#!/bin/sh

helpme() {
  echo "usage:"
  echo "  $0 full|partial|restore [--name NAME] SRC DEST [options]"
  echo "    COMMANDS:"
  echo "      full: Make a full backup of SRC to DEST/HOST/TIMESTAMP_full/"
  echo "      partial: Make partial backup of SRC to DEST/HOST/TIMESTAMP_part/"
  echo "               relative to the latest full backup in that directory"
  echo "      restore: Restore the backup at DEST/ to SRC/"
  echo "    NAME:"
  echo "      Force main subdir inside DEST instead of hostname."
  echo "      Useful if backing up, eg, external media."
  echo "    SRC:"
  echo "      Relative or absolute path for the source to backup or restore from."
  echo "      When backing up, can be a remote path in the form of user@host:path;"
  echo "      The HOST component of the kyanite backup path is gleaned from this if so."
  echo "      When restoring, this is the full path to the timestamped backup folder."
  echo "    DEST:"
  echo "      Relative or absolute path for the destination to backup or restore to."
  echo "      When backing up, this is path to the root of your kyanite backups."
  echo "      When restoring, this is the path to your restore destination."
  echo "    OPTIONS:"
  echo "      anything provided after DEST is passed as additional options to rsync,"
  echo "      e.g. '--exclude .cache'"
}

if [ -z "$3" ]; then
  helpme;
  exit;
fi

if [ "$1" = "full" ]; then
  mode=full;
elif [ "$1" = "partial" ]; then
  mode=part;
elif [ "$1" = "restore" ]; then
  mode=restore;
else mode=none;
fi
shift;

if [ "$1" = "--name" ]; then
  shift
  forcedName=$1;
  shift;
fi

srcDir=$1;
shift;

destDir=$1
remoteHost=$(echo $srcDir | awk -F : '{ print $1 }' | awk -F @ '{ print $2  }');

if [ ! -z "${remoteHost}" ]; then
  host=${remoteHost};
else host=$(hostname);
fi

if [ ! -z "${forcedName}" ]; then
  host=${forcedName};
fi

shift;

case $mode in
  full)
    fullDest=${destDir}/${host}/$(date +%Y-%m-%d_%H:%M)_full;
    mkdir -p ${fullDest};
    rsync -av $@ ${srcDir} ${fullDest};
    ;;
  part)
    fullDest=${destDir}/${host}/$(date +%Y-%m-%d_%H:%M)_part;
    lastFullBackup=$(ls -1d ${destDir}/${host}/*_full | tail -n 1);
    mkdir -p ${fullDest};
    rsync -av --link-dest=${lastFullBackup} $@ ${srcDir} ${fullDest};
    ;;
  restore)
    rsync -av $@ ${srcDir} ${destDir}
    ;;
  *)
    helpme
    ;;
esac