#! /bin/sh
# This file is part of BEAM
# Copyright (C) 2012-2014 Sergey Poznyakoff
#
# BEAM is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# BEAM is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with BEAM.  If not, see <http://www.gnu.org/licenses/>.

libdir=@LIBDIR@/beam
set -e
. $libdir/common.sh
set +e

dir=
suffix=
retainweeks=3
dry_run=
verbose=:

help() {
  cat <<EOF
usage: $0 [OPTIONS] DIR
cleans up old backup files in DIR

OPTIONS are:
  -s, --suffix SUF        consider only file names ending in SUF
  -r, --retain N          retain N last weeks of backups (default $retainweeks)
  -v, --verbose           verbosely list what is being done
  -n, --dry-run           do nothing, print what would have been done
  -h, --help              print this help list

EOF
  exit 0
}

while [ $# -ne 0 ]
do
    case $1 in
	-s|--suffix) shift; suffix=$1;;
	-r|--retain) shift; retainweeks=$1;;
	-v|--verbose) verbose=echo;;
	-n|--dry-run) dry_run=echo; verbose=echo;;
	-h|--help) help;;
	--wtf) wtf $(basename $0) clean up old files; exit 0;;
	--) shift; break;;
	-*) echo >&2 "$0: unrecognized option $1"
	    exit 1;;
	*)  break
    esac
    shift
done

case $# in
    0) echo >&2 "$0: not enough arguments"
       exit 1;;
    1) dir=$1;;
    *) echo >&2 "$0: too many arguments"
       exit 1;;
esac

thisweek=$(date +%U)

# Warning: do not use shell arithmetic expansions on week numbers,
# because weeks prior to 10 begin with 0 and therefore are processed
# as octal numbers.  This causes grief for weeks 08 and 09.
if [ $thisweek -gt $retainweeks ]; then
    lastweek=$(expr $thisweek - $retainweeks)
else
    lastweek=$(expr $thisweek + 54 - $retainweeks)
fi
   
$verbose \# removing from $dir files ending in $suffix and older than week $lastweek

if [ -z "$suffix" ]; then
    find $dir -maxdepth 1 -type f -printf '%f\n' 
else
    find $dir -maxdepth 1 -type f -name "*$suffix" -printf '%f\n' 
fi | 
 while read name
 do 
     $verbose \# considering $name 
     week=$(expr "$name" : '[^-][^-]*-\([0-9][0-9]*\)-.*')
     if [ $thisweek -ge $week ]; then
	 if [ $(expr $thisweek - $week) -gt $retainweeks ]; then
	     $verbose \# removing $name
	     $dry_run rm $dir/$name
	 fi
     else
	 if [ $(expr $thisweek + 54 - $week) -gt $retainweeks ]; then
	     $verbose \# removing $name
	     $dry_run rm $dir/$name
	 fi
     fi
 done