able to run
#  arbitrary bash commands on the desthost.
#
#  Any maildir which is deleted from the source will be moved to
#  "deleted" directory in the destination. It is up to you to
#  periodically remove this directory or old maildirs in it.
#
##############################################################

getconf rotate yes
getconf remove yes
getconf backup yes

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
getconf destid_file /root/.ssh/id_rsa
getconf sshoptions

getconf multiconnection notset

failedcount=0
# strip trailing /
destdir=${destdir%/}
srcdir=${srcdir%/}

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

[ "$multiconnection" == "notset" ] && fatal "The maildir handler uses a very different destination format. See the example .maildir for more information"

if [ $test ]; then
   testflags="--dry-run -v"
fi

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

function do_user() {
   local user=$1
   local btype=$2
   local userdir=${3%/}
   local source="$srcdir/$userdir/$user/"
   local target="$destdir/$userdir/$user/$btype.1"
   if [ ! -d $source ]; then
      warning "maildir $source not found"
      return
   fi

   debug "syncing"
   ret=`$RSYNC -e "ssh -p $destport -i $destid_file $sshoptions" -r \
      --links --ignore-existing --delete --size-only --bwlimit=$speedlimit \
      --exclude '.Trash/*' --exclude '.Mistakes/*' --exclude '.Spam/*' \
      $source $destuser@$desthost:$target \
      2>&1`
   ret=$?
   # ignore 0 (success) and 24 (file vanished before it could be copied)
   if [ $ret != 0 -a $ret != 24 ]; then
      warning "rsync $user failed"
      warning "  returned: $ret"
      let "failedcount = failedcount + 1"
      if [ $failedcount -gt 100 ]; then
         fatal "100 rsync errors -- something is not working right. bailing out."
      fi
   fi
   ssh -o PasswordAuthentication=no $desthost -l $destuser -i $destid_file $sshoptions "date +%c%n%s > $target/created"
}

# remove any maildirs from backup which might have been deleted
# and add new ones which have just been created.
# (actually, it just moved them to the directory "deleted")

function do_remove() {
   local tmp1=`maketemp maildir-tmp-file`
   local tmp2=`maketemp maildir-tmp-file`

   ssh -p $destport -i $destid_file $sshoptions $destuser@$desthost mkdir -p "$destdir/deleted"
      cd "$srcdir"
      for userdir in `ls -d1 */`; do
         ls -1 "$srcdir/$userdir" | sort > $tmp1
         ssh -p $destport -i $destid_file $sshoptions $destuser@$desthost ls -1 "$destdir/$userdir" | sort > $tmp2
      for deluser in `join -v 2 $tmp1 $tmp2`; do
         [ "$deluser" != "" ] || continue
         info "removing $destuser@$desthost:$destdir/$userdir$deluser/"
         ssh -p $destport -i $destid_file $sshoptions $destuser@$desthost mv "$destdir/$userdir$deluser/" "$destdir/deleted"
         ssh -p $destport -i $destid_file $sshoptions $destuser@$desthost "date +%c%n%s > '$destdir/deleted/$deluser/deleted_on'"
      done
   done
   rm $tmp1
   rm $tmp2
}

function do_rotate() {
   [ "$rotate" == "yes" ] || return;
   local user=$1
   local userdir=${2%/}
   local backuproot="$destdir/$userdir/$user"
(
   ssh -T -o PasswordAuthentication=no $desthost -l $destuser -i $destid_file $sshoptions <<EOF
##### BEGIN REMOTE SCRIPT #####
   seconds_daily=86400
   seconds_weekly=604800
   seconds_monthly=2628000
   keepdaily=$keepdaily
   keepweekly=$keepweekly
   keepmonthly=$keepmonthly
   now=\`date +%s\`

   if [ ! -d "$backuproot" ]; then
      echo "Debug: skipping rotate of $user. $backuproot doesn't exist."
      exit
   fi
   for rottype in daily weekly monthly; do
      seconds=\$((seconds_\${rottype}))

      dir="$backuproot/\$rottype"
      if [ ! -d \$dir.1 ]; then
         echo "Debug: \$dir.1 does not exist, skipping."
         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=\`find $backuproot -maxdepth 1 -type d -name \$rottype'.*' | @SED@ 's/^.*\.//' | sort -n | tail -1\`
      #echo "Debug: oldest \$oldest"
      [ "\$oldest" == "" ] && oldest=0
      for (( i=\$oldest; i > 0; i-- )); do
         if [ -d \$dir.\$i ]; then
            if [ -f \$dir.\$i/created ]; then
               created=\`tail -1 \$dir.\$i/created\`
            else
               created=0
            fi
            cutoff_time=\$(( now - (seconds*(i-1)) ))
            if [ ! \$created -gt \$cutoff_time ]; then
               next=\$(( i + 1 ))
               if [ ! -d \$dir.\$next ]; then
                  echo "Debug: \$rottype.\$i --> \$rottype.\$next"
                  mv \$dir.\$i \$dir.\$next
                  date +%c%n%s > \$dir.\$next/rotated
               else
                  echo "Debug: skipping rotation of \$dir.\$i because \$dir.\$next already exists."
               fi
            else
               echo "Debug: skipping rotation of \$dir.\$i because it was created" \$(( (now-created)/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 "Debug: daily.\$max --> 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 "Debug: weekly.\$max --> 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=\`find $backuproot -maxdepth 1 -type d -name \$rottype'.*' | @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
            if [ -d $backuproot/rotate.tmp ]; then
               echo "Debug: removing rotate.tmp"
               rm -rf $backuproot/rotate.tmp
            fi
            echo "Debug: moving \$rottype.\$i to rotate.tmp"
            mv \$dir.\$i $backuproot/rotate.tmp
         fi
      done
   done
####### END REMOTE SCRIPT #######
EOF
) | (while read a; do passthru $a; done)

}


function setup_remote_dirs() {
   local user=$1
   local backuptype=$2
   local userdir=${3%/}
   local dir="$destdir/$userdir/$user/$backuptype"
   local tmpdir="$destdir/$userdir/$user/rotate.tmp"
(
   ssh -T -o PasswordAuthentication=no $desthost -l $destuser -i $destid_file $sshoptions <<EOF
      if [ ! -d $destdir ]; then
         echo "Fatal: Destination directory $destdir does not exist on host $desthost."
         exit 1
      elif [ -d $dir.1 ]; then
         if [ -f $dir.1/created ]; then
            echo "Warning: $dir.1 already exists. Overwriting contents."
         else
            echo "Warning: we seem to be resuming a partially written $dir.1"
         fi
      else
         if [ -d $tmpdir ]; then
            mv $tmpdir $dir.1
            if [ \$? == 1 ]; then
               echo "Fatal: could mv $destdir/rotate.tmp $dir.1 on host $desthost"
               exit 1
            fi
         else
            mkdir --parents $dir.1
            if [ \$? == 1 ]; then
               echo "Fatal: could not create directory $dir.1 on host $desthost"
               exit 1
            fi
         fi
         if [ -d $dir.2 ]; then
            echo "Debug: update links $backuptype.2 --> $backuptype.1"
            cp -alf $dir.2/. $dir.1
            #if [ \$? == 1 ]; then
            #   echo "Fatal: could not create hard links to $dir.1 on host $desthost"
            #   exit 1
            #fi
         fi
      fi
      [ -f $dir.1/created ] && rm $dir.1/created
      [ -f $dir.1/rotated ] && rm $dir.1/rotated
      exit 0
EOF
) | (while read a; do passthru $a; done)

   if [ $? == 1 ]; then exit; fi
}

function start_mux() {
   if [ "$multiconnection" == "yes" ]; then
      debug "Starting dummy ssh connection"
      ssh -p $destport -i $destid_file $sshoptions $destuser@$desthost sleep 1d &
      sleep 1
   fi
}

function end_mux() {
   if [ "$multiconnection" == "yes" ]; then
      debug "Stopping dummy ssh connection"
      ssh -p $destport -i $destid_file $sshoptions $destuser@$desthost pkill sleep
   fi
}

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

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

end_mux
start_mux

## SANITY CHECKS ##
status=`ssh -p $destport -i $destid_file $sshoptions $destuser@$desthost "[ -d \"$destdir\" ] && echo 'ok'"`
if [ "$status" != "ok" ]; then
   end_mux
   fatal "Destination directory $destdir doesn't exist!"
   exit
fi

### REMOVE OLD MAILDIRS ###

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

### MAKE BACKUPS ###

if [ "$backup" == "yes" ]; then
   if [ $keepdaily -gt 0 ]; then btype=daily
   elif [ $keepweekly -gt 0 ]; then btype=weekly
   elif [ $keepmonthly -gt 0 ]; then btype=monthly
   else fatal "keeping no backups"; fi

   if [ "$testuser" != "" ]; then
      cd "$srcdir/${user:0:1}"
      do_rotate $testuser
      setup_remote_dirs $testuser $btype
      do_user $testuser $btype
   else
      [ -d "$srcdir" ] || fatal "directory $srcdir not found."
      cd "$srcdir"
      for userdir in `ls -d1 */`; do
         [ -d "$srcdir/$userdir" ] || fatal "directory $srcdir/$userdir not found."
         cd "$srcdir/$userdir"
         debug $userdir
         for user in `ls -1`; do
            [ "$user" != "" ] || continue
            debug "$user $userdir"
            do_rotate $user $userdir
            setup_remote_dirs $user $btype $userdir
            do_user $user $btype $userdir
         done
      done
   fi
fi

end_mux